A 547273 DUPL T 1 ARTES LIBRARY 1837 SCIENTIA VERITAS OF THE UNIVERSITY OF MICHIGAN ZIMURIOUS UMUM TUEBOR SI-QUÆRIS-PENINSULAM-AMŒNAME CIRCUMSPICE : THE Young Gentleman's TRIGONOMETRY, MECHANICKS, AND Un OPTICK S. Containing fuch ELEMENTS of the faid Arts or Sciences, as are moſt Uſeful and Eaſy to be known. By EDWARD WELLS, D.D. Rector of Cotesbach in Leicester- ſhire. LONDON, Printed for James Knapton, at the Crown in St. Paul's Church-Yard. 1714. THE Young Gentleman's TRIGONOMETRY CONTAINING Such ELEMENTS of Trigonometry, as are moft feful and Eaſy to be known, By EDWARD WELLS, D. D. Rector of Cotesbach in Leicester- Shire. LONDO N Printed for James Knapton, at the Crown in St. Paul's Church-Yard. 1714. THE PREFACE B EING once prevail'd upon to draw up the Young Gentle- man's Geometry, I judg'd it requiſite alſo to draw up this Trea- tife of Trigonometry; forafmuch as Trigonometry is really no other than one Branch of Geometry, and that too Branch, which is of principal Vſe in the common Concerns of Life; at leaſt that Part of it, which is call'd Plain Trigonometry. As for Spheri- cal Trigonometry, it carrying in it much more of Difficulty, and at the fame time being of much less Ufe in the common Affairs of Life, (as re- lating chiefly to Aftronomical Calcula- tions or the like,) I have omitted it, A 2 as The Preface. as not agreeabls to the Defign of this Treatife. On the like Account, tho' I judg'd it not proper wholly to omit the Fun- damental Theorems of plain Trigo- nometry; yet I have plac'd them ſo in Chap. II. that the young Student may pass them over, without any A- bruptness, if the Demonftration of the two latter prove too difficult, or at leaft if he cares not to take the Pains to make himſelf Mafter of the faid Demonftrations. ? THE THE CONTENTS. CH HAP. I. Containing the Explicati- on of Trigonometrical Terms Pag. I Chap. II. Of the Solution of plain Triangles by Calculation II 29 Chap. III. Of the Solution of plain Trian- gles by Protraction Chap. IV. Of Taking the Altitude or Height of an Object, viz. Tower, Tree, &c. 32 Chap. V. Of Taking the Distance between two Object's 47 Chap. VI. Of Surveying or Meaſuring of Land Chap. VII. Of Fortification 58 7.2 Chap. VIII. Of the Tables of Logarithms and Artificial Sines and Tangents, ad- join'd to the End of this Treatife 82 THE " { The CONTENTS Of the Young Gentleman's Mechanicks. CH HA P. I. Wherein are explain'd fuch Terms as relate to Mechanicks in ge- neral Chap. II. Of the Leaver Chap. III. Of the Balance Pag. 1 12 22 Chap. IV. Of the Axle in the Wheel 27 Chap. VI. Of the Screw Chap. V. Of the Pulley Chap. VII. Of the Wedge Chap. VIII. Of Staticks Chap. IX. Of Hydroſtaticks 31 35 38 41 54 The CONTENTS Of the Young Gentleman's Opticks. CHAP. A P. I. Of Opticks in general Pag. 83 Chap. II. Of Opticks more properly fo call'd, or Direct Vifion 90 Chap. III. Of Captoptricks, or Reflex Vi- fion 99 Chap. IV. Of Dioptricks, or Refracted Vision Chap. V. Of Perſpective 123 157 THE (1) ! THE Young Gentleman's TRIGONOMETRY. + CHAP. I. Containing the Explication of Trigo- nometrical Terms. F I. Trigono metry, VERY Triangle confifts in all of ſeven Parts, viz. three Sides, three Angles, and the Area or what. Space comprehended by the Sides. Now, although the Word Trigonometry do's in the Greek Language literally fig- nity the Meaſuring of a Triangle; yet, in its proper Senfe, or as it is diftinguiſh'd from Geometry, it (do's not denote the Meaſuring of the Area of a Triangle, this being deduced from (*) other than what are (*) The Meaſuring of the Area of a plain right-lin'd Triangle, is deduced from the Principles of Geometry, (as B 2 The Young Gentleman's : 2. The Solu- tion of a are properly call'd Trigonometrical Prin- ciples, but it) denotes only the Meafu- ring, or rather the Art of finding the Meaſure of, the unknown Sides and An- gles of a Triangle, by the Help of thoſe that are given or known. And the actual finding of the un- known Sides and Angles of a Triangle, Triangle, is call'd, in one Word, the Solution or Re- folving of a Triangle. what. 3. The Solu- tion of on what founded. The Solution of Triangles is founded on that mutual Proportion, which is be- Triangles tween the Sides and Angles of any Tri- angle. And this Proportion is known by finding the Proportion, which the Ray of a Circle has to certain other right Lines apply'd to the fame Circle. And theſe right Lines are diftinguifh'd in general by the Names of Chords, Sines, Tangents, and Secants. 4. A Chord, what. Fig. 1. A (†) Chord is a right Line drawn from one Extremity of any Arch to the other. Thus, Fig. 1, CH is the Chord, (as diftinguifh'd from Trigonometry,) viz. from Theorem 7, Chap. 1, of the Young Gentleman's Geometry. And the Meaſuring of the Area of a fpherical Triangle, is dedu- ced from the Meafuring of a fpherical Surface. (†) As an Arch is fo call'd, becauſe it reſembles a bent Bow, fo a Chord is fo call'd, becauſe it reſembles the String of a bent Bow. It is otherwiſe call'd a Subtenje, becauſe it fubtends, (i. e. is extended under) the Arch from one End of it to the other. both A 3 Trigonometry. both of the leffer Arch CTH, and alſo of the greater Arch CDH. And it is to be noted, that a Chord of 60 Degrees, is always equal to the Ray of the fame Circle. 5. A Sine, or right Sine, A (1) Sine is either a Right or Verſed Sine. A right Sine is one Half CA of a Chord CH, bifected by the Diameter what. DT; or, it is a Perpendicular CA, let fall from Cone End of an Arch CT, upon a Diameter DT, drawn from T the other End of the Arch. A right Sine is fre- quently ftil'd fimply a Sine; and it is to be obferv'd, that by the Word Sine, put fimply or by it. felf, is always to be un- derſtood a right Sine. 6. whole Sine,what. It is alſo to be obferv'd, that, accor- ding to the fore-going Definition of a 4 total or Sine, the Sine BK of an Arch KT of 90 Degrees, is always equal to the Ray of the fame Circle; and fo the greateſt Sine that can be. Whence it is call'd, the total or whole Sine. 7. A (*) vers'd Sine is the Segment of the Ray intercepted between the right 4 vers'd Sine,what. (1) The Ufe of Sines is faid to be introduced by the Arabs; and for what Reafon a Sine is fo call'd, I know no good Account. (*) A vers❜d Sine is otherwife call'd, at least by fome ancient Writers, the Sagitta or Arrow, becauſe it ſtands to its Arch and Chord, as an Arrow do's to its Bow (when bent) and String. B 2 Sine ། The Young Gentleman's 4 1 8. gent, and Secant, what. Sine and the Arch. Thus, AT is the vers'd Sine of the Arch CT, and AD the vers'd Sine of the Arch CD. A (†) Tangent and a Secant mutually A Tan- explain one the other. For, if a right Line BN of an indeterminate Length be drawn from the Center B, through C one End of an Arch CT, and from T the End of the Diameter DT, there be erected a Perpendicular TN, extended till it meets with BN; the faid Perpen- dicular TN will be the Tangent of the Arch CT, and the Line BN will be the Secant of the fame Arch. And it is to be noted, that the Tangent of 45 De- grees, is always equal to the Ray of the 'fame Circle; as may be ſeen, Fig. 2. 9. 4 Cofine, Coran- gent, Cofe- As when the Arch CT is less than 90 Degrees, the Arch CK (which, being ad- ded to the Arch CT, do's compleat or Cant, and make it up an Arch of 90 Degrees, Covers'd, thence) is call'd the (1) Complement of the Arch CT; fo (Fig. 1,) the Sine CQ, the Tangent KO, the Secant BO, and the vers'd Sine KQ of the Arch CK, are re- what. { (†) A Tangent is fo nam d, becauſe it touches (not cuts) one End T of its Arch CT; and a Secant is fo nam'd, becauſe it cuts or croffes the other End C of its Arch CT. (1) It is not to be omitted, that the Excefs CK of the Arch CD above 90 Degrees, is by fome Writers call'd, the Complement of the faid Arch CD. fpectively Trigonometry. in ſpectively call'd the Sine, the Tangent, the Secant, and the vers'd Sine of the Com- plement of the Arch CT; or in fhort, the (*) Cofine, the Cotangent, the Cofecant, and the Covers'd of the faid Arch CT. 10. The Sup- plement or what. The Arch CD, (which, being added to the Arch CT, makes it up a Semicir- cle,) is peculiarly (†) ftil'd the Supple- Conjunct ment or Conjunct of the Arch Cr. And of an Arcb, it is to be noted, that both the Arch CT, and its Conjun& CD, have the "fame Sine CA, the fame Tangent TN, and the fame Secant BN. 11, Tables of Sines and Tables of (||) Sines and Tangents are fo call'd, becauſe in them is fet down the Ratio or Proportion, which Sines and Tangents, Tangents have to their Ray. B 3 what. And (*) It is of Uſe to obferve, that the Cofine CQ is al- ways equal to BA, the Segment of the Ray between the Center B, and the Sine CA. Wherefore, if the Arch CD be greater than 90 Degrees, then the Sum of the Ray and Cofine is equal to the vers'd Sine; viz. DB+BA DA. But, if the Arch CT be less than 90 Degrees, then the Difference of the Ray and Cofine is equal to the vers’d Sine, viz. BT-BAZAT, (†) Namely, to avoid Confufion by giving the fame Name of Complement, both to CK and to CD, as is done by fome. (It appears from §. 5, of this Chapter, that every Sine, (i. e. right Sine) is the Half of a Chord, and that the Arch of the Sine, is the Half of the Arch of the ſaid Chord.. Wherefore, becauſe there is the fame Propor- tion between two Halves, as there is between their Wholes, and the faid Proportion between the Halves (as The Young Gentleman's Y 12. Natural and artifi- cial Sines and Tan gents, what. 13. Chords, And it is to be noted, that, if the faid Proportion be exprefs'd in the Tables by natural or common Numbers, then the Table is call'd, a Table of natural Sines and Tangents. But, if the faid Propor- tion be express'd by artificial Numbers, i. e. Logarithms, then the Table is call'd, a Table of (*) artificial Sines and Tan- gents. If the faid Proportion be not exprefs'd A Scale or by Numbers, but the feveral Sines and Line of Tangents, as alfo (†) Chords and Se- Sines, Tan- cants, be themfelves actually transferr'd gents, and into, (i. e. their feveral Lengths fet off &c. what. upon) feveral diftinct Scales or Lines, (as Fig. 2. Fig. 2); then the faid Scales or Lines are reſpectively Secants, t (as being expreffible in lefs Numbers) is much easier to be calculated, than the Proportion between their Wholes; hence, Sines are used rather than Chords in Trigonome trical Calculations, and the Proportion of Sines (not of Chords) to the Ray is fet forth in Trigonometrical Ta- bles. (*) It has been afore obferv'd in my Arithmetick, that the Multiplication and Divifion of great Numbers is much easier to be perform'd by Logarithms than na- tural Numbers. Hence it is that Tables of artificial Sines and Tangents, are more uſed than thofe of natural Sines and Tangents, and confequently adjoin'd to moſt Trigonometrical Treatifes. (†) The Reafon, why there are no Tables of Chords, has been obferv'd already in the Note on §. II. There are however Scales of Chords, thefe being as easily made as Scales of Sines, and as eafy or eafter for Uſe in fome Refpects. And the like is to be understood of Secants, ! viz: Trigonometry. 7 reſpectively ftil'd, one a Scale or Line of Chords, the other of Sines, the other of Tangents, and the other of Secants. And the like is to be underſtood of the Scales of any other Sort of Trigonometrical Lines, as of vers'd Sines, Cofines, &c. 14. A Scale of Beſides the fore-mention'd Scales, there is also another Sort of Scale, call'd a Scale of equal Parts ; which, although it Parts, equal what. Fig. 3, & 4. viz. as to the Reafon, why there are few or no Tables of them, but there are ufually, if not always, Scales of them adjoin'd to the other Scales. If it be ask'd, why the Scale of Chords is never continued beyond 90 De- grees, when the greatest Chord is the Diameter or Chord of 180 Degrees? The Reaſon is, becauſe the Chords above 90 Degrees, may be very eafily fupply'd by a Scale of Chords to 90 Degrees, viz. Chord of 105 De- grees Chord 90 Degrees + Chord 15 Degrees. And fo of any other to 180 Degrees. The Reafon, why Tables and Scales of Sines go no further than 90 Degrees, is obvious, viz. becauſe a Sine of 90 Degrees, is the grea- teſt Sine that can be, as appears from §. 5, and 6, of this Chapter. In like manner, the greateſt Tangent and Secant is of 89 Degrees, 59 Minutes. For, at 90 De- grees, Lines drawn in like manner as a Tangent and Secant, become parallel one to the other, and fo never meet to conſtitute a Tangent and Secant, at leaſt pro- perly fo call'd. Hence Tables of Tangents proceed on- ly to 89 Degrees, 59 Minutes. And as for Scales of Tangents, and alfo Secants, they are uſually continued no farther than to about 70 or 75 Degrees; becauſe, after that they extend to a vaft Length, if the Scales be of any confiderable Size, fo as to be fit for Uſe. Which may be perceiv'd by Fig. 2, where the Scales are of a very ſmall Size, as being defign'd not fo much for practical. Ufe, as to fhew only the Manner of Making fuch Scales. Such Scales, as are fit for Practice, are to be bought ready made of fuch as fell Mathematical Inftruments. B 4 be 8 The Young Gentleman's Scale of equal Parts, what. be not deduced from Principles of Tri- gonometry, yet is of fo great Ufe there- in, (as well as in other Parts of the Mathematicks,) that it will be requifite to deſcribe it here, eſpecially, fince it has not been afore deſcrib'd. It is then call'd, a Scale of equal Parts, becauſe it fhews the Meaſure of any Line or Ex- tent, apply'd thereto, or taken there- from, in fome Number of equal Parts, denoting either Inches, or Feet, or Yards, &c. IS. It is ufually diſtinguiſh'd into the fim- Afimple ple or plain Scale, and the diagonal Scale. or plain The fimple or plain Scale, is no other than a right Line divided into any Num- ber of equal Segments or greater Parts: One of which greater Parts, (viz. at ei- ther End of the faid Line,) is fub-divi- ded into Ten other leffer and equal Parts, as Fig. 3; So, that this Scale repreſents any two Degrees of decuple Proportion, viz. if the Sub-divifions of the Segment BA be taken to denote Units, then the other equal Segments CB, DC, &c. will denote Tens. If the aforefaid Sub-divi- Gions denote Tens, then the Segments will denote Hundreds, &c. Hence, the Extent from C to 4 will denote either 14 or 140 (c.) Inches, or Feet, or Yards, &c. The 1 Trigonometry. 9 16. Scale what. The diagonal Scale will be better ap- prehended by 'Fig. 4, than by Words. A diagonal It thence appears to differ from the fim- ple Scale principally in this, viz. that one of its extreme Segments (being like the fimple Scale) fubdivided into ten e- qual Parts, each of the faid ten equal Parts, are again ſubdivided into ten o- ther ſtill lefs and proportional Particles, by ten right Lines obliquely croffing the Scale, which are the Diagonals of fo ma- ny (1) Parallelograms; whence this Scale takes its Name. Hence, by the Divifions and Sub-divifions of this Scale, are re- preſented three Degrees of decuple Pro- (1) This is illuftrated, Fig. 5, which is divided after the fame manner, as is the Segment KL of the diagonal Scale, Fig. 4; and has withal the Sides of each Paralle- logram defcrib'd by prickt Lines, fo that the faid Figure contains five Parallelograms, viz. ABCD, and CDEF, and EFGH, and GHIK, and IKLM; which are each croſs'd by Diagonals, viz. the firft by the Diagonal CB, the ſe- cond by the Diagonal ED, the third by the Diagonal GF, the fourth by the Diagonal IH, and the fifth by the Diagonal LK. And thefe Diagonals anfwer the right Lines obliquely croffing the Segment KL of the diagonal Scale, Fig. 4, and which divide each Part of the faid Segment into lefs and proportional Particles, as is illu ftrated by Fig. 6. For the Lines bk, and cl, and dm, &c. being all parallel one to the other, hence (by Theo- rem 9, Chap. 1, of the Young Gentleman's Geometry) ab: bk : : ac : el :: ad : dm :: ae : en: : af: fo, &c. But ab— to ax; ac ax, adax, &c. therefore bk === ux, cl_² ux, dm2ux, &c. And confequently, the Line ax is divided by the Diagonal au, into ten leffer and proportional Parts, viz. bk, cl, Sic. HX portion 10 The Young Gentleman's 17. Trigonome- portion. For Inftance: If you would denote the Extent of 245 equal Parts, (viz. Inches or Feet, &c.) one Foot of your Compaffes being placed in the mid- dle or prickt Line over-againft 200, open the other Foot to that Point of the Sub- divided Segment KL, wherein meet the two Lines mark'd, one with 40 on the Side of the Scale, the other with 5 on the Top of the Scale. That Extent of your Compaffes will denote 245 equal Parts, (viz. Inches or Feet, &c.) accor- ding to the faid Scale. Further, It is to be here obferv'd, that Plain and Trigonometry is two-fold, Plain and Sphe- ſpherical rical. Plain Trigonometry is fo call'd, be- try, what. caufe it teaches how to refolve any (*) plain (i. e. right-lin'd) Triangle: Sphe- rical Trigonometry is fo call'd, becauſe it teaches how to refolve any Spherical Tri- angle, i. e. any Triangle whoſe Sides are made by the Concurrence of Lines on a fpherical Surface, and are no other than the Arches of Circles. It will be fufficient to the (†) Deſign of this Trea- tife, to ſpeak only of plain Trigono- metry. (*) Hence, by a plain Triangle is to be understood throughout this Treatife a right-lin'd Triangle. (†) See the Preface. Lastly, 1 Trigonometry. II 18. on and Lastly, The Solution of plain (as alſo of fpherical) Triangles is two-fold, ei- Calculati, ther by Calculation, i. e. Working by Protracti Numbers, to which are fubfervient the on, what. Tables of Sines and Tangents; or by Protraction, i. e. drawing Lines and An- gles, to which are fubfervient the Scales of Chords, Sines, &c. of each in its Order; and firſt of the Solution of plain Triangles by Calculation. CHA P. II. Of the Solution of plain Triangles by Calculation, I. reſolve a always gi- F the fix Trigonometrical Parts of a plain Triangle, viz. its three In order to Sides, and three Angles, any three being plain Tri- given, excepting the three Angles alone, angle,there the reſt may be found either by Calcula- must be tion or Protraction. From the three An- ven one gles given by themſelves, can be inferr'd Side, and or found out, only the Proportion of the Fig. 7, & Sides, not the Sides themselves, or their 8. respective determinate Lengths. For In- ſtance: Suppofing the three Angles of the Triangle BCD, Fig. 7, to be given, viz. B 27 Degrees, D 38 Degrees, and confe- why. 1 . ་ 1 1 12 The Young Gentleman's confequently, C 114 Degrees; from hence it may be known, that the Side CD=1BD, and the Side CB BD. But from hence can never be diſcover'd the determinate Length of BD, (or any other Side,) and confequently not of the Reft CB and CD. Namely, becauſe ÷=÷ 흥 ​÷÷÷÷÷÷÷, &c. hence the Proportion of CD to BD will be the fame, whether BD be 2 Inches (or Feet, &c.) and CD one; or BD 4 Inches, and CD 2; or BD 6 Inches, and CD 3; or BD 20 or 200 In- ches, and CD 10 or 100, &c. That is in ſhort, it can never be difcover'd by the three Angles alone, whether the Tri- angle fought be BCD, Fig. 7, or BCD, Fig. 8, (or any other equiangular Trian- gle,) forafmuch as both theſe Triangles have the fame Angles, and confequently their Sides alike proportional one to the other; though the Sides of the one are much longer than the Sides of the other. Wherefore, to determine the Length of the Sides fought, there must always be gi- ven one Side, or (which is the fame) its determinate Length; and hereby will be determin'd the Length of each Side fought. Thus, the Side BD, (Fig. 7,) 'being given, whofe Length according to the diagonal Scale, (Fig. 4.) is 324 (e- qual Parts, fuppofe) Inches; hence, it being found, that CD=BD, and CB= 'BD, Trigonometry. 13 E BD, thereby it is known, that CD- 162 Inches, and CB=216 Inches. But, if the Side BD (Fig. 8,) be given, whoſe Length according to the fame Scale is 135 (equal Parts, fuppoſe) In- ches; then in the fame, Fig. 8, CD= 67 Inches, and CB=45 Inches. 2 2. The Solu tion of plain Tri- angles re- It evidently appearing from what has been faid, that, in order to refolve a plain Triangle, of the three Parts given, one muſt be always a Side; it hence fol- lows, that all the Cafes, that can be pro- three gene pos'd, are reducible in general to theſe ral Cafes. Three, viz. 1. One Side and two Angles being gi- ven, to find the other two Sides, and the (*) third Angle : Or, 2. Two Sides and one Angle being gi- ven, to find the third Side, and the two other Angles: Or, 3. and lastly, All the three Sides be- ing given, to find the three Angles. ducible to Theſe three general Cafes are diſtin- 3. guifh'd into a great Variety of particular All the Cafes, (according to the particular Sides Cafes are particular (*) Two Angles being given, the third may be known (without Trigonometry) by Corol: 1, Theorem 4, of the Young Gentleman's Geometry. And by the fame Corollary, one Angle being given in Caſe 2, and one of the fought be- ing found, the other fought is known. And fo in Cafe 3, two of the Angles ſought being found, the third foughc is known. and contain'd in the twe following Tables. 14 •The Young Gentleman's angle 10. 4. and Angles given or fought,) which are all contain'd in the two following Ta- bles. Whereof, the former contains all the particular Cafes, that relate to the Solution of plain rectangular Triangles; and the latter contains all the particular Cafes, that belong to the Solution of plain obliquangular Triangles. In Reference to which Tables it is to The literal be obferv'd, that for Brevity's fake it is Symbols ufual to denote the feveral Parts of a of the Se- veral plain Triangle by Letters, instead of Parts of a Words. In order whereto a rectangular plain Tri- Triangle is wont to be denoted by A, B, Fig. 9, & and C, fo placed, as (Fig. 9, viz.) that A always denotes the right Angle, BA the Bafis, CA the Cathetus or Perpendi- cular, which falling upon the Bafis makes the right Angle; BC the Hypotenufe; B the Angle between the Bafis and Hypo- thenufe, call'd in ſhort, the Angle at the Bafis; C the Angle between the Cathe- tus and Hypotenufe, call'd in ſhort, the Angle at the Cathetus. And an obliquan- gular Triangle is wont to be denoted by B, C, and D, fo placed, as (Fig. 10, viz.) that by a Cathetus CA, let fall from C, it may be divided into two Tri- angles, the Cathetus CA being a common Side to both Triangles. And then, as BD is eſteem'd the Baſis of the whole Triangle BCD, fo BA and DA are the particular Trigonometry. 15 particular Baſes, and BC and DC the particular Hypotenufes of the two Tri- angles BCA and DCA. Hence, B. and D denote the two Angles at the Bafis BD of the whole Triangle BCD; whereof B is always the Angle oppofite to the Side CD, and D. the Angle oppofite to the, Side CB, as C is always the Angle oppo- fite to the Bafis BD. 5. Other It is likewife to be obferv'd, that in the following Tables, the Letters de- Symbols notes a Sinę, ta Tangent, and the Greek used in the a Cofine. Thus, Tab. I, Cafe I, B, following t tB. Tables. denotes the Tangent of the Angle B. And Cafe 3, sC denotes the Sine of the Angle C. And Tab. II, Cafe 16, ºB and D denote the Cofines of the Angles B and D. Alfo note, that Z do's (in this Treatife, as in Algebra) denote the Sum of two Things; X their Difference. Laft- ly, This Character denotes an Angle, 24 two Angles; la Leg or Side, ll two Legs or Sides. And confequently, Zll denotes the Sum of two Legs of a Trian- gle; Z44 the Sum of two Angles, &c. Obferva- tions in It is alfo to be obferv'd, that a right 6. Angle being always 90 Degrees, hence it Some other is put down, neither among the Parts given, nor the Parts fought, in the feveral Reference Cafes of Tab. I. As for the other two to the twe following oblique Angles of a plain rectangular Tables. Triangle, they are both put down among the 條 ​16 The Young Gentleman's the Parts given in each of the first fix Cafes in Tab. I, (not (†) becauſe it is neceffary both the faid Angles ſhould be actually given, but) becauſe one of them being given, the other is in effect given alfo, its Quantity being known (by Corol. 1, Theorem 4, of the Young Gentleman's Geometry,) to be the Complement of the given oblique Angle. On this and the like Accounts, fome Tables are drawn up in a much more contracted or ſhorter Form, than the two which follow. But I judg'd it more agreeably to my Defign, to have all the particular Cafes diftinctly fet down: So, that the young Student may, both more readily find the Cafe propos'd to him; and alſo, having found it, may more readily perform the Calcu- lation, having Nothing elſe to do, but to Work according to the Proportion, which anſwers to the Cafe propos'd. (†) Hence it is faid in the firft fix Cafes of Table I, thus, viz. B or C, denotifig, that if either be given, it is fufficient. F TAB. Trigonometry, #7 TABLE I. Shewing the Solution of plain rectangular Triangles. * Cafe. Parts given. Bought. I B or C. BA CA Proportions. R: tB: BA : CA. : 2 B or C. CA BA _3 B or C. BA BC 4 B or C. CA BC 5 B or C. BC BA : 6 B or C. BC CA CA C 9 BC • CA B 10 BC BA C 7 BA CA B 8 BA R: tC CA: BA. SC: R: BA : BÇ. B: R:: CA : BC. R: SC BC: BA. R: SB BC: CA. BA:CA:: R: tB. CA:BA:: R : tC. I BA 12 BC 13 BC CA BC BA CA CA' BA BC: R:: CA: sB. BC; R :: BA : sC. CA:R: BA: TC; & then sC: BẠ :: R: BC. BC R::BA: SC; & then CC: BA:: R: CA BC: K:: CA: SB; & then tB : CA ::R: BA. C TAB. 18 The Young Gentleman's II. TABLE Shewing the Solution of plain obliquangn- lar Triangles. Cafe Given Sought Proportions. 1 BC. BD. D. C BC: BD:: SD: (||) C• sD 2 BC.BD.C. D BD: BC:: SC: SD 3 BC.CD.D. B BC: CD::sD: sB. 4 BC. CD. B. D CD: BC :: SB: SD. 5 BD. CD. C. B BD: CD :: sC :~ a sB. 6 BD. CD.B C CD: BD:: sB : . sC. L 7 B.C.D. BC BD SD: BC :: SC: BD 8 B.C.D. BC CD SD: BC:: SB: sB CD 9 B.C.D. BD BC SC: BD:: SD: BC 10 B.C.D. BD CD SC: BD :: SB: CD. --II B.C.D, CD BC ·sB : CD :: sD : BC. 12 B.C.D.CD BD sB : CD :: sC : BD (1) It is to be noted, that in this Cafe it may be doubtful, whe- The Reafon of which ther the Angle fought C be Acute or Obtufe. Doubtfulneſs arifes from what is faid, §. 10, Chap. 1. This happens, when two Sides being given, whereof one is the greateft Side, toge- ther with the Angle oppofite to the leffer of the given Sides, the An- gle oppofite to the greater of the given Sides is demanded. And, in this Cafe, the Doubtfulneſs can't be better taken away, than by Pro- trafting the Triangle; as is fhewn, Chap. 3. Cafe. Trigonometry. 19 # Cate Given Sought C ·(t). of 13 EC. BD.B Proporcions. BC+BD BC BD D+C 2: DDCCDC, and 2 2 (*) == C-D Then 2 D+C C-D 2 BC+CD BC-CD B+D 2 2 2 B-D. ::t : C Then 2 2 B+D+ B-DB, and + B. (+) or 14 BC. CD.C D 2 B (+) 2 or* 15 BD. CD.D C+B C 3 4 2 BD+CD BD-CD 2. B+D ___ B-D—B. 2 2 2 C-B. Then C+B :: [ : t 2. C+B_C-B B. 2 2 C-BC, and 2 E or DB: DG:: DF: DE. Then DB-DE—2BA. And DB-BA-DA. Then D 16 BC. CD. BD or C. CB: R :: BÃ: ☛B; and CD: R:: DA : σD. And Complement of B+D to 180=C. 1 } (*) It is to bé obferv'd, that, in this and the like Cafes, the Sum of the two Angles fought, C and D, is found by fubftracting the Quan- tity of B, the Angle given, out of 180, according to Theorem 4, of the Young Gentleman's Geometry. (tt) It is alſo to be obferv'd in Reference to Cafe 13th, 14th, and 15th, that having found the three Angles B, C, and D, the third Side not given in either Cafe may be found by fome of the twelve fore-going Cafes. C A The 20 The Toung Gentleman's 7. The Ufe The Ufe of the fore-going Tables fhall be illuftrated by one or two Examples. of the fore- going T4- And firft, fuppofing of the rectangular bles illu Triangle ABC, (Fig. 9.) I have the Side ftrated, as to artifi-" BA given, viz. 8 (I) Foot long, and the cial Sines, Angle B, viz. 36 Degrees, 52 Minutes; &c. and it is requir'd to find the Side CA. I confult the fore-going Tables, and find that this is Cafe 1, of Tab. I, and conſe- quently, that R:tB :: BA: CA, the Side requir'd. Hereupon I turn to my Table of artificial Sines, &c. whofe Ray I find to be 10.000000, and the Tan- gent of 36 Degrees, 52 Minutes, to be 9.875010. Then in my Table of Laga- rithms, I find the Logarithm of 8 to be 0.903090. Having thus found the Num- bers, that are to conftitute the three first Terms of the Golden Rule in my Calcu- lation, I then (according to the Method of Working the Golden Rule by Loga- rithms) add the 2d and 3d 36 Degr. 52 Min. Terms, and BA 8 f. long. Tangent of B } 9.875010 0.903090 out of the Sum fubftra&t Sum 10.778100 the ift Term, The Ray 10.000000 and the Refi- Refidue 0.778100 due is the 4th (1) This Extent of BA in Fig. 9, anfwers to the dia gonal Scale, Fig. 4, and fo of BC. Term 1 Trigonometry. 21 } Term of my Proportion, and fo the Number fought, viz. 0.778100. I look for this Number in my Table of Loga- rithms, and (though I find not exacly the fame Number, yet) I find one very near it, viz. 0.778151, the Logarithm of the Number 6. Wherefore, the Side re- quir'd CA is 6 Foot long very nearly, viz. wanting only of a Foot. 5 I 8. to natural The Reaſon, why the fore-going Ex- ample is wrought by artificial rather than The Ufe of the Ta- natural Numbers, is, becauſe (as has been bles illu- (*) afore obferv'd) Tables of artificial frated, as Sines, &c. are more eaſy to work by, Sines, &c. and fo are generally made Ufe of, and therefore ufually adjoin'd to Books of Trigonometry. Whereas few Books have Tables of natural Sines, c. Howfoever I fhall here ſhew (for the Satisfaction of the more Curious) how natural Sines, c. may be found by artificial Sines, and alfo, how the fore-going Example is to be wrought by natural Sines or Tangents, &c. when they are found. If then you would have the natural Sine or Tangent of any Angle, and want a Table of them, but have a Table of artificial Ones; then look out the artifi- cial Sine or Tangent in the Table, and (*) See the fecond Note on §. 12, Chap. I. C 3 not 22 The Young Gentleman's not much regarding the Characteriſtick thereof, fee what Number anfwers to the other Part thereof in the Table of Loga- rithms, and that will fhew you the natu- ral Sine or Tangent defir'd. For In- ſtance: Not regarding the Characteriſtick of the artificial Tangent (above-found) of B, viz. 9.875010, I look in the Table of Logarithms for the other Part, viz. 875010; and the nearest to it, there to be found,is the Logarithm 875061, which anfwers to the Number 750, which, therefore may be taken as the natural Tangent fought of the Angle E, the Dif ference being only ... S I Having thus found the natural Tan- gent of B, if thereby you would find the Side CA requir'd; then you muſt place (as afore) the Terms according to the Direction anſwering to Cafe 1, Tab. I, and must work the Golden Rule, (as in natural Numbers, i. e.) by multiplying the 2d and 3d Terms together, and di viding the Product by the ft Term. The Quotient will be the Number Sought or CA, viz. Ray. (†) Nat. Tang. BA. 1000: 750 : : 8 1 CA. : 6. (+) The Ray always confifts of an Unit, and fo many Cyphers, as there are Figures in the (natural or artificial) Sine or Tangent. ; For Trigonometry. 23 For 750×8=6000, and 1000) 6000 (6. And thus the Length of the Side CA re- quir'd, hath been found to be 6 Foot by both Sort of Operations. Again, of the fore-mention'd Trian- gle ABC, fuppofe CA and B to be given, and BC to be requir'd. I find this to be Caſe 4, of Tak. I, and confequently, the Rule for finding BC to be this, viz. SB: R: CA: BC. Wherefore, As artifi. Sine of B 36 Deg. 52 Min. 9.778119 To the Ray So CA 6 Foot long To BC the Side requir'd (10 f.) 10.000000 0.778151 1.000032. For 10.000000+0.778151=10.778151; and 10.778151-9.778119-1.000032, which is (but, i, e. is nothing different from 1000000) the Logarithm of the Number 10, which, therefore is the Meaſure of the Side requir'd BC. And thus having given the Side BA (=8 f.) of the Triangle ABC, the Side CA has been found equal to 6 Feet, and BC to ten Feet; agreeable to what is obferv'd in the Ufe of Theorem 12, of the Young Gentleman's Geometry; whence may be obferv'd the Truth of trigonometrical, as well as geometrical Principles, CA I pro- 9. Another Example. 24 The Young Gentleman's 10. Theo- rems, on I proceed now to ſpeak of the funda Of the four mental Theorems of Trigonometry, fo call'd, becauſe on them is founded the Solution which plain of plain Triangles, in all the Variety of Trigono- Cafes contain'd in the two fore-going founded. Tables. And theſe Theorems are four う ​metry is Fig. 11. on the first of which is founded, Tab. I; or the Solution of plain rectangular Tri- angles; and on the other three is foun- ded, Tab. II, or the Solution of plain obliquangular Triangles. THEOREM I. Whereon is founded the Solution of plain rectangular Triangles. In every plain rectangular Triangle ABC, if BC be the Ray, then BA is the Sine of the Angle C, and CA the Sine of the Angle B. If BA be the Ray, then BC is the Secant, and CA the Tangent of the Angle B. But, if CA be the Ray, then BC is the Secant, and BA the Tan- gent of the Angle C; as is illuftrated, Fig. 11. Whence it follows, 1. R:sB :: BC: CA. 2. RSC :: BC: BA. 3. RtB:: BA: CA. 4. R tC :: CA: BA. R: And 1 25 Trigonometry. And theſe four Proportions are the fame with thofe appertaining to Cafe 6, 5, 1, and 2, of Tab. I, and from thefe are deduced all the other Proportions, belonging to the feveral other Cafes of Tab. I, as may be feen by comparing them together. And therefore it evident- ly appears, how on this fundamental Theorem I, is founded Tab. I. Proceed we to Theorem 2. THEOREM II. Whereon is founded the Solution of plain obliquangular Triangles, when, there being given either all the Angles with one Side, or two Angles with the Side oppo- fite to one of the faid Angles, the Reft are fought. $ In every plain Triangle, the Sides are proportional to the Sines of the oppoſite Fig. 12. Angles; that is, sB: DC:: SC: BD:: sD: BC. For BC BD 2 2 2 : 2 BC CD ::sD: SB, and CD BD :: SD: SC, and 2 SB: SC; as is illuftrated, Fig. 12. sC 2 THE- : 26 The Young Gentleman's THEOREM III. Whereon is founded the Solution of plain obliquangular Trian- gles, when, there being given two Sides with the Angle con- tain'd between them, the Reft are fought. ZII XII 2 2 ::t, ZL Lop ZLLop: XLLOP; that is Lop 2 2 in Words, as Half the Sum of the (Legs or) Sides given, is to Half the Difference of the Sides given; fo is the Tangent of Half the Sum of the oppofite Angles fought, to the Tangent of Half the Dif ference of the oppofite Angles fought: Fig. 13. That is, in Fig. 13, GE: BE:: GH: FH. Demonftration. In the Triangle BCD, Fig. 13, let the Legs or Sides given be BD and BC. Draw BG BC; and fo XII ZIL there will be GE: and BE 2 2 and the (1) extern Angle GBC=BCD+, BDC, the two intern and oppofite An- Ey Theorem 4, Chap. 1, of the Young Gentleman's Geometry. gles } Trigonometry. 27 ! gles of the Triangle BCD. Then draw CG, and after that draw EH, and alfo BF parallel to CD; whence will arife the Angle (*) GBF=BDC, and (†) FBC BCD. Then bife& CG by BH, and there will arife the Angle (|) GBH: HBC. But GBH+HBC=GBC=GBF+ FBC=BDC+BCD, i. e. ZLLopp. And therefore, (becaufe GBH HBC, and GBH+HBC=GBC,) GBH= ZL Lopp ; 2 and ſo GH the Tangent of ZLLopp. Then 2 make the Angle HBK FBH. Now, be- caufe (as afore has been fhewn) the An- gle GBH HBC, therefore GBH-FBH HBC—HBK, i. e. GBF=KBC. Where- fore FBC (BCD) -KBC (GBF or BDC) =FBK or XL Lopp. Wherefore FBH= XLLOPP, and fo FH is the Tangent of Lopp ; 2 XL Lopp. But now GE: BE:: GH: IH, BE::GH: 2 that is, ZII XII :: t,ZLLop: + XL Lop. t₂XL 2 2 2 (*) By Theorem 3, Chup. I, of the Young Gentleman's Geometry. (†) By Corol. 2, Theorem 3, Chap. 1, of the Young Gen- tleman's Geometry. (1) By Theorem 5, Chap. 1. of the Young Gentleman's Geometry. THE 28 The Young Gentleman's Fig. 14. THEOREM IV. 1 On which is founded the Solution of plain obliquangular Trian- gles, when, the three Sides being given, the Angles are fought. DB: DG :: DF: DE, that is in Words The greateſt Side DB of any plain Tri- angle, is to the Sum DG. of the other two Sides, as is the Difference DF of thoſe Sides, to that Segment DE of the greateſt Side, which being taken away, the Ca- thetus CA will bifect the remaining Seg- ment EB of the greateſt Side. Demonftration. By Prop. 36, 3 Euclid, DG×DF=DTq=DB×DE. Wherefore, by Prop. 15, 6 Euclid, DB: DG :: DF: DE. From the three laſt Theorems is dedu- ced, Tab. II, or the Solution of plain obliquangular Triangles, in all the Varie- ty of Caſes that can be propos'd. Nay, the faid Theorems may ferve for the Re- folving of all plain Triangles whatever, Rectangular as well as Obliquangular. But forafmuch as the first Theorem do's fuffice to fhew the Solution of plain rectangular Triangles, and that after a more cafy Manner in fome Cafes, hence the Trigonometry. 29 A the three laft Theorems are wont to be reſtrain'd to the Solution only of plain obliquangular Triangles. And confe- quently, Tab. II, is accommodated on- ly to obliquangular Triangles. Of which Table the twelve firft Cafes are founded on the 2d Theorem, the three next Cafes, (viz. 13th, 14th, and 15th,) on the 3d Theorem; and Cafe the 16th or laft on the 4th and laſt Theorem. And thus much for the Solution of plain Tri- angles by Calculation. CHA P. III. Of the Solution of plain Triangles by Protraction. HER + I. to be here taught. ERE are two Things to be fhewn; Two ift, How to protract or deſcribe Things any plain Triangle requir'd. 2dly, How to refolve the faid Triangle, when it is protracted i. e. how to find the Mea- fure of the unknown Angles or Sides in the faid Triangle, when protracted. ; 2. to protract Protraction is either of fome Side, or of fome Angle. A given Side is A given Side is protra- First, how cted by drawing a right Line BC, Fig. any given 15, taken off from the (fimple or diago. Side. nal) Fig. 15. 30 The Young Gentleman's 3. how to Angle. nal) Scale of equal Parts, at fuch a Length, as to contain the fame Number of equal Parts according to the Scale, as is the Number of Inches or Feet, &c. in the Side given, viz. 254. A given Angle B=48 Degrees, is pro- Secondly, tracted, by (taking a Chord of 60 De- protract grees for your Ray, i. e. by) opening any given your Compaffes to the Extent of 60 De- grees on your Scale of Chords, and then, one Foot being faſtened on one End B of the given Side BC, drawing with the o- ther Foot the Arch CA; and on the faid Arch fetting off from A to E, the Extent of 48 Degrees taken from your Scale of Chords; and after that drawing the right Line BD. 4. A plain how to be when the After this manner is any given Side and Angle to be protracted, and fo any plain Triangle Triangle to be defcrib'd, when either one defcrib'd, Side and two Angles, or two Sides and one Angle are given. But, if the three are given, Parts given be the three Sides; then the and no An- Triangle is to be defcrib'd, as is fhewn, Chap. 2, Problem 2, Cafe 1ft, or 2d, or 3d, of the Young Gentleman's Geometry. three Sides gle. 5. How to The Triangle BCD, (Fig. 15,) being protracted, the Meaſure of any Side not find the given, is found, by applying the Extent 4 Side not thereof with your Compafles to your (fimple or diagonal) Scale of equal Parts, and fo finding how many fuch equal Meafure of a given. · he Parts Trigonometry. 3. Parrs are contain'd in the faid Side. Which equal Parts are to be eſteem'd In- ches, or Feet, or Yards, accordingly as the Meaſure of the given Side is denoted by Inches, or Feet, or Yards, &c. Thus, fuppofing BC to be 254 Feet long, CD will be 198 Feet, and BD 204 Feet. 6. find the not given In like Manner, the faid Triangle be- ing protracted, the Meaſure of any An- How to gle C or D not given, is found, by open- Measure of ing your Compafs to the Extent of 60 an Angle Degrees on your Scale of Chords, and then fixing one Foot on the Point of the Angle fought, and making an Arch from one Leg to the other of the faid Angle. The Extent of the Arch apply'd to your Scale of Chords, will fhew the Degrees of the reſpective Angle. Thus, Fig. 15, the Extent of the Arch FG, fhews C to be an Angle of 52 Degrees; and the Extent of the Arch EG, fhews D to be an Angle of 80 Degrees. 7. tion of plain Tri- Protrachi- It remains to be obſerv'd, that the So- lution of plain Triangles by Protraction, The Solu- is founded on Theorem 9, Chap. I, of the Young Gentleman's Geometry. Namely, angles by becauſe the protracted Triangle is equi- angular to the real Triangle, (i. e. the what triangular Ground, or the like,) there- founded. fore, the Sides of that have the fame Proportion one to the other, as have the Sides on, on 32 The Young Gentleman's 8. plain Tri- Sides of this; albeit thoſe are in a man- ner infinitely leſs than theſe: And thus having fhewn, how to re- The Use of folve any plain Triangle, either by Cal: culation or Protraction; I proceed now to illuſtrate the great Uſefulneſs of plain Trigonometry, in taking Heights and Di- gonome- try ap- pears in taking Heights Stances, as alfo in Surveying and Fortifi- and Di- ftances, cation. dc. I. The Height CHA P. IV. Of Taking the Altitude or Height of an Object, viz. Tower, Tree, IT &c. that T is to be remember'd, that (according to Definition 42, Chap. 1, of the Young of an Ob- Gentleman's Geometry) the Altitude or ject, what. Height of an Object, viz. Tower, Tree, and the (*) like, is meafur'd by a Per- pendicular from its Top to its Bottom. Thus, the Height of the Tower, Fig. 16, and of the Tree, Fig. 17, is denot- (*) For as to the Height of the Sun, or any other Celestial Light, that is computed by its Diſtance above the Horizon on a vertical Circle: Of which in Aftro- nomy. ed Trigonometry. 33 ed by the Perpendicular CA; and fo in all other fuch Cafes through this Trea- tife. 3. bols made Uſe For the Line CA of Altitude, and the Line BA of Diſtance, (viz. between the The Sym Obferver B, and the Foot of the Object Use of in. A,) and the Line BC of Viſion do always taking conſtitute the three Sides of a rectangular Heights, Triangle ABC. Wherein the Height of the Object is the Cathetus or Perpendi- cular, and therefore, (according to the receiv'd Method of denoting the feveral Parts of a rectangular Triangle in Trigo- nometry,) is aptly denoted by CA. In like manner, the Diſtance of the Ob- ferver from the Object, making always the Baſis, is aptly denoted by BA, and the Line of Vifion, making always the Hypotenuse, is aptly denoted by BC. And fo as to the feveral Angles, A de- notes the right Angle between the Line of Altitude and the Bafis, B the Angle between the Bafis and Hypotenufe, which may be call'd, the Angle of Altitude, be- cauſe the Altitude of the Object is al- ways either (†) its Sine or Tangent; and fo C will denote the remaining Angle (†) Namely, if BA be taken for the Ray, then CA is the Tangent of B; but if BC be taken for the Ray, then CA is the Sine of B. D between 34 The Young Gentleman's 3. How to take the Angle of Altitude. 4. An acceffi- between the Lines of Viſion and Alti- tude. The beſt Inftrument for taking the Angle of Altitude is the Quadrant, thence commonly diſtinguiſh'd by the Name of the Quadrant of Altitude; by which it is done thus. Hold your Quadrant up- right, fo as the String may have Liberty to flip to either Edge, and move the Quadrant fo held, 'till through the Sights you fee the Top of the Object, whofe Height you would take. Then the De- grees, intercepted between the Beginning of the Quadrant and the String, are the Degrees of the Angle of Altitude; name- ly, of the Altitude of the Object above your Eye. Wherefore, if you ftand up- right, when you take the Angle of Al- titude, to the Altitude found by the faid Angle of Altitude, there muſt be always added the Height of your Eye above the Ground, to know the Altitude requir'd of the Object. If one may come to meaſure from the Place B of Obfervation, to the Foot A ble and in- of the Object, (i. e. to the very Bottom acceffible of the Perpendicular CA,) then it is call'd an acceffible Height. But, if any Thing hinders from coming to A the Foot of the Object, then it is call'd an inacceffible Height. Height, what. PRO Trigonometry. 35 PROBLEM I To find an acceffible Height. 5. Calculati Meaſure your Line BA of Diſtance, and find the Meaſure of the Angle B First, by by your Quadrant. Theſe two being known, CA is found by Tab. 1, Cafe 1, Fig. 16. viz. RtB:: BA: CA. For Inftance: R:tB::BA:CA. Suppofe BA 347 Feet, and B-35 De- grees. Wherefore, As the Ray To the Logarithm of BA 347 Feet So the artificial Tangent of B 35 Degr. To the Logarithm of the Side fought CA 243 Feet very 10,000000 2.540329 9.845227 S }Add Add 12.385556 10.000000 Subſt. on. near. 2.385556 Refidue. by Pro- If you would find the Height fought 6. CA by Protraction, work thus. Draw Secondly, (according to Chap. 3, §. 2,) the Line traction. of Diſtance BA=347 (equal Parts or) Fig. 16. Feet. Then, (by Chap. 3. §. 3.) make the Angle B 350, and the Angle A= 90 Degrees, or a right Angle. Then draw the Sides BC and CA, 'till they meet in C. Apply CA to your diagonal Scale, and it will be equal to 243 (equal Parts thereof, or) Feet. D To 36 The Young Gentleman's 7 Some O- ceffible Heights. To the Method of taking Heights by Protraction, may be referr'd the Method ther Me- thods of of taking Heights by a Staff, or a Bowl taking ac- of Water, or the like. Forafmuch as by Help of the Staff or Bowl of Water, (c.) there is as it were protracted a Triangle, equiangular to the Triangle made by the three Lines of Viſion, of Diſtance, and of the Altitude fought. Namely, in Fig. 17, or 18, the Tri- angle bac, is equiangular to the Triangle BAC, (as fhall be fhewn by and by.) and therefore, the Meaſure of the Sides ba and ca being known, as alfo of BA, thereby is found (according to the Rule of Proportion) CA the Altitude fought. For, (according to Theorem 9, Chap. 1, of the Young Gentleman's Geometry,) ba: ca:: BA: CA. 8. Now the Way to find the Altitude of Acceffible an Object by a Staff, is two-fold, either Heights may be ta- by the Staff and its Shade, when the ben by a Sun fhines; or elfe by the Staff alone, at any Time, or whether the Sun fhines Staff two Ways. Height by or Not. 9. To find the Altitude of an Object by To take an a Staff and its Shade, work thus. At B, acceffible the End of the Shadow caft by the Top * Staff and of the Object, fet up your Staff ca per- pendicularly, (as Fig. 17,) and mark the End b of the Shadow made by your Staff. For, as baca :: BA: CA, i. 1. its Sha- dow. Fig. 17. As Trigonometry. 37 As the Length of the Staff's Shadow, is to the Height of the Staff; fo is the Length of the Object's Shadow, to the Height of the Object. For Inftance: Suppoſe your Staff ca to be three Foot long, or juſt a Yard, and its Shadow ba to be nine Foot long, and the Shadow BA of the Object to be 60 Foot long; then the Height of the Object will be twenty Foot. For 9: 3 :: 60: 20. This Method depends (as is afore faid) on Theorem 9, Chap. 1, of my Geometry, or) on the Triangles bac, and BAC being mutually equiangular. And that they are fo, is thus fhewn, viz. the Staff ca being erected perpendicularly, therefore, the Angle a is a right Angle, and fo e- qual to A. Alfo, becauſe the (D) Ray of the Sun, (or, which comes to the fame, the Extremity of the fhaded Air) bc, is always parallel to the other Ray BC, therefore, (by Theorem 3, Chap. 1, of my Geometry,) the Angle b-B, and confequently, the Angle C; and fo (Although the Rays of the Sun, as proceeding from the Sun as their Center, are in Strictnefs, not parallel, yet by Reaſon of their immenfe Length or Distance from the Sun, wherein they concur, their Obliquity is not dif cernible in fuch Cafes, but they may be efteem'd as par- allel, efpecially as to fuch fmall Segments or Portions of them as are herein concern'd. D 3 the $8 The Young Gentleman's a 10. lone. Fig. 18. • the Triangle abc, equiangular to the Tri- angle ABC. If the Sun do's not fhine, then you To take an may nevertheless find the Height of the acceffible Height by Object by your Staff alone, thus. Ha- Staff a ving fet up (as afore) your Staff ca per- pendicularly, go backward 'till you can fee the top C of your Object, in a Line with the top c of your Staff, as is repre- fented, Fig. 18, by the Line bC or BC. Then (*) baca :: BA (or bA): CA, that is, as the Distance ba of the Place b where you faw the Top C of the Object, and the Top c of your Staff in one Line be (or Be) from the Place a of your Staff, is to the Height ca of the Staff; fo is the Diſtance of the former Place (b or) B from the Foot A of the Object, to the Height CA of the Object. II. Height by a Dith or If you would for Curiofity Sake know, To take an how to find the Height of an Object by acceffible a Bowl or Difh of Water, it is done thus. Go backward from the Bowl, 'till ftand- ing upright, you can fee the Top Cof the Object in the Water. Then ba: ca :: BA: CA, i. e. as is the Diſtance ba of Bowl of Water. Fig. 19. (*) For here alfo bca and BCA are equiangular Tri- angles. For CA and ca being both Perpendiculars, are therefore Parallel. And confequently, (by Theor. 4, Chap. I, of my Geometry, the Angle C, as well as aA; and the Angle Borbis common to both Triangles. your Trigonometry. 39 your Station a from (†) the Bowl b, to your own Height ca as far as to your Eyes; fo is the Diſtance BA of the Foot A of the Object, to the Height CA of the Object. For, according to that prin- cipal Theorem of Catoptricks, the Angle of Reflexion Pbc, is equal to the Angle of Incidence PBC. And therefore, the Angle abc (=1 Right-Pbc=1 Right— PBC) ABC. And the Angle Aa, becauſe both Right; and therefore, the remaining Angles C and c are equal; and fo the Triangles ABC and abc equi- angular. 20. only. Fig. 29. Laftly, There is one Way more to take an acceffible Height, which I ſhall here To take an mention by Reafon of its Eafinefs and Height by acceffible Expediteneſs, when it may be us'd. It Quadranc is thus. Go towards or from your ob. ject CA, if you have Room, 'till the String of your Quadrant falls juſt on the 45th Degree. Then the Height CA of your Object, will be equal to BA the Diſtance between your Place B, and the Foot A of the Object. For the Angles B and C will be equal, (viz. each 45 Degrees,) and therefore, the Triangle A (t) If you would be exact, your Distance, and the Diſtance of the Object must be both taken from the very Point of the Water, whereon you fee the Top of the Object. D 4. ABC 40 The Young Gentleman's 1 13. lation. Fig. 21. ABC will be an Ifofceles, i. e. BA=CA, by Theorem 5, Corol. 2, of the Young Gen- tleman's Geometry. PROBLEM II. To find an inacceffible Height. Take two Stations B and b lying in a By Calcu- direct Line with the Foot A of the Ob- ject. The Diſtance Bb between thefe two Stations, with the two Lines of Vi- fion BC and bC, make an obliquangular Triangle BCb. All whofe Angles are known, by taking the two Angles of Al- titude CBA and CbA, in their respective Triangles BCA and CA. For 180-An- gle CBA CBb; and 180-CBb+b= BCb. The three Angles of the Triangle BCB being thus known, and the Diſtance Bb between the two Stations being mea- fur'd, the Side BC is found by Cafe 11, Tab. II, (viz. SB: CD:: SD: BC. For, that is in Reſpect of the Notation of the feveral Sides of the Triangle BCb, Fig. 21,) sBCb: Bb: sCbB BC. But now BC is alfo the Hypotenufe of the rectan- gular Triangle ABC; and the Meaſure of BC being known, as alſo of the Angle CBA, (viz. CBA=180-CBb,) hence may be found CA the Height of 1 کیا ہم کچھ the Trigonometry. 41 the Object, by Cafe 6, Tab. I, viz. R: SB:: BC: CA. For Inftance: I would know the Height of the Church-Steeple, Fig. 21, between A the Bottom of which, and b the Place where I am, runs a River, fo that it is an inacceffible Height. Where- fore, by my Quadrant, I take the Angle GbA of Altitude at my Station b, which I find to be 27 Degrees. Then meafu- ring in a ſtraight Line from b to B my fecond Station, (which I find to be 92.7 Foot,) I take the Angle CBA of Altitude again at my fecond Station B, and find it there to be 52 Degrees. Hence it follows, that the Angle CBb=127 De- grees, (for CBb-180-CBA ;) and al- fo, that the Angle BCb=25 Degrees, (for BCb-180-: CBb+CbB:=180 -155) Having thus in the Triangle BCb the three Angles, and one Side Bb given, thereby is found the Side BC, by Cafe 11, Tab. II, Viz. 1 As 2. 41 The Young Gentleman's As the Sine of BCb 25 D. 30 M. To the Log. of Bb 92.7 Foot 9.633984 1.967080 So the Sine of CbB 27 D. 30 M. ·9.664406 211.631486 14. To the Log. of BC fomewhat above 9.633984 99.4 f. viz. 100 f. very nearly 1.997502 3 Having thus found the Meaſure of BC, and having afore found the Angle CBA, thereby is found CA the Height fought by Cafe 6. Tab. I. viz. As the Ray To the Log. of BC 100 So the Sine of CBA 52 D. 30 M. To the Log.of CA=793 and fome- what more, viz. 80.3 very nearly › * 10.000000 2.000000 9.899467 11.899467 10.000000 1.899467 If you would work by Protraction, you To take an muft proceed thus. Having (as afore) inacce fible Height by at the two Stations B and b, found the Protracti- Angles of Altitude, viz. CbB and CBA, on. and meafur'd the Length of Bb, then Fig. 21. draw a right Line Bb of as many Parts on the Scale, as the Meaſure of Bb is found to be of Feet (or Yards, c.) At the two Points B and b make two An- gles CBA and CbA equal to the Angles of ' Trigonometry. 43 of Altitude taken by you at B and b. From C the Point, where CB and Cb in- terfect or croſs one the other being drawn, let fall the Perpendicular CA to the Line of Diſtance Bb extended, if need be, 'till it meets with CA. The Perpen- dicular CA apply'd to the Scale of equal Parts will ſhew the Number of Parts, i. e. of Feet or Yards, &c. Height by dow. 15. An inacceffible Height may alſo be To take an found by the Help of a Staff, and its inacceffible Shade, thus. Set up the Staff ca perpen- a Staff and dicularly, and mark the End b of its Sha- its Sha- dow Fig. 23; and at the very fame time Fig. 22, mark the End B of the Shade of the inac- & 23. ceffible Object CA Fig. 22. Then three or four Hours after mark again the End d of the Staff's Shadow, and alſo the End D of the Shadow of the inacceffible Object. Then meaſure the Diſtance between the two mark'd Ends b and d of the Shade of the Staff, and alfo between the two mark'd Ends B and D of the Shade of the inacceffible Object. As bd to ca, fo BD to CA, i. e. As the Diſtance between the two different Ends of the Staff's Shadow, to the Height of the Staff; fo will the Diſtance between the two different Ends of the Object's Shadow, be to the Height of the Object. For (by Theor. 9. Chap. 1. of my Geom.) da: ca :: DA: CA. Where- fore ļ 44 The Young Gentleman's fore da― (†).ba: ca :: DA—(†) BA: CA. i, e. bdca :: BD: CA. 16. If it should happen, that you have not To take an Room to take two Stations, as Fig. 24. nacceffable then an inacceffible Height may be found when there thus. First take the Arch CBA of Alti- Height, is not Room to take two Stations on the Ground. tude on the Ground B; and then go up to the Top of the Houfe (or Tree) where you are, and there take the Angle CDB. Draw an indeterminate Line BA, and Fig. 24. thereon at Berect the Perpendicular BD, of an equal Length with the Height of the Houfe DB, (which is fuppos'd to be known,) and thereon at D make an Angle CDB equal to the Angle taken on the Top of the Houfe, and at B make an Angle CBA equal to the Angle of Altitude ta- ken on the Ground. Then extend BC and DC 'till they meet in C. A Perpen- dicular CA, let fall from C upon the in- determinate Line BA, being apply'd to the Scale of equal Parts, will ſhew the Height of the Object CA. (tt) For as the Lines da and DA are proportional by the fore-mention'd Theorem, fo will their Parts ba and BA; becauſe, the Shade of the Staff will be proportion- ably lengthened or fhortened, as is the Shade of the Object. PRO. T لا Trigonometry. 45 PROBLEM III. 3 A To meaſure the Height of an Ob- ject, which ftands on the Top of another Object. I would know the Height of the Spire Fig. 25, Cd above the Tower Aa. Find the whole & 26. Height CA (by Prob. 1. if A be acceffible, as Fig. 24; if inacceffible, as Fig.25, then by Probl. 2.) Then find the Height Ad (or ca) of the Tower alone (as afore by Probl. 1. or 2.) Then CA-Ad (or ca) Cd the Height of the Spire. PROBLEM IV. To find the Height of an Hill or Mountain. This may be done in fome Manner by Fig. 27. Probl. 2. But becauſe the Tops of Hills or Mountains, if of any confiderable Height, do appear higher than really they are, by reafon of the Refraction of the Ray of Vifion; therefore there is an- other more exact Method to find the Height of Hills and Mountains, by the help of an Inftrument called the Brazen T, from 1 ! F { 46 1 The Toung Gentleman's from its reſembling the Letter of that Name, as may be ſeen Fig. 27. For this Inftrument being plac'd between two Staves (or Spikes, divided into a certain Number of Feet, and thoſe ſubdivided into Inches) thereby may be obferv'd (at least by the Help of flipping Marks, to be mov'd upwards or downwards) what Number of Feet and Inches the Hill rifes or the Aſcent increaſes at all the feveral Poſitions of the ſaid Staves, from the Bottom to the Top of the Hill or Mountain. And confequently, by ad- ding together the feveral Feet and Inches, which at the feveral Pofitions of the two Staves, have been obferv'd to be contain'd, between the horizontal or le- vel Lines, thence will ariſe the Sum of all the Feet and Inches from the Bottom to the Top of the Hill, and fo the Height fought. Thus the Height CA of the Hill or Mountain Fig. 27. is equal to the Sum of ab+cd+ef+gh. And this Method is called Cultellation. CHAP. Trigonometry. 47 CHAP. V. Of Taking the Distance between twe Objects. IN tak F I. rent gene- taking Diſtances (as well as Heights) there are in general two different Ca- Two diffe- fes. For either we may come to (*) One, ral Cafes or Neither of the Two Objects, whofe in taking Distances. Diſtance one from the other we would take. The Angle which is oppofite to the 2. Line of Diſtance (between the two Ob- The Angle jects) may be call'd, the Angle of Di- of Di- ftance, Stance, and is here denoted by the Letter what. D: Forafmuch as the Triangles arifing in taking Diſtances are generally obliquan- gular Triangles. The most commodious Inſtrument for 3. taking Angles of Diſtance is the Theodo- How to lite or Circumferentor, i. e. a Braſs Circle take the Angle of divided into 360 Degrees, and fitted with Diftance. (*) As for the third Cafe, viz. wherein both the Ob. jets, whofe Diſtance is requir'd, may be come at, that de's not ftand in need of Trigonometry to find the Di- ance, becauſe it may be meafur'd (without any more do) by a Chain or other long Meature. four J 48 The Young Gentleman's 1 40, of Geometry. four Sights. For the Sights being fo mov'd, as that you can through two of See Fig. them (lying in a ſtrait Line AB) ſee one, A, of the Objects, and through the other two (on the Line DE) fee the other, E, of the Objects, the Angle ACE will be the Angle of Diſtance; whofe Meaſure will be the Degrees intercepted between CA and CE ; and are always equal to the Degrees between CD and CB, becauſe the Angles ACE and DCB are verti cal Angles, and confequently equal. Whence BCD as well as ACE may be e- ſteem'd the Angle of Diſtance. lation. Fig. 28. PROBLEM I. To take the Distance between two Objects, when One of the Ob- jects is acceffible. I would know the Diſtance of the Ob- By Calcu- ject B (Fig. 28.) from the Object C 49 one, B, of which Objects is acceffible, but the other, C, is not. On one Side of B, I chooſe a Station D, at a (†) confiderable Diſtance from B. The Line BC of Di- (†) Note, That the greater the Distance BD is be- tween the acceffible Object B, and the Station D, fo much more exact will the Operation be. ftance Trigonometry. 49. ftance between the two Objects B and C, and the Lines BD and CD of Distance be- tween each Object and my Station, make an obliquangular Triangle, BCD. Now the Angles CBD and BDC being found by the Theodolite, and confequently the Angle DCB being known, (viz. DCB=180— CBD+BDC) and the Side BD being meafur'd, hereby may be found BC the Diſtance requir'd between the two Ob- jects B and C, by Tab. II, Cafe 9, viz. SC: BD:: SD: BC. ple. 5. For Inftance: Suppofe BD, the Diſtance of my Station D from the acceffible Ob- An Exam- ject B, to be one hundred and four Yards; and the Angle BDC=86 Degr. and the Angle DBC=63 Degr. and confequently the Angle BCD=31 Degr. It follows, according to the foremention'd Caſe 9, Tab. II, that As the Sine of C 31 Deg. 9.711839 To the Logarithm of BD 104 Yards 2017033 1 So the Sine of D 86 Deg. 9 999404 12.016437 To the Log.of BC 202 very nearly 9.711839 2.304598 6. if you would take the Distance by Pro- traction, you must work thus. Draw By Pro- BD containing 104 equal Parts upon your Fig. 28. E dia- traction. 50 The Young Gentleman's 7. or Pole only. diagonal Scale, equal to the Number of Yards found upon meaſuring BD. And then at one End B defcribe the Angle B equal to its Meaſure of 63 Degrees found by the Theodolite; and likewife at the other End D defcribe the Angle 'D=86 Deg. as found by the Theodolite. Then draw the Lines BC and DC, 'till they meet in C, the Line BC apply'd to your di- agonal Scale, will fhew the Diſtance of the two Objects B and C, viz. about 202 Yards. If you have no Theodolite, or fuch By a Chain like Inftrument by you, the Diſtance BC may be taken only by a Chain or Pole Fig. 29. (or the like) thus: Meaſure with the Chain the Diſtance BD between the ac- ceffible Object B and your Station D; which your Station chooſe ſo in this Cafe, as that it may be (as near as you can guefs) at an equal Diftance with B from the inacceffible Object C. Then in the Lines of Viſion DC and BC mark out any two Points d and b, and meaſure with the Chain the feveral Lines DB, Eb, bd, đ□, and dB. Then protract a Trapezium BDdb of the fame Sides ; the two Sides Bb and Dd of which being produc'd, will meet in C, which will denote the Place of your inacceffible Object. And confe- quently the Line BC, being apply'd to the Scale of equal Parts, will thereon fhew the Trigonometry. 5x the Diſtance fought. For by meaſuring and protracting the Sides of the Trapezi- um BDdb, you do in effect find and pro- tract the Angles B and D of the obliquan- gular Triangle BCD, as well as the Side BD of the faid Triangle. And therefore the protracted Triangle BCD is equian- gular to the Triangle made by the Lines of Viſion at B and D, and the Line BD ; and confequently the Sides of the protra- &ted Triangle are proportional to the Sides of the real Triangle, reprefented by the protracted one. By this laſt Method may the Breadth of a River be taken. For if you fuppofe BD to be one Bank of the River, and C to denote a Point of the Bank on the o- ther Side of the River; then the Diſtance of the Banks or Breadth of the River will be equal to BC. Where it is to be noted, that in this Method the Trapezium BDbd may be taken or meafur'd out, on either Side of BD, viz. either towards the inac- ceffible Object C, or on the other Side of BD, as you have Room or moſt Conve- niency. 8. To take the Breadth of a River. Fig. 29. 9. like Di- The fame may be performed alſo after To take the this Manner. Set up a Staff perpendicu- a River, larly on the Bank where you are, and or any fuch thereon place a fquare Rule with its An- gle downwards on the Head of the Staff. Move the fquare Rule, 'till the Line BA E 2 a tance, by Staff and a Square- rule. of Fig. 30. 52 The Young Gentleman's IO. the Di as of a of Viſion from B a Point in the oppofite Bank of the River, falls in directly with the upper Edge of one Side of the fquare Rule; and then from the Point C (where the upper Edges of the two Sides of the fquare Rule meet) draw, along the upper Edge of the other Side, a String, or Rope, or Chain, 'till it comes in a ſtraight Line to the Ground at b. As (†) bA : CA :: CA: BA, i. e. As the Diſtance bA be- tween the Point b, where the String came to the Ground, and the Foot A of your Staff, is to CA the Height of your Staff; fo is the Height CA of your Staff to the Diſtance BA of A (the Foot of your Staff, or) the Bank where your Staff is, from B the other Bank. And after the fame Man- ner may any other Diſtance be taken, where only one Object is inacceffible. If the inacceffible Object be an Obje& To take of Height, viz. a Tower, or Tree, or the ftance of like, then having found (by the Problem an Object for taking an inacceffible Height) the of Height, Height CA of the faid Object, and its Tower, &c. Angle B of Altitude, thereby may be Fig. 21, found the Diſtance fought BA by Tab. I, or 22, & Cafe 2; viz. R : tC :: CA: BA. For the Angle B being known, thereby is the An- gle C known; viz. C=90-B. 23. (†) Namely, by Corol. I, Theorem 11, of the Young Gen- tleman's Geometry. ་ PRO Trigonometry. 53 PROBLEM II. To take the Distance between two Objects, when both are inac- ceffible. 11. Take your firſt Station D as you pleaſe; and on the Side of the former chooſe a By Calcu- fecond Station d, fo as Dd may be paral- lation. lel to BC as nearly as you can. Then with Fig. 31. your Theodolite at D one of your Stati- ons, take the Angles BDC and CDd, which together make the Angle BDd. Then at your other Station d take the Angles BdC and CdF, (the Mark F being ſet up in a right Line with your two Sta- tions D and d) which together make the Angle BdF. Now in the Triangle BDd the Angles BDd+DBd=BdF. Where- fore the Meaſure of the Angle BɗF being found by the Theodolite, DBd=BdF -BDd. And therefore the ſtationary Di- ftance Dd being meaſur'd, sDBd: Ďd :: sBDd: Bd by Cafe 12, Tab. II; viz. sB ; CD::sC: BD. In like manner in the Triangle CdD, the Angles CDd+DCd CdF, Wherefore the Meaſure of CdF being found by the Theodolite, the An- gle DCd CdF-CDd. And therefore by Cafe 12, Tab. II; sDCd: Dd: sCDd; E 3 محمد Cd, 54 The Young Gentleman's 12. By Pro- traction. Fig. 31. * Fig. 32, & 33. Cd. Wherefore the Angle CdB of the Triangle BCd being found afore, and the Angle CBd CDd found alfo afore, it follows by Cafe 12, Tab. II, that sCBd: Cd: sCdB: BC the Diſtance fought. To take the like Diſtance by Protracti- on, you muſt work thus. Take (as afore) at your two Stations, D and d, the feve- ral Angles BDC and Cdd, and CdB and BdD. Then having meafur'd your ſtati- onary Distance Dd, and protracted it, on one End D thereof protract its reſpective Angles BDC and CDd; and on the other Ended its reſpective Angles CdB and BdD. Draw out the feveral Sides of the Angles meet refpectively, two BD and Bd in B, the other two, Cd and CD, in B. The Diſtance BC apply'd to your Scale of equal Parts, will give you the Diſtance fought. PROBLEM III. To take the Draught of a City, or Port, or the like. This is done after the fame Manner as is taken the Diſtance between two Ob- jects, when both are inacceffible; it be- ing no other than a Repetition of the faid Operation, according to the Variety of the Trigonometry. 35 • the remarkable Objects which you would delineate or defcribe in the Draught. For Inſtance: Let A, B, C, D, E and F de- note ſo many remarkable Buildings (viz. Churches, or Pillars, or other publick E- difices) in a City; or elfe let them de- note fo many Ships lying in a Port or Harbour. I take two Stations M and N at ſo confiderable a Diſtance, as that the Line MN of the faid Diſtance may be long enough to ſerve conveniently for the Baſis of all the Triangles to be taken. Then at M placing the fixt Index of my Theodolite in a right Line with MN, I turn the moveable Index, as Occafion re- quires ; and ſo take in order the feveral Angles MNA, MNB, MNC, &c. and fo to the laſt MNF. Then removing to my other Station N, and placing (as afore) the fixt Index of my Inftrument in a Line with MN, I take the feveral Angles NMA, NMB, NMC, &c. Having done this, I (†) protract the Line MN of Distance between my two Stations M and N, taking from my Scale of equal Parts the Line mn anfwerable to (†) Having the Bafis MN, and the two Angles at the Bafis in each Triangle, the other Sides in each Triangle may be found by Calculation; but this Method being tedious, therefore Protraction is generally made Uſe of in this Cafe. E 4 MN 56 The Young Gentleman's } Fig. 34. mn, MN. And then at the End m of the Line I protract the Angles mna=MNA, nb MNB, mnc-MNC, &c. Like- wife at the other End n of the Line mn, I protract the Angles nma=NMA, nmb NMB, nmc-NMC, &c. The Legs of the feveral Angles being produced, will fhew in the feveral Points of Interfecti- on a, b, c, &c. the refpective Places of the ſeveral Objects A, B, C (c); and confequently their refpective Distances, both one from the other, and alfo from each of my Stations M and N ; viz. the Extents ab, or ac, &c, or bc, or bd, &c. being apply'd to my Scale of equal Parts, give the Meaſure of the ſaid Di- ſtances. PROBLEM IV. To find the Horizontal Line or Length of an Hill or Moun- tain. On the Top of the Hill, at C, fet up a Staff or Mark of an equal Height with your Eye (above the Ground) or with the Staff to which the Quadrant is faſt- ned at B the Bottom of the Hill. Then move the Quadrant 'till you fee the Top of the (Staff or) Mark at C, whereby you'll Trigonometry. 57 } You'll take the Angle CBA. Then mea- fure up the Side BC of the Hill. 4 Being come up to C, meaſure the Level Cc on the Top of the Hill. Then meaſure the other Side be of the Hill, and take the Angle cba, as you did afore the Angle CBA. Having done this, you may find the Length of the Hill, either by Calcu- lation or Protraction. If you work by Calculation, then in the Triangle ABC, having the Angle (CBA or) B, and the Hypotenuſe BC, the Bafis BA is found by Cafe 5, Tab. İ, viz. R: SC: BC: CA. In like manner, in the Triangle abc having the Angle b, and the Hypotenufe be, the Bafis ba is found by Cafe 5, Tab. II. If you work by Protraction, then ha- ving protracted the Hypotenufe BC, and on one End B thereof protracted alſo the Angle (CBA or) B; from the End C of the Hypotenufe let fall a Perpendicular CA upon the other Leg of the Angle B. The Extent BA will be the Bafis of the Trian- gle ABC. In like manner will be found ba, the Bafis of the other Triangle abc. Having thus found (either by Calcula- tion or Protraction) the Meaſure of the two Baſes BA and ba, theſe two added together, and alfo to the Length of the Level-Line Ce on the Top of the Hill, will give the total Meaſure of the hori- zontal 58 The Young Gentleman's zontal Line or Length of the whole Hill. Namely, Suppofing BA=160 Yards or Chains, &c. and ba=182, and the Le- vel-Line Co=122, the total Meaſure of the Length of the Hill will be 464. And thus much for taking of Diftances. Pro- ceed we next to Surveying. I. Surveying, why e- CHAP. VI. Of Surveying or Meaſuring of Land. ΤΗ HE Surveying or Meaſuring of Land is eſteem'd as belonging to Tri- gonometry, and fo ufually taught in Steem'd as Treatifes of Trigonometry, becauſe the to Trigo- Way formerly us'd to ſurvey, was by ta- nometry. king the Angles and Sides of the feveral 2. Triangles, into which any Spot or Tract of Ground may be divided; and then protracting the faid Angles and Sides on Paper; and after that finding the Area or Content of the feveral Triangles ſo pro- tracted. This Method is illuftrated Fig. 35. An Exam- wherein the feveral Lines AB, BC, CD, ple of the c. reprefent the feveral Sides or Hed ges of a Ground thod of and the ſmall Cir- Surveying. cle T reprefents the Place of the Theodo- old Me- 3 lite. Trigonometry. 59 • lite. Which being there plac'd, by turn- ing the moveable Index thereof as Occafi- on requires, the feveral Angles ATB, BTC, CTD, &c. are taken. And then by meaſuring with a Chain (or the like) from T respectively to A, B, C (&c.) thereby is found the Length of the feve- ral Sides TA, TB, TC, TD, &c. of the feveral Triangles ATB, BTC, CTD, &c. And fo by the Help of the Angles and Sides thus found, the other unknown An- gles and Sides of the feveral Triangles may be found, (either by Calculation or Protra- &tion ;) and fo the feveral Triangles may be protracted, and confequently the whole Ground, made up of the faid Triangles. The Ground being thus protracted, its A- rea or Content is found (as has been ob- ferv'd in the Ufe of Theor. 7, Chap. 1, of the Young Gentleman's Geometry) by let- ting fall a Perpendicular from any Angle in each Triangle to its oppofite Side, and multiplying the faid oppofite Side in- to half the Perpendicular. Thus the Content of the Triangle ATB may be found, by letting fall a Perpendicular from the Angle ABT to the Side AT, and multiplying the Side AT into half the faid Perpendicular, (or, which comes to the fame, by multiplying half the Side AT into the whole Perpendicu- Jar.) And in like manner may be fonnd the 6.0 The Young Gentleman's 3. the Contents of the other feveral Trians gles BTC, GTD (c.) and confequent- ly of the whole Ground ABCDEF. But now forafmuch as the Finding of A better the Angles and Sides in each Triangle, Method of Surveying. into which any Ground may be divided, is only in order to protract the Triangles, and fo to find the Contents of the ſaid Triangles when protracted; hence there is found out another and much more ex- pedite and exact Way for finding the faid Contents, (without being at the Trouble, firft to find the Angles and Sides of each Triangle, and then to protract them when found, viz.) by finding the Mea- fure of the Perpendicular and its Bafis in the Field or Ground it felf. I fhall there- fore fay no more of the old Method of. Surveying, (which properly belongs to Trigonometry) but. fhall forthwith pro- ceed to ſhew the other Method, as being much to be preferr'd before the old Me- thod, for the Reaſons already mention'd. And this Method I fhall illuftrate, by fhewing how to furvey thereby the fame Ground ABCDEF. ple. 4. An Exam Fig. 36. And this Method is illuftrated Fig. 36. For being come into the faid Ground, after viewing it, I perceive it may be con- veniently diſtinguiſh'd into two Trapezi- um's ABCD and ADEF. Wherefore ha- ving Trigonometry. 61 ving fet up (*) Marks at the feveral An- gles or Corners of the Ground ABCDEF, the ſtrait Line AD (fuppos'd to be drawn between the Angles A and D) will divide the Ground into the two Trapezium's a- foremention'd. Then I (†) meaſure with my Chain from A to C for the Diagonal AC, whereby the Trapezium ABCD is di- ftinguiſh'd into two Triangles ABC and ADC. And (either () as I go along mea- furing the Diagonal AC, or elſe after I have meaſur'd it) I find the Perpendicu- lars PB and PD by the Inftrument for that Purpoſe, which from its Uſe and Shape (*) Theſe need be no other than Sticks, with fome white Thing (as linnen Rags or Paper) faſtened on theis Tops. (t) In order to meafure aright the Diagonal AC, (or any other ftraight Line or Side of your Ground,) with the Chain, you must take great Care, that you keep in a ftraight Line (as you go meaſuring) from A to C. In order whereto, he that carries the End of the Chain, must take Care that he that carries the Beginning of it, is always (at leaſt that Hand of his which carries the Be- ginning of the Chain) directly between him and the mark C they are meaſuring to, every Time the Chain is laid down, And in order to prevent any Miftake as to the Number of Chains, it is advifable for him that goes firft at the Head of every Chain's Length to thruſt or faften a Stick into the Ground, to be taken up by him that carries the End of the Chain. And fo ac laft the Number of Sticks will fhew the Number of whole Chains. (1) It ſeems most adviſable to measure the whole Dia- gonal firit, becaufe, hereby there is the lefs Danger of miſtaking the Length of the Diagonal, may 62 The Young Gentleman's may be call'd the (*) Perpendicular-Top. In like manner I meaſure from A to E for the Diagonal AE, which diſtinguiſhes the Trapezium ADEF into two Triangles ADE and AEF. And then by my Per- pendicular-Top, I find (one after the o- ther) the two Perpendiculars PD and PF, and meaſure them with my Chain. And thus, the outer Sides or Hedges AB, BC, CD, DE, EF, FA, being all of them ſtraight or right Lines, the Work is done in the Field; all that remains to be done, being only to multiply half the Perpendi- culars into their reſpective Diagonals, in order to know the Area or Content of each Triangle or Trapezium; and ſo of the whole Ground: Which may be done at Home, the Numbers of the Meaſure (*) For this Inftrument is beft made in the Shape of a common Top, which Boys ufe to whip. It is beft made of a dried Piece of Box or Pear-tree, that will bear three Inches, or three Inches and an half Diameter. This being turn'd flat on the upper Round, (with a Neck to fit to the Head of a Staff,) find the Center of the faid upper Round or circular Surface, and thereon draw two or three concentrical Circles, (as you fee, Fig. 38,) divide the faid Circles exactly into four equal Parts, (as in Fig. 38,) and then, with a Whipfaw very thin, faw by the Marks a, b, c, d, the two Lines ab and cd at right Angles pretty Deep. Thus, your Inftru- ment is made; only in order to uſe it, it muſt be ſet on the Head of a Staff, as has been above intimated. To which End it is to be made with an Hole at the Bottom to flip on upon the Head of a Staff. of Trigonometry. 63 of the feveral Diagonals and Perpendicu- Jars being fet down in Writing, as foon as taken. 5. Chain, and the by Num- Content of a Ground by the faid Chain. And here it muſt be fhewn, how the Numbers, denoting the Number of whole of Gunter's Chains or of fingle Links, are to be mul- tiplied in order to find the Content. The Way of Chain then here fuppos'd to be made ufe Working of by the Surveyor is that, which from bers, to its Contriver goes by the Name of Gun- find the ter's Chain, and which is beft contrived for Surveying. It contains four Statute- Poles or Perches, each Perch containing fifteen Feet and an half, or five Yards and an half: fo that the whole Chain is fixty- fix Feet or twenty-two Yards long. The whole Chain is divided into an hundred equal Links, fo that twenty-five Links are juſt a Pole or Perch. And for the more ready counting the Links, it is uſu- al to diſtinguiſh every Ten with a Braſs Plate, (or the like) fo contriv'd as to fhew, fome way or other, whether it be the first, or fecond, or third, &c. Length (i. e. the 10th, or 2cth, or 30th, &c.) Link from either End; the 50th or Mid- dle Link having a more remarkable Plate than the rest. In meaſuring any Line or Extent by this Chain, regard need be had only to whole Chains or whole Links; which are to be writ down with a feparating Note, (whe- 64 The Young Gentleman's : (whether Full-point or Comma, or any o ther Mark) between the Chains and Links, (as is ufual to do between Integers and Decimals,) viz. 6.35 denotes 6 Chains and 35 Links. If the Links be under 10, a Cypher must be prefix'd, viz. 7.09 denotes 7 Chains and 9 Links. ; The Numbers denoting the Chains and Links being fet down, as has been direct- ed; to find the Content (of an exact Square or other rectangular Parallelogram, you multiply (*) the Length by the Breadth but it feldom hap'ning that Grounds are of fuch a Shape, hence it is generally requifite to diftinguish your Ground into Trapeziums, as has been a- fore fhewn, and then to find the Con- tent) you multiply the Diagonal by (†) half the Perpendicular, (or (1) the like) and from the Product cut off five Figures (accounting Cyphers for fuch,) reckon'd from the right Hand, with a Daſh of (*) Agreeably to what has been taught in Defin. 41, Chap. 1, of the Young Gentleman's Geometry. (†) Agreeably to what has been taught in the Ufe of Theorem 7, Chap. I, of the Young Gentleman's Geometry. () Namely, the Product will be the fame, whether you multiply the whole Diagonal (or Bafis) by Half the Perpendicular, or the whole Perpendicular by Half the Diagonal, or the whole Diagonal by the whole Perpen- dicular; and take Half the faid Product for the Product fought. your Trigonometry. 65 your Pen: So that the Figures to the left Hand denote the Acres. ! If the five Figures cut off to the right Hand were not all Cyphers, multiply them by 4; and from the Product cut off again five Figures towards the right Hand, and the reft will denote Roods or Quarters of an Acre. Laftly, if among the five Figures of the laft Product, cut off towards the right Hand, there be any Figures befides Cy- phers, multiply all the five Figures by 4c. From the Product cut off again five Figures to the right Hand; and thofe of the left Hand will denote fquare Perches or Poles. I ſhall now illuftrate the fore- going Rules by fome Examples. Suppoſe then in Fig. 36, the Diagonal AE to be juſt 7 Chains long, and the Per- pendicular PF to be 2 Chains and 88 Links, and the other fhort Perpendicular pD to be 60 Links. I (†) add the two Perpendiculars together, and the Sum of them makes 3 Chains and 48 Links. (†) For this is the most expedite Way, hereby ha ving fav'd the Trouble of two diftinct Multiplications, firft of PF by 70%, and then of pD. F 1 Then 66 The Young Gentleman's Then the Half of the faid Sum of my Perpendiculars,viz. 174, I multiply by the whole of my Diagonal (700. I cut off the five Figures to the right Hand, and the remaining 1 de- notes one Acre. 174 700 121800 Then I multiply the five Figures cut off by 4, and the Product, (viz. 21800×4=) 87200, not amounting to above five Fi- gures, I perceive the Trapezium ADEF do's not contain a full Rood (or Quarter of an Acre) above the whole Acre found afore. 87200 40 Therefore I multiply again the fecond Product 87200 by 40; and cutting off again the five Fi- gures to the right Hand in this third Product, the two remain- ing Figures 34 denote fo ma- ny fquare Perches or Poles. Which wants almoſt fix fquare Perches of a Rood, or Quarter of an Acre, this con- taining 40 fquare Perches. For a Sta- 34/88000 tute-Acre contains 160 fquare Statute- Perches. (1) I chooſe my Diagonal for the Multiplier, becauſe it being 700, I need multiply only by the Figure 7, and to the Product thereof add the two Cyphers. Upon Trigonometry. 67 } Upon the Whole therefore I find, that the Trapezium ABEF contains one Acre, and a Quarter of an Acre over, wanting fix fquare Perches. I proceed then to find the Content of the other Trapezium ABCD; whofe Diameter AC fuppoſe to be 5 Chains and 15 Links; the Perpen- dicular PB to be 1 Chain and 61 Links ; and the other Perpendicular PD to be 1 Chain and 89 Links. Where- } fore 1 multiply the Diagonal 5.15 by Half the Sum of the two Perpendiculars, viz. 175; and the Product not arifing to above five Figures, I perceive that the faid Trapezium does not contain a Whole Acre. 515 175 2575 3605 515 90125 90125 Then I multiply the Product found by 4; and from the ſecond Pro- duct cutting off five Figures to the right Hand, there remains the Figure 3, which denotes the 4 Contents of the Trapezium to 360500 be 3 Roods or three Quarters of an Acre, and ſomewhat more. 60500 I proceed therefore to find what more it is, which I do by multiplying the 5 Fi- gures cut off by 40. From this third Product I cut off a- gain the five Figures to the right Hand, and the remain- ing 24 denote fo many fquare F 2 40 24/20000 Perches; 68 The Young Gentleman's Perches which is a little above Half a ; Quarter of an Acre. So that upon the Whole I find the Trapezium ABCD to contain 3 Roods and a little (viz. 4 ſquare Perches) above half a Rood. Acres Roods Sq. Per. I . 00. 34 0. 03. 24 In the last Place then, by adding the Contents of the two Trapeziums ABCD and ADEF toge- gether, I find the whole Ground ABCDEF to con- tain one Acre, three Roods, and fifty-eight ſquare Perches: Which ſquare Perches a- 1. 3. 58, that is, 2. 0.18 mounting to a Rood more, and eighteen fquare Perches over, therefore the Con- tent of the faid Ground is in all, (when exprefs'd after the more proper Manner) two Acres, and eighteen odd fquare Per- ches. After the fame Manner may the Con- tent of the Ground ABCDEFGHIKL, re- prefented Fig. 37, be found. Name- ly, firſt, ſet out in it as large a Trape- zium ABGL as you can; and find the Content of the ſaid Trapezium, by mul tiplying Half the Diagonal, AG into the Whole Sum of the two Perpendiculars PB and PL. Then find the Content of the Triangle BFG by multiplying its Bafis BG Trigonometry. 69 BG into Half the Perpendicular PF. Then find the Content of the Nook CDE by diſtinguiſhing it into as many Trian- gles (*) as you fee requifite, viz. CDc, Ded, and dcE; and finding the Content of each Triangle, as you did of the Tri- angle BFG. And in like manner is the Content of the other two Nooks GHI and IKL to be found. And then at laſt, the feveral Contents of the feveral Parts of the faid Ground being added all together, will give the Content of the Whole Ground. And after this Method may a- ny Piece of Land be ſurvey'd, the feveral Cafes that can happen in meaſuring the Sides or Hedges of any Ground being re- preſented in Fig. 37. 6. or Setting Hitherto it has been fhewn, how to furvey or meaſure a Piece of Land already of Laying Set or laid out within its reſpective out a Piece Bounds. It may be of uſe to obſerve of Land here next, how to fet or lay out a Piece requir'd. of Land or Ground of fuch a Meaſure, as fhall be requir'd, or containing ſuch or fuch a Number of Acres, &c. (*) Namely, by this Method circular Nooks may be meaſur'd as exactly as by any other; at least fo exactly, as that what is wanting of Exactnefs, fhall be fo little as to be altogether inconfiderable. But it must be noted, the more Triangles fuch circular Nooks or Windings are divided into, the nearer you'll come to the exact Meaſure of it. F 3 In 70 The Young Gentleman's 7. Acre, what. In order hereto, it is to be known in A Statute the first Place, that an Acre according to Statute-Law does contain one hundred and fixty fquare Statute-Poles or Perches ; each fuch Pole or Perch containing (as has been above obſerv'd) fifteen Feet and an Half, or five Yards and an Half. Such being the Content of an Acre, it follows, that all rectangular Pieces of Ground,any of whoſe contiguous Sides are of any of the two Lengths fet oppofite here- to, will contain juſt an Acre. Whence it is obvious, how a Ground of a fin- Perches 80 * 40 × 32 * 2 4/ Square Perches 5=160=1 Acre: 8 20 x 16 × 10 &c. gle Acre may be laid out, if there be Room to make its contiguous Sides per- pendicular one to the other, viz. by ma-. king the two contiguous Sides of fome of the two Lengths ſet together above, Hence alſo it is obvious, that Grounds which have very different Sides, may yet have the very fame Content. If there be not Conveniency to lay out the Acre of Ground in a rectangular Shape, then it may be laid out it in any other Shape or Figure, by confidering what Proportions are to be taken, to make the Content of the faid Figure juft equal Trigonometry. 7 1 equal to 160 equal Perches. For In- ftance; if I can lay out the Acre in a Triangular Bafis Perpend. Shape; then the Baſe and Perpendicular of the faid Triangle muſt have ſome of oppofite the 160 & 2 160 × I 80 × 2 80 & 4 64 & 5 for 64 ×21=160 40 & 8 40 × 4 32 & 10 32 × 5 &c. (&c.) Perpend. Bafis (or fuch like) Proportions one to the o- ther; forafmuch as the Bafis multiplied into Half the Perpendicular (or vice ver fa) gives the Content of a Triangle. The Way, how to lay out an Acre of Ground in a triangular Shape, being known, thereby may be known the Way to lay out an Acre of Ground in any múl- tangular Figure; forafmuch as all Poly- gons may be conftituted by adjoining to- gether feveral Triangles. And it being thus known how to lay out a fingle Acre of Ground in any Shape or Figure; thence may be known how to lay out Grounds of more Acres than one in any Shape, by proportionably encreafing the Lengths of the reſpective Parts. And thus I have taken notice of ſo much of Sur- veying, as feems requifite to the Defign of this Treatife. F A CHAP. The Young Gentleman's I. A Fort, what. 2. B CHA P. VII. Of Fortification. Ya Fort or Fortress is fignify'd a Place fortify'd, i. e. made ftrong by the Art of Military Architecture, or For- tification. The principal Part of a Fort, is that A Ram- which is called the Rampart or Rampire, part,what. being a Wall of a good Height and Breadth, compos'd chiefly of Earth, and encompaffing the Place fortify'd. It is re- prefented Fig. 39, by DEWXYZ. 3. The Bulwark or Bastion of a Rampart Bulwark is that Part of it, which runs farther out Baſtion, than the reft, ending in an Angle. It is reprefented Fig. 39. by IFEGH, &c. bat. 4. ·oulder, on, what. The feveral Parts of a Baftion are its be Face, Face or Front FE; its Gorge (or Neck) :orge, IH; its Shoulder F; and its Flank (or d Flank Wing) FI; which, according to the new oj a Baſti. Method of the French, is not built in a ftrait Line, but rounding, as is repreſent- ed in fome of the other Baftions, by the Prick'd-circular Lines about the Flank. The Part of the Rampart between two A Curtain, Baſtions is called the Curtain KI, which xbat. joyns together the two Baftions IFEGH 5. and KLDMN. + 1 More- { Trigonometry. 73 Moreover, forafmuch as (according 6. outer and what: to the Rules of Fortification) every Ram- The Side part is either a (*) Polygon, or at leaſt of the a Tetragon; hence the Line DE is cal- inner Po- led the Side of the outer Polygon; BC the lygon, &c. Side of the inner Polygon; AC the Semi- diameter of the inner Polygon; AE the Semidiameter of the outer Polygon; pA the Cathetus of the inner Polygon; PA the Cathetus of the outer Polygon; Pp the Distance of the Polygons. Befides which there are wont to be 7. peculiarly diſtinguiſh'd alſo theſe feveral TheGorge- Lines, viz. the Gorge-line IC; the Head- Line, Line CE; the (†) Longest Line of De- Line, &c. fence KE, the Shortest Line of Defence what. kE. Head- 8. Angles in By the foremention'd Lines and Parts of the Rampire are constituted feveral of the Angles, whereof the Chief are theſe ; viz. principal BAC the Angle of the Center; BCA or Fortifica CBA the Angle of the Polygon; FEG the tion. Angle of the Baftion, otherwife called the Diamond Point, and the Flanked Angle; DOE the outer Flanking Angle; Fkl the (*) The Reaſon of this Rule of Fortification depends upon the due Proportion there ought to be between the feveral Parts of the Rampart. And hence, according to the faid Rules, a regular Polygon is to be preierr'd before an Irregular. The Rampart, Fig. 39, is a regular Hexa- gon. (†) See Set. 30, 31, 32, of this Chapter. 1 inner 74 The Young Gentleman's 9. inner Flanking Angle; FCE the Front- angle, or Angle forming the Face; FCI the Flank-angle, or Angle forming the Flank; CEF the Head-line Angle, &c. It is alfo obvious, that by the foremen- How For- tion'd Lines are made feveral plain Trian- belongs to gles, viz. ABC, ADE, APD, APE, ApB, Trigono. ApC, pFl, kFI, FIC, FCE, &c. Hence tification metry. 10. any three Parts of each of the faid Trian- gles (except the (1) three Angles) being known, the other three unknown may be found by Trigonometry, as has been a- fore fhewn. Such as would have parti- cular Illuſtrations by Examples, may con- fult fuch Treatifes as are profeffedly writ- ten of Fortification. Thofe young Gen- tlemen, for whoſe Uſe this Treatife is e- fpecially defign'd, being fuch as are not likely to concern themſelves in the practi- cal Part of Fortification, it feems abun- dantly fufficient to my Defign, to have thus fhewn in general how Fortification depends upon Trigonometry. However being thus led, by (the Sub- The Expli- je&t of this Treatife) Trigonometry, to cation of take notice of the foremention'd Parts Terms of and Terms of Fortification, becauſe it Fortifica- may be of good Ufe, in order to make other tion. (1) The Reafon of this Exception is largely given, Chap. 2. §. 1, of this Trigonometrical Treatife. young Trigonometry. 75 young Gentlemen underſtand, in a com- petent meaſure, Relations given of Sieges, I fhall therefore here add the Explication of fuch other Parts and Terms of Fortifi- cation, as are of principal Note and Ufe, and ſo moſt frequently occur in the Ac- counts of Sieges. II. A Parapet then is (properly) a Work rais'd on the Rampart, behind which the A Parapet, Soldiers ftand, and where the Cannon is what. plac'd for the Defence of the Fort. As in Fig. 51 and 52, ab denotes the Breadth of the Rampart at its Bafis or Bottom, fo de denotes the Breadth of the Parapet at its Bottom, or where it is rais'd on the Rampart. I 2. A Banquet is no other than a Foot- pace at the Bottom of a Parapet, upon A Ban- which the Soldiers ftand up to fire into quet,what. the Ditch, or upon the Covert-way be- yond the Ditch. Some Parapets have on- ly one Foot-pace, as is reprefented by de, Fig. 51. But it is the more commo- dious to have two, one for the taller Sol- diers, and another (fomewhat above the former) for the fhorter, as is reprefented between d and e, Fig. 52. 13. According to the old Way of Fortifica- tion, there is erected between the Ram- 4 Fauffe- parts and the Ditch, a Work called the bray, Fauffe-braye, or Falf-brage, being a fmal- ler Sort of a Rampart, having a Parapet, and whats 76 The Young Gentleman's 14. The Co- vert-way, what. 15. The Gla- and running round the whole main Ram- part of the Fort. It is repreſented Fig. 51, by xyz. But the French omit this Work now-a-days in their Fortification, leaving between the Rampart and the Ditch only a Space about three or four Foot wide, to receive the Earth which falls from the Parapet. This Space they call the Berme. See Fig. 52. Wherein, as alfo Fig. 51, klmn denote the Ditch. On the outer-fide of the Ditch is the Covert-way, being a Way or Walk (round the out-fide of the Ditch) cover'd or de- fended by the Glacis. It is reprefented Fig. 51 and 52, by np. The Glacis ferves as a Parapet to the cis, what. Covert-way, and lofes it felf infenfibly in the Field. Hence the Largeſt are e- ſteem'd the Beft, becauſe they lofe them- felves more infenfibly than fhorter ones. It is denoted Fig. 51 and 52, by prs. 16. The Counterfcarp is properly the Slope The Coun- nm of the Ditch on its Out fide, as being terfcarp, oppofite to the Scarp or Slope kl of the what. 17. Ditch on its Infide. But by this Term now-a days is generally understood the Covert-way with its Parapet. Befides the Works hitherto ſpoken of, of the ad- and which are requifite to all Fortificati- Works of ons, there are alfo other additional Works Fortificati- contrived by Maſters of Military Architec- ditional n. ture. Trigonometry. 77 ture,for to further fortify the feveral Parts of Fortification already defcrib'd. And fuch are Half-Moons, Horn-works, Crown- works, Star-works, Ravelins, Tenailles, &c. Of which the four former take their Names from their Shape. They will all be better apprehended by their refpective Draughts, than by verbal Deſcriptions. 18. what. I begin with the Tenaille; of which there are three Sorts, reprefented Fig. 40, ATenaille, 41, and 42. They are placed in the Ditch, and before the Curtains of the Rampart. They are faid to be contriv'd by the French inſtead of the Fauffe-braye. The Tenaille, Fig. 41, is diftinguifh'd by the Name of the fingle Tenaille; and that Fig. 42, by the Name of the double Tenaille. 19. what. A Ravelin is reprefented Fig. 43; be- ing a ſmall triangular Work. It is gene- A Ravelin, rally rais'd alſo before fome Curtain, ei- ther of the main Rampart, as Fig. 43, and 46, or of fome Out-work, as the Ravelin, Fig. 44. before the Curtain of the Horn-work, Fig. 47, or elſe before ſome other Part analagous to a Curtain, as the Ravelin, Fig. 45, before the fingle Tenaille, Fig. 41. 20. Moon, An Half-Moon (Fig. 53.) is generally confounded with a Ravelin, its Diffe- An Half- rence being principally (if not only) what' this, that its Gorge df is an Arch in Shape of 78 The Young Gentleman's 21. work, what. of the Concave Part of an Half-Moon, and it is placed overagainst Z, the Point of a Baſtion to cover it; whereas a Rave- lin confiſts of two ſtraight Demigorges, as de ef, Fig. 46, and is placed overagainſt fome Curtain, as is afore obferv'd. An Horn-work is reprefented Fig. 47. An Horn. The Fore-part of it confifts of a Curtain between two Half Baftions, which run out like Horns, whence it takes its Denomi- nation. It is placed either before a Cur- tain or a Baſtion. 22. work, what. A Crown-work is reprefented Fig. 48. It A Crown is fo called, becauſe the Fore-part of it reſembles a Crown. It is ufually made before an Horn-work, to keep the Ene- my at a Diſtance. It is alfo placed imme- diately before a Curtain or Baſtion of the Rampart. 23. A Star- work, what. 24. A Re- doubt, what. Out- 25. works, what. A Star is a Work with feveral Fa- ces, which flank one the other, as Fig. 49. A Redoubt is a ſmall fquare Fort, or a Guard-houſe, having no Defence but in Front. It is ufually defigned for main- taining the Lines of Circumvallation, or Countervallation. In watery Places they are often made of Mafon's Work, It is repreſented Fig. 50. All the foremention'd Works, which lie without the Rampart of the Forts, are in general call'd the Out-works, A Trigonometry. 79 26. A Battery is a Place rais'd whereon to plant the great Cannon, in order to bat- A Battery, ter or play upon the Place befieg'd. what. what. Cavaliers are Works rais'd on the Para- 27. pet of a Rampart, whereon to plant Can- Cavalliers, non in order to fcour the Field, and to oppoſe any Work rais'd by the Befiegers, which commands the Place befieg'd. Fafcins are a Sort of Faggots, made to 28. throw into the Ditch, where there is Fafcins, much Water, in order to make the Paf- what. fage over to the Wall or Rampart of the Place befieg'd, more eafie. 29. Gabions are Baskets filled with Earth, and uſually placed upon Batteries, and Gabions, Parapets, that have fuffer'd very much, what. and alſo before other Places, to ſecure them from the Enemies Shot. Leffer Ga- bions are call'd Corbeilles. 30. A Gallery is a made Way or Walk, co- ver'd with Earth or Turf, and upheld A Galery, with Planks. They are made in the Ditch what. already fill'd with Fafcins, to the end the Miners may approach fafe to the Ba- ftion. The Line of Defence is that, which is 31. reprefented by the Diſcharge of the fmall Line of Shot towards the Face of a Baftion. It Defence, is diftinguifh'd into the Longest and Short- est, otherwife called Fichant and Ra- Sant. what. The 80 The Toung Gentleman's 32. Line of Defence Fichant, what. 33. Defence Razant, what. The Line of Defence Fichant (or Long- est Line of Defence) is the Line KE, fo called, becauſe the Bullets or Shot, which paſs along this Line, may fix on the Face of the oppofite Baſtion. The Line of Defence Rafant (or the Line of Shortest Line of Defence) is the Line kE, drawn from the Face of the Baſtion, to that Point k, of the adjoining Cur- tain, where the Face of the faid Baſtion begins to be diſcovered. It is fo call'd, becauſe the Shot, that paffes along the faid Line, only rafes the Face of the ſaid Baſtion. 34. A Lodg- ment, what. 35. A Lodgment is a Work caft up in a dangerous Poft won by Attack, to ſecure the Befiegers againſt the Enemies Fire. It is made of any Materials, that are capable of making Reſiſtance. To nail up a Cannon, is to drive a To Nail up Nail (or the like) into its Touch- a Cannon, hole. what. 36. To Sap, what. To Sap, is to dig deep into the Earth of the Covert-way and Glacis in the Form of a Trench. The Earth dug out ſerves for a Security on the Right and Left, and covers above, the Soldiers (or others) in the Trench againſt the Enemies Fire- works, by the help of Hurdles laden with the faid Earth. Military Trigonometry. 8: what. Military Trenches are of the fame Kind 37. with common Trenches, only larger, be- Trenches, ing uſually from fix to feven Foot in Depth, and from eight to ten Foot in Breadth. They are made by the Befieg- ers, to approach more fecurely the Place befieged whence they are otherwife cal- ; led the Lines of Approaches, or fometimes the Approaches. And they are therefore fo carried on, as not to be in View of the Enemy, or preſently and eafily difco- verable by the Enemy or Befieg'd. Circum- vallation, Lines of Circumvallation are Trenches 38. made by the Befiegers about their Camp: Lines of as well to hinder the Relief of the Be- fieged, as to ftop Deferters from their what. own Army. They are guarded with a Pa- rapet. Lines of Countervallation are Trenches 39. which the Befiegers make to fecure then- Lines of felves from the Sallies of the Befieg'd. Counter- They are alfo guarded with a Para- what. pet. vallation, Lines of Communication are Trenches 40. made from one Work to another by the Lines of Befiegers, for the better holding Commu- Commu- nication one with the other, and helping what. one the other, in cafe of an Attack by the Enemy, in any of their Works. nication, 41. A Retrenchment is a Work made by the Befieg'd to fecure themſelves, and fo to 4 Re- enable them to hold out fome time lon- trench- C menc, ger what. $ 2 The Young Gentleman's ger againſt the Enemy, who is fo far ad- vanc'd as to be lodg'd on the Rampart. It has either a good Parapet, or inſtead thereof Gabions. And thus I have ex- plain'd the more ufual Terms of Fortifi- cation, and fuch as more frequently oc- cur in Relations of Sieges. I. The Me- adjoin'd to tife. CHA P. VIII. Of the Tables of Logarithms, and Artificial Sines and Tangents. T HE Tables of Artificial Sines and Tangents belonging properly to i hod of the Trigonometry, they are therefore here artificial adjoin'd to the End of this Treatiſe. Sines and They are ſo contriv'd, by placing the Tangents, Sines and Cofines by the Side one of the this Trea- other, and likewife the Tangents and Co- tangents, that each Page fhews the Sine and Cofine of two Angles, one whereof is fet down on the Top of the Pages, the other (being the Complement of the former to 99) at the Bottom of the Page. Thus the Page (or Pages,) that hath Degree 2 at the gree 87 at the Bottom. and Cofines, Tangents Top, hath De- And as the Sines and Cortangents belonging Trigonometry. 83 belonging to the Degrees fpecified at the Top, are reſpectively fhewn by the refpective Words fet at the Top of the feveral Columns in each Page; fo the Sines and Colines, &c. belonging to the Degrees ſpecified at the Bottom, are re- ſpectively fhewn by the refpective Words fet at the Bottom of the feveral Columns in each Page. 2. The Minutes between each two De- grees are fet down on the Sides of the Pages, thoſe appertaining to the Degrees at the Top increafing downwards ; the other appertaining to the Degrees at the Bottom increaſing upwards. And on the Side of each Minute ſtands its reſpective Sine and Cofine, Tangent or Cotangent. And, although Logarithms are of Ufe, in other Parts of Mathematicks as well The Table as in Trigonometry, yet becauſe they rithms, of Loga- muſt always be uſed with Artificial Sines why ad- and Tangents; I have therefore judg'd join alf this the most proper Place alfo for the Treatiſe. Table of Logarithms belonging to my Mathematical Treatifes: of which I need fay no more here, the Ufe of the ſaid Ta- ble of Logarithms having been already explain'd, in the Appendix to the Young Gentleman's Arithmetick. to this G 2 A TA- A TABLE OF Logarithm's, From One to Ten Thoufand ་ N Log. N Log. |N| Log. 110.000000 13411.531479 671.826075 20.301030 351.544068 681.832509 30.477121 361.556303 691.838849 40.602060 371.568202 70,1.845098 50.69897381.579783 711.851258 60.778151 391.591064 1721.857332 70.84509814c1.602060 73 1.863323 80.903090||41|1.612784 74|1.869232. 90.954242 42 1.623249 751.875061 101 000000431.633468 761.880813 111.041393 44 1.643452 77 1.886491 121.079181|45|1.6532-1-2) 1781.892094 131.113943 161.662758 179 1.897627 141.146128 471.672098801.903090 151.176091 48 1.681 241 811.908485 161.204120 19 1.690196 821.913814 171.230449 50 1.698970 831.919078 181.255272511.707579 841.924279 191.278753 521.71600385|1.929419. 201.301030 531.724276 86 1.934498 211.322219 541.732394 87 1.939519 221.342422551.740362 881.944482 231.361728 561.748188 89|1.949390 241.380211 571.7558751 1901.954242 251.397940 1582.763428) 1911.9590417 261.414973 591.770852 92 1.963788 271.431364 601.778151931.968483 281.447158611.785330 941.973128 291.462398621.792391 951.977723 301.477121 6311.799240 1961.982271 311.491361| |64.1.806180| 1971.986772 321.505150 651.812913 981.991226 331.518514 661.819544] 1991.995635 ! The Table of Logarithm's. N|| 。 | 이 ​1 2 | 3 34 100/1000000000434000868001301001734 101004321004751005181005609006038 102 008600009026009451009876010299 103 012837013259013679014100014521 10401703301745017868 018284018700 105|021189 021603022016022428022841 106 025306025715026125026533026942 107029384029789030195030599031004 108 033424033826034227034628035029 1090374261037825038223038620039017 110041393041787042182042576042969 111045323045714046105546495046885 112049218049606049993050379050766 113053078053463053846054229054613] 114056905051286057666058046058426 115||060698061075061452061829062206 116064458064832065 206065579065953 117068186058557068928069298069668 118071882072249072617072985073352 1190755470759120762760766401077004 1200791811079543079904080266080526 121 082785083144083503083861084219 122086359086716087071087426087781) 123089905090258090610090963091315 12409342209377209412209447109482c 125||0969100972570976040979511098298 126 100371 100715 101059101403101747 127 103804104146 104487104828 105169 128 107209107549107888 108227 108565 129 110589110926 111263111599111934 The Table of Logarithmes., 1 5 | 6 | 7 | 8 | 9 |D 002166002598003029003461003891 | 432 006466006894007321,0077480c8174 010724011147011570011993012415 424 014940015359015779016197016516419 428 01911601953201 99470203610207751416 0232520236640240750244861024896||412 027349227757028164028571028978408 031408031812232216232619033021||404 035429035829036229036629037028400 03941403981104020406020409981496 04336210437550441480445390449321393 047275047664048053048442048830389 05115305153805192405230905 2694 386 054996055378055760056142056524 382 058805059185059563059942c60320379 06258206295806 3 3 3 30 637091064083|376 066326 066699 067071067443067815372 070039070407070776 071145071514 369 366 073718074085074451074816075182 077368 077731078094|078457078819363 108 0987 081347 | 281707|082067082426||360 1080987 084576084934285291085647086004||357 688136c88490088845 089198 009552 355 091667092018 092369092721 092071 251 095169095518095866 096215096562349 098644098989099335099681|100026||346 102091,102434 102777103119103462 342) 105510 105851106191 106531106871 340 108903 109241 109579 109916110253 338 112269112605112939 113275113609335 H The Table of Logarit hmes. N|| 0 | 1 | 2 | 3 | 4 130|113943114277114611|114944|115278 131 17271117603117934118265 118595 132120574120903121231121559121888 123 1238521241781 24504124830125156 134 127105127429127753128076128399 1 35|| 130334|130655|130977|131298|131619 136 133539133858134177134496 134814 137 136721137037137354137671 137987 138 1398791401941 40508 140822141136 139143015143327143139143951144263 1 140||146128 146438|146748|147058147367 141 149219 149527 149835150142150449 142 152288152594 152899153205153509 143155336 155639155943 156246156549 144158362158664158965159266 159567 145||161368161667|161967|162266|162564 146 164353164650164947165244165541 147 167317167613167908 168202168497 48 170262170555170848 171141171434 149173186173478173769174059174351 150||175091|176381|176669|176959177248 151|17897717926479552179829|180126 1 152181844182129 82415182699182985 153 184691 18497518525985542185825 154||187521|187802|188084|188316|18864. 17 55||190332,190612|190892|191171191451 156||193125|193403|193681|193959194237 157 195899 196176196453967291 97005. 158 198657198932199206 99481199755 158 201297 201670201942 202216202488 The Table of Logarithmes. | 5 | | 6 | 7 | 8 | 9 || D 1156 11 || 1 5943|116276|116608116939 333 118926 119256 119586119915120245 330 122216122544122871123198 123525 328 325 12548125806 12613112645612678 128722/129045 12926812968930012 323 1319391322591132579132899133219||321 135133135451135769 1360861 36403318 138303 138618138934139249139564 315 141449141763142076 142389142702314 144574144885|145196|145507145818|3 I I 147676 14798511482941148603148911309 150756157154151369151676151982 307 153815154119154423 154728155032 305 156852157154 157457 157759158061 303 159868 16016160469160769161068||301 162862163161|163459|163758164055 259 65838166134 166430 166726167022 297 168792169086|169380169674169968 295 171726 172019 172311 172603 172895 293 174641 174932175222 175512175802 291 177536 177825 178113,178401 178689||289 180413180699180986 181272181558 287 183269183555183839 184122 184407 285 186108186674 186674186956187239 283 188928189209189490 189771190051281 191739|192009|192289|192567|192846|| 279 194514 194792195069195346195623278 197281 197556197832198107198382 276 200029 200303 200577 200850201124 274 202761 203033 203303120357712038481272 H 2 The Table of Logarithmes. |N|| 0 | | 2 | 3 | 4 t 1601204119/204391 204663 204924 205 204 161 206826207096 207365 207364207904 162 209515209782210051 210319210586 163 212187212454 212720212986 213252 164 214844215109 215373215638/215902 16521748421774721801c21827 2 | 218536 165 22010822036922063 220892 221153 167222716222976223236223496 223755 16225209 225568 225826226084 226342 16522788722814222840c 228657 | 2 2 8 9 1 3 170 | | 2 3 0 4 4 9 1 2 3 0704 230959 231 21 5 2 3 1 469 171 232996233250 233504233757234011 172 235528 235781 236033236285 239537 173 238046238297238548238799239049 174240549240799241048241297 241546 175|| 243038/243286 243534 243782244027 176 245513245759 246C06246252246499 177 247973 248219248464248709 248954 178 250420 250664250908251151 251395 179125285325309512533342535S253822 180/2552731255514|255755 255996 256237 181257679'257918258158 258398258637 182 260071 260309 260548 260787261025 182 262451 262688 262925 263162263399 184264818 265054265289 265525265761 1851267172 267406267641 267875/268109 186 269513269746269979270213270446 187 271842272074 272206272538 272769 188 27415274389 274619274850275081 184 27462276692 276921277151277372 The Table of Logarithmes. 5 | 6 | 7 | 8 | 9 ||D 2054751205746 206016 206286 206556||27| 208173 208441 208710,208978 209247 269 210853 211121 211388 211654211921 267 213518 213783 214049 214314214579 266 216166 216429 216694 216957217221| |264 218798 212060 219323 219585 219846 267 221414 221675 221936 222196 222456 [261 224015224274 224533|224791 225051259 226599 226858 227115 227372 227629 258 229169 229426 229682 229939230193 256 231724 231979 232234232483 232746 254 234264 2345 17|234770|235023 235276||253 236789 237041237202 237544 237795252 239299239549239799 240049 240299 250 241795|242044|242293|242441 242789249 244277 244525 24+772 245019245266248 246745 246991247237 247482,247728 246 248198 249443 249687 249932250176245 351638 251881 2521 25/252268|252610243 454064/254306 25+548/254789 255031| |242 256477 2356718 256958|257198 257438 241 258877 259116 259355 25959+,259833, 239 261 263 261501 261739 261976 262214 263636 263873|264109|264:46'264582||237 255996 256232|266467|2667c2|266937||235 238 268341268578268812 269046 269279 234 |270679 270912271144 271377 271609 233 273001273233 273464 273696 273927 232 275311275542 275772 276002 276232 230 277609277838|278067|278296278525||229| The Table of Logarithmes. 1 I N|| 0 | 1 | 2 | 3 | 4 190278754278982 2792111279439279667 191 281033 281 261 281488 281714 281942 192 283301 283527 283753 283976284205 193 285557 285782286007286232 286456 194287802288026288249 288 4 7 3 2 8 8 6 9 6 195||290035|290257|290479|290702|290925 196 292256 292478 292695 292920|293141 197394466294687 294907 295127295347 198 296665 296884 297104 297323 2975421 199 298853299071 2.99289|2995071299725 2001 3010293012473014641301581301898 201 303196303412303628|303844304059) 202 305351305566|30578 305996 306211 203307496 307709307924308137 308351 204|1309630309843|310056|3 10268 310421 205|||3117541311956;3 1 2177|31 238931260c 206 313867314078314289314499314709 207 3 159703161803 163893.16 599 316809 208|| 318063318270318481|318689318898| 209 3201463 203543 2056 23 20769320977 وم 2 1 0 || 3 2 2 2 1 9 3 2 2 4 26,32 26 3 3 1 3 2 2 835 | 323046 211 3242823244883246943 24899|325105 212 326336326541 3267453 26945 327155 213 328379328583 328787328991329194 213330414330617330819331022331225 21133243833264033284213330441333246 21 216 334454334655 334856335057 335257 336459336659336856337059337259 218 338456338656338856339054 339253 219340444 340642 340841341039 341237 The Table of Logarithmes. - r 5 | 6 | 7 | 8 | 9 | D 1 1 279895280123|÷80351| 28057828089 ‹ || 228 282169282396282622 282849 233075 227 284431 284656284882285107 285332||226 286681 286905287125287354 28757225 288919/289143 289366| 289585|289812|| 223 2911471291369|291591/291813|292034||222 293362 293584293804 294025 294246221 295567 295787|296007|296226 296446|| 220 297761 297979298198298416298635||219 299943 3001613303780000595/300813218 3021141302331302547302764302979 217 304275304491304706304921305136 216 306425 306639306854307068307282 215 308564308778308991 309204309417313 310693310906311118311329311542212 312812313023313234313445313656|| 211 3149103151303 15349 315551315760 21C 3170183172273 17436317646 317854 209 3191063193143195223197203 1993 208 321184321391321598321805 322012||207 32325232345 3 23665 3 2 38711324077206 325310325516325721325926326131205 327359 327563327767527972328176204 329398 329601329805330008330211 203 331427 331629|331832/33 2034332256202 333447 333649333850 334051334253||202 335458335658335859336059336259 201 3374593376593785833805338257 200 339451 3396503984934004740246 199 341425341631|341830342028|342225||198 1 The Table of Logarithmes. N|| 0 | 1 | I 1 | 2 | 2 | 3 | 4 220134242234262C 4281713430143212) 221 223 344392344589|344785344981345178 222 346353346549346744346939 347135 34830524849534869434888249082 224350258350442350636350829351023) 2 2 5 | | 3 5 2 1 8 3 3 5 2 3 7 5 1 3 5 2 5 6 8 1 3 5 2761352954 226354108 354301 354493354685354876 227 35602635621735640835659935679c 228 357935 358125|358316358506 358696 229||359835360025360215360404360593 239136 17 28 3619173621051362294362482 231363612 363799363988364176 364361 232 36548 365645 365862 366049366236 233 367356 3675423677293679153 68 234|| 369216369401|369587|369772369958 ICI 235371068371253, 271437 371622371806 236 372912373094373279373464373647 237 376577374932375115375298 375481 238 376577 3767593769423771 24377336 39|378358 378579378761378942379124 240 13802113803921380573 380754380934 241 282017 382197382377382557 382737 242 383815383995 28417438435 3 3 8 4 5 3 3 243 385606385785 385964 386142386321 2443873891387568287746|38792338810 245 38916613893431389529138 9 6 9 8 3 89 875 246 39093539111239128839146439164 247 392697392873393048393224 393399 248 394452394627394802394977395152 249 396199'396374 396548396722 196896 ' ! } The Table of Logarithmes. ' 5 | 6 | 7 | 8 | 9 || Dj ||DI 343409343606343802343999344196||197 345373 345569345766 345962 346157 196 347330 347525 347720 347915 348110|| 195 349278349472349659 349860 350054 194 351216 351409|351603351796 351989 193 353147 353339 353532353724353916193 355068355239355452355642355834 192 356981 357172357363357554357744 191 358886359076359266359456 35964 190 360783 360972361161 361350361539|189 362671 362859363048363236|363424||188 364551 364739 364926 365113365301 188 366423 366609366796366982 367169 187 368287358473368659368845 369030 186 370143 3703281370513370698370882||185 371991 372175372359372544372728||184 373831374015374198 37438: 374565 184 375664375846 376029 376212376394 183 377488 377670377852 378034378216 182 379306379487379668379849 380030181 3 8 11 15 3 8 12 9 6381476|381656 381837|| 181 382917383097383277383456 3 8 36 3 384712 384891385c69385249385428 179 3 86 199 386677386856387034387212 178 388279388456388634388811388989 178 180 390051390228390405 390582390759177 391817391993392169392345 392521 179 393575393751393926394101 394177 17t 395326395501395676 395850 96025 175 1297071297245397419397592397766174 ( The Table of Logarithmes. Ꮓ | | 0 N|| 0 | I 250 | 2 | 3 | 4 397940398114[398287 398461398634 251 399674399847 400019400192400365 252 401401401573 401745 401917402089 253 403121403292403464403635403807 254 404834405005 405176405346405517 25511406540406710406881407051407221 256 408239408409 408579408749408918 257 409933410102 410271410439410609 258 +11619411788 411956412124412293 259413299413467413635413803413969 26C1414973/4151404153071415474415641 261416641416807416973 417139417306 262 418301 418467418933418798418964 253 419956420121 420286 420451420616 264 421604421768421933 422097422251 26511423246,423 409142357414237371423901 266 424882 425045425208425371 425534 267426411426674426836426999 427161 268428135428297428499428621 428783 265429752429914430075 430236430398 270 | | 431364431525|431685,431846432007 271 432969433129433289433449433609 2721434569434729434888 435048435207 273 436163436322 436481 436639 436799 274437751437909438067438226438384 275 439333 4394911396484398061439964 276 440909441066 441224 441381441538 277 442479442637 442793442949 443106 278 444045 444201 444357 444513444669 279 1445604/445759445915446071446226 The Table of Logarithmes. 1 5 | 6 | 7 | 8 | 9 || D 39880398981399154399328399501 || 173 400538 40071 1400883401056401228 173 402261 402433402605402777402949 172 403978 10414940432040449 404662 171 405688 405 858 406029|406199405869|| 171 107391 407561407731407901408079|| 170 409087409257 409426 409595409764169 410777 410946 411114411283411451 169 412461412629412796412964413132 168 414137414405414472414639414806||167 415808415974416141416308416474 167 417472417638417804417969418135||166 419129419295419460 419625419791 165 420781 420945421110421275 421439 165 422426422589422754422918423082164 4240651424228424392 424555|424718||164 +25697425860426023126186426349 163 162 427324427486427548 +27811427973 428944 429106429265429429 129591 162 4305594307191430881431042431203161 +32167432328 432488;432649432809 || 161 +33769 +33929434089434249434409160 +35366 +35526 +35685435844 +36004159 +36957 +371 16 37275437433437592 159 +38542 +38701438859439017439175|148| 440122 440279440437440594440752 | | 158 441695441852442009 442166442323157 443263 443419443576 443732 443889157 444825 444981445137445293445449156 | 4 4 6 38 2 4 4 6 5 37 416692 416848447003||155 I 2 The Table of Logarithmes. No 1 | 2 | 3 | 4 1 2801 +47158447313447468|4476231447778 281 448705448851449015449169449324 282 450249450403450557450711450865 283451786 451939 +52093452247452399 284 453318453471453624453777454929 285454845 45+997455149455302455454 286 +56366 4 5 6 5 1 8 4 5 6 6 6 9 4568 1456973 287457889458033 453184458336458487 288459392459543459694459845459995 2891460898461048,461196461348 461499 2901462398462548462697462847462997 291 +63893464042 +64191464340 464489 292 +65383465532 +6568046829465977 293 +66868 46701646716446731246746ċ | 294|1458347 1468495+68643468790 468938 295469822469969470116 +70263 +70410 296471292471438471585 +71732471878 297 472756472903473049 +73195 473341 298 +74216474362474508 +74653 +74799 299 +75671475816475962 +76107 +76252 300 +77121+77266477411477555 477699 201 +78566 +78711478855478999479123 302 +80007180151480294480438480582 202481443481586481729 481872482016 304482874 +83016483159483302483445 305||484299484442,484585|484727/484869 306485721485853486005485147486289 307 48713848727948742 487564487704 208488551488592488832 +88974 +89114 209 489958490099'490229 490279 1905 20 › The Table of Logarithmes. 5 | 6 | 7 | 8 | 9 || D 447932448088/448242,44839714485521155 44947449633 449787 449941450095154 451018451173451326451479451633154 452553 452705152859453012453165153 4550 2454235/454387454539454692|| 463 455606455758 455910456062456214 152 45712545727045742845757945773152 4 5 8 638 45 87 8 9 +58939459091459242 15 1 460146460296460447 460597460748|151 461649461799461948 4620984622481|150 463146463296463445 463594 463744|150 464639454788464936465085 465234 149 466126 466274466423 466571166719 149 467608 467756467904 468052 +68199 148 459085 469233469380 469527469675447 | 146 4705571+70704470851 +70998471145147 472025472171 472318172464 47261C 140 47 3487 ± 7 3 6 3 3 473775 +7392597407: 474944 +7508175235 +75381 475528 146| 476367476542476687 +76833476976 145 145 477844477989 +78133478278 | 478422 479287479431479575 479719 179863 144 480725 480865481012481156 481299 144 4821594823048244548258848273143 4835874837 29 483872 184015484157143 4850 185153 185295/485437 +85575 | | 142 4864356572486714 186855486997142 487845.87986488127 +88269 +88409141 48925 +8939648953 189677 489818141 490661190801490941 +91081491122||14C The Table of Logarithmes. N|| 0 | 1 | 2 | 3 | 4 I 3101 491362 491502491642191782191922 311 492760492900 493039 193 179 +933 19 312 494155|494294494433|49457249471 313 495544495683495822 195960496099 314 +96929497068497206+9734497483) 3151498311/4984481198586498724/198862 31649968749.9824 499962500099500236 317 501059401196501333501470501607 818502427502564502700502837502973 31915037911503927150406315041991504335. 3201505149505286505421 | 5055 5 7 1 5 0 5 6 9 3 321 506505506640506776506911507046 322 50785650799.508126508260508395 323 509203509337 509471509606|50974C 3241 1510545 5106795 10813510947511081 3255118835120175121515122841512418 326 513218513351513484513617513750 327 514584514681514813514946515075 328 515874516006516139516271516403 329 5171955 17 328517459|517592517724 3 39 15 1 8 5 1 41 5 18646518777518909|519040 33151982851995952009 520221 520353 1 3 2 || 5 2 1 1 3 8 5 2 1269 521399 52153952166 333522444522575 522705522835522966 334 523746523876523876524136524266 3351 52504515 25 17 4 5 25 304|5254341525563 336 526339526469526598 526727526856 337 527629 527759527888528016528145 338 528916529045 529174529302529430 33953019953032815304565305841530711 I The Table of Logarithmes. 1 5 | 6 | 7 | 8 | 9 ||D 4920624922011492341492481 492621||140 49345 493597493737 493876 494015 139 494850 +94989495128 +95267 495406 139 49623 496376496515 +96653 196791 139 497621 497759497897 498035 498173 138 498999 49913749927514994121499549; 1138 50037 5005 10500648500785500922137 501744 50188c502017 502154502291 137 503109 503246503382503518503655 136 504471504607504743504878 505014136 505828505964|506099|5062341506369 507181 5073 16 507451 507586 507721 135 508529508664508799508934509068 135 509874 510009510143 510277510411 134 511215511349511482511616511749 134 36 512551512684512818512951 | 513084 || 133 5138835140165 14149 514282514415 133 515211 515344515475 515609 515741 133 5165355166685167995 16931517064 132 5178555 17987518119518251518382||132 51917 1519303519434 519566,51969||131 520484 520615520745520876521007 131 521792 521922 522053 52218352231413 523096 523226 523356523586523616 13C 523096 523226 5233565 52429615245261524656'424785 524915130 } 5 25 692 | 525 822 | 52595 1|526081|5 2621c 129 526985527114527243 527372527501129 528274528402 528531528659528788 129 529559 529687529815529943530072 128 53283「7356s8[5ལྟïo96l;༢222「5313;1[ 125 The Table of Logarithmes. N|| 0 1 | 2 | 3 | 4 340 531479531607|531734|53 1862 | 5 3 1989 341 532754532882533009533136533264 342 534026534153534280534407534534 343 535294535+21 535547535674535800 344 536558536685536811536937537063 345537819537945538071538197538322 346 539076539202539327539452539578 347 540329540455540579540705540829 348 541579541704 541829541953542078 349542825542929543072543199543323 350544008544192|544316|544440 544562 351 545307545431545555545678 545802 352 546543546666546789546913547036 353 547775 547898 548021 548144548267 354549003549126549229549371549492 3 5 5 5 5 0 2 285 503555047355059555071-7 356 551449551572551694 551816551938 357 552668552789552911553033553155 358 553883 554004554126554247554368 359155509455521515553361555457555578 360 | | 556303 | 556423155654 4 5 5 6 6 6 4 5 5 6 7 8 5 361 557507557627557748557868557988 362558709558829558948559068559188 363 559907560026560146 560265560385 364561101561221 561339561459561578 365562293562412562531 562649 | 562769 366 563481563599563718 563837 563955 367 564666564784564903 565921 565139 368 565848 565966566084 566202566319 369567026567144 567262 567379567497 The Table of Logarithmes. 5 | 6 | 7 | 8 | 9 || D| 522117532245532372 532499532617) j128 533391533518533645533772523099 127 53 4661534787534914535041 53 5167|| 127 535927536053536179536304536432||120| 5371895373155374415375671537693, 12. 538448538574538699538825538951126 5-970353982953995454 07954-204125 5409,5541079541205541329541454125 542203542327542452 542576542701125 543447543571543696543819543944|12. 544688544812544934 545059 545183 || 1 545925546049546172546296,546419124 54715954728254740547529547652 123 548389548512548635548758 548881||123 4. 549616549739 549861549984550106122 550839.550962551084|551206|551328| 122 552059,552181 552303552425552547 122 553276 55338655351955364055375212 55448955461c554731554852554973121 5556991555819555940556061556182121 20 556905 557026|5571465572671:573871 558108558228568349558469558589|| 120 $59308559428559548559667559787||120 560504 560624560743 560863 560982 115 561698 561817561936 | 562055 56 2174| 562887 563006563125563244563362119 564074564192564311564429564548 119 565257565376 565494565612565729118 566437566555 566673566791566909||118 567614567732 567849567967:68084118 K The Table of Logarithmes. X } No | 0 | 0 | 1 | 2 | 3 | 4 370|| 56820256831956843656 8 5 5 4 1 5 6 8 6 7 1 371569374569491 569608569725 569842 37257054357065957077657089: 571009 373 571709 571825 571942 572058 72174 374|572872 572988573104573219573336 375574041 574147 574263574379574494 376 575188 575303575419575534575649 377 576341 576457 5765725766875,6802 378 577492577607577722577836 577951 379 5786395787545788681578983579097 3801579784579898 580012580126580241 381580925581039'581153581267581381 382 582063582177582291582404582518 383 583199583312583426583539:58365 384||584331584444584587|584670584783 385585461585574 585686585799585912 386585587586699586812586925587037 387 587711 587823587935 588047588 59 288 588832588944589056 589167589279 3891589949590061590173590284590396 390 | | 59 10 65 59117659128 1591399 591509 391592177592268592399592509592621 392 593286593397593508593618593729 393594393 94503594614594724594834 394595496595606595717595827595937 395 596 597 5967 07596817|596927|597037 396 597695 597805 597914598024598134 397 59879 598899599009599119599228 399599883599992600101600210600319 399|60097360108260119160129901408 The Table of Logarithmes. 5 | 6 | 7 | 8 | 9 || D ליי 568788 | 5689051569023| 569139 | 5 6 9 2 57 569959570076570193 570309570426 117 57 126 571243571359571476571592117 57229 572407572523572639572755 115 57 245 2573568573684573799573915||116 57460947+726574841 574957|575072||116| 575765 575880 575996576111576226 115 576917577032 5771475772625773 75 578066 578181578295.578409578525115 579212 579326 579441 5795551579669114 580355 5804 691580583 580697580811114 581495581608581722 581836 581.949 114 582631 582745582858582972 583085 114 583765583879583992 584105 584218 113 848965850095851221585235585348113 こ ​5860245861375862495863621586475 587149587262587374587486587599||1 12 588272588384588496588608588719 112 589391589503589615589726589838||112 590507590619590750590842590953||112 591621 59173259184359195559206. 592732592843592954593064593175 1 593839593950 594061594171594282 11 594945 595055 59516559527559538611C 596047 596167596157596377.596487||118 597146 597256 5973665 7476 597586||110 598243 598353598462 598572 598681 110 599337599446599556599665599774|109 6004286 0537600646,600755600864 109 601517601625601734601843 601951109 K 2 2: The Table of Logarithmes. N| O 1 | 2 | 3 | 4 405020596021696022771602386,602494 40 503144603253603361603409503577 1403 40 60422660433460 +442604550604658 505 205, 60541 265521 605628605736 40606381606489606596606704606811 405 607455607562507669607777607884 406 6085261608633608739 608847608954 407 609594609701 609808,609914610021 408 610660510767610873610979611086 409 61172361 829611936612042612148 41061278461 2889612996|613102|613207 41 16 2842613947614053 614159614264 412614897615003615108615213615319 41 31 615950616055616160616265616370 414617000617105 617210617315 617419 4.15 618048618153518257 618362618466 4166190935191986 9302619406619511 417620136620240620344620448620552 418621176621280621384621448 621592 419622214622318622421 622525622628 +20 | | 62 324 96 23 3 5 31623456 623559623663 421624282624385624488 624591624695 +22625312625415 625518625621625724 4236263406264436 26546 625 6 48 626751 424627 36 6 6 27468527571 527673 627775 +25628389628491162859362869568797 426294096 951262961362971629817 427630428630529630631630733630835 428 63144463 164763 1647,631748631849 42916324576325591632559163276632862 The Table of Logarithmes. 718 110 5 | 6 | 7 | 8 | 9 || D 6026036021176028191602928603036|108 603686,603794|603902|604009|604118||108 604766604874604982 50508005197 08 60584460595 506059606166 606274 108 606919607026607133607241607348107 607991608098608205601312608419 107 609061 6091676092746~9381609488 107 610128610234610341610447610554 107 61119261129861 140561151161 1617 106 612254612359612466612572|612678||106| 613313613414613525|613630613736||106 614369614475514581614686 614792 06 615424 615529 615634615739615845||105 C5 616476616581616686616790616895 617525 617625|517734|6178396 17943 || 105 618571;618676618780|61 834618989|| 105 619615 619719619824619928620022104 620656620760620864620968621072||| 104 521695621799 52190262200 221 C 04 62273262283562293962204262314304 6 2 3 7 6 6 6 2 3 8 6 9 | 6 2 3973|624076|6 ≥4179||103 624798624901625004625 625827625929526032626135526237 107625209 10 103 626853 62695652705862716162726103 627878627979628082628185628287 102 628899629002 629104 | 6292066293081103 629919 630021530123530224620326 102; 630936631038631139531241631342|| (02: 531951 632052632153632255632356 101 6320636230641633165633266623267101 The Table of Logarithmes. } ! 3 | N|| 0 | 1 1 2 | 3 | 4 IN 4 43063346 16 33 569 6336706337711633872 431634477534578634679634779634880 432635484 635584 635685635785635806 433636488536588636688636789636889 434637489537589637689637789637889 4356384896 3 8 5 8 3 | 538 68 91 63 87 8 9 6 3 5 888 436 6394866395803968653978; 639085 437 640481640581540680640779640879 438 641475641573641672641771 641871 43964216542563 64266254276164 2860 44 || 5 4 3 4 5 3 64 355 15436505437 49 1 0 4 3 8 47 441544439644537044636644734544832 444045422645521645619 5457. 545815 44 54540464650264659964669 646796 4441547383 647481647579 647670547774 44554836064845864855564865 2 1 5 4 8 7 5 0 446549335649432549529649627549724 447550308650405550502,650599550696 551278651375147265156651666 44 4 4 9 11 5 5 2 2 4 6 6 5 2 3 4 652439652536652633 1; 8. 4 5 0 1 1 5 5 3 2 1 5 5 3 3 0 9 6 5 3 4051553502 55359 45 6541775427365436955446555450 45 55512 555235 55331555427555523 456560956194 55628 656386556482 45455705657152 657247557343 557438 455 | | 558011558107658202|65 8 2 9 8 1 658 39: 456 55896565906065915565925065934 45 559916560011660106 56020166029 458 660865660960361055 661149561245 459661813661907 66200266209666219! The Table of Logarithmes. 5 | 6 | 7 1617 | 8 | 9 || D 633973634075634015342766343761|100 6351835283635383 100 634981635081 6 359 8 6 6 3 6 0 8 763618-535288636388 10 636989637089637189 637289637389|| 100| 637989638089628 893828963838 婆 ​6 3 8 9 8 8 6 3 9 0 8 0 | 639188639287|639387 639984640084640183 64028364038 640978641077641177641276641375 641969642069642168642267642360 99 99 99 99 99 642959643058 6431566432556433541 99 643946164404416441431644242 544340 ၄င် 644931645029645127645226645324 98 93 645913646014610964620546306 64689464699254708964718 517285 98 647872647969648067548165548262 6488 486 48945|549043649140549237 6498216499195500 6650113550210 98 97 97 97 65079365089065098765108455118: 65176265185965195665205 552145 97 652729652826155292365301; 553116 653695 65379165388853984554080 97 96 96 6546585547546548555 9+6555042 55619655715655819 559-6556002 96 656 577 556672556769568 6 4 5 5 6 9 6 0 657534657629557725657820557916 96 96 95 6584 8 7 1558584155867955877-1558869195 659441 559536659630659726559821 660391 66048666058166067 560771 661335561434661529661623 561718 9 662286 562380662475662569 66266 95 95 95 The Table of Logarithmes. N| O| I 1 | 2 | 3 | 4 +6 01166275 8 6 6 2852662947663041663135 +61 663701 66379 663889663983664078 462 664642664736664829664924665018 463 665581565675665769665862665956 464 666518666611666705 666799 | 666892 4656674536675461667639667733667826 568386668479668572668665668759 669317669409669503669596 669 689 468 670246670339670431670524670617 469671173671265671358671451671543 466 467 4701 6720986721906722836723751672467 471 673021673113673205673297673389 472673942674034074126674218674309 473 674861674953675045675137675228 474 675778675869675962676053676145 475 | | 6766941 6767851676876676968 | 677059 476 677607677698677789677881 677972 477 67851867860y678700678791678882 478 579428679519679609679700679791 479 580336680426680517680607680698 48 4801681241681332|681422681513581603 481 682145682235682326682416682506 482 583047683137683227683317683407 483 583947684037 84127684217584307 484684845 684935685025585114/685204 485 16857425858315859211586010686099 486 586636 58672668685685904 686994 487 687529 587618687707687790 687885 488 68841958850968859858687688776 489|1689309589398689486689575689664 The Table of Logarithmes. 1 5 1 6 1 7 | 8 | 9 ||D 6632296 63324663418663512,663607|| 94 664172664266664359664454664548|| 665112665206665299665393665487|| 94 6660496661436662376063315664.4 666986667079667173667266 6673 9 94 94 94 6679196680 13668106668199668293 | 93 668852668945669038669131669224 669782 669875669967670060670153 93 670709670802670895670988671080 671636671728671821671913672005 93 93 93 672559672652672744672836672929|| 92 673482673574673666673758673849 92 674402674494674586674677674769 92 675319675412675503675595075687 92 676236676328676419676511676602 92 6771516772426773336774246775161 91 678063 678154678245678335678427 91 678973679064679155679246679337 91 679882579972680063680154680245 91 680789680879680969681060681151 91 681693681784681874581964682055 || 90 682596682686682777682867682957 90 683497683587683677683767683857 90 684396684486684576684666684756 90 685294685383685473685563685652 90 1686189686279/686368,586458686547 89 387083 687172687261 687351687439 30 587975688064688153 688242688331 688865688953689042 689131689220 89 689753689841689930690019 6901071 891 L 89 The Table of Logarithmes. N|| 0 | 1 | 2 | 3 | 4 } 490||690196690285690373690462690550 491691081691169691258691347691435 192691965 692053692142692229692318 493 692847692935693023693111693199 49469372769381.5693903|6939911694078 495/169460516946931694781694868694956 496 1695482695569695657695744695832 497 696356696444696531696618696706 498 97229697317697404697491697578 499 698101698188698275698362698449 700184 50011698970,6990576991446992311699317 301 699838 699924 700011700098 502 700704700790700877700963701049 503 701568701654701741701827 701913 504702430702517702603702689702775 5051703291 703377|703463703549703635 506 704151704236 704322 704408 704494 507 705008705094705179705265 705350 508 705863 705949706035 706120706206 509 706718706803706888 706974707059 510707570707655707740707826 707911 511708421 708506 708591 708676 708761 512 709269709355709439 709524 709509 513 710117710202 710287710371 710456 514710963711048711132711217711301 515||711807711892|711976 7120601712144 616712649 712734712818712902712986 51773491 713575715659713742713826 518 714329714414714497 714581714665 1519715167715251715335 715418715501 f The Table of Logarithmes.. 5 | 6 | 7 | 8 | 9 || D 1 690639|690728|690816'690905|690993!| 89 6915246916126917 0691789691877 692496692494692583 692671692759 88 88 692287693375,693463693551693639 88 694166 694254694342694429|694517|| 88 695044 695131 695219|695307,695394|| 88 695919696007645094696182696269 87 696793696880696068697055 697142|| 87 697665697752 697829697926 698014 87 698535698622698709698706698883 87 87 699404699491699578,699664 699751 70027170035870044470053700617|| 87 701136701222701309701395701482|| 86 701999 702086 702172702258702344 702861702947 703033703119 703205| 86 86 86 703721|703807|703893703979704065|| 86 704579 704665704751704837704922 705436 705522705607|705693|705778 706291706376 706462706547706632 85 7071441707219707315707399707485 86 85 85 85 707996 708081 708166708251708336|| 85 708846 708931709015709100709185 709694 709779 709863709948710033 710540710625710709 710794710879 85 711385711469|7115547116391711723|| 84 712229|712313712397|712481|712566|| 84 7130707131547132387 3223713407 7139107139947140787 4162714246 714749714833714916714999715084 84 84 84 715586 715669715753 715836|715919|| 84 L 2 The Table of Logarithmes. N!! 0 | | 2 | 3 | 4 52 716003 716087716170716254716337 521 716838716921717004717088 717171 522 717671717754717837717920718003 52371850278585718668718751718834 524 719331|719414719497719579719663 525720159720242720325720407720490 526720986721068 721151721233721316 527721811721893 721975722058722140 28722634 722716722798722881722963 529 17 2 3 4 5 6 7 23538|723619|723702723784 5301724276,7243581724439|724522724604 531725095725176725258725339725422 532 725912725993726075726156726238 333 726727726809726890726972727053 $34 727541 727623727704727785727866 5 3 5 || 728 3 5 4 7 28435728516728597728678 536729165729246729327729408729489 537 729974730055 730136730217730298 538 730782730863730944731824731105 539 731589 731669731749731832731911 540732394732474732555 7 3 2 6 3 5 | 73 27 15 541 733197733278733358733438733518 542 733999734079734159734239734319 543 734799734879734959 735039735119 5+4 7355997356797357591735838735918 $45 736397736476|736556|736635736715 546 737192737272737352737431737511 547 737987738067738145738225 738305 548 738781 738859738939739018 739097 549739572739651|739731|739809639886| The Table of Logarithmes. 5 | 6 | 7 | 8 | 9 ||D 7164217165041716588|716671|716754|| 83 717254 717338 717421717504717587 83 718086 718169718253718336718419 83 718917718999719083719165719248|| 83 719745 719828719911719994720077 83 720573720655720738720821720903|| 83 721398 721481 721563 721646721728| 82 722222722305722387722469722552|| 82 723045723127723209723291723374 82 723866723948724029|724112|724194|| 82 82 724685724767|724849|724931|725013|| 725503725585725667725748725829|| 82 726319726401 726483 726564726646|| 82 727134727216727297 727379727459 81) 727948728029728110728191728273 8: 728759728841 728922 729003729084|| 8: 729569729651729732 729813729893 81 730378730459730540730621730702|| 81 731186 731 266731347731428731508 8 731991 732072/732152732233732313 381 732796 7328767329:6733637 733117 80 733598 733679733759733839733919 734399734479 734559734639 7347!! 735199 735279735359735439735516 735998736078736157736237 / 7 3 6 3 17 80 80 80 80 80 736795 73687417369547370341737113 737590737669737749737829737908 19 738384 738463 738543738622738701 79 739177739256 739335 739414739493 79 739968740047|740126|740205740284|79| The Table of Logarithmes. N|| 0 | 1 | 2 | 3 | 4 | 559 7403631740442740521|740599 740678 551741152741230741309741388 741467 552 741939742018742096 742175742254 553 742725 742802742882742961743039 554743509743588743667|743745743823 555 744293744371|744449|74452 × 1744606 556 745075745153745231 745203745387 557 745855745933745011746089 746167 558 74663474671274678974686 746945 8 559 747412 747489747567|747645 747722 560748188748266 7483431748421748498 561748963 749040 749118749195749272 562 7497361498 14 749891749968750045 563750508750586750663750739750817 564751279751356751433751510751587 565||7520481752125752202752279|752356 566 752816752893752969753047753123 567 753583753659753736753813753889 568 754348754425754501754578754654 569 755112755189755265 755341755417 5701755875 7559517560277561031756179 571 756636756712756788756864756940 572757396757472757548757627 757699 573758155758230758306758382758458 574758912758988 759063759139759214 5751759668 759743759819759894759969 576 760422760498760573 760649 760723 577 761176 761251761326761402761477 578 761928 762003 762078762153 76222 579 752675 762754762829762904762978! 28 The Table of Logarithmes. 5|6| 7 1 8 1 | 8 | 9 || D 79 79 74075774083674091574099474107: 741546741624 741703 74178274186c 742332742411742485742568742647 79 743118743196 743275 743353743431 78 743902743979744058744136744215 78 74468474 47621744840744919|744997|| 78 745465 745543 745621 745699 745777 78 746245 746323746401 746479746556 78 747023 747 101 747179 747256747334 747800 747878747955748033|748110 74811c 78 78 74857674865317487317488087488851 77 749349 749427 7495047495821749659 77 750123 750199 750277 75035475043 77 750894 75097751048 751125751202 77 751664 751751751818751895 751972 77 752433752509752586|752663752735|| 77 77 77 753199 753277 753353753429753506 753966754042 754119754195754272 754730754807 754883754959755036 76 7554947555691755646 755722755799|| 76 7 5 6 2 5 6 1 7 5 6 3 3 217564281756484175656|| 76 1757016757092 757168 757244 757320 76 757775 757851757927 758003758079 76 75 85 33 758609758685 758761 758836 76 759290759366759441759517759592|| 76 760045760121 760196|760272|760347|| 75 760799 760875 760949 761025 761101 75 761552761627761702761778 761853 75 762303 762378 762453762529762604||||75| 763053 763128763203|763279763356 The Table of Logarithmes. |D||| I | 2 | 3 | 4 | 5801763 42 8176350317635787636531763727: 581 764176764251764326764400764475 582764923764998765072765147 765221 583 765669 765743765818765892765966 584 | | 766413766487766562766636 766710 58 57 6 7 1 5 6 76 7230767304767379|767453 586 767898767972 768046768119768194 587 76863876871276878676886068934 588 769377769451769525 76959 769673 589770115770189770263 770336770410 5901 77085217709261770999|771073|771146 591 771587 771661771734771808771881 592 772322772395 772468772542772615 593 773055773128 773201 773274773348 594 773786 773859 773933774006774079 5957745171774585 7746637747367748 596 775246775319775392775465775538 597775974776047776119776193776265 809 598 776701776774 776846776919776992 599||777427777499777572777644777717 60011778151778224177829617783681778441 601778874778947779019779091779163 602779596779669779741779813779885 603||780317780389780461|780533780605 6041781037781109781181781253781324 605|17817551781827781899781971782042 606782473782544782616 782688 782759 607 783189 783260 783332 783403 783475 608 7839047839757840467841 18784189 609|784617784689784759784831784902 The Table of Logarithmes. T71 5 | 6 | 7 | 8 | 9 ||D 75 763802763877763952764027|764101 754549764624764699764774764848 75 765296765370765445765519765594 766041 766115766189766264766338 766785766859766933767007767682 74 767527767601 767675767749767823|| 74 74 74 74 768268768342768416768490768564 769008769082769156769229769302 769746 769820769894769968770042 770484 770557770631770705770778|| 74 74 74 73 771219771293771367771440971514|||| 771955772028772102772175772248 772688772762772835772908772981 773421 773494773567773640773713 774152774225774298774371|774444 | 73 73 73 73 774882 774955775028 775100775173 775610 775683775756775829775902 73 77633877641177648377655776629 73 777064777137777209 777282777354 73 777789777862777934778006778079 72 72 72 72 778513778585778658778729,778802 77923677930877938077945277-524 779957780029 700101 780173780245 780677780749780821780893 780965 72 781396781468781539781612781684 72 N N 72 7 72 71 782114782186782258782329780401 782831782902782974783046|783 783546783618783689783761 783832 784261784332784403784475 74546 71 78 497 478 50 45 785116785187785259|| 78 M kring. The Table of Logarithmes. | 1 | 0 ||N 2 | 3 | 4 610|| 7853291785401|785472|785543|7856×5 611786041 786112786183785254 786325 612 786751786822786893|786964787035 613 787460 707531787602787673787744 614708164788239788309|788381788451 615|| 7888751788946|789016|789087789157 616 789581 789651789722789792,789863 617 790285790356790426790496790567 6.879098879105979112979119979:269 619791691791761791831791901|791971 620||792392792462792532792602792672 621 793092793162793231 793301793371 622 793791793860 79393 793999794069 623794488794558794627794697794767 624|| 7951851795254795324795393795463 625795880795949 796019|796088196158 626 796574796644796713 796782796852 627 797268797337797406797475 797545 728 797959798029798098798167798236 629 798651798719798789798858798927 630||799341 799409799478799547799616 931800029 800098800167800236 800305 532800717800786800854800922 800992 533801404 801472801541601609 801678 634802089802158802226802295|802363 635802774802842802910802979803047 536 803457003525 803594803662803730 637 804139804208804276804344804412 638 804821804889 804957805025805093 3918055011805569805637805705|805773) The Table of Logarithmes. 7 | 8 | 9 || D ||D 5 | 6 | 16171 7856861785757|7858281785899785979|| 71 786396786467786538786609786680|| 71 787106787177787248787319787389|| 71 787815787885787956788027788098|| 71 788522788593788663788734788804 71 789228789299789369,789439,789510 71 789933790004 790074790144790215 70 790637790707790778790848790918|| 70 791339 791409 791480 79155c791620 70 792041792111|792181|7922527923221! 70) 792742.7928121792882 792952793022|| 70 793441 793511793581,793651793721 794139 794209794279794349794418 794836794900794976 795045795115 70 70 70 795532 7956027956727957417958r0|| 70 69 796227796297796366|796436|796505: 59 796921796990 797059797129 797198 797614 7976837977;2797821797890 69 798305798374798443798513798582|| 69 7989961799065799134799203799272|| 69 799685799754799823|799892,799961|| 69 800373800442800511800579800648 69. 801061801129801 19880126680 335 69 801747 801815801884801952802021|| 69 802432802500802568802637802705 68 803116803184 803252 803321803389|| 68 803798803867 803935 804003 804071 68 804480804548804616 804685 S04752 68 805161805229805297 805365805433 68 Bo5841 8o5908805976 8o6o44 8o61126 M 2 The Table of Logarithmes. N|| 0 | 1 | 2 | 3 | 4 540061798062481806316806384806451 641 806858806926 806994807061807129 642 807535807603 807670807738807806 643 808211808279808346808414808481 644808886808953809021809088809156 6451809559 809627809694 809762809829 646 810233810299810367810434810501 647810904810971811039811106 811173 648 8115758.16428 1709811776811843 64981224512312812379812445812512 650812913812980,813047813114813181 551 813581813648 813714813781813848 652814248814314814381 814447814514 653814913814979815046815113815129 654 815578815644815711 815777815843 6558162418163088163748164401816506 656 816904816910817036817102817169 657 817565817631817698817764817829 658318226818292 818358818424818489 659318885818951819017819083|819149 66c|| 819543|819609819676|8197411819807 661 820201 820267820333820399820464 662820258820924820989821055821120 663 821514821509821645821709821775 664822168822233822299822364822429 1660 6 6 5 1 3 2 282 2822887822952823018823083 666 823474823539823605823669823735 567824126 824191824256824321824386 668824776824841 824906824971825036 669325426825491825556825621825686 1 The Table of Logarithmes. 5 1 6 | 7 | 8 | 9 D 1 8065198065878066558067238067901 68 807197807264807332807399807467 68 68 807873807941808008 808076808143 808549 808616808684 208751808818 67 809223809290809358 809425809492|| 67 8098961809964810031810098810165 810569810636810703810770810837 67 811239 811307811374811441811508 6 811909811977S12044 812111812178 812579812646812713812779812847 67 8132478133148133811813448813514|| 67 81391481398181404881411481418 87 814581814647814714814780814847 67 815246815312815378815445815911 66 815909 815976 816042816109816175 66 816573816639816705 816771816838|| 66 817235817301817367817433817499 66 81789681796281828818094 818159 818556818622818688 818754 818819 66 66 819215819281819346819412819478 66 819873819939|820004820074|820136|| 66 820529 820595 820661820727820792 66 821186821251821317821382821448 66 82 841821906 821972822037822103 65 822495822560 822626|822691 822756|| 65 65 823148823213823279 8233441823409|| 65 823800823865823930823996824061 65 824451824516824581824646824711 825101825166825231825296|825361|| 65 825751825815825880825945826009|| 65 ず ​The Table of Logarithmes. 1 靠 ​N|| o | I 1 2 1 3 1 4 67082607518261398262041826269826334 671 826723826787 826852826917826981 672827369827434 827499 827563827628 673 828015 828079828144 828209828273 674|| |1828659|828724828789 828853828918 6.751182930418293681829432829497 829561 676 829947830011830075830139830204 677 830589830653 830717830781830845 678 831229831294831358831422831486 679 || 831869 831934831998 832062832126 6891832509832573822637832700832764 681833147833211 833275 833338833402 682 83378483384883391 2833975834039 683 834421834484834548 834611834675 684835056835119.835 183835247 835310 6851 83 5691835754183581718358811835944 68 836324836387836451836514836577 687 836957 837019837083 837146837209 688 83758883765283771583777783784 689 83821983828282834583840883847 169011838849 | 83891218389751839038 | 839101 691 839478839541|839604839667839729 692840106840169840232840394840357 693 840733 840796 840859840921840984 594 841359 841423841485 041547841509 69518419558420471842109|842172 | 342235 596 842609,842672 842734842796842859 697 843233843295 843357843415343482 698 843855843918843979 844042844104) 6991844477844539844601844664844726 The Table of Logarithmes. Y 5 | 6 | 7 | 8 | 9 || D 826399826464|82652882659382665865 827046827111827175 827239827305 65 827692827757827822827886827951 65 828338828402828467 828531828595 64 828982829046829111829175829239 64 82962582968982975482981882988211 64 830268830332830396 830460830525 64 830909830973 831037831102831166 64 821614831678831742831806 832185832253832317832381832445 831549 8 3 2 8 2 8 1 8 3 2 8 9 2 | 0 3 29 5 6 | 8 3 3 0 1 9833083 833466 833525 833593833657 8337 2 834103834166 834229834294834357 34739834802834866 834929834993 835373835437835500335564835627 836007 33607|836134|8 3619 7 | 8 36 26 1 83664183670483676783683c | 836894 837273837336837399837463837525 837904837967838030838093838156|| 64 64 64 64 64 6.4 62 63 63 63 63 838534183859783866083 872 318 38786|| 63 8391648392278392898393528394151 63 839792 839855 839918839981840043 63 840419840482840545840608840671 841049 8411c9|841172841224841297 841672841736841797 841859 841922 63 63 63. 842-97842359 8424321842484842547|| 62 842921842983843046 843108843170 62 62 843544843606843669843731843893 844166844229844291844353844415 62 1844788844849844912844974845026 624 The Table of Logarithmes. N|| 0 | 1 이 ​I 1 2 3 4 700 845098845160845222845284845346 701 845718 845779 345842845904845966 702 846337846397846461 846523846585 703846955847017847079847141 847202 704847573847634847696847758847819 7251 8481898482518483 12/848374848435 06 848805 848866848928848989849051 707 849419 849481 849542 849604 849665 708 8500338500958501568502 17 850279 709 850646 8507078507698508291850891 710185125885 1 3 191851 38 1185 14421851503 711 851869851931851992 852053 852114 712852479852541 852602852663 852724 713853089 853150853211853272853333 714853698853759853819853881'853941 7 +5 1854 30 6 1 8 5 4 3 67|85 44 281854488;854549 716 854913854974855034855095 855156 717 855519855579855640855701855761 718 856124856185856245856306 856366 719 | 856729856789|856849|856910 856970 72018573321357393857453857513857574 721 857935357995 858058858116858176 722858537358597 858657858718858778 723 859138859198859258859318859379 724859739859799 859859859918859978 72586033886039818604581860518860578 726 860937 860996 861056851116861176 727861534 851594861654861714861773 728 86213186219186225 18623 10 862369 729862728862787852817862906 862966 The Table of Logarithmes: 5 | 6 | 7 | 8 | 1 61 9 || 1 9 D 845408845470845532845594845655| 62 8460288460898461518462138.6275 62 846646846708846769846832846894 62 847254847326847388 847449 84751 62 84788118479431848004848067848128 62 84849-18485598486 20 848682848743, 62 849112 849174849235 849297849358|| 61 849726849788849849849911849972 61 850339850401850462850524850585 61 85095:1851014851075851136851197 61 85156485162518516868517471851809 61 852175 852236852297852358852419 61 852785 852846 852907852968853029 61 853394853455853516853577853637 61 854002854063 854124854185854245|| 61 8546098546708547318547921854852 | 61 855216855277855337855398855459|| 61 8558228558828559438560038,6064 61 856427 856487856548856608856668 60 857031857091857152857212857272 60 85763485769418577551857815857875 | 60 88236858297858357858417858477 60 858838858898858958859018859078 6c 859439859499859559859619859679 60 8600388600981860158860218860278 60 860637|860697|86c757|8608171860877 861236861295861355861415 861475 60 861833 861893861952862012862072|| 60 862429 86.489862545862608862668 60 863025 863085 | 863144863204863263|| 601 N The Table of Logarithmes. |N|| 0 | 1 | 2 | 3 | 4 730 | | 85 3 3 2 3 | 8 6 3 3 8 286 3442|863 5 0 1 1 863561 863917863977864036864096864155 864629864689864748 731 733 86510486516386522:865282865341 732864511864570 7341865696,865755 1865814865874865933 735 || 86628 7 | 866346,8664051866465866524 736 866878866937 866996 857055867114 737 367467 867526 867585867644867703 738 368056868115868174868233868292 739 3656438687031868762868821868879 740 86923286929|869349|869408|869466| 741 869818869877869935 869994870073 742 870404870462870521870579870638! 743870989871047271106871164871223 744|871573871631871689871748871806 745872156872215872273|8723311872389 746 872739872797872855 872912872972 747873321873379873437873495873553 748 873902 873959874018874076874134 749874482874539874598 874656874714 750|1875061|875119875177875235|875293 751 875639875698875756875813875871 752 876218876276876333876391876449 753 876795876853876910876968877026 754877371877429877487877544877602 5518779478780041878062|878119878177 756878522878579878637878694878752 757 879096879152879211879268879325 758 879669879726879784879841 879898 $7598802428802998803568804131880471 The Table of Logarithmes. 51617 । 8 | 9 ||D 1 63620 | 863 6 79 | 8637391363799|863858|| 59 364214864274864333 86439286445 59 164808864857864925864985865045 59 365400865459865519 865578865637 59 365992|866051866119866169|866228 59 366583 1866642|866701|866759866819|| 59 367173867232867291867349867409 59 867762867821867879867939 86799 868350868409868468868527368586 868938868997869056869114 869173 59 59 59 869525 18595841869642|869701|369759 | 59 870111870169870228870287870345 59 870695870755 870813870872870930 58 871281871339371398871456871515 58 871865871923 8719811871039|872098|| 58 872448137250687256418726221872681|| 58 87302987308887314687220+873264 58 873611873669873727873785873844 58 874192874249874308874366874424|| 58 8747728748298748888749458750021 58 187 5 3 5 11 8 7 5 4 99,875466875524875582|| 58 875929875987876045876102876160 876507876564876622876679876737 58 58 877083 877141 877199877256877314 58 877659877717|877774877832877889|| 58 8782341878292 87834918784071878464|| 57 678808878866878924878981879039 57 879382879459879497-79555879612 57 379955880013880070 8801 27880185 57 1880527380585880642880699880756|| N 2 57 The Table of Logarithmes. * N|| 0 | 1 | 2 | 3 | 4 760 880814880877,88092818809851881042 761 081385 881442881499881556381613 762 881955 882012882 69882126 38218 762 882525 882581882638882695 882752 764 883093 883050883207883264383321 765 | | 883661 | 883718883775883832883888 766 884229884285 884342884399884455 767 884795884852884909884965 885022 768 885361885418885474885531 885587 769188592688598388603918860961886152 7701886491886547886604886659 886716 771 887054887111 887167 387223.887279 772 88761788767488772 887786 887842 773 888179888236888 92888348 888404 774888741 888797 888853388909.888965 775889302889358889414889459889526 776 889862 889918889974890029890086 777 890421890477890533890589890645 778 890979891035891091891147891203 779 891537891592891649891705891760 78018920958921508922061892262892317 781 892651892707892762892818 892873 782893207893262893318893373893429 783 893762,893817893873893928893984 7841894316894371894427894482894538 7851894869894925894980895036|395091 786 8754238954788955339558 895644 787 895975896029 896085896140 96195 788 896526896581896635396692896747 1789 897077897132897187397242897297 The Table of Logarithmes: 5 | 6 | 7 | 8 9 || D 081099881156881212881271 881328 57 881669581727881784881841 881898 882239882297882354882411882468 57 57 882809882866882923882979883037 883377883434883491883549 883605 57 57 8839458840021884059|884115|884172 57 884512884569884625884582084739 57 885078 885135885192885248885305 57 885644885700885757 885812885869 57 8862c88626588622188637858643456 8 8 6 773 8 8 6 829 8868≥ 5886941 886981 56 887336887392887449587505 88,561 56 887898887955888011388067868123 5 5.0 88846088851688857368862888685 56 889021 88907788913488918889246 56 889 5 8 2 8 8 9 6 34 | 389694889745089806 ||56| 890141890197 390253890309 390365 56 890700 890756 390812890868890924 56 891259 89131439137089142691482 56 89181 8918739192889198:1892039|| 56 89 2 373 39 2 4 2 5 189248418925391 8 9 2 5 9 5 1892925 392985893040 893096 893151 89348489353993595893651893706 894039594094894149 894205894261 894595 59464889470-189475989481 56 56 56 55 551 55 551 8951461895201 1895257895312 9536, 55, 895699095754375809.895864895919 896251 896300596361896416896471 896802896857896912896967897022|| 55 897352897407897462897517897572 55 The Table of Logarithmes. N || 0 | 1 | 2 | 3 | 4 1 1 7900976278976828977-7897792897847 79 598176898221598286 898341898396 792 598725898780898835898889898944 79399273899328899383 899437899492 7948998218998751899929|899985500039 795 900367900422190047619005 311900586 796 900913 900958 9010 22 901077 901131 797,901458901513901567901622 901676 798 902003 902057902112902166 902221 799 902547 7026019026551902709902764 800 19030890314490319919032531903307 801 903632903687|903741|903795903849 802 904174904229904283904337904391 805 904716904769904824704878 904932 80411905256'9053107053641905418905472 805119057961905849 305904905958906012 806 906335906389906443 906497 90655.1 807 906874906927 907981 907035907089 808 907411907465 90751907573 907626 80919079491908002 908057708109908163 1810 908485908 5 3 919085 9219086461908699 811909021909074909128909181909235 812 909556909609909663 909716 909769 31391COS1910144910197910251910304 31491062491067910731910784910838 315191115819112119 112639 1 1 3 17|9 11 371 316 911690911743911797 911849911903 317912222912275 912323912381912435 318 912753912806912859912913912966 31 0191 32841 913 3 3 7|913389912443912496 The Table of Logarithmes. 1 5 | 6 | 7 | 8 | 9 | D 397902897957 898012898067898122 898451898506898561898615898670 898999899054899109399164899218 899547 899602 899656899711 899766 900094/900149900 203 9002581900312 55 551 55 55 55 900640900695 900749900804900859 55 901186 901240 901295 901349 901404 55 90173190178590183901894 901948 902275902329 90238490243902492 54 54 9028189028731902927|902981|903036 54 9033611903416903469/90352490357811 54 903904903956904012904066 904120 904445 904499904553 904607904661 904986 905039905094705148905202 9055259055809056349056881905742 54 541 54 54 54 906066|906119906172|906227|906281||54| 906604 906658906712906766906819 907143 907196907250907304907358 907680 907734907787 907841 907895 90821719082709083249083781908421 54 54 54 90875319088071908860 1909 190890711 54 909289 909342 909396109449909503|| 54 909823909877909930|909984910037| 53 910358910411910464910518910571|| 53 910891910944|7109989110511911104|| 53 911424911477911539911584|911637|| 53 119569120099 1 206 39 12 116912169 53 912488912541912594912647912700 913019913072913125913178913231 53 53 913549/9136029136551912708912761|| Sine Co-fine | Tangeut | Co-tang. IM 0'8.71880019.9994041 118.721204 9.999398 28.7235959.999391 8. 38.7259729.999384 48.7283369.999378 5'8.73 68819.999371 68.7330279 999364 7 8.7353549.999357 8 8.7376679.999350 98.7399699.999343 18.719346|11.280604|60 8.721806 11.278194159 .724254 11.275796 58 8.726588 11,27341257 8.7289591 1.27104156 8.73131711.268683'55 8.73366311.266337|54| 8.735996 11.26400453 8.73831711.26168352 8.740626 11.25937451 10 8.7422599.999336) 8.74292211.257078 50 11(8.7445369.999329 18.745207|11.25479349 128.7468019.999322 8.747479 11.252521 48 138,7459559.999315 8.749740 11:25024047 148.7512979.999308 158.7535289 999301 8.751989 11.24801146 8.75422711,24577345 168.7557479.999294| 178.757955 9.999286 18 8.7601519.999279 198.762337,9 999272 20 8.7645119.999265 218.766675 9.999257 228 7688 289.999250 238.7709709.999242 [8.756453 11.243547144 758668,11.241332'43 8.760872 11.23912842 8.763065 11.23693541 |8.765246|11.234754 40 18.757417 11.232583139 8.769578 11.23042238 8.771727 11.228273 37 8.773866,11.22913436 8.775995 11.22400535 248.7731019.999235 258.775223′9 999227) 268.7773339.999220| 18.778114 11.22188634 278.779434 9.999212 288.7815249.999204 298.783605 9.999197 3018.7856759.999119 8.783222 11.219778 33 8.782320 11.21768c32 | Co-fine Sine Degree 86. 8.78440411.21559231 8.78648611.21351430 1 Co-tang. Tangent M Degree 3. M Sine Co-fine 1 | Tangest Co-tang. 1 308.78567519 999189 | 18.786486|11.21351430 3118,7877369,999181 8,781554|11,211446|29| 328,7897879,999174 8,7906131,20938728 338,7918289,999166 8,79266211,207338|27| 348,7938599,999158 8,794701 11,205299|26 358,7958819,999150! 8,79673111,20326925 36,8,7978949,999142 18,798752|11,201248 24 378,7998979,999134 8,800763 11,199237 23 388.8018919,999126 8,802765|11,197235,22 398,8038769,999118 8,807458 11.19524221 408,8058529 999110 8,80674211,193258/20 413,8078199,999102 18,808717111,191283|19| 423,8097779,999094 8,81268311,189317 18 438,8117269,999086 8,81264111,187359 17 448,813667 9,999077 8,814589 11,185411 16 458,815598 9.999069| |8,816529|11,18347115 468,8175229,999061| (8,818461 11,181539 14 478,8194369,999052 8.82038411,179616 13 J 488,8213429,999044 8,822298 11,177702 12 498,8232409.999036 8,82420511,175795 11 508,8251309,999027| 8,82610311,173897 10 5118,82701119,999019| 8,82799211,172008 9 528,8288849,999010 8,82987411,170126 8 538,8307499,999002 8,83174811,168252 7 548,8321069,998993 8.83361311,166377 6 55'8,8344559,998484 8,83547111,164529 5 568,8362979,998976 18,83732111,162679 578,838130 9,998967 8,83916311,160837 3 $88,8399569.998958 8,84099811,159002 2 593,841774 9,998940 8,84282511,157175 1 603,8435859,998941 8,844644 1,155355 of I Co fine l Sine ! Co-tang. Tangent. IM Degree 86. Degree 4. M Sine Co-fine Tangent Co-tang. | 18.84464411.15535 6 6 0 08-8435849.9989411 118.8453879.998931. 8-84645511·15344559 28.8471839-998923 38.848979-998914 48.850759.9989:5 5/8.8525259.998896 8.848240115174058 8.850057 11499437 8.85 +846 11.148154 8.85+846 8.853628 1.14637 2'55 5415 61 1.85429119.9988871 3.8560499.998878 3.857801.9.998869 18.85540311.144597 54 8.85717111.1428293 8.858932 11.14106852 9.8595469-998860 8.860686 11.139314 51 13.8612839-998851 8.86243311.13756750 118.863014/9.998842 8.86417311.135827149 128.8647389-998832 8 865906 11.13409448 138.8664549-998823 8.86763211.132368 47 148.8681659.998813) 8.86935111-130649 46 158.8698689.998804 18.871064 11.128936145 168.8715659.998795) 8.872750 11.12723044 178.8732559.998785 8.874469 11.125531 43 188-8749389-998776 8.876162 11.12383842 198.8766159.998766 8.877849 11.12215141 2c18.8782859.998757 [8.87952911.12047140 219.8799499-998747 8.881202'11.11879839 228.8816079.998738 8.88289611.117131381 238.8832589.998728 8.88453011.11547037 248.8849039.998718 8.88618511.11381536 2518.88654219.998708 18.887833111216 216735 268.8881749.998599 (8.889476 11*11052834 278.8898019.998689 8.8911121110888833 288.8914219.698679 8.892742 11.10725832 298.8930359.998669 1308.89464319.9986591 8.894366 11.105634|31 8.8959841.10401630 Co-fine Sine | Co tang Tangent,M Degree 85. Degree 4. i M Sine, Co-fine, I Tangent Co-tang. I 30|8.894642|9•998659 3118.8962469-998649 328.8978429-998639 18.84598411,104016|30 18.89759641.102404|29 8.89920 11.100797 28 35|4.95259€ 19.99860g| 338.8994327.998629 348.9010179986198 363.9041699.9985991 8.900803|11.099197|27 8.902398 1 1.09760226 18.90398711.096013|25 18.905570 1.09443024 378.9057369.998589 8.907147 11.09285323 388.9072979.998577 8.90871911.091281 22 398.9088539.998568 8.910285 11.08971521 40/8.910404/9.998558 8.91 1846 11 088154/201 418.911940 9.998548 18.913401|11.086599|19 428.9134889-998537 8.91495111-085049 18 438.9150229.998527 8.91649811.08350517 448.916559.998516 8.91803411.081966 16 458.9180739.998506 18.9195681108043215 468.91959119.998495 8.92109611.07890414 478.9211039.998.485 8.92261911.07738113 +88.922619.998474 8.924136 11.075864|12| 49.9241129.998464 8.92564911.07435111 5c89256099.998453| 18.927156 11.07284410 518-9271-09-998442 8.92865811.071344 9 $28.9285879.998+31 8.930155 11.069849 8 538.9300689.998421 8.93164711.068353 7. 548.9315449.998410 8.933134 11.066866 6 5518.93301519.9983991 8.934611.065384) 58.9344819.998388] 57 8.9159429.998377 1588.937398 9.998366 $93.938809998*3.5 60.94029619.998344 |8.936093|11.063907| 4 8.937565 11.062435 3 8.93903211.060968 2 8.940494 11.059506.1 18.94195211.058048 0 Co-fine Sine | Co-tang. | Tangent | Degree 85. Degree 5. M Sine Co-fine | Tangent Co-tang. \ o18.94029619.998344 18.94195211.05804816 c 1,8-941738/9.998333) 8.943404 11.056596159 28.9431749.998322 8.944852 11.05514858 38-9446069.998311 8.9462911.05370557 48.9460349.998300 81947734 11.05226656 5|8.957456|9.998289 8.949168 11.75083255 618-9588149.998277 18.950597111.04940354) 78.9502879.998266 8.952021 11.047979 53 $8.9516969.998255 S.95344111.04655952 98.9530999.948243 8.95485611.0451445 108.954499'9.998232 13.956267 11.04373315 18.9558049.998220 8.957674 11.042326|49 28-9572849.998209 8.959075 11.04092548 38.9586709.998197 8.960473 11.039527 47 48.9600529.998186 8.96186611.03813446 1518.9614299.998174 18.963254|1 1.036746|45| 168.9628019 998163| 178.9641709.998151 18,8.9655349.998139 198.9668939.998 128, 20'8.96824919.998106 218.96960c2.998 104 228.970947.998092 238.9722899.998080 248.973626.998068 258.9749629.998056 26.9762939.99804+ 27 8.9776199.998032 28 8.9789419.99802c 29 8.980259 9.998008 3cl8.981573 9.997996 | Co-fine 1 Sine 18.96463911.03536144) 8.966019 11.033981 +3 8.967 394 11.03260642 8.968766 11.0312344 [8.970133|11.029867|40 18.971495 11.02850539 8.972855 11.02714538 8.974209 11.02579137 8.97556011.044403€ 8.976906|11.0230941 5 1993 18.978248 11.021752 34 8.979586 11.020414 33 8.98092 11.019079 32 3.932251|11.017749,31 18.9835711.01642330 | Co-tang. Tangent M Degree 84. Degree 5. MI Sine Co Sine I Tangent Co-tang. | 3018.9815739-997996| 18.983577 11.01642330 368.9893749 9979221 378.9906609-997910 386.9919439.997897 398.993228 9.997885 318.9828839-997984| 328.9841899.997971 8.9854919.997959 348.9867899.997947 358.9880839.997935 33 8:984899 11.015101|29| 8.986217 11.013783 28 (8.98753211.012468 27 8 98884211.011158 26 8.990149'11.00985125 18.99145111.008 549124 8.992750 11.00725023 8.994045 11.00 595522 8.995337 11.00466321 408.9944979.997873) 8.996624 11.00337620 41,8.99576819.997860] 18.997908 11.00209219 428.9970369.997847 8.999188 11.000812 18 438.9982999.997835 448.9995609.9978221 4519.0008169.9978091 9.000465 10.99953417 9.001738 10.99826216 19.00300710.996993 15 4619 00206919.997797 479.0033189.997794 489.0045639.997771 19.00427: 10.99572814 9.005534 10.994466 13 9.006752 10.993208;12) 499.0058059.997758 9.008047 10.991953 11 5019.007044'9.997722 19.009292199070210 5119.008278 9.9977321 19.01054610.9894541 529.0095109.997719 9.011790 10.988210 539.0107379.997706 9.013031 10.986969 549.0119629.997693 9.014268 10.985732 559.0131829.997680 9.015502 10.984408 569.0143999.997667| 19.016732|10.983268 4 579.0156139.997654 901795910 982041 589.0168249.997641 9.019183 10.98081, 599.0180319.997628 9.020403 10.979597 1 (609.01923519.997614 9.021620 10.97838c| c Co-fine Sine | Co-tang. | Tangent. M Degree 84. R Degree 6. M Sine | Co-fine 1 Tangeut Co-tang. I 1 019 01923519.997614|- 19.0204359.997601 1.021620f10 97838060 19.022834110.977166159| 29.0216329.997588 9.024044 10.97595658 39.0228259.997574 9.025251 10.97474957 4'9.0240169.997561 9.026455 10.973545 56 59.0252039.9975481 19.02765510.97234555 6.9.0263869.997534| 7 9.0275679.997520 8 9.0287449.997507 9 9.029918 9.997493 10.9.031089'9.997480 [ 19.032257|9.997466| 129.0334219.997452 19 034791|10.965209149 9.035969 10.96403148 9.037144 10.96285647 9.038316 10.96168446 19.02885210.97114854 9.030046 10.96995453 9.03123710.96876352 9.03242510.96757551 19.033609/10.966391 50 139.0345829.997439 14,9.0357419.997425 159.03689619.997411 9.039485 10.96051545 169.038048 9.997397 179.0391979.997383 19.04065110.959349144 9.04181310.95818743 189.040342 9.997369 9.042973 10.95702742 199.0414859.997355 9.04413010.95587041 |20|9.04252519.997341| 19.045284 10.954716 40 2119.0437629.997327 19.046434 10.95356039 229.0448959.997313 239.0460269.997299 249.0471549.997285 259.04827919 997271 26|9.0494009.997256) 279.0505199.997242 28'9.051635'9.997228 29 9.0527499.992714 30 9.053859'9.997119} | Co-fine | Sine | 1 9.047582 10.952418 38 9.04872710.95127337 9.049869 10.950131 36 19.051008 10.94899235 19.052144|10.947856134 9 053277 10.94672333 9.054408 10.94559232 9.055535 10.94446531 9.056640'10.94334030 1 Co-tang. Tangent M Degree 83. * Degree 6. | M Sine Co-fine | 3019.0538599.997199| 3119.0549669.997185| 329.0560719.997170 339.0571729.997156 349.0582719.997141 359.05936719.997127 36 9.0604609 997112 379.0615519.997098 38 9.0626389.997083 39 9.06372319 997068 40 9.0648069.997053 Tangent Co-tang. I 19.05664010.943340130| 19.057781 10.942219;29 9.058900 10.94110028 9.06001610.93998427 9.061130'10.93887026 19.062240 10.937760|25| 19 063348110 936652/24 9.064453 10.93554723 9.065556 10.93444522 19.066655 10 933345 21 19.067752|10.932248 20 4119.0658859.997039| 429.0669629 997024 9.068847 10 93115319 9.069938 10.93006218 439.0680369.997009 9.071027 10.928973 17 449.0691079.996994 9.07211310.92788716 459 0701769.996979 19.073197|10.926803!15 4619.0712429.996964 479.0723069 996949 489.0733669.996934 499.0744249 996919 ¡9.07427810.925722 14 9.075356 10.924644 13 907643210.923568,12 509.0754809.996604 9.077505 10.92249511 9.078576 10.92142410 5419.07653319.9968861 529.0775839.996874 539.0786319.996858 549.079676 9.996843 559.0807199.9968231 569.08175919.996812 579 0827979.996797 $89.0838329.996782 $99.0848649.996766 6019.0858949.996751 19.079644 10.920356, 9 9.080710 10.919290 8 2.081773 10.918227 9.082833 10.917167 6 9.08389110.916109 19.084947 10.915053| 4 9.085999 10.914000| 3 9.087050 10.912950 2 9.088098 10.911902 9.089144,10.910856) 1 ! Co-fine Siae Sine | Co-tang. | Tangent. M Degree 83. R 2 Degree 7. Sine Co-fine | 09.0858949.9967511 19.0869229.9967351 9.0879.479.996720 39.088970 9.996704 4/9 089990′9.996688 19 091088 9.996673 69.0920249.996557, ;9.0930379.9966413 89.0940479.996625 99.0950569.996610 109 096062 9.995594 119.0970659.9965781 129.0980669 996562) 139.0990659.996546 149.1000629.996530 159.1010569 996514. 16 9.10204819.99649 17.9.1030379.996482) 189.104025 9.996465 199 1050109.996449 20/9.1059929.996433 2119 10697319.99641 229 1079519.996400 239.1089279.996384 249.109901 9.996358 259.1108739.9963511 2619.1118429.9963351 279.1128099 996318 289.1137749.996302 299.1147379 996285 399 115698 9.995269| · 1 Co-fine Sine Sine I ་ ་ ་ Tangent Co-tang. \ 1 19.089144110.91085660 19.090187 10.90981359 9.091228 10 908772 58 9.092266 10.907734 57 9.093302 10.90669856 9.094336 10 905664155 t 19.095367,10.904633154 9.096395 10.90360453 9 09742210.902578 52 9.098446,10.90155451 19.099468/10.90053250 19.1004810 89951349 9.101504 10.898496 48 9.102519 (0.897481 47 9.103532 (0.896468 46 9.10454-10.895458145 19.105550 10.894450144 9.106556 10.89344443) 9.107559 10.892441 42 9.108560 10 8914401 19.109559 10.890441|40 9.110556 10.889544139 9.111551 1088844538 9.112542 10.887457 37 9.113533 10.88646-36 9.114521 10.885478 35 19 115507110.884493134 9.11649110.88350933 9.117472 10.88252832 9.118452 10.88154831 19.119429.10.88057130 Co-tang i Tangent f Degree 82. M Degree 7. M Sine Co fine. I 309.1156989.996269| 329 3119 116656|9,996252 9,1176129,996235 339,118567 9,995218, 349,1195 99,996 202 3519,120469 9,996185′ 362,1214179,996168, 372,1223629,996151 Tangent Co-tang. I 19.11942910.880571/30 9,12040410,87959629 9,121377 10,87862328 9,12234810,877652.27 9,12331710,87668326 19,12428410,87571625 9,12524810,874751|24 9,12621110,87378923 389,1233069,996134 9,12717210,872828 22 i 39,1242489,996117 9,128130|10,871870 21 409,12518719,996100l 19,12908710,870913|10| 419,1261259,996083 19,130041 10,86995919 42,9,1270609,996066 9,130994 10,8690c618 43,9,1279939,996049 9,131944 10,86805617 449,1289259,906032 9,132893 10,86710716 459,1298549,996015 19,1338391086616115 4619,130781|9,995998| 479,1317069,995,80 489,132630 9,995963 49,1335519,995946 5019,13447019,995928] 9,134784|10,865216|14| 9,135726 10.86427413 9,136666|10,863334 9,137605 10,86239511 19,13854210,86145810 12 5119,1353879,995912| |9,139476|10,8605249 529,1363039,995894 9,14040910,859591 8 539,1372169,995876 9,141340 10,858660 7 549,1381279,995859 9,14246910,85773 6 5519,1390379,995641) |9,143196|10,8568041 5 5619,139944 9,99 5825) 579,140850 9,995806 $89,141754 9,995788 529.1426559,995770 609,1425559,995753 9,14688510,853115 1 19,14780310,852197 0 | Co-fine | Sine | Co-tang. | Tangent | Degree 82. 9,14412110,85587 4 9,145044 10,854956 3 9,145965 10,854035 2 } F Degree 8. } MI Sine Co-fine | 09.1435559.995753 19.14445319-995735) Tangent | Co tang. I 19.14780310-852197|60| 19• 148718 | 10.851282/59 9.4963210.85036858 9.159544 10.84945057 29.145349|9·995717| 39.1462439995699 49.1471369.995681 9.151454 10.84854656 59.14802619.9956641 9.1523631c.84763755 69.1489159.995646| 9.153269 10.846731|54| 79.1498019-995628 9.154174 10.84582553 89.150686'9.995610 99.1515699.995 592 1olg. 15 24519.995573 | 9.155077|10.844923|52 9.155978110.84402251 19.156877 10.843123501 119.1533309.995555 | $29 • 1542089.995537 139.155082 9.9955 19 149.1559579.995501 15'9.15683cl9.9954821 19.157775 1.842225149) 9.158671 19.841329 48 9.159565 1.840435 47 9.160457 10.839543 46 19.16134710-838653145 169.157700 9.995464 179.1585699.995446 189.159436 9.995427 1199.160301|9.99540y 2019.1611649-99539¢ 219.162025 9.995372 229 162885 9.995353 239.1637439.995334 249.164600 9.995316 259.1654549.9952971 2619.166307j9.995278 279.1671589.995260 289.1680089.995 24 1 299.1688569.995222 309.1697025.995203 9.16223610-83776414 9.163123 10.83687743 9.1640c8 10.83599242 9 164892 10.83510841 9.165773 10.834226′40 9.16665410.833346139 9.167532 10.832468|38| 9.168409 10 831591 37 9.169284 10 83071636 9.17015710 82984335 9.171029 (c.82897134 9 171899 10.82810133 9.172767 10.82723332 9.173634 1c.82636631 '9∙174499|10.825501 30 Co-fine | Sine | Co-tang. Tangent M Degree 81. Degree 8. I My Sine | Co-fine | 3919.16970 219.995 2051 3119.1705469.995 184 329.1713899.995 165 Tangent | Co-tang. I 9.174495 10.825501130 [9.17536210.824638 29 9.176224 10.823776 28 9.177084 10.82291627 339.1722309.995146 349.1730709.995127 9.177942 10.82205826 359.173908 9.995108 19.1787991c.821202/25 369.1747449.995089| 19.17955510.82034524 379.1755789.995070 9.180508 10.81949223 389.1764119.995061 9.181360 10.81864c22 399-1772429.995032| 9.182211 10.81778921 409.178072 9.99501 2| 2.183060 10.816640 20 4119.17890019.994993| 19.183907 10.81609319 429.1797269.994974 439.1805519.994955 9.184752 10.815248 18 9.185597 10.81440317 449.1813749.994935 9.186439 10.81356116. 452.1821909.994916 9.187280 10.81272015 469.1830169.994896| 9.188120 10.81188c|14| 479.1838349-994876 489.1846519.994857 499-1854669-994838 509.1862809.994818 |9.188957|10.81104213 9.189794 10.81020612 19.190629 10.80937111 9.19146210.808538 10 519.1870929•994798 9.192294 10 2077061 9 529.1879039.994779 9.193124 10.806876 8 539-1887129.994759 9.193953 10.806047 7 549.1895199.994739 5519.1903259.994719| 2.194780 10.805220 6 7.195606|10.804394| 5 5621911309.994699 579.1919339.99468c 589.1927349.994660 599.1935349.994640 609.1943329.994620 |9.196440|10.803569 4 9.197253 10.802747 3 9.198674 10.801926 2 9.198894 10.801106 1 19.199712 10.800287 | Co-fine Sine I | Co-tang. | Tangent | Degree 81. Degree 9. M Sine Co-fine | Tangent Co-tang. I 09.19433219.994620| 19.199712 10.800287160 19.1951299.994500 9.200529 10.79947959 29.1959259.994580 9.201345 10.79865558 39.1967189.99+56 9.202159 10.79784157 49.1975119•994540 9.20297110.79702956 59.1983029.994519} 19.20378210.79621855 6,9.1990919•994495 9-204592 10.75540854 79.199879994479 89.200660 3.994459 99.2014519.994438 1019.20223419*9944181 9.205400 10.794600 5 3 9.206207 :0.793793 52 9.207013 10.792987|51 19.20781710.792183|50 11|9.203017.9.994398| 129.2037979-994377 139.2045779.994357 149.2053549.994336 159'2051319.994316| 169.2069069.994295 179.1076799.99427+ 189.2084529.994254 199.2092229.994233 20′9.2099929.994212} 119.21076019.994191 229.2115269.994171 9.2122919.994150 2 249.2130559.994129 259.2138189.994108 269.214579,9.9940871 27 9.2153389.994066 289.2160979 994044 29 9.2168549.994024 3019.2176099.994003| Co-fine Sine | 19.20861910.79138149 9.20942010.79058048 9 210220 10.78978047 9.211018 10.78898-46 9.211815 10.78818545 9.21261110.78738944 9.213405 10.78659543 9.214198 10.78580242 9.214989 0.78501141 9.215780 10.784220 +0 1 19.216568 10.78 3 4 3 2 1 39 9.217356 10.78264438 9.218142 19.781758 37 9.218929 10.78107436 9.219710 10.78029035 |9.220491|10.779508134 9.22127210.77872833 9.22205210.777948 32 9.2228310 77717031 |9.22360; 10.776393|3 | Co-tang. Tangent (M) } Degree 80. } Degree 9. + M Sine | Co-fine | 3019.2176099.994003, Tangent Co-tang. | 19.223607|10.776393130 31|9.21836319.993982| 329.2191169.993960 19.224382'10.775618129 9.225156 10.774844 28 339.2198689.993939 9.225929 10.774071 27 349.2206189.993918 9.226704 10.773300 26 359.2213679993897 19.227471 10.77252925 369.2221159.993875 |9.228240|10.771760;24 379.222861 9.993854 9.229007 10.770993 23 289.223606 9.993832 9.229774 10.770226 22 399.2243499.993811 499.2250929.993789 9.230539 10.76946121 19.231302 10.768698 20 4119.2258339.993768| 19.232065/10.76793519 429.2265739.993746 9.232826 10176717418 439.2273119.993725 449.2280489-993703 [5]9.22878419.993681 9.233586 10.76641417 9.234345 10.76565516. 9.235103 10.76489715 4619.23951819.9936601 47 9.2302529.993638 48 9.2309849.993616 49 9.2317159 993594 5019.2324449.993572] 5119.2331729 993550| 529.2338999.993528 53 9.2346259.993506 54 9.2353499.993484 559.2360739.993462| 19.235859|10.764141|14| 9.236614 10.76338613 9.237368 10.76263212 9.238120 10.761880'11 9.23887210.761128 10 19.239622 10.7603781 9 9.240371 10.79629 8 9.241118 10.758882 7 9.241865 10.758135 6 9.242610'10.757390 5 56,9.23579519.993440 57 9.2375159.993418 589.2388359.993396 $99.2389529.993374 6019.23967019.993351 19.24335410.756646 4 9.244097 10.755903 3 9.244839 10.7551612 9.245579 10 754421| I 9.24631910.753681 0 Co-fine | Sine | | Co-tang. Tangent. [M Degree 80. S Degree 10. M: Sine Ce-fine 1 Tangent Co-tang. I 19.2396709 99335 | 19.246319|10.75368 160 119.240386|9.993329| 19.247057110.752943159 29.2411019.993307 39.2418149.993284 9.247794 10 75220658 9.248530 10.75147057 49.2425269.993262 9.249264|10.750736 36 5'9.24323719.993240 9.249998/10.75000255 69.2439479.993117| 79.2446569.993195 192507301074927054 89.2453639.993172 99.2460709.993149 10 9.2467759.993127) 9.251461 10.74853953 9.252191 10.74780952 9.252920 10.747680 51 19.253648|10.74635250 1119.24747819.993104 9.254374110.745626149 129.2481819.993011 9.255200 10.744900|48| 13.9.2488839.993059 9.255824 10.74417647 149.2495839.993036 9.256547 10.74345346 159.2502829.993013| 19.257269|10.7427345 |16|9.25098019.992990| 19.257990110.742010144 179.2516779.992967 9.258710 10.741290 43 189.2523739.992944 9.25942910.74057142 199.2530679.992921 9.260146 10.739854|41| 2019.2537619.992898 19.260863 10.739137,40 2119.254453 9.992875) 19.261578 10.738422139 249.255144 9.99282 239.2558349-992829 249.2565239.992806 259.2572119.992783| 9.262292 10.737708 38 9.263005 10.73699537 9.26371710.73628 36 9.26442810.735572 35 2619.257897.9.992759 279.2585839.992736 28'9.2592689 992713 29 9.2599519.992690 309.26063319.992666| | | Co-fine Sine | (9.265138/10.734865|34 9.265847 10.73415333) 9.266555 10.73344532 9.26726110.7327393 9.267967 10.73203330 Co-tang. Tangent M Degree 79. Degree 10. MJ Sine Co-fine | 1 Tangent Co-tang. I 3019.2606359.992666| 3119.2613149.992643 19.267967|10.732033 30 19.26867110.731329129 329 2619949 992616 9.26937510.73062528 339.2626739.992596 9.270778 10.72992327 349.2633919.992572 19.27147910.729221 26 35.9.2640279.992549 9.271479 10.72852125 9.272178 10.727822/24 409.267395'9.992430 4119.2680659.992406 429.2687349.992382 36,9.264703,9.992525 37.9.265378 9.992501 38,9.266051 9.992478| 399.266723.9.992454 9.272876 10.727124 23 9.273573 10.72642722 9 274269 10.72573121 19.274964 10 725036|2€ 19.275658/10.724342115 9.276351|10.723649|1 439:2694029.952362 9.277043 10.72295711 449.2700699.902335 459.2707359.992311| 9.277734 10.72226716 19,27842410.72157615 +49.27140019.992287 47 9.2720639.992263 489.2727269.992239| 49 9.273388 9.992214 5019.2740499.992190| 19.279113[10.72088714 9.279801 10.720199|13| 9.280488/10.71951212 9.281174 10.7188-26 11 9.281858 10 718142 10 $9.274708,9.992166| 529.2753679.992142 539.2760259.992118 549.276681 9.992093 559.2773379-992069| 69:27799119.9920451 379.2786859.99202 $58 912792979.991996) 599-2799489.991971 609.2805999.991947 |9.282542|10.717458, 9 9.283225 10.716775 8 9.28390710.716093 9284588 10.715412 6 9.285268 10.714732 5 19.285946110.714053 9.286624 10.713376 3 9.28730110.712699 9.287977 10.712023 9.288652 10.711348 c | | Co-fine Sine I Co-tang | Tangent ↑ Degree 79. S 2 Degree 11. ? MI Sine Co fine | 09.28059919.991947 119.2812299.991922 29.281897 9.991897 9.2825449.991873 49.283190|9.991848 59.28383619.991823 69.284480|9.991799 79.2851249.991774 Tangent Co-tang. I 19.288652110.711348160 19.28932610,710674159 9289999 10.710001 58 9.290671 10.709329 57 9.291342 10.70865856 19.292013110.707987155 1 89.2857669.991749 99.2864089 991724 109.287048 9.991699 11 9.28768819.991674 12 9.2883269.991649 13 9.2889649.991624 14 9.289500'9.991592 15 9.290236 9.991574 19.292682,10.70731854 9:293350 10.706650 53 9:29401710.70598352 9:294684 10.705316|51 .295349/10.704651150 19.296013|10.703987149 9 29:67710.70332348 9.29733910.702661|47| 9.298001 10.701999 46 9.298662 10.70133845 9 29932210.70067844 9.299980 10.70002043 9.300638 10.69936242 9.301295 10 69870541 1619.2908709.991 549) 179 2915049.991524 189,2921379.991498 199.292768 9.991473 2019.29339919.991448] 9.301951 10.69804940 2119.29402919.991422| 229.2946589.991397 239.2952869.991373 249.2959139.991346 259.2965399.991321 19.302607|10.697393 39 9.303261 10.696739 38 9.303914 10.696086 37 9.304567 10.69543336 19.30521810.69478235 269.29716419.991295 279.2977889.991270 289.2984129.991244 29 9.299034′9.991218 30 9.2996559.9911931 1 | fine Sine 19.305867 10.694131|3 9 306519 10.69348133 9.307168 10.69283232 9.307816 10.69218431 9.308463110.69153730 Co-tang. Tangent. M Degree 78. ={4» c%eu{gy&%.Y==v、t、༨༧་ Degree II. MI Sine | Co-fine. | Tangent Co-tang. I 30 9.2996559.991193| 19.308463 10.691537130 319,2002769,991167 9,309109 10,690891129 329,3008959,991141 9,30975410,690246 28 339,3015149,991115 9,31039910,689601 27 349,3021329,991090 359,3027499,991064 9,311042 10,688958 26, 9,311685 10,68831525 369,3033649,991038| 19,312327|10,687673124 379,3039799,991012 9,312968 10,687032 23 389,3045939,990986 9,313608 10,686392 22 399,3052079,990960 9,314247 10,685753|21 409,3058199,990934! 19,31488510,685115 20 4119,3064309,990908 19,315523|10,68447719 429,3070419,990882 9,316159 10,68384118 439,3076509,990855 2,316795 10,68320517 449,3082599,9908 29 2,317430 10,68257016 45.9,3088679,9908031 31806410,681936|15 469,3094749,990777 479,3100809990750 48 9,3106859,990724 499,312899,990697 |50|9,3118999,990671| 51|9,312495|9,990645 529,3130979,990618 53 2,3136989,990591 549,3142979.990565 5519,3148979,990538| 5619,31549517,990512 579,3160929,990485 589,3166899,990458 599,317284'9,990431 609,317879,9,990404 |9,318697|10,68130314 9,319330 10,68067013 9,319961 10,68003; 12 9,320592 10,6794081 1 19,32122210,678778|10| 9,321851 10,678149 9 9,322479 10,677521 8 9,323106 10,676894 7 9,323733 10,676267 6 19,324358 10,675642 |9,324983|10,675017 4 9,32560710,674393 9,32623110,672769 9,32685310,673147 19,327+7510,672525 | Co-fine | Sine || Co-tang. | Tangent | Degree 78. Degree 12. ቲ i My Sine Co-fine | | Tangent Co-tang. I 0.9.31787919-99049419.3274750.672525160) 19.328095110.671905159 19.3184739.999377 29.3190669.990351 39.3196589.990374 9.328715 10.67:28558 |9 • 329 33 4 1 0.670656 57 49.3202509.990397 59.3208409.990370 |9.329953| 10.670047 56 19.320570|10.669430'5 5 69.3214309,990247| 79.3220199.998215 19.331187 10.66882354 9.331803 to.66819753 89.3226079.990188 9.33241810.66758252 99.323194 9.990$61 9.333033 10.6669675 1 1019.32378c19.9901341 19.333646 10.66635450 119.3243669-990197 19.33425910.665741149 $29.3249509·990079] 9.334871 10.66512948 139-3255349.990052] 19.335482 10.66451847 149.3261179.990025 9.336093 10.663907 46 15,9.326699'9.989997 19.336702 10.663298 49 169.3272819-9899701 19.337311[10.66268944 179-327862 9.989943 9.33791910.66208143 189.3284419-9899) 5 9.33852710.66147342 199.3290209.98988; 9.339133 10.56086741 2019.32959919.989860 19.339739/10.66626140 219-33017619.989832 19.34034410.65965639 229-3307539.989804 9.34094810.65905238 23 9.33 13289,989777 249•331903 9.989749 2519.3324789•989721} 2619-3330519-989693 279•3336249•989 565 28 9.33419 9.989637 299.334766 9.989609 399-3353379.989581] 9.34155210.55844837 9.34215 10.657845 36 (9.342757|10.65724335 9.34335810.656642|34| 9.3+395810-65604233 9.344554 10.65544232 9.345157 10.65484331 9.34575510.654245/30 Co-fine Sine I | Co-tang. I Tangent IM Degree 77. Degree 12. M Sine | Co-fine I Tangent Co tang. I 19.345755|10.65424×130 309.3353379•989581] 319-3359069-9895531 329-3364759-989525 339.3370439.989597 |9.346353|10.653647|29| |9.346949 10.65305128 9.347545 10.652455 27 349.3376 109.989469 9.34814110.651859 26 359-3381769.989441| 19.348735 10.651265|25 369.3387429.989413 19.349329 10.650671124 [379.3393069.989384 9.349922 10.65007823 389.3398709.989356 9.350514 10.649486 22 399.3404349 989328 9.351106 10.648894 21 4019.34099619.9892991 19.351697 10.648303 20 4119.34155819-9892711 42 9.342119 9•989243| 439.3426799.989214 +49.3432399.98918. (+59•3437979 989157| 19.352287 10.647713|19 9-352876 10.64712418 9.353465 10.64653517 |9•354053|10.645947|16 9.354640 10.64536015 46,9•3443559.989128) 19.35522; 10.544773|14 +79.3449129.989100 9.35581210.64418713 489•3454699.989071 9.356398 10.64360212 499.3460249.989042 9.356982 10.643018'11 509.3465799.989014 9.357566 10.642434 10 519.3471349.988985) 19.358149 10.641851 9 529.3476879.988956 539.3482409.988927 549.3487929.988898 559-3493439 988869 9.35873110.541269 8 9.35931310.640587 7 9.35989; 10.64 107 6 9.560474 10.639526 5 5619.34989319.988840 579-3504439.9888 1 589.3509929.988782 9.361053[10.635947| 4 9.361632 10.638369 3 9.362210 10.637790 2 599.351540 9.988754 609.3520889.988724 9.362787 10.637213 1 9.363364 10.636636 0 1 Co-fine Sine I | Co-tang. Tangent M Degree 77. 1 Degree 13. 09.35208819-9887241 19.35263519-988695 29.35318.9.988666 33.3537269.988636) M Sine Co-fine 1 Tangent Co-tang. I 19.363364|10.63663660 19.363940 10.636060159 9.364515 10.635485 58 9.365090 10.63491957 49.354271'9.988607 9.36566410.63433656 5/9.354185 9.988578 19.36623715.63376355 69.355358 9.988548| 9.36681c[10.633190154 79-3559019-9885 19 9.367382 10.63261853 89.3564439.988489 9.367953 10.632047 52 99.3569849.988460 1019.3575249.98843° 9.368524 10.63147651 19.569094 10.630906150 119.35806419.988401 129.358603 9.988371 139.359141 9.988341 149.3596799.988312 [159.3502159.988282 19.369663|10.630337|49| 9.370232 10 629768 48 9.370799 10.629201 47 9.371367 10.62863346 9.37193310.62806745 16.9.3607529.988252 [9.372499¸10.627501|44| 179.3612879.988223 9.37306410-62693043 189.3618229.988193 9.373629|10-62637142 199.3623569.988163 20 9.362889'9.988133 9.374193 10.62580741 9.374756 10.62524440 |21|9.36342219.988103 229.36395.988573 19.375319|10.524681|39 9.37588110.62411638 239.3644859.988043 9.376442 10.62358 37 249.36501.988013 9.377003 c.62299; 36 259.3655469.987983 9.377563|10.622437:5 |26|9.36607519.987953| 19.378 12 2 1 1 0,621878 34 279.3666049.987922 9.37868110,62131933 289.3671329.987892 9.379239 10,620761 32 29.3676599.987862 9.379797 10,62020331 309.3681859.987832 9.380354 10,619646 30 | Co-fine Sine | Co-tang. | Tangent | Degree 76. Degree 13. M Sine | Co-fine | 3019.368185 9.98 78321 31/9.36871119.987801| 329.3692369.987771 Tangent Co-tang. I 19.380354|10.619646130 19.380910 10.619090|29| 9.381466 10.618534 28 339.369761 9.987740 349.3702859.987710 359.370808 9.987679 9.382021 10.617980 27 9.382575 10.617425 26 19.383129 10.61687125 369-371330 9.987649 379.3718529.987618 389.3723739.987588 399.3728949.987557 19.383682 10.61631824 9.384234 10.6157662 9.384786 10.615214|22| 9.385337 10.61466321 > 409.373414'9.987526 9.385888 10.61411220 41|9.3739339.987496| 19.386438 10.613562|19 429.3744529.987465 9.386987,10.61301318 439.374970 9.987434 9.387536 10.61246417 449.3754879 987403 9.388084 10.61191616 459.3760039.987372 9.388631 10.61136915 4619.37651919.987341| 47 9.3770359.987310 48 9.3775499.987279 499.3780639.987248 509.3785779.987217 5119.379089,9.987186| 529.379601 9.987155 19.389178 10.610822,14 9.389724 10.61027613 9.390270 10.60973012 9.390815 10 60918511 19.391360 10.608640 10 19.391907|10.608097 9 9.39246710.607553 8 539.3801139.987124 9.39298910.637011 7 549.3806249.987092 9.39353110.606469 6 559.3811349.9870611 9 394074 10.605927 5 5619.3816439.987030| 19.394614 10.6053861 4 579.3821529.986998 9.395154 10.604846 3 589.3826619.986967 9.395694 10.604306 9.396233 10.603767 I 599.3831689.986936 609.3836759.9869041 396771 10.603229 0 | Co-fine | Sine || Co-tang. | Tangent. [M Degree 76. T Degree 14. M Sine Co-fine | Tangent i Colang. I 19:39677110603229|60 109.38367519.9869041 19.38418119.986873) 29.3846879.986841 |9.397309|10.6q2694159| 9.397846 10.6021 54 58 39.3851929.98680g 9'398383 10.60161757 49.3856979.986778 9.39891910.601081 56 59.3862019.986746| [9.39945510.600549155 (59.3867049.986714 9.399990|10.60001054 1 7.9.3872079.986682 18 9.3877099.986651 99.3882109.986619] 9.400524 10.59947653 10 9.3887119.9865871 9.401058 10.59894452 9.401591 10.59840951 19.402124 10.597876 50 119.38921149.9865551 129.3897119.986523 139.3902 109.986491 149.390708 9.986459 1519.391206 9.986427 (9.402656|10.597344149 9.408187 10.59681348 9.403718 10.59628247 9.404249 10.59575146 9.40477810.595222|4 169.39170319.9863951 179-3921999.986363 [9.405306|10.594692144 9.405836 10.59416443 189.3926959.986331 9.406364 10.59363642 199.3931909.986299 9.406892|10.59360841 2019.3936859.986266 19.40741910.59258140 2119.39417919.9862341 229.3946739.986201 239.395166 9.986169 19.40794510.592055139 9.408471 10.591529 38 9.408996 10.59100137 249.395654 9.986137 9.409521 10.59047936 259.3961509.986104 9.410045 10.59995435 2619.39564119.986072| 19.410569|10.58.9431134 279.3971319.986039 9.411092 10.58890833 289.3976219.086007 9.411615 10.588385 32 29 9.3981119.985974 9.41213710.587863 31 30 9.3986009.9859421 | Co-fine 9.412658 10.58734230 Sine | Co-tang. | Tangent. M Degree 75. 1 Degree 14. Mp Sine Co-fine | 3019.39860019.985942 3119.3990879.9859091 329:3995759.985876 339.4000629.985843 349:4005499.985811 35.9.40 0359.985778 36.9.401520|9.98′5745 719.402005 9.985712 389.4024899.985679 399.402972 9.985646 4019.4034559.985613| Tangent Co-tang. [ 19.412658|10.5873423c 19.413179 10.586821129 9.413699 10.586301 28 9.414219 10.58578127 9414738 10.58526225 9.415257.10.584742 25 A 415775|10.58422 5/2 4 9.416293 10.58370722 9.416810 10.58319022 9.417326 10.58267421 19.41784210.58215720 4119:40393819198558. 429:4044209.985547 439.404901 9.985513 449.405382 9.985480 459:4058629.985447 9.418357|10.58164219 9.418873 10.58112718 9.419387 10.58061317 9:419901 10.58009916 9 420415'10.579585|1'5 4619.406341 9.985414 479.4068209.985380 489.4072999.985347 49 9.407776 9.985314 5019.4082549.9852801 $119.40873119.985247 $29.4092079.985213 539.4096829.985180 549.4101579.985146 559.4106329:985112 5619.411106 9.985079 579.4115799.985045 589.4120529.985011 599.4125249.984977 609.41299619.984943 | Co-fine \ Sine 1 19.420927110.579072 14 9.4214400.578560 1 9.42195110.578048 12 9.422463 10.5775371 9.422973 10.5770261 19:423484110.575516 9 9.423993 10.576007 8 9.424503 10.5754977 9.425011 10.574989€ 9.425518 10.574480 19.426027|10.573973.4 9.426534 10.573466 3 9.42704110.572959 2 9.427547 10.572453 1 9.428052 10.571947 c Co-tang Tangent | M Degree 75. T 2 Degree 15. M Sine Co-fine | 09.4129969.984944 Tangent Co-tang. | 19.42805210.571947160 9.4134679.98491c 19.428557110.571442159 29.413938 9.984876 9.429062 10.570938 58 39.4144089.984842 9.429566 10.570434 57 49.4148789.984808 9.420070 10,579939 56 59.4153479.984774 9.42057310.57942755 69.4158159.98474 9.431075|10.568925|54| 79.4162839.984706 9.431577 10.56842353 89.4168509.98467: 9.432079 10.567921 52 99.4172179.984637 9.432580 10.567420|51| 1919.457684'9.984603| 9.43308010.566920 50 11194181499.984569 19.433580/10.566419149 129.4186159.984535 139.4190799.984500 149.4195449.984466 159.4200079.984431 9.43408c 10.56592048 9.434579 10.56542147 9.435078 10.56492246 9 435576 10.56442445 1619.420470,9.984397) 179.420933 9.984363 189.4213959.984328 199.421856'9.984293 19.436073|10.56392744 9.436570 10.563430 43 9.437067 10.562933 42 9.437563 10.562437 41 2019.422317,9.984259. 19.438059 10.561941 40 2119.42277819.984224| 19.439554|10.56144639 229.4232389.984189 239.423697 9.984155 249.424156 9.984120 2519 424615|9 984085| 9.439548 10.56095238 9.439543 10.56045737) 9.440036 10.559964 36 19.440529|10.55947135 2619.42507219.9840501 279.4255309.984015 28 9.4259879.983980 299.4264439.983945 39.426899 9.983910) Co-fine Sine | 19.441022110.558978 34 9.441514 10.55848633 9.441006 10.55799432 9.442497 10.55750331 9.442988 10.55701130 Co-tang. Tangent/M Degree 74. Degree 15. MI Sine 1 Co-fine. | Tangent Co-tang. I 3019.42689919.983910 19.442988 10.557011/30 3119.4273549.983875 9.443479110.55652129 329.4278099.983840 9.443968 10.556031 28 339.4282649.983805 9.444458 10.55554227 349.4287179.983770 9.444947 10.55505326 13519.42917019.9837351 9.445435 10.554565,25 3619.42962319.983699 19.445923 10.55407724 379.4300759.983664 9.446411 10.55358923) 389.4305079.983629 19.446898 10.55310222 399.4309789.983593 9.447384 10.35261621 409.43142919-983558 19.447870 10.552129 20 4119.4318799.9835231 19 448356 10.55164419 429-4323289.983487 439.4327789.983452 449.4332069.983416 45.9.4336749.983380 9.448841 10.55115918 9 449326 10.55067417 9.449870 10.55018116 19.450294 10.55970615 4619.43412219.983345 9.45077710.549223 14 479.4345699.983309 9.451260 10.54874013 9.45174310.54825712 945222510.547775 11 9 452706 10.54729410 48 9.4350 69.983273 49.435462′9.983238 5019.4359189.983202 5119.43635319.983166| 529.4367989.983130 53 9.4372429.983094 54 9.4376869.983058 559.4381299.983022 569.4385729.982986 579.4390149.982950 589.4394569.982914 599-4398979.982878 609.4303389.982842 Co-fine Sine | 9.453187110.546813) 19.453668 10.546332 8 9.454148 10.545852 7 9.454625 10.545372 6 19.45510710.5448931 5 9.45558610 544414 9.456064 19.542936 3 9.45654210.543458 2 9.45 7019 10.542980|| 1| 9.457496110.542503| Co-tang. Tangent M Degree 74. Degree 16. 19.4407789.982805 29.4412189.982769 39-4416589.982733 49.4420969.982696 M Sine Co-fine | 019.440338|9.982842 || 1 Tangent Co-tang. | 19.457496/10.542503160 19.457973 10.542027|59 9.458+49 10.54155158 14 9.458925 10.541075 57 9.459400 10.54060056 59.4425359•982660| 9.459875 10.540125'55 619.44297319.982623) [9.460349|10.53965154 79.4434169.982587 9.460829 10.53917753 89.4438489.98 2550 9.461297 0.53870352 99.4442849.982514 9.461770 10.53823051 109.44472019.2824771. 19.46224210.53775850 119.44515519-982441| 9.46271410-537285,49 $ 29.445 5909·982404 9.463186 10.53681448 139.446025 9.982367 $49.4464599-982330 159.4468939.982294 9.463658 10.53634247 9.464129 10.53587146) 9.46459910.53540145 169.4473269-982257 179-447759 9.982220 189.4481919.982 183 199.4486239.982146 9.465069 10.53493144 9.465539 10.534461 43 9.466008|10.53399242 9.466476 10.53352341 2019.4490549.982109 19.466945!10:53305540 219.44948519.982072) 229.449915 9.982035 239.4403459.981998 249.4407759.981961| 2519.4412039.981923 19.467413110.532587|39| 9.467880 10.93212038 9.468347 10.531653 37 9.468814 10.53118636 9.46928010.53072035 2619.45163:19.981886 27 9.4520609.981849 289.452488 9.981812 299.45 29159.981774 309.4533429.981737 19.4697461(0.53025434 9.4702 11 10.52978933 9.470676 10.529324 32 9.47114110.52885931 9.471605 10.528395130 Co-fine Sine | Co-tang. Tangent | Degree 73. Degree 16. 319-4537689.981699| J 329.4541949-981662| | M₁ Sine | Co-fine | 3019-45334:19.981737 | Tangent Co-tang. 19.471605/10.5283953 19.472068110.52793129 9.472522 10.527468 28 339-4546199.981624 349.4550449.981587| |35|9.4554699.981 549) 9.472995 10.527005 27 9.473457 10.526543 26 |9.473919|10.526081/25 369-4558929.981512 |9.474381|10.525619|24| 37 9.4563 169.981474 9.474842 10.525 158 23 389.4567399.981436 9.47530310.524695|22| 399.4571629.981398 9.47576310.52423721 4019.45758419.9813611 19.47622310.523777 20 4119:45800619 9813233 19.476683|10.523317 | 19 42 9.458427 9.981285 9.477142 10.522858 18 名 ​439-458840 9.981247) 9.477601 10.52239917 449•4592689.981209 9.478059 10.521941|16| 4519.459684 9.981171 9.478517 10.52148315. + 4619.460108|9.98 1133 479.4605279.981095 489.460946 9.98 1057 499.4613649.981019 5019.4617829.980980 |9.478975|10.521025|14| 9.479432 10.520568 13 9.479889 10.52011112 9.480345 10.519655,11 6.480801/10.519199′10 51|9.46219919.980942| 529.4626169.980904 539.4630329.980866 549.4634489-98 827 5519.46386419.980789| 569.4642799.980750| 579-4646949.980712 58 9.465108 9.980672 599.4655229.980635| 609.4659359.980596| | Co-fine | Sine 19.481257110.518743| 5.48171210.518288 8 9.482167 10.517833 9.482621 10.517379 |9.483075|10.516925 5 9.4835281c+516471 9.483982 10.516018 9.484434 10.515565 9.484887 10.515113) 19.485339:0.51466|| | Co-tang. | Tangent Degree 73. 3 23 Degree 17. MI Sine | Co-fine | 19.46593519.980596| Tangent Co.tang. | 19.4853398*0.514668|6 0 119,4663489,980558 29,4667619,980519 19,485791 (10,51420959 9,486242 10,51375858 39,4671739,980480 9,486693 (0,51330757 49,46758519,980441 9,48714310,5128576 59,467996/9,980403 19,48759310,51240755 69,45840719,980364| 19,48804310,511957 54 52/54 79,4688179,980325 9,48849310,511507 53 89,4692279,980286 99,4696379,980247 9,48894 10,51105:52 9,489390 10,5гc61051} 109,469446 9,980208 9,48983810,510162|50| 119,47045 59,980169|| 129,4718639,980130 19,490286110,50971449 9,4907331,509267|48| 139,471071 9,980091 49,4716789,980052 9,491180 10,508820 47 9,49162710,508373 46 159,472086|9,980012 |9,492073|10,507928|45| 16 99472492/9,979973 19,492519 10,50748144 179,4728989,979934 189,4733049,979894 199,4737109,979855 491964 10,5703543 9,493410 10,50659042 9,49385410,50614541 209,474115|9,979816| 19,494299[10,505701 40 29,4745199,979776 |9,494743|10,50525 39 |22|9,474923|9,979737 9,495180 10,504813|38| 239,4753279,979697 9,49563 10,50437037 249,4757309,979658 9,4960730,503928 36 259,47613319,979618) 9,4965110,503485;5 269,4765369,979578 9,49695710,503043134 27′9,476938|9,979539 9,49739910,5026)1|33 28,9,477340 9,979499 299,4777419,979459 309,47814219,9794 9 9497840 10,50216032 9,498282 10,50171831 19,49872210,501278 30 | Co-fine | Sine | Co-tang. Tangent M Degree 72. Degree 17. M Sine Co-fine | Tangent Co-tang. I 19.49872210.501278130 3019.4781429.979419|. + 319.4785429.979380| 329.4789429.979340 339-4793429.979300 349.479741 9.979260 3519.4801409.979220 19.499163|10.500837|25| 9.499502 10.500398|28| 9.500042 10.499958 27 9.500481 10.49951926 19.50092010.499080125 3619.480538 9.979180 379.4809369.979140 389-4813349 979099. 399.481731 9.979059 409.482128 9.979019 19.501359 10.498641124 9.501797 10.4982032; 9.502234 10.49776522 9.50267: 10.497328/21 19.50310910.49689: 20 14119.48252519.978980 19.50354510.49645419 429.4829219.978939 9.503982 10.49601818 439.4833169.978898 9.50441810.49558217 449-4837119.9-8858 19.504854'10.49514616 14519.48410619.978817 9.505289 10.49471115 4619'484501,9.978777 479.4848959.978736 48 9.4852899.978696 499.4856829.978655 5019.485075 9.978615 5119.486467 9.978574 529.486859 9.978533 539.487251 9.978493 549.487642 9.978452 559.488033 9.9784111 $69.48842419.978370 579-4888149.978329 58 9.4892049.978288 599.4895939.978247 6019.4899829.978206 19:505724|10.49421614 9.506158 10.493841|13 9.50 593 10.49340712 9.507026 10.49297311 19.50745910.492540/10 19.507892/10492107 9.508326 10 491674 8 9.508759 10.491241 7 9.509181 10.490809 6 9.509622 10.490377 5 19.510044.0.489946 9.510486 10 489515 3 9.510916 10.489084 19.511346 10.489654 1 9.511776 10.488225 0 Co-fine Sine | | Co-tang. Tangent. | M Degree 72. U : t Degree 18. } M Sine 1 Co-fine | 019.48998219 9782061 19.49037119.9781651 29.4907599.978124 39 4911479.978083 49.49 534 9.978042 59.491922 9.978000 Tangent Co-tang. | 19.511776.10.48822460 19.512206 10.487794159 9.51263510.48736558 9.513064 10.486936 57 9.513493 10.48650756 9.513921 10.48607955 69.4923089.977959. 79.4926959.977918) 89.4930809.977877 99.4934669.977835 19.514349,10.485651154 9.51477710.48522353 9.515204 10.48479652 9.51563110.48436951 10 9.4938519.977794 19.51605710.48394250, [119.49423619.977752 9.516484 10.483516149 129.4946209.977711 9.516910.10.48309048 139.4950059.977669 9.517335 10.48266547 149.4953889.977628, 9.517761 10.48223946 $59.495779.977586. |9.518185 10.48181445 1619.49615419-977544 9.51861010.481390144 179.496537977503 189.496919 9.977461 199.497301 9.977419 209.4976829 977377 9.51903410.480966 43 9.519458 10.48054242 9.519882 10.480118 41 9.520305 10.48969540 2119.498063,9.977335 19.520728|10.479272139 229.4984449.977293 9.52115110.478849 38 239.4988249.977251 9.521573 10.47842737 249.4992049.977209 9.521995 10.4780036 259.49958419 977167 9.522417|10.477583135 269.4999639.977125 279 5003429.977083 289.5007209.977041 299.5010999.977999 3019 5014739.977956 Co-fine Sine 19.522838110.47716234 9.523259 10.47674133 9.523679 10.476320/32 9.524109 10.475900 31 19.524520 10.47548030 Co-tang. Tangent. M Degree 71. Degree 18. 339.5026079.976830 349.5029849.976787 3519.50336019.976745 1369.50373519.976702 379.5041109.976560 38 9.504485 9.976 17 399.50484019.976574 4019.5052349 976532 MI Sine Co-fine 1 3919 50147€ 19.977956 3119.50185419.976914) 329.5022319 976872 | Tangent Co-tang. I 9.52452010.47548030 19 5249361.475060129 9.525359 10.4746428 9 525778 10.47422227 9.526197 10.47380326 19.526615 10.47,38525 9.52703310.472957/24 19 52745110.47254923 9.527868 10.47213242 9.52828510.47:71521 19.52870210.471298 20 4119.50560819 976489| 19.529118110 470881j19 429.5059819.976446 9.52953510.47046518 439.5053549.976404 9.529950 10.47004917 449.5067279.976361 9.530366 10.469634|16| 14519.5070999.976318| 9.53078110.46921915 469.5074719-976275 19.53119610.468804 14 479.5078439.976232 9.5316110.468389 13 489.5082149.976185 9.532025 10.467975.12 499.5085859.976146 9.532436 10.46756611 5019.5089559.976103 19.53285210.467147 10 5419.50932619.976060 19.533266|10.466734, 9 529.509696 9.976027 9.533679 10.466321 8 539.5100659.975970 9.53409210.465908| 7| $49.5104349.975930 9.534504 10.465496 6 55.9.5108039.975887 9.5349:610.465084 5 5619.51117119.9758441 579.5115409.975800 $89.5119079 975757 599.5122759.975713 5019.512642 9.975670 | | Co-fine Sine 1 19.535328 10.464672 41 9.535739 10.464261 9.536150 10.463849 2 9.53655: 10.463439| 1 536972/10.463028) o Co-tang Tangent | M Degree 71. U 2 Degree 19. MISine Co-fine Tangent Co-tang. 019.51264419.975670 19.53667210.463028160 19.5130099.975626 9.5133759.975583 39.5137419.975539 19.537382[10.462618159 9.53779210.462208 58 9.538202 10.461798 57 9.5141079.975496 9.53861010.461389 56 59.5144729.975452) |9.539020|10.46098055 69.5148379.975458 9.539429/10.460571|54. 9.515208 9.975364 9.539837 10.46016353 89.515;669.975321 9.540245 10.459755 52 99.5159399.975277 9.540653 10.459347|51| 19,9.5152949.9752331 19.541061/10.45893950 119.5166579.97518 19.54146810.458532149 12,9.5170209.975145 13.9.5173829 975101 9.54187510.458125 48 9.542281 10.45771947 149.517745 9.975057 15,9.5181079.975013| 9.5426881c.45731246 19.54309410.45690645 169.5184689.974969| 179.5188299.974925 189.51919 9.974880 199.5195519.974836 20 9.51991112.9747921 2119 520271 9.974747) 229.520631 9.974703, 230.5209909.974659 249.5213499.974614 259.521707|9.9745701 19.543499|10.456501|44| 9.543905 10.45609543 9.544310 10.45569042 9.54471510.455285 41 9.54511910.454881 40 19.54552410.45447639 9.545927 10.45407238 9.546331 10.45366937 9.546735 10.45320536 9.547138 10 45286235 2019.52206519 974525 9.54754010.452459|34| 279.5224239.974480 28 5227819.974436 9.547943 10.45205733 9.548345 10.45165532 9.54874710.45125331 299.5231389.97439 309.5234959.9743461 Co-fine Sine 4 1 9.549149.10.45085130 Co-tang. Tangent | M Degree 70. Degree 19. I IMI Sine | Cofine. | |Tangenti Co-tang. 3019.52349519.974346| 19 54914910.450851.30 43119.52385 9.97430) 19.549550 10.45045029 329.5242089.974257 9.549951 10.450049|28 339.5245649.974212 9.55035210.44964827 349.5249209.974167 9.55075210-449248 26 3519.525275'9.974122 9.55115210.448848:25 3619.5256309.974077 19.55155210.44844824 379.5259849.974032 9.551952 10.448048 23 389.5263399.973987 9.552351 10.447649 22 399.5266939.973942 9.552750 10.447250 21 409.52.70469.9738971 19.553149/10.446951 20 419.52740019.973852 9.553548 10.44645219 429.5277539.973807 9.553946 10.4460548 439.5281059.973761 449,5284589.973716 9.554344 10.44565617 9.554741 10 44525916 459.5288109.973671 19.55513910.444861|15 46,9.529161|9.973625| 19.555536|10.44446414 479.5295139.973, 80 489.5298649.973535 9.555932 10.444068 13 9.556329 10.44367112 499.5302142973489 9.556725 10.44327511 509.53056519·9:3443] 5119.53091519.973398| 529.5312659.973352 539.53 6149.973307, 54 9.531963 9.973261 559.5323129.973215 569.532661|9 973169| 579.5330099.9731 23 589.5333579.973078 599 5337049 973032 609.5340529.972986 Co-fine | Sine I 19.557121 10.44287910 |9*55751710.442483| 9 9.557912 10.442088 8 9.558308 10.441693| 7 9.558702 10.441298 19.559097.10.440903| 5 3 9 559491 10.440509 4 9.559885 10.4401 9 56027910.439721 2 9.550573 10.439327| I 19.561066 10.438934 | Co-tang, | Tangent | Degree 70. Degree 20. M Sine Co-fine | 919.53405219.97 29861 19•534395 [9.97294″ 29.534746 9.972894 Tangent Co-tang. \ 19.56106110.43893460 9.5614590.43854159 9.551851 10.4381488 39-5350919-972848 49.5354379.972801 $.53578:1).972755 | 9.5622441043775657 9.56263610.4373641.6 19.56302810.43697255 69.53612919-972709) (9.563419/10.43658. [5° 4 79.5364749.972663 9.56381110.43618953 9.564202: •435798 52 9.564592 10.435+07|51| 9.564983143501750 89.5358189.972617 99.537 639-972570 109.5375079.9725241 119.537859-972477| $29.5 38 1949-972431 139-538579-972384 49.5388809-972338 1519-5392229.972291 15 9.53956519·972245 £79.5399079.972198 189.5402499.972151 199.5405909.972105 209.54093 119.972058] 21 19.54127219.972011 229•5416129.971964 9.56537310.43462749 9.565763 10.43423748 9.566153 10.433857 9.566542 10.43345746 19.566932!10.4330684 19.56732010-43267944 9.567709 10.43229143 9.568097|10.43190242 9.568486 10.43 £5441 19.56987310.4311264 239.541959.971917 249.542292 971870 259.5426329.971823! |9.569261|10.43073919 9.56964 10.43055 38 9.56003510.429964|37 9.560422 10.42957836 9.56080910.491911.5 26.9-5429719-971776 279-5433109-971729 1289.5436499.971682 299.5+39879-97163 309.54432519.971588 | i 19.571195 10.4288c 5 3 4 9.57158110.4284193: 9.571967 10.4280, 32 }• 572 3521 ^ •427648|31 2.572748119.427262,0 Co-fine Sine | Sine | Co-tang. ' Tangent Degree 69. Degree 20. MI Sine Co-fine | | 3019 544325 9 971988 |3 | | 9.544663|9•971540| 329-54500019.971493 339.545338 9.97144' |349-545674 9+971398 25/9.54601119-971351 Tangent Co-tang. 19.572738 0.427262;0 9.573123|1c•426877|29| 9.57350710.426492|28| 9.573892 10.42610827 9.574276 10.42572426 |9.574660|10.4253401 25 369.5463479-9713031 37 9•546683 9.971256 389.5470199.971208) 399.5473549•971161, |9.575044) 10.424956|24 9.575427 10.424573 23 9.5758110.424189 22 6.57619310.42380/21 4019.5476899.971112) 19.576576) 10.423424/20 4119.5480249.971065) 429.5483589.971018 439486939·9:0970 |9.576958 10.423041 | 19 3.577341 10.42265918 9.577723 10.42227717 9.578104 10.42189616 9.578486|10.421514/15 44 9.5490269-970922 459.5493609.970874 46 9.549693 9.970826 147:9.5500269.970779 489.5503599.970731 499.5506929.970683 5 19.5 0249.970634 15-19-551355-970586 529.551687970538 539.5520189 970490 $49.55*3499•970442 $59.526899703941 ६ [56]y•$$3©£Q9•970345] 5755334970247 589.55367-970249 599.55+000).970200 6019.554329.970 152 Co-fine Sine 14 19.578867|10.42 19.5 78867 | 10.421133|1 9.579248 10.42075213 9.579628 10.42037112 |9.58000910.419991|11 2.580389|10.41961 1 1 0 { 9.580769/10.419231 9 9.58149 10.4188518 9.581528 10-4:84727 9.581907 10.418092 6 9.582286 10.417713 9.582665110.417335 4 9.5.8304310.416956 3 9.583422 10.416578 2 9.583300 10.410200] 9.584177 10.415723) 0 Co-tang. Tangent M Degree 69. ཏྭཱ Degree 21. MJ Sine Co-fine I $9,5543299701528 19,5546589,970103] 29,5549879,97005 39,5553159,97000( 49,555643 9,969957 59,5559719,9699-91 69,5562999,969860 | 79,5566269,969611 89,556953 9,969762 99,5572799,969713 109,5576069,969665) Tangent Co.tang. | 19,584177|10,415822160 |9, 5 8 4 5 5 5 || 1 0,4 1544559 9,5849210,41 5068 58 9,585308 10,414691|57| 9,58568610,414314 16 19,58606210,41393855 19,58643910,41356154 9,586815 10,41318553 9,587190 10,412800/52 9,587566 10,41243451 19,587941 10,41205950 |1 1|9,5579329,969616| $29,5582589,969567 19,588316/10,411684149) 9,58869110,41130948 139,5585839,969518 149,5589099,969469| 1519,559 2349,969419 169,5595589,969370| 179,5 59883 9,96932 1 9,58906610,41093447 9,589440 10,410560 46 19,58981410,410285(45) 9,590188110,409812/44 189,56c2079,969272 199,5605319,969223 2019,560855'9,969173 9,590561 10,409438 43 9,590935 10,40906542 9,591308 10,40869241 19,591681 10,40831940 219,5611789,969124 229,5615019,969075 239,5618249,969025 249,5625469,968976 259,5624689,998926 19,592054110,40794639 9,592426 10,407574 38 9,592798 10,407201 37 9,593170 10,40682936 19,593542|10,40545735 269,5627909,968877| 279,5631129.968827 |28|9,5634339,968777 299,5637549,968728| 309,5640769,958678, | Co-fine | Sine | 59391410,40608634 9,594285 10540571533 9,594656|10,4°534432 9,595027 10,405073 31 19,595397|10,404602 30 Co-t ang. Tangent M Degree 68. Degree 21. MI Sine Co-fine I 3019.56407519.968678| 319.56439619.968628| 329.5647169.968578 339.5650369.968528 349.5653569.968478 359.56567519.968428 3619.56599519.968378 379.5663149.968328 389.566632 9.968278 399.566951 9.968228 409.567269'9.968178 Tangent Co-tang. | 19.595397|10.404602130 19.59576810.40423229 9.596138 10.403862 28 9 59650810.40349227 9.596878 10.403122|26| 9.597247 10.402753125 9.597616|1.4-2384124) 9.597985 10.4020152; 9 598354 10.40164622 9.598722 10.40127721 9'599091 10.400909|20| 419.5675879.968128 429.5679049.968078 19.599459|10.400541|19|| 9.599827 10.40017318 439.5682229.968027 9.500194 10.39980617 449.5685399.967977 9.50056210.399438|16|| 59.5688559.967927 9.500929 10.39907115 4619.56917219.967876|| 9.60129610.398704 14 479.5694889.967826 9.60166210.39833713 89.5698049.967775 9.60202910.39797112 99.5701209.967725 9.602395 10.39760511 5019.57043519.967674 9.60276110.39723510 $19.5707519.967623 9.603127,10.396873 9 $29.5710659.967573 9.603493 10.396507 8 $39.5713809.967522 $49.5716959.967471 $59.5720099.967420| 5.603858 10.396142 7 9.604223|10.395777 6 9.604588 10.395412 69.5723229.967370, 19.604953 10.395047 4 79.5726369-967319 9.605317,10.394683 $8 9.572949 9.967368 |9.605681|10.39431 2 99.5732639.967217 9.60604610.393954 I 09.5735759.967166 9.60640910.39359 0 Co-fine Sine | | Co-tang. Tangent. M Degree 68. # Degree 22. Sine | Co-fine | Tangent Co-tang. | 09-573575′9.967165 19.606409|io 393590 60 119.5738889.967115) 9.666773110.39322715 29.5742009.967064) 9.607136.39286358 39.5745129.967012 9.607500 10.39250057 49.5748249.966961 9.60786210.392137:56 59.5751359.966910 19.60822510.391774 55 6,9.57544719.9668591 9.608588 10.391412154 7.9.5757589.966807. 89.5760689 966756) 99.5763799.966705 10 9.5766899.966653 1119 576999 9.966602 129.577309:9.966550 139.577618,9.966499 149.5779279.966447 159 57823619.9663951 169.5785459.9663441 79.5788539.966292 £8 9.5791619.966240 199.579469).966188 9.608950 10.391050ls 9.609312 10.390688:52 9.609674 10.39032651 19.600036|10.399964,50 9.610397,10.389603149 9.610758 10.38924148 9.61111910.38888047 9.611480 10.38852046 9.61184-10.38815945 [9.612201|10.387799144 9.61256110.387438 43 9.612921 10.387078 42 9613281 10.38671941 2019.5797779.966136 9.61364110.386359'40 219.58008419.966084 229.5803929.966032 23'9.5806989.965980 19.614000|10.386000139 9.61435910.385641 38 9614718 10.38528237 24.9.5810059.965928 9.615077 10.384923|36| 25.9.5813119.965876 9.615435 10.38456535 2619.581618 9.965824 279.5819239.965772 289.582229 9.965720 9.615793|10.384207134 9.61615110.383+48:33 9.616509 0 38349132 299.5825349.96566; 3019.582840 9.965615 9.616867 10.3831 33 31 9.61722410.382776 30 1 Co-tine ། Sine | Co-tang. Tangent. M Degree 67. Degree 2 2. MJ Sine i Co-fine | 3019.582840 9.965615. 3119.58314419.965563! 329.5834499.965511 339 5837539.965458 | Tangent Co-tang. | 19.617224110 382776130 19.61758110.382418129 9.617938 10.382061 28 9.618295 10.381705 27 349.5840589 965406 9.618652 10.381348 20 9.619008 10.380992 25 19.619364 10.38063524 9.619720 10.38027923 9.62007610.37992422 9.62043210.379568 21 9.62078710.379213/20 19.62114210.37885819 9.621497 10.378503 18 9.621852 10.378148 17 9.622206 10.37779316 9.622561 10.37743915 359.584361 9.9-5353 36 9.58466519.965301 379.584968,9 965248 389.4852719 965195 39 9.5855749.965 43 40 9.5858779.965090 ; 4119.5861799.965037 429.586481 9.964984 439.586783 9.964931 44.9.587085 9.964878 459.58738619.964825 4619.587687 9.964772) 479.587988 9.964719 489.5882899.954666 499 588519 9.964613 5019.5888909.964560 519.589190 9 964507) 529.5894899.964454 53 9.5897899.964400 549.5900889 964347 55.9.5903879.964:94 569.5906869.964240| 579.5909849.964167 589.5912829.964133 599.5915809.96408c 6019.5918789.964026 Co-fine Sine 9.62291510.377085,14 9.6232691 .37673113 9.623623 10.37637712 9.62397610.376024 11 9.62433010.375670 10 19 624683110.375317 9.625036 10.374964 9.625388 10.374612 7 9.625741 10.374259 6 |9.626093|10.373907 5 19 626445 10.373555) 4 9.626797 10 373203 9.627149 10.37-850 3 9.627501 10.372499 19.627852 10.372148 | Co-tang | Tangent | M Degree 67. X 2 Degree 23. MI Sine Co-fine | Tangent Co-tang. I 09.591878 9.964026|| '9.62785210.37214860 19.592175 9.963972| 19.628203/10.371797,59 29.5924739.963919 9.62855410.371446 58 39.5927709.963865 9.828905 10.371095 57 49.5930679.963811 9.62925510.370744 56 59.593363.9.963757 19.629606 10.370394 55 69.59365819.9637031 19.629956 10.370044154 9.5939559.963650 8.9.5942519.963596 99.5945479.963542 109.5948429.9634881 I 119.595137|9.9634331 129.5954329.963379 139.5957279.963325 149 5960219.963271 630306 10.369694 53 9.630655 10.369344 52 9.631005 10.368995|51| 9.631354'10.368645 50 15.9.596315'9.963217 [9.631704|10.368296149 9.632053 10.367947 48 9.632401 10.367598 47 9.632750 10.36725046 9.633098 10.36690145 169.59661019.963102} 179.596903 9.963108 189.5971969.963054 19.633447110.366553|44| 9.633795 10.36620543 9.634143 10.365857 42 199.597490′9.962999 9.634490 10.36551041 209.5977839.962945 9.634838 10.36516240 219.5980759.9628921 9.63518510.364815139 229.5983689.962836 9.635530 10.364468 38 239.5986609.962781 9.635879 10.364121 37 249.5989529 952726 9.636226 10.36377436 259.5992449.962672 9.636572 10.36342835 269.59953 19.962617 279.5998279.962562 289.6001189,962507 299.6004099.962453 309.600700 9.962398 19.636918|10.363081134 9.637205 10 36273533 |9.637610|10.362389|32| 9.637956 10.36204431 9.638302 10.361698 30 ¡Co-fine Sine 1 1 Co-tang. Tangent M Degree 66. Degree 23. M Sine Co-fine. | |Tangent Co-tang. 19.638302|10.361698|30| 309.600700.9.9623981 319.60099019.9623431 9.638647 10.361353|29| 329.6012809.962288 9.638992 10.36100728 339.6015709.962233 9.639337 10.350662 27 349.6018609 962178 9.639682 10.360318 26 359 6021499.962122) 9.640027 10.369973/25 369.6024399.962067| |9.640371|10.359624|24| 37.9.6027289.962012 9.640716 10.359284 23 389.6030179.961957 9.641060 10.358940 22 309.6023059.961902 9.64140410.35859621 40 9.6035949.961846 9.641747 10.35825320 419.60388219.9617911 429.6041709.961735 43 6044579.961680 449 604745 9.961624 459.6050329.961569| 19.64209110.35790919 9.64243410.3575568 9.642777 10.35722217 9.643120 10.35698016 19.643463 10.356537 15 4619.6053199.961513 479.605605 9.961458 489.6058929.961402 499.6061799.961346 sol9.6064659.361290 5119.60675019.961235| 529.6070369.961179 539.6073229.961123| 549.6076079.96 1067 19.643804110.35519414) 9.644148 10.35585213 9.644490 10.35551012 9 644832 10.355168 11 19.64517410.354826/10 9.645516 10.354484) 9 9.645857 10.554142 8 9.64619910.353801 7 9.546540 10.353460 6 559.6078929.96 101! 19.646881|10.353119) 5 5619.6081759.9609551 9.64722210.352778 4 579.6084619.960899 9.647562 10.352438 3 589.6087459.960842 9.547903 10.352097 2 599.6090299.960785 6019.6093139.960730 9.648243 10.351757 1 19.648583 10.351417 0 | Co-fine | Sine | | Co-tang. | Tangent Degree 66. 赛季 ​" Degree 24. M Sine Co-fine | ol9.60931319.960730| Tangent Co-tang. \ (9.6 48 5 8 3 | 10. 3 5 1417 60 9.64892, 10.35107759 9.649263 10.35 737 58 9. 49602.0.35039857 9.649942 10.350058.6 9.650281|10.3+9719′5 5 1|9.609597|9.96067+ 29.6098809.960617 3.60169.960561 4.6104469.960ses 59.6107299.960448) 69.6110129.960392 9.550620 10.349380 54 79.6112949.960335 89.6115769.960279 39.6118-89.960222 10.612 409.960165) 119.61242 9.960 19 125.5127 29.9 0052 139.6129839.959995 1 4'9.6 1 3 264 9·9 9938 159.6354 19.9598811 169.6138:59.959824) 179.6141059.959768 189.6143859.959710 1199.614665.91965; |20|9.5149449.959596| |21|9.5 15 22 3 9.95953 22.5155029.959482 239.6157819.959425 249.6160609.959;67 25.9.6163389.959310 2619.616…. . É 19.959253 279.6168949.959195 289.61172 y•959138 299•6174509•959~80 30.6177279.95902; Co-fine Sine i 1 [9.650959 10.34904.53 19.65129710.34870352 9.65163 10.34836451 9.65 97410.348026|50| 2.552312 10.347688 49 •651650 10.34735048 ).652988 10.34701247 9.653326 10.346674|46| 1.6:3563110. : 3663 | 10.3 + 633745 } 19.654000 10.34 99944) 9.65433710.34566243 9. 5407410-34532542 9.655011|10.144989′41 [9.65-348 10.344052 40 [9.655684] 1 0·3+43 1 639 9.656020 10.34398038 9.656356|10.343643|37 9.656692 10.34310836 19.657-2810.34297735 [9.6 <7,63 | 10.34263634 9.65769910.34230133 9.65303 +10.34 1966 3 2 9.558369 10•3 + * 5 3 1 3 4 9.65870434129630 Co-tang. Tangent M Degree 65. Degree 24. 369-6193869.958 6 7 7 1 M] Sine | Co-fine | 3 cl. 61772719-959023' 301-6177 319.6180049.958965 329.6.8281 9.9⋅ 8908 339.0185589.95 88 € 349.61883 +9.958792 |35/9.6191,0′9.9 < 873 4| 9.9586771 Tangent Co-tang. 19.658704'10-341296130 |9.659039|10.340926|29| 9.659373 10.34062; 28 9.659708 10.34029227 9.66004210.33995826 9.66037610.33962425 19.660710 10.33929024 379.61966 9.958619 9.661043 10.33895723 389.619939.958561 9.661377 1-3862322 399.6202139.958503 9.661710 10-338290:21 40.9.6204889.9-8445 19662043 10.337956 20 4119.62076319.958387 9.662375|10.337623119 429.6210389.95 8 3 29 9.662709 10.3372918 439.6213139•958271 9.662042 0.33695817 449.6215879.958212 9.6633741-33662516) 459.6218619-958154 19.66370710.33529315 46 9.622 13:19.958096| 479.6224099.958038 489.6226829.957979 499.6229569.957921 509.623229.957862 519.6235029.957804 529.6237769.957745 539.6240479.957687 549.6243199-957628 559.624-919-95-5:0 5619,6248639,95 7 5 × 1| 579,6251349,957452 589,625 +06:9,957393 599,6256779,95 7 3 3 4 609,625948 9,957276 | Co-fine Sine 19.66403511r.33596 1/1 9.664371 10.335 129! 9.664793 0.33529712 9.6653510.334965 11 9.66536010.33453410 1966;66710-334302 9) $9.666029|10.333971, 8 9.666;60 10.333640 기 ​9.666691 10.333309 6 19.66702 Pro.13-979 31 3 | 9, 6673 5 2 1 0,1 3 26 1 132643; 4 9,66,682 10,33 23 9,668012|10,33 19 9,6683+3 0,331657 |9,663672|·0,33 132¯| 0 Co-tang. 、 Tangent ! Degree 65. 1 + m Degree 25. MI Sine | Co-fine | + Tangent Co tang. | |9,668672|10,331327|60| 019,62594819,957276| 19,6262199,957217 19,669002|10,330998/59 29,6264909,957158 9,669332 10,33066858 39,6267609,957099 9,669661|10,33033957 49,6270309,957040 9,669990 10,33000956 59,6273009,956981| 19,670320|10,329680|55| 69,627570 9,956922|| |9,670649|10.329351 54 79,6278409,956862 9,67097710,32902253 89,6281099,956803 9,67130610,328694|52| 99,9283789,956744 9,671634|10,328 36 551| 1019,62869:19,9566841 |9,671963|10;328037150 119,6289109,956625) 19,672291|10,32770949 129,6291849,956565| 9,672619 10,327381 48 13,6294539.956506 9,67294710;32705347 149,6297219,956449 9,573274 10,326721|46| 159,52998919,956387 | 5, 673 503 | 10,326398|45 9,673929|10,32607044 9,67425610,32574343 9,67458410,325 416 42 9,674910 10,32508941 19,67523710,32476340| 16 9,6302579,956327 176,6305249,956267 189,630792 9,956208 199,6310599,956148 209,63132619,9560881 21 2,631592 9,9560291 221,6318569,955969 269,63 29239,955739 239,5321259,95;909 249,6323929,955849 259,6326579,955789 27.9,6331899,955665 289,6334549,955609 299.6337199,955548 309,6339849,955488 | Co-fine | Sine 1. 2,67556410,324436|39| 9,675890 10,32411c|38| 7,6762 16 10,323783 37 |9,676543 10,32345736 9,676869 10,323 13 13 5 9,67719411,322805134 9,677520 (0,322480 33 9,67784510,32215432 9,67817110,321829 31 |9,678496|10,321504 30 Co-tang. Tangent (M Degree 64. Degree 25. MI Sine Co-fine 309.6339849.9554881 Tangent Co-tang. I 19.678496|10.321504/30 319.6342499.9554281 329.6345149 955367 19.678821 10.3-1179129 9.679145 10 320854 28 339.6347789.955307 9.679471|10.320529|27| 349.6350429.955246 9.679795 10 32020526 359.6393069.955186 19.68012010 31988025 3619.63557019.955125| 19.680444110.31955624 379.63.58339.95 5065 9.680768|10.31923223 389.6360979.955004 9.681092 10.318908 22 399.6363609.954944 9.681416 10.31858421 409.6366239.954883 9.681740 10.31826020 4119.63688619.954823) 9.682063|10.31793719 429.637148 9.954762 9.682386 10.31761318 439.6374119.954701 9.682710 10.317290 17 449.6376739.954640 9.683033 10.31696716 459.637935′9.954579! 19.683356 10.31664415 4619.6381979-954518 19.683678|20.316321(14 479.6384589.954457 489.6387209.954396 4919.638981.9.954335 9.684001 10.31599913 9.684324 10.315676 12 9.684646 10.31535411 50 9.6392429.954274| 9.684968 10 315632!10 } 5119.639503 9.954213 9.68529c|10.314710 529.6397649.954152 9.68561216314388 8 539.6400249.954090 549.6402849.954029! 9.685934 10.314066 7 9.68625510 313745 6 559.6405449 9549681 9.686577|10.313423 5 569.6408049.953906| 9.686898 10.31310 | 4 9.687219 10.31278 579.6410649.953845 58 9.6413239.953783 599.6415839.953722 60 9.64184219.9536601 | Co-fine Sine 9.687540 10.312460 9.687861 10.312138 9 688182 10.311818 Co-tang Tangent | M Degree 64. Y Degree 26. M Sine | Co-fine Tangent | Co-tang. 09.64184219.953660 19.688182f10.31181860 119.6421019.953598; 29.6423609.953537 39.642618 9.953475 49.6428769.953413 59.6431359.953351| 19.688502110.311498159 9.688823|10.317758 9.689143 10.31085757 9.68946310.31053756 9.689783 10.31021755 6 9.643393 9.953290| 79.6436509.953228 89.643908 9 953166 99.6441659.953104 10 9.6444239.953042| 1119.64468019 952980 129.6449369.952917 19.690103|10.30989754 9.690423 10.30957753 9.690742 10.30925852 9.691063 10.308938 51 9.691381|10.30861950 19.691700|10.30830049 9.69201910.0798148 139.6451939 952855. 9.692338 10.30766247 149.6454499.952793 9.692656 10.30734346 159.6457-69.952731 [9.692975|10.30;02545 16|9.645962|9.952668 179.6462189.952606 189.6464739.952544 199.6467299 95248 i 2019.64698419.952419 2119.64723919.952355 229.6474949.952294 239.6477499.952231 19.693293|10.306706144 9.693612 10.306388'43 9 693930 10.30607042 9.694248 10.30575241 9 694566 10.305434 40 |9.694883|10.30511739 9.69520110.304799 38 9.69551810.30448237 249.6480049.952168 9 695835 10.304164|36| 259.64825819.952105 19.69615310.30384735 26.9.64851019.9520431 279.648766 9.951980 28 9.6480209.951917 29 9.9492749.951854 309.6495279.951791 Co-fine Sine Sine 9.697420 10.30258031 9 697738 10.302264301 Co-tang. Tangent, M Degree 63. 19.696+7910.303539134 9.696786|10.30321333 9.697103|10.30289732 4 Degree 26. MI Sine Co-fine | | Tangent Co-tang. | 3cl2.649527.9.951791 19.69773810.39225430 319.64978119.951728 19.69805-10.39.94729 329.500349.951665 9.6983691 30163128 339.6502879.9516021 9.698-8510.301315 27 349.6505199.951539 9.699001 10.300999 26 359.6504989.951476 19.6993 610.300684 25 369.651044,9.951412) 379.6512969.951349 389.6516489.951286 399 6518009.951222 40 9.6520529.951159 19.69963210.300358,24 9.59994710.300:52 23 9.70025310.299737 22 9.700578 10.29942221 4119.65230319.951095 429.65255 9.951032 439.6528069.950968 9.700893 10.299107|20 9.71208110.29874219 9.70152210.298477 9.701837.10.29816317 449.6530579.950905 9.7 2152 10.297848116 459.6533079.950841 19.702466.10.297534 15 4619.65355819.950777 479:6538089.950714 489.6540599.950650 499.6543099.950589! 50 9.6545589 950522 519.654808 9.950458 529.6550579.950394 $39.6553079.950330 549.6555569 95-266 559 6558059.950202 5619.6560539.950138 589.6565509.950009, 599.6567999.949945 60 9.6563479.919881| 1 | Co-fine Sine [ 579.65630.9.950074) I 9.70278210.29721614 9.703095 10.29695513 9.703499 10.290591 12 9.703722 10.2962; 711 9.704026 10.295964 10 19.704350 10.2956501 9 9.704663 10.295337 8 9.704976 10 295 23 7 9.705290 10.294710 6 19.70570310.294397 5 3 9.705915 10.2940841 4 9.706228 10.29377 9.706541 10 2934-92 9.706853.10.2931+ 9.707100 10.292834 Co-tang. Tangent Degree 63. Y 2 1 1 Degree 27. } 1 M Sine | Co-fine Tangent | Co-tang | o'9.65704719.9408 cl 19.707166 10.292834160 IC 11{9.659763|9.949170 129.6600099.949105, 139.6602559.949040 14:9.660 009.948976 15'9.6607469-948910l 119.6572959.949816) 29.657542 9.949,52 39.6577909.949687 4.6580379.949623 519.6582849.949598 €19.65853819.949494! 79.6587779.949429 89.6590249 949364) 90 6592719.949300 c|o6595179.949225 9.707790 10.29221058 9.708102 10.291897 57 9.70841410.291 586 56 9.70872610.29127455 19 709037.10.290962154 9.709349.10.290651 53 9 709660 10.290340 52 9.709971 0.2929|51 9.710382 10.28971850 19.710593] .289407149 9 710904 10.28909648 9.711214 10.28378547 9.711525 10.28847546 9.711836 10.28816445 9.707478 10.29252359 169.66099119.9488451 179.6612369.948760 |9.712146}10.287854 44 9.712456 10.287544 43 189.661481 9.948715 9.712766 10.287234 42 199.6617269.948650 9.71307610.28692441 pol9.661970 9.948584) 9.713386 10.28661440 219.6622149.948519| 19.713695 10.28630539 229.6624599.948453 9.714005 10.28599538 239.662702 9.948388 9.714314 10.28568637 249.662947 9.948323 9.714624 10.28537636 259.66319 9.948257 19.71493310.28506735 269.6634239-948191| 9.71524210.28465834 279.6636777.948126 9.715550 10.28444933 289.6639.948060 9.715859 10.28414032 299.6 41639.947995 9.716168 10.28383231 309.66440019.947929 19.716477 10.283523/30 | Cofine Sine | Co-tang. Tangent M Degree 62, Degree 27. |Tangent I, Go-tang. 19.7.1647.7110.283523130 MI Sine Co-fine. | 309.6644069.947929 3119.6646489.947863) 329.654891 9.947797 19.71678510,283215129 9.717093 10.28290728 339.6651339.947731 9.717401 10.282598 27 34 9.6653759.947665 9.717709 10.28229026 359.6656179.947599] 9.71801710.281983 25 3619.66585819.947533 |9,718325|10.28167324 379.6661009.947467 9.718633 10.28136723 389.666341 9.947401 9.718940 10.28106022 399.666583 9.947335 9.719248 10.28075231 4019.66682419.947269 19.719555110.28044520 4119.66706519.9472031 19.71986210.280138/19 429.6673059.947136 9.720169 10.279831 18 439.6675469.947070 9.720476 10.279524 17 449.667786 9.947004 9.720783 10.279217|16| 4519.6680259.946937 19.721089|10.27891115 4619.668266,9.94687! 9.72139510.27860414 479.6685069.946804 9.721702 10.278298 13 489.6687469.946738 9.722008 10.277991 12 499.6689869.946671 9.72231510.27768511 509.6692259.946604 9.722621j10.277379 10 $119.6694649.945537 19.722927|10.2770731 9 $29.667039.946471 9.72323210.276768 8 $39.6690429.946404 9.723538 10.276462 7 549.670181 9.946337 9.72384310.275156 6 $59.6704199.946270 19.72414910.275851 | 5 569.6706579.946203 $79.6708969.946136| $89.6711349.946069 $99.6713729.946002 6019.67160919.945935| | Co-fine | Sine | 19.72445410.275546| 9.724759 10.275240 3 9.725035 10.274935 2 7.725369 10.274630|| 1 19.725674 10.274326 0 Co-tang. | Tangent M Degree 62. Degree 28. MI Sine Co-fine I | Co-fine Tangent | Co tang. 09,67169019,945935! 19,725674|10,274326|60| 119,671847 91945 868 29,6720849,945800 9,7259790,274021|59 9,72528410,27381658 39,6723214,94573 1 9,726581,27341257 49,5725589,945666 9,72689: 10,27310756 59,67279519,945598 9,72719710,27280355 619, 6730329,945531 79,6732689,9454 89,673509,94396 99,673741 9,945328 109,5739779,945261| 19,7275010,27249954 9,7278050,27219553 9,728109 10,271891 52 9,72841219,27158751, |9,728716 10,271284150 119,6742139,945193} 9,729020|10,270980149 129,6744489,945125 9,72932310,270677|48| A 139,6:46849,945058 9,729626 0,270374 47 149,6749199,944990 159,675 (5419,944922 9,7299290,270070|46| 9,730232110,26976745 169,6753899,944854| |9,730535|10,269464|44| 179,6756239,944786 189,6758599,944718 199,6760949,944650 |20|9,676328|9,94458 2 9,730838 10,269162 43 9,73114110,26885942 9,731443 10,26855641 19,73 1746' 10,26825440 219,6765629,944514 229,676 796 9,944446| 239,6770309,944377 249,5772649,944309 2519,6774979,9442411 9,732048 10,26795239 9,73235110,267649|38| 9,732653 10,267347 37 9,732955 10,267045|36| 19,733 257|10, 2667435 269,67773119,944172 |27|9,677964|9,944104 289,6781979,94401€ 19,733558/10,266441134 9,733860|10,26614033 9,73416210,26583832 92734463110,265537 31 299,678430 9,943967 3019,678663 9,943898| | Co-fine | Sine I 19,734764 10,265236 30 Co-tang. Tangent | Degree 61. Degree 28. M Sine Co-fine | Tangent Co-tang. I 309,67866319,9438981 19,734764110,265236130 |31|9,67889)943830 |9,735666|10,264934|29| 329,6791289,943761 |9,735362|10,264633 28 339,67936c9,943692 9,735668 10,26433227 349,6 9592 9,943624 9,735968 10,264031|26| 359,67982419,94355 9,736÷69|10,26373125 369,6800,69,943486] 37,6802889 4 3 4 17 389,6805199,943348 399,68075´ |9,943279 4019,68098219,9 +3 210! 4119,6812139,943141| 420,681443 9,943-72 43 9,6816749,943003 449,681904 9,742933 45}9,682135′9,942864 19,736570|10,263430124 9,736870 10,26313023 9,7371710,262829 22 9,73747262529,21 9,7377710,262229'20 19,738071 10,26192919 9,738371 10,26629 18 9,738671 10,26132917 9,738971|10,261029|16 19,73927110,16072915 4619,682365 9,942795| 9,739570 10,260430|14| 479,6825959,942725 9,739870 10,26013013 489,682825 9,942656| 499,683055 9,942587| 509.683284'9,94 25 17 9,740169 10,259821 12 |9,740468|10,259 53211 } 19,740767|10,25923310 5 19,68 35 1419,942448 529,6837439:942378 539,683972 9,942308 549,684201 9,942239 5519,6844309,942169 19,741066|10,258934 9 9,741365|10,258635 8 9,74166410,258336 7 |9,741962|10.258038 6 19,7422610,257739 5 569,6846589,942099 579,6848879,942029 [9,74 2559|10, 257441 4 9,742858 10,257142 3 589,6851159,941059 9,743156 10,256844 2 599,68 53439,941889 9,74345410,256546 1 609,6855719,941819 9.74375 10,256248 Co-fine Sine | | Co-tang. | Tangent. M Degree 61. Degree 29. 1 M Sine Co-fine n 9,685579,9+18191 1|9,6857999,941749| 29,6860279,941679 39,6862549,941609 49,686489,941539 59,6867cy 9,941468 69,6869369,941398 7:9,6871039,941328 89,6873899,941257 99,6876169,941187 109,6878429,941116 119,6880699,941046| 129,68 8295 9,94097 Tangent Co-tang. I 9,74 375 2|10,25 6248 16 07 9744050 10,255950 9,744348 10,255652 158 9,744645 10,255355 57 9,744943 10,255057 56 9,745240 10,254760'55 19,7 +55 38; 10,254462|54 9,745835 10,25426553 9,7461321025386852 9,746429 10,2535751 |9,746726′ 10, 25327450 9,747023|10,252977149 9,747319 10,25268048 99747616 10,25238447 9174791210,252087146 19,748209 10,251791 45 136,6885239,9409°5 49,6887479940834 159,68897219,940763| 169,6891959,940693| 9748505 10,251495 44 179,6894219,940622| 9,748801 10,251199 43 189,6896489,940551 199,6898739,940480 20 9,6900989,940409! 219,69032319,94 338| · 9,749097 10,25090242 91749393 10,25060741 |9,749689 10,25031140 229,6905489,940267 239,6907729,940196 249,5909969,940125 259,6912209,940053} 269,691444 919 39y8 2| 279,091668|9,939911 2289,691892 ,9 ;9840 299,69211,939768 309,6923359,939697) | | Co-fine Sine 9.749985110,25001539) 9,75028110,249719|38 9,7505 76 10,24942437 9,750872 0,249128|36| 9,75116710,248833′35 • 19,7514620,-4853834 6,751757 10,24824333 9,75205210,24794832 9,752347 10,24765331 9,7526+210,247358130 | Co-tang. Tangent. M Degree 60. 1 Degree 29. MI Sine Co-fine I Tangent Co-tang. I 3' 19.692339:9.9396971 19.752642 10.24:358130 31/9.5925629.939625) 329.6927859.939554 339.6930089.939+82 19.75293710.247063/29 9.75323110.246769 28 9.75352610.246474 27 349.693231 9.939410 359.6934539.939339| 9.753820 10.246180 26 19.754115 10.245885/25 36:9.69367619.939267| 379.693898'9 939195 389.6941209 939123 399.694342 9.939051 4019.694664 9.938980 19.754409|10.24559124 9.754703 10.24529723 9.754997 10.24500322 9.755291 10.244709|21 9.75558410.24441520 4119.694786 9.9389081 429.695007.9.938835 439.6952299.938763 44.9.695450 9.938691 459.695671 9.9385,9 4619.69589219.938547. 479.6961139.938475 48 9.6y63349.938402 1499965549938330 509. 967749.938257 519.09699519.938185| 529.69721 2.938112 539.69743593804 549.697659-937967 559.697874 9.937895 19.75587810.244122|19| 9.75617210.243828 18 9.756465 10.24353517 9.756759 10.243241|1 9.75705210.242948 15 9.75734510.2426551 9.757-48 10.242362/13 9.75793110.2420691 9 75822410.24177511 9.758517 10.241483 10 758810 10.241190 9 9.759102 10.24 898 8 9 759395110.240605 7 9.759087·10.2403136 19.7599-9 16.240021) 5 5619.69809319.9378221 19.760271110.239728 14 $79.6983139.937749 9.760564 10.2394363 $89.6985329.937676 9.720856|10.239144 2 599.6987519.937603 9.76114710.238852 1 609.6989709.937535 19.751439 10.238561 0 | Co-fine Sine i Cotang. Tangent M Degree 60. Z Degree 30. C MI Sine | Co-fine | o/9.6989799.937531 1 Tangent Co-tang. 19.761439 10.23856160 119.699189 9.937458 29.6994079.937385 39.6996269.937312 49 6998449.937238 19.761731110.238269159 9.762023 10.237977 58 9.762314 10.237686 57 9.762606 10.237394 56 59.7000629.937165 9.762897 10.237103 55 69.70028019.937092: 79.70@498 9.937019 89.7007169.936945 99.700933.9.936872 10 9.701151 9.936799| 1119.7015679.936725 129.7015859.936652 139.7018029-936578 149.702019 9.936505 |9.763188|10.23681254 9.753479 10.23652153 9.763770 10.23623052 9.764061 10.23593951 9.764352 10.235648 50 19.764643|10.235357149 9.764933 10.23506748 9.765224 10.23477647 9.765514 10.23448646 159.7022369.936431 9.765805 10.23419545 16|9.7024529.935357) 179.7026699.935284 19.766095 10.23390544 9.766385 10.23361543 189.7038859.935210 9.766675 10.23332542 199.7031019.936136 9.766965 10.233035|41 209.7033179.936062 9.76725510.232:45/40 21|9.703533,9.9359881 229.7037489.935914 19.767545|10.23245539 9.767834 10.232166 38 23 9.7039649.935840 9.76812410.231876 37 249.7041799.935700 259.7043959.935692 9.7684 310.23158736 9.768703|10.23129735 2619.704610,9.9356181 279.7048259.935543 28'9.705040 9.935469 29 9.705254 9.935395 30 9.705469 9.935320 | | Co-fine Sine I 9.770148|10.22985230 | Co-tang. Tangent. IM Degree 59. 19.768992/10.231008134 9.769281|10.23071933 9.769570 10.23043032 9.76985910.23014131 } Degree 30. MI Sine Co-fine | Tangent Co-tang. | 3019.70546919-935320 19.77014810.229852130 3119.70568319.935246) 329.705897 9.935171 33 9.7061129.935097 349.706326 9.935022 359.70653919-934948 19.770437110.229553120 9.77072610.22927428 9.771015 10.228985|2. 9.771303 10.22869726 19.77159210.228408/2 5 3619.70675319.934873| 19.771880 10.22812024 379.7069679.934798 9.77216810.22783223 389.7071809.934723 9.77245610.22754322 399-707393 9.934649 9.77274510.22725521 409.70760619.934574 19.77303310.226967|20| 4119.707819 9.9344991 19.773321110.226679119 429.7080329.934424 439.7082459.934349 449.7084579.934274 459.7086709.934199| 9.773608 10.22639118 9.773896 10.226104 17 9.774184 10.22581616 9.774471 10.22552915 4619.7088829.934123| 479.7090949.934048 48 9.7093069.933973 499.7095189.933897 19.774759 10.225241 14 9.775046 10.22495413 9.775333 10.224666 12 9.775621 10.22437911 5019.7097309.933322 9.775908 10.224092|10 5419.709949.933747 529.7101539.933671 539.7103649.933596 549.7505759.933520 559.7107869.933444 19.77619510.223805, 9 9.776482 10.223518 8 9.776768 10.223232 7 9.77705510.222945 19.77734210.222658 5 569.710997;9-933369 19.777628|10.222372 $79.7112089.933293 9.77791510.222085 589.7114189.933217 9.778201 10.221799 3 $99.7116299.933141 609.7118399.9330651 9.77848710.221513 19.77877410.221226 | Co-fine | Sine I | Co-tang. Tangent Degree 59. Z 2 1 x Degree 31. 1 Sine Co fine) Tangent Co-tang I 19.778774 10.22122660 019.7118399.93306 19.71204919.932990| -9.7122599.932914 9.712469'9.932838 49.7126799.932761 59.7128899 932685 9.779060 10.220940159 9.779346.10.22065458 9.77963210.220368 57 9.779918 10.220082 56 19.780203 10.219796 55 19.780489 10.219511154 9 71309819.932609 9.713308 9.932533 3.7135179.932457 2.713726 9.932380 2.713935 9.9323041 9.780775 10.219225 53 9.781060 10.21894 52 9.781346 10.21865451 19.781631|10.218369|50 {119.71414419.932227 29.7143529.932151 !39.7145619.9320-4 1499.7147699.931998, 15 9.7149779.9319211 519.715185,9.931845 79.715394 9.931768 189.715601 9.931691 '99.715809 9.931614 2019.7160179.931537 19.781916 10.218084149 9.782202 10.21779948 9.782486 10.21751447 9.782771 10.21722946 |9.783056|10.216944 45 9.783341|10.21655944 19.78,626 10.21637443 19.783910 10.21609c42 9.78419510.21580541 9.84479 10.2155240 19.7162249.931460 29.7164319.931383 33.7166399.931306 9.7168459.931229 ·19.7-70539·931152 9.7172599.931075 9.717456 9.930998 89.7176729.930920 299.717 699.930843 9.718 859 930766 | Co-fine 19.784764110.21523639 9.785048 10.21495438 9.78533210.2 4668 37 9 78561610.214384 36 9.785900 10.21409935 9.786184|10.21381634 9.786468 10.21353233 9.786752 10.2:3248 32 9.787036 10.21296431 19.7873 910.21268130 1 Sine | Co-tang. Tangent j M Degree 58. Degree 31. [M] Sine | Co-fine. | 309.71808 519.930766 3119.71829 9.9306881 329.7184979 930.11 339.7187039 930533 349.7189299.930456| 359.7191149.9303781 Tangent Co-tang. | 19.78731910.212681/30 9.787603|10.212397|29| 9.787886 10.21211428 9.788170 10.21183027 9.788453 10.21154726 19.78873610.211264 25 369.7193209.930300| 19.78901910.210981|24 379.7195259.930223 9:789302 10.210698 23 389.7197309.93014- 9.789585 10.21041522 399.7199359.930057 9.789868 10.210132|21| 409.72014019.929989 9.79015110.209849 20 419.7203459.929911 429.7205499.929833 439.720754 9.929755 449.720958 9.929677 45.9.7211629.929599| 469.721366 9.929521| 19.790433 10.209565|19| 9.790716 10.20928418 9.790999.10.20900117 1 9.790281 10.20871916 9.791563 10.20843615) 479.7215709.929442 489.721774.9.929364 499.721978 9.929286 509.7221819.929207 19.791846|10.208154|14 9.792128 10.20787213 9.792410 10.207590 12 9.79269210.20730811 19.792974 0.20702410 ፡ 5119.722385 3.929129 529.7225889.929050 539-722791|9.928972 54 9.7229949.928893 5519-7231979 928814) $19.7234009.928736 57 9.723603 9.928657 589 7238059.928578 599.7240079.928499 609.7242109.928420 Co-fine | Sine | 9.794945 10.205054 3 9.79522710.204773 2 9.795508 10 204492 I 19.79578910.20421110 Co-tang. Tangent M Degree 58. 19.79325610.206744| 9 9.79353810.206462| 8 9.79381910.2061807 9.794101 10.205899 6 9.79438310.205617 5 19.794664|10.205336| 4 Degree 31. M] Sine Co-fine | Tangent | Co-tang. | 19,795789/10, 204211†60 09,7242109,928420| 19,7244129,928341 29,7246149,928262 [9,796070|10,203930|59 9,796351|10,20364958 39,7248169,928183 9,796632 10,203368 57 49,7250179,928104 59,7252199,928025 9,79691310,203087 56 19,797194 10,2028-6′55 69,72542019,927946) 9,797474 10,202523|54| 79,725622 9,927867 9,797755 10,20224553 89,7258239,927787 9,798036 10,20196452 99,7260249,927703 9,798316 10,201684|51 109,7262259,927528 9,798596 10,201404 50 [119,726426|9,927549 19,79887710,20112349 129,7266269,927469 9.79915710,200843 48 139,7268279,927390 9,79943710,20056347 9,799717 10,20028346 9,79999710,20000345 19,800277,10,19972344 9,80055710,199443 43 149,727027927310 159,7272289,927231| 16 9,7274289,927428 179,7276289,927628| 189,7278289,926828 199,7280279,926027 209,7282279,926227| 219,728437 9,926751 229,728626 9,926671 239-728825 9,926591 24917290249,926511 2519,729 22319,926431| 269,7294229,926351 | 27'9,7296219,926270 289,7298209,926190 299,7300189,926110 309,7302169,926029 | Co-fine | Sine 9,80083610,199163 42 9,801116 10,19888441 9,801396 10,19860440 |9,801675|10,198325|39| 9,801955 10,198045 38 9,802234 10,19776637 9,802513 10,19748736 9,80279210,19720735 19,80307210,19692834 9,80 3351 10,19664933 9,803630 10,19637032 9,803908 10,19609131 |9,804187|10,195813′30 | Co-tang. | Tangent. M Degree 57. Degree 32. M Sine Co-fine I 1 Tangent Co-tang. I 3019,7302169,9260291 19,804187/10,19581330 319,7304159,925949 329,730613 9,925868 339,7308119,925787 349,731009 9,925707 359,73120619,925626 9,804466 10,19553429 9,804745 10,195255 28 9,80502310,194977 27 9,805302|10,194698|26| 19,805580 10,19442025 369731404/9,9255451 379,7316019,925464| 9,805859110,194141|24 9,806137 10,193863|23 389,731799 9,925384 |39|9,73 1995 9,925303 409,73219319,925222| 4119,732390 9,925141| 42 9,7325879,925060 43 9,732784 9,924978 449,7329809,924897 459,7331779,9248:6| 9,806415 10,193585 22 9,80669310,19330921 19,806971|10,193018|20| 9,807249|10,192751|19| 9,807527 10,192433 18 9,80780510,192195|17 9,808083 10,191917 16 19,808361|10,191639|15 4619,733373,9,924735 19,808638|10,191362|14 479,7335699.924653 9,808916 10,191084 13 489,7337659,924572 9,809193 10,190807|12 499,7339619,924491 509,7341979,924409| 9,809471 10,19052911 9,809748 10,190252'10 519,7343539,924328 529,7345489,924246| 5 39,7347449,924164| 549,7349399,924083 5519,73513419,934001| 5619,73533019,923919 579,7355259,923837 589,7357199,923755 599,7359149,923673 |60|9,736109|9,92359: | Co-fine Sine 19,810025|10,189975| 9 9,810302 10,189697 8 9,810580 10,189420 7 9,810857 10,189143 6 9,811134 10,188866 5 9,81141010,:88,891 9,811687 10,188313 3 9,811964 10,188036 9,812241 10,187759 9,81251710,187483 | Co-tang | Tangent | M Degree 57. 1 Degree 33. 39,736692 9,923 345 49,7368869,923263 519,737-809,923180 69,7372749,923098| M Sine Co-fine I 09,73610919,923591| 19,736309 9,923509 29,786497 9,923427 . Tangent Co-tang. | 19,812517 | 10,18748360 [9,812794 10,18720659 9,813070 10,8693058 9,8133470,18665357 9,81362310,186 77 19,813899 10,18610: 55. i 9,81417510,18,824 79,7374679,923016 9,814452 10,18554853 89,737661,92 2933| 9,814728 10,18527252 99,7378549,922851 9,815004 10,18499651 109,7380489,922768 9,815279 10,18472050. 119,7382419,922686) 19,81555510,18444549 129,7384349,922603 9,815831 10,184169 48 139,7386279,922520 A 149,7388209,922438 9,81610710,183893 47 9,81638:10, 18361746 1519,73901319,922 35 51 9,816658 10,18334245 16|9,739205|9,92 2 2 7 2 | 179,7393989,922189 19,816933|10,183066|44| 9,817209 10,18279143 189,739590 9,922106 9,81748410,12251642 199,7397839,922023 9,817759 10,18224041 2019,73997519,921940| 19,81803510,18196540 219,7401679,921857 229,7403599,921774 239,7405509,921691 249,7407429,921607 |2519,7409349,921524 |26|9,7411259,9214411 279,7413169,921357 289,7415079,921274 299,7416989,921198 309,74188919,921107| | Co-fine | Sine I 9,818310f1c,18169039 9,818585 10, 18 1415 38 9,818860 10,18114037 9,81913510,18086536 19,819410 10,18059035 9,819684|10,180315134 9,819959 10,180041 33 9,820234 10,17976632 9,82050810,179492 31 19,820783110,179217 30 | Co-tang. Tangent Degree 56. 2 Degree 33. M Sine Co-fine I 3919.7418899.921107| Tangent Co-tang. I 9.820783 10.179217|30 3119.74208019.921023] 329.742271 9.920939 339.7424619.920855 349.7426529.920772 19.821057|10.178943|29| 9.821332 10.178658 28 9.821606 10.178394 27 9.821880 10.17812026 359.742842′9.920688) 19.822154 10.17784625) 3619.743032 9 920604 9.822429 10.17757124 379.743223 9.920520 9.822703 10.177297|23| 389.7434129.920436 9.822977 10.177023 22 1399.7436029.920352 9.823250 10.17673921 4019.7437929.920268 9.82352410.176476 20 4119.7439829.920184| $429.744171 9:920099 439.744361 9.920015 449.7445509.919931 14519-74473919.919846 46|9.7449289.919762| 47 9.7451179.919677 48 9.745306 9.919593 49 9.745494‍9.919508 sol9.7456839 919424 5119.74587119.9193391 529.7460599.919254 539.746248 9.919169 19.823798,10.17620219 9.824072 10.175928 18 9.82434510.17565517 9.82461910.17538116 (9.82489210.175108 15 19.825166|10.17483414 9.825439 10.17456013 9.82571310.17428712 9.825986 10.17401411 9.82625910.17374110 19.82653210.1734681 9 9.826805 10.173195 8 9.827078 10.12922 7 549.7464369.919084 |55|9.7466249.918999| 9.827351 10.172649 6 9.827624 10.172376 569.74681119.918915) 19.827897 10.172103 $79.7469999.918830 589.7471879.918744 9.828442 10.171558 9.828170 10.171830 599.7473749.918659 9.82871510.171285 16019.74756219.918574) 9.82898710.171012 | Co-fine | Sine | Co-tang. ↑ Tangent. Degree 56. A a Degree 34. ' MI Sine | Co-fine | | Tangent Co-tang. ol9.7475629.918574 19.828987 10.17101260 119.7477499.918489 19.829260 10.170740159 29.7479369.918404 9.829532 10.170468 58 39.7481239.918318 9.829805 10.17019557 49.7483109.918233 9.830077 10.169923|56| 59.7484979.918147 19.830349 10.16965155 6|9.748683|9.9180621 19.830621|10.16937954 79.7488709.917976 9.830893 10.15910653 89.7499569.917891 9.831165 10.168834 52 99.7492429.917805 9.831437 10.16856351 10 9.7494299.917719 9.831709 10.168291 50 1119.74961519.917634 19.831981|10.16801949 129.7498019.917548 9.832253 10.167747 48 139.749986 9.917462 9.832525 10.16747547 149.750172 9.917376 9.832796 10.16720446 159.750358 9.917290 9.833068 10.16693245 16|9.75054319.917204| 179.7507299.917118 18 9.7509149.917032 199.7510999.916945 2019.751 284'9.916859 19.833339|10.166660144 9.833611 10.16638943 9.833882 10.16611842 9.834154'10.16584641 9.834425 10.165575 40 219.7514699.916773 |9.834696|10.165304139 229.7516549.916686 9.834967 10.165033 38 239.7518389.916600 9.835238 10.16476237 249.7520239.916514 9.835509 10.16449136 259.7522079.916427 9.835780 10.16422035 |26|9.752392|9.916340 279.7525769.916254 19.836051|10.163949134 9.836322 10.16367833 289.7527609.916167 9.836593 10.16340732 299.7529449.916080 3019.7531289.915994 9.83686410.16313631 9.83713410.102866 30 | Co-fine Sine | Co-tang | Tangent |M Degree 55. Degree 34. MJ Sine Co-fine 309.75312819.915994 | Tangent [- Co-tang. [ 9.837134 10.162866130 319.7533129.91 5907| 9.837405 10.162595129 329.7534959.915820 9.837675 10.162325/28 339.7536799.915733 9.837946 10.162054 27 349.7538629.915646 9.838216 10.161784|26| 13519.75404619.915559 19.83848710.16151325 369.754229.9.915472| [9.83875710.161243 24 379.7544129.915385 9.839027 10.16097323 38 9.7545959.915297 9.83929710.16070222 399.7547789.91 5210 9.839568 10.160432'31 4019.7549609.915123 9.839838,10.160162 20 4119.75514319.915035 19.840108/10.159892/19 429.7553259.914948 439.755508 9.914860 9.840378 10.15962218 9.840647 10.15935217 449.755690 9.914773 9,840917 10.159083 16 4519.7558729.914685 9.841187/10.15881315 4619.7560549.914597| 841457,10.158543 14 476.7562369.914510 48 9.7564189.914422 499.7566009.914334 5019.7567819.914246 9.841726 10.15827313 9.841996 10.158004 12 9.842266 10.15773411 19.84253510157465 10 5119.7569639.914158 19.842804|10.157195, 9 529.7571449.914070 9.843074 10.156926 8 539-7573269.913982 9.843343 10.156657 7 549.7575079.913894 9.843612 10.156387 6 5519-7576889.9:3806 9.843882110.156118 5 .019.75786919.913718 19.844151|10.155849 4 $79.75804919.913630 9.844420 10.155580 3 89.7582399.913541 9.844689 10.155311 2 599.7584119.913453 9.841958 10.155042 I 6019.758591|9.913364| 9.84522710.154774 o | Co-fine Sine | | 1 Co-tang. Tangent M Degree 55. A a 2 Degree 35. Sine Co-fine 】 Tangent | Co-tang I 919.758591|9.9133641 19.84522710.15477460 19.758772;9.913276 19.845496 10.154504159 29.7589529.913187 6.84576410.154235 58 39.7591329.913099 9.84603310.153967 57 49.7593129.913010 519.7594929.912921| 9.846302 10.15369856 9.84657010.153429|55| 619.7592729.912833) 19.846839|10.153161|54| 79.7598519.912744 89.7600319.912655 9.847107 10.15289-53 9.847376 10.152624 52 99.7602109.912566 9.847644 10.15235651 10 9.7603909.912477 9.84791310.15208750 1119.76056919.912388 19.848181110.15181949 129.7607489.912299 9.848449 10.15155148 139.7609279.912210 9.84871710.15128347 149.7611069 912121 9.84898510.15101546 159.7512859.912030 [9.849254/10 15074645 16|9.7614649.911942 19.849522 10.15047844 179.7616429.911853 9.84978910.15021443 189.7618219.911763 9.850057 10.14994342 199.7619999.911674 9.85032510.14967541 2019.7621779.911584 19.850593 10.149467140 21|9.762356|9.911495| 19.85086110.14913939 229.7625349.911405 9.851128 10.14887238 239.7627129.911315 9.851395 10.14860437 249.7628899.911226 9.851664 10.14833636 2519.763067|9.911136| 9.851931 10.14806935 269.7632459.911046| 19.85219910.14780134 279.7634229.920956 9.852466 10.14753433 289.7635999.910866 9.852731 10.14726732 299.7637779.910776 9.853001 10.14699931 3019.7639549.910686 9.853268 10.14673230 | Co-fine | Sine | | Co-tang. Tangent. M Degree 54. Degree 35. M Sine Co-fine | Tangent Co-tang. | 309.76395419.910686) 3119.7641319.910596, 329.7643089.910506 339.764485 19.853268.10.1466732'30 19.853532/10.14646529 9.853802 10.14619828 9.910415 9.854069 10.14597027 349.764662 9.910325 9.854336 10.145664 26 359.7648389.910235 19.85460310.14539725 369.7650159.9101441 19.854870 10.14513024 379.7651919.910054 9.85513710.144863|23 389.7653679.909963 9.855404 10.144596 22 1399.7655449.909873 9.855671 10.144329|21 4019.76572019.9097821 19.855937!10.144063|20 419.7658969.909591| 9.85620410.143795|19| 429.7660719.909601 439.7662479.909510 9.856471 10.14352918 9.856737 10.143268|17 449.7664239.909419 9.857004 10.14299616 459.7665989.909328| 9.857270|10.14273015 4619.7667749.509237| 479.7669499.909146 489.7671249.909055 9.858069 10.1419311 499.7672999.908964 5019.7674749.908873 19.85753710.14246314 9.85833610.14166411 9.858602 10.14139810 9.857803 10.14219713 5119.7676499.908 7811 529.7678249.908690 53 9.767997.9.908599 19.858868 10.141132 0 9.859134 10.140866 8 9.859400 10.140600 7 549.768173 9.908 507 5519.768348 9.908416 9.859666 10.140334 6 9.85993210.140068 5 15619,768522|9.908324) 19.860198|10.139802|4) $79.7686969.908233 9.86046410.139536 3. $89.76887119.908141 599-7690459.908049 609.7692199.907958| 9.860730 10.139270 2 9.860995 10.139005 I 19.86126110.138739 0 | Co-fine | Sine | Co-tang. | Tangent. | Degree 54. Degree 36. MI Sine | Co-fine | | Tangent | Co-tang. \ 19,76922919,907958 19,861261|10,13873960 19,769392|9,907866 19,861527 10,138473159 29,7695669,907774 9,86179210,138208 58 39,7697409,907682 9,862058 10,137942 57 49,7699139,907590 59,77008719,907498| 9,86232310,137677 56 19,862589′10,137411'55 69,7702609,907406| 19,86285410,13714654 79,7704339,907314 9,863119 10,13688053 89,7706069,907221 9,863385 10,13661552 99,7707799,907129 9,863650 10,13635051 109,7709529,907037| |9,863915|10,136085 50 119,7711259,906945 19,864180|10,13582049 129,7712989,906852 9,86444510,13555448 139,7714709,906760 9,864710 10,135289 47 149,771643 9,906667 9,864975 10,13502446 1519,7718159,906574 9,865240 10,134759'45 |16|9,77198719,9064821 19,865505|10,134495|44 179,7721599,906389 9,865770 10,13423043 189,7723319,906296 9,866035|10,13396542 199,7725039,906203 9,866300 10,13370041 209,7726759,906111 9,86656410,13343640 219,7728479,906018 19,866829 10,13317139 229,7730189,905925 9,86709410,132906 38 239,7731909,905832| 9,867358 10,132642|37 9,867623 10,13237736 19,86788710,13211335 249,7733619,905738 |25|9,773 5 3 39,905645| 269,7737049,9055521 279,773875 9,905459 289,7740469,905365 299,7742179,905272 309,77438819,905179 Co-fine Sine I { 19,868152|10, 13184834 9,868416 10,13158433 9,868680 10,13132032 9,868945|10,131055 31 19,869209|10,13079130 Co-tang. Tangent M Degree 53. t Degree 36. My Sine Co-fine I Tangent Co-tang. I 3019,774388/9,905179| 19,869209/10,130791/30 319,77455819,9050851 19,86977310,13052729 329,7747299,904992 9,869337 10,130263|28| 339,7748999,904898 9,870001 10,129999|27| 349,7750709,904804 9,870265 10, 2973526 359,77524019,90471 1 9,870529|10,129471|25| 369,7754109,904617 19,870793110, 129207|24 379,7755809,904523 9,871057|10,128943|23 389,7757509,904429 9,871321 10,128679 22 399,7759209,904335 9,871585 10,128415 21 4019,7760909,904241 19,871849 0,128151|20 4119,7762599,9≈4147| 429,7764299,904053. 439,7765989,903959 9,872112110,127888119 9,872376 10,12762418 9,872640 10,127360|17| |449,7767689,903864 9,872903|10,127097 16 459,7769379,903770 |9,873167|10, 126833|15 469,77710619,903676 19,873430 10,126570|14 47 9,7772759,903 581 489,7774449,903486 499,7776139,903392 9,873694 10,12630613 9,873957 10,126043 12 9,874220 10,12578011 509,7777819,903 298 9,87448410,12551610 519,7779509,903203| 19, 529,7781199,90 3108 ,874747 | 10, 125253] 9,87501010, 124990 9 8 539,7782879,9°3013 9,87527310,124727 549,7784559,902919 $519,778623'9,902824) 5619,778792 9,902729| 579,7789609,902634 589,7791299,902539 599,7792959,902444 609,7794639,902349 Co-fine Sine 9,87553610,124464 6 9,875799 10,124201| 19,876063|10,123937| 4 9,876326 10,123674 3 9,876589 10,123411 2 9,876851|10,123149|| 1 19,87711410, 122885 0 Co-tang. Tangent M Degree 53. Degree 37. MI Sine | Co-fine. | |Tangenti Co-tang. | 99,77946319,9023491 19,877114/10,12288560 19,7796319,902253 9,87737710,122623/59 29,7797989,90 2 158 9,877640 10,12236058 39,7799659,902063| 9,877903 10,122097 57. 49,7801339,901967 9,878165 10,12183456 $19,7803009,901872) 9,878428/10, 12157255 6|9,780467|9,901776 9,87869110, 12130954 79,7806349,901681 9,878953|10,121047 53 89,7808019,901585 9,87921610,120784 52 99,7809689,901488 9,879478 10,12052051 109,7811349,9013911 19,879741105:20259150 149,781301|9,901298 19,880003|10,119997|49 $29,7814679,901202 9,880265 10,11973448 139,7816349,901106 9,880528 10,119472 47 149,781800 9,901010 9,880790|1c,r1921046 159,7819669,900914 19,88105210,11894845 169,7821329,900828| 9,88131410,118686|44 179,7822989,900722 19,8 189,7824649,900626 199,7826909,9005 29|| 881576 10,11842443 9,881839 10,11816142 9,882101 10,11789941 pol9,78 279619,9004331 19,882363/10,117637140 219,78296119,900337 9,882625 10,117375 39 229,7831279,900240 9,882886 10,11711438 239,783292 9,900144 9,883148 10,11685237) 249,7834579,900047 9,88341010,11659036 259,7836239,899951: 19,88367210,11632835 2619,78378819,8998541. (279,7839539,899757 289,784118 9,899660 299,7842829,899563 309,7844479,699467| Co-fine Sine | 9883934|10,116066|34 9,884195 10,115805 33 9,88445710,11543 32 9,884719 10,1 152813 19,884980/10,11502030 31 Co-tang. Tangent M Degree 52. Degree 37. M Sine Co-fine 3019.78444719.899267| Tangent Co-tang. I 19.88498010.115020'30 9.885242/10.114758129 3119.78461619.89937c 329.7847769.899273 9.885503 10.114497 28 339.784941 9.899175 9.885765 10.114235 27 349.7851059.899078 9.886029 10.113974 26 3519.78526919.898981 19.886288 10.11371225 3619.7854339.898884 19.886549110.113451124 379.7855919.898784 9.886810 10.11319023 389.7857619.898689 9.887072 10.11292822 399.7859259.898592 9.887333 10.112667|21 409.7860889.898494| 9.887594 10.112406 20 4119.78625219.898397 19.88785510.112145|19| 429.7864169.898 299 9.888116 10.11188418 439.7865799.898201 449.786742 9.898104 459.7869099.8980061 9.88837710 111623 17 9.888638 10.111362 16 19.888899.10.11 4619.7870199.897908 479.7872329.897810 48 9.7873959.897112 49 9.7875579.897614 5019.7877209.897519 5119.7878839.897418 $29.7880459.897320 $39.788208 9.897222 549.788370 9.897123 559.7885329.897025 9.88916010.110840114 9.889421 10.11057913 9.889682 10.11031812 9.889943 10.11005711 9.88020410.109796 10 19.890965,10.109535 9 9890725 10.109275 8 9.890986|10.109014 7 9.891247 10.108753 6 19.891507, 10.108493 5 5619.78869419.896926] 19.891768|10.108232 579.7888569.896828 $89.7890189.896729 9.892028 10.107972 3 9.892289 10.107711 599.7891809.896631 9.892549 10.107451 609.7893429.896532 19.892810/10.107190 Co-fine Sine | | Co-tang. Tangent M Degree 52. Bb 1 Degree 38. M Sine | Co-fine | Tangent Co-tang. I 09.7893429.896532 19.892810|10.10719960 119.7895049.896433 [9.893070|10.106939159 29.7896659.896335 9.893330/10.10666958 39.7898279.896236 9.893591|10.106409 $7 49.7899889.895137 9.893851 10.106149 56 59.7901499.8960381 9.894111 10.10588955 69.7903109.895939 19.894371|10.105628154 79-7904719.895840 9.894632 10.105368 53 89.79063 29.895741 9.894892 10.10510852 99.7907939.895641 9.895152 10.10484851 10 9.7909549.895542) 9.895412 10.104588 50 1119.79111519.8954431 19.895672 10.104328149 129.7912759.895343) 9.895932 10.10406848 139.7914369.895244 9.896192 10.10380847 149.7915969.895144 9.896452 10.10354846 159.7917569.8950451 9.896712 10.10328845 1619.7919179.894945 9.896971|10.103028144 79.7920779.894846 9.897231 10.10276943 189.7922379.894746 9.897491 10.102 50942 199.7923979.894646 9.897751 10.10224941 2019.79255719.894546 9.898010 10.10199040 2119.7927169.894446 19.89827910.101.739139 229.7928769.894346 9.898530 10.101470 38 239.7930359.894245 9.89878910.10121137 249.7931959.894146 9.899049 10.100951 36 259-7933549.894046 19.899308|10.10069235 2619.7935139.893946|| 279.793673,9.893845 289.7938329.893745 1299-793991 9.893645 30′9.7941499.893444) | Co-fine Sine | 19.899568 10.100432134 9.899827 10.10017333 9.900086 10.09991332 9.900346 10.09965431 19.900605|10.099395 30 Co-tang. Tangent M Degree 51. Degree 38. MI Sine Co-fine | Tangent Co-tang. | 3©19.794149|9,893444) 19.90060510.099395|30 3119.79430819,8934441 19.900864|10.099135|29| 329.7944679.893343 9.901124 10.09887628 339.7946269.893243 9.901383 10.09861727 349.7947849.893142 9.901642 10.09835826 35.9.7949429.893041 19.901991 10.098099 25 3619.79510119.892940| 19.902160 10.09783-124 379.7952599.892839 9.902419 10.097580 22 389.7954179.892738 9.902678 10.097321 22 399.7955759.892637 9.902937 10.09706221 4019.795733'9.892536) 9.903196 10.096803/20 4119.79589119.8924351 429-7960499.892334 439.796206 9.892233 44 9.7963649.892132 459.7965219.892030 9.903973 10.09602717 9.904232 10.095768 16 19 904491|10.09550915 19.903455|10.096544|19 9.903714 10.09628518 4619.79667819.8919281 479.7968369.891827 19.90475010.09525014 9.90500810.094991|13 489.7969939.891726 49 9.7971509.891624 sol9.79730719.891522 9.90526710.094733|12 9.905526 10.094474|11 9.905784 10.094215|10 519-79746719.891421 529.797621 9.891319 539-7977779.891217 549.797934 9.891115 559.7980919.891013| 19.906043|10.093957, S 9.906302 10.093698 & 9.90651010.093440| 7 9.906819 10.093181 6 9 907077 10.092923 5619.79824719.8909111 $79.7984039.890809 589.7985609.890707 $99.7987169.890605 609.1988729.890503 | Co-fine | Sine | 19.907336110.0926641 9.907594 10.092406 3 9.90785210.0921472 9.908111 10.091889 1 9.908369 10.091631| ( Co-tang. Tangent: N Degree 51. Bb 2 Degree 39. MI Sine | Co-fine Tangent | Co-tang | 019.79887219.8905031 19.908369|10.091631|60| 119.79902819.8904001 19.908627/10.091373159 29.7991849.890298 9.908886 10.09111458 39.7993369.890195 9.909144 10 090856 57 49.7994959.890093 9.909402 10.090598 56 $19.7996519.889990! 19.909660 10.090840155 69.799806|9.889888 9.909918|10.090081154 7.9-799961 9.889785 9.910176 10.089823 53 8.9.8001179.889682 (9.910435 10.089565 52 99.8002729.889579 9.910693 10.08930751 10 9.8004279.889476 19.910951 10.089049 50 1119.80058219.8893741 19.911209|10.088791149 129.8007379.889271 9.911467 10.08853348 139.8008929.889167 9.911724 10.088275 47 149.8010479.889064 9.911982 10.08801746 159.801209.888961 9.912240 10.08776045 16|9.80135619.888858 19.912498'10.087502144 179.8015109.888755 9.912756 10.087244 43 189.8016659.888651 9.913014 10.086986 42 199.8018199.888548 9.913271 10.08672941 2019.801973 9.888444 9.913529 10.086471 40 219.80212719.888341 19-913787|10.08621339 229.8022829.888237 9.914044 10.085956 38 239.8024359.888133. 9.914302 10.08569837 249.8025899.888030 9.914560 10.085440 36 2519.8027439.887926 9.91481710.08518335 269.8028979.887822 19.915075 10.08492534 279.8030509.8877189.915332 10.08466833 289.803204 9.887614 9,91559010.08441032 299.8033579.887510 9.915847 10.08415331 3 019.80351019.887406 19.916104 10.083895/30 | Co-fine Sine | Co-tang | Tangent M Degree 50. ' Degree 39. IM Sine Co-fine Tangent | Co-tang. \ 3019.8035109.887406) 19.916104|10.083895 30 3419.80366419.8873021 329.8038179.887198 19.916362|10.083638|29| 9.916619 10.083381 28 339.8039709.887093 9.916876 10.083123 27 349.8041239.887909 9.917134 10.082866 26 359.80427619.886884 9.917391 10.082609 25 3619.80442819.886780 |9.917648|10.082352|24| 379.8045869.886675 9.917905 10.082094 23 389.8047349.886561 9.91816210.081837 22 399.8048869.886466 9.91842010.081580 21 409.805038 9.886361 9.918677 10.081323 20 419.8051919.896257, 19.918934|10.081~66|19| 429.8053439.886152 9.919191 10.08080918 439.8054959.886047 9.919448 10.08055217 449.8056479.88 5642) 9.919705 10.08029516 459.8057999.88 5837 9.919962 10.08003815 4619.80595119.885732 479.8061039.885627 489.8062549.885521 499.806406 9.885416 09.8065579.885311 |9.920219|10.07978114 9.920476 10.07952413 9.920733 10.07926712 9.920990 10.07901011 19.921247 10.07875310 5119.8067099.8852051 9.921503|10.078496) 9 529.8068609.885100 9.921760 10.078240 8 $39.8070119.884994 9.92201710.077983 7 549.8071629.884889 9.922274 10.077726 6 5519.8073149.884783 19.92253010.077469 5 569.8074649.884677 579.8076159.884572 589.8077669.884466 599.8079179.884360 609.800679.884254 | Co-fine | |9.922787|10.077213| 9.923044 10.076956 31 9.923300 10.076699 2 9.923557 10.076443| 1 (9.923813|10 076186 c Sine | Co-tang. | Tangent. M Degree 50. Degree 40. " MJ Sine Co-fine Tangent Co-tang. I .0|9,808067|9,884254| 19,923813|10,076186|60| 119,80821819,884188) |9,924070|10,075930159 29,8083689,884049 9,924327 10,07567358 39,8085199,883936 9,92458310,075417 57 49,8086699,883829 9,924839 10,07516056 519,80881919,883723) 19,925096|10,074904′55 69,8089699,883617 |9,925352 10,074647 54 79,8091 199,8835 10 9,925609 10,07439153 89,8092699,883404 9,925865 10,074135 52 99,8094199,883297 109,8095699,883:91 9,926121|10,073878 51 19,926378 10,07362250 119,80971819,883084| 9,92663410,07336649 129,8098689,882977 9,926890 10,073110 48 139,8100179,882871 9,927147 10,07285347 149,810166 9,882764 9,927403 10,07259740 1519,8103169,882659 9,92765910,072341′45 1619,81046519,882550 (9,927915|10,072085|44 179,8106149,88 2443 9,928171 10,07182943 189,81076; 9,882336 9,928427 10,071573 42 199,8109129,882228 9,928683 10,07131741 209,81006119,882121 (9,928940|10,07106040 219,8112109,882014) 9,92919610,070804|39| 229,8113589,881907 9,92945210,070540 38 239,8115069,881799 9,92970810,07029237 249,8116559,881692) |9,929964|10,070036|36| 2519,8118549,881584] 19,910219 10,069781135 26,9,8119529,881477) 9,930475110,06952534 279,8121009,881369| 9,930731 10,069269'33 289,8122489,881261 9,930987 10,06901332 299,8123969,881153 9,931243 10,06875731 309,8125449,881045 9,931499 10,068501 30 | Co-fine | Sine | | Co-tang. | Tangent. IM Degree 49. Degree 40. M Sine | Co-fine | Tangent Co.tang.| 3019,81254419,881045| 19,931499110,068501|30 319,81269219,880937 |9,931755|10,068245|29 329,8128409,880829 9,93201010,067989|28| 339,8129889,880721 9,932266|10,067734 27 349,8131359,88-613 9,932522 10,067478 26 359,81328319,880505 |9,932778|10,067223|25| 369,8134309,880397 [9,933033|10,066967|24| 37 9,813578 9,880289 9,933289|10,066711|23 389,8137259,880180 9,933545 10,066455 22 399,8138729,880072 4019,81401919,879963| 9,933800 10,06620021 19,93405610,065944|20| 4119,814166 9,879855 429,8143139,879746 43 9,8144609,879637 44 9,8146079,879529 14519,81475319,879420 |9,934311|10,065688|19| 9,934567 10,065433 18 9,93482210,065177 17 2935078 10,064922 16 19,93533310,064666|15 4619,814900 9,879311 19,935589 10,064411|14 479,8150469,879202 9,93584410,064156 13 489,8151939,879093 9,936100 10,063900|12 499,8153399,878984 9,93635510,06364511 |50|9,815485|9,878875 19,936610|10,063389'10 519,81563119,878766| |9,936866|10,063134 9 529,8157779,878656 539,8159239,878547 549,8160699,878438 $59,8162159,878328) 9,937121 10,062879 8 9,937376 10,062623| 7 |9,937632 10,062368 6 19,937887110,0621131 5619,81636119,878219 579,816506 9,878109 589,8166529,871999 599,816797 9,877890 609816943 9,877780l | Co-fine | Sine | 9,938142 10,061858) 9,938397 10,061602 9,938653|10,061347 2 9,93890810,61092 |9,93916310,060837| © ICo-tang. Tangent M Degree 49. Degree 41. MI Sine 1 Co-fine. I Tangent Co-tang. I ol9,8169439,877780| 19,939163|10,060837160 1/9,81708819,877670 92939418 10,06058259 29,8172339,877560 9,939673 10,060327 58 39,8173789,877450 9,939928 10,06007257 49,8175239,877340 9,940183 10,05981656 59,8176689,877230 19,94043810,05956255 69,8178139,877120 19,940693:10,0593075 4 79,8179589,877009 9,940948 10,059052 53 89,8181039,876899 9,941203 10,058797 52 99,8182479,876789 9,941458 10,05854251 109,8183929,876678| 19,941713 10,058287150 119,81853619,876568| 19,441968 10,058032|49| 129,8186819,876457 9,942223 10,057777|48| 139,8188259,876347 |9,942478|10,05752247 149,818969 9,876256 9,942733 10,057267 46 159,81811319,876125| 19,942488130,057012|45| 169,8192579,876014 179,8194019,875904 189,819545 9,875793 199,8196899,875682 2019,8198329,875571 219,819976/9,8754591 229,8201 199,875348 239,820263 9,875237 249,8204069,875125 2519,8205499,875014| 9,943243 10,056757|44 9,943498 10,05650243 9,94375210,05624842 9,944007|10,05 5993 41 19,9 4 4 2 6 2 | 1 0,05 573840 19,944517/10,055483139 9,944771 10,055229|38| 9,945026 10,054974 37 9,945281 10,05471936 19,945535/10,054464|35| 19,945790 10,054210134 9,946045 10,053955 33 269,8206939,874903 279,8208369,874791 289,820979 9,874679 299,821122 9,874568 309,8212649,874456| 9,946299 10,053701 32 9,94655410,053446 31 19,946808 10,053192 30 | Co-fine | Sine | Co-tang. | Tangent. Degree 48. Degree 41. M Sine Co-fine | 309.8212649.874456| Tangent Co-tang. I 19.946808|10.05319230 3119.82140719.8743441 19.947063|10.052937129 329.8215509.874232 9.947317 10.052682 28 339.8216929.874120 9.947572 10.052428 27 349.8218359.874008 9.947826 10.052173 26 359.8219779.873896| 9.948081 10.051919 25 3619.8221209.873784 379.8222629.873672 38 9.822404 9.873560 399.8225469-873447 40 9.82268819.873335 9.94833510.051664124 9.948590 10.05141025 9.948844 10.05115622 9.949099 10.05090121 19.949353|10.05064720 419.82283019.873223) 19.949607|10.05039319 429.8229729.873110 9.949862 10.05013818 439.8231149.872998 9.95011610.04988417 449.8232559.872885 4519.8233979.872772 9.950370 10.04963016 19.950625 10.04937515 4619.82353819.872659| 479.823680 9.872546 489.8238219.872434 19.95087910.049121/14 9.951133 10.04886713 9.951388 10.04861212 49 9.823962 9.872321 5019.824104/9.872208| 9.951642 10.048358|11 9.951896 10.048104 10 5119.82424519.872094 529-8243869.871981 539.8245279.871868 $49.8246679.871755 55'9.824808 9.871641 19.952150/10.047850 9 9.952404 10.047575 9.952659 10.047341|| 7 9.952913'10.047087 6 9.953167 10 0468331 8 5619.8249499.871528 $79,8250909.871414 589.8252309.871301 $99.8253709.871187 609.825511 9.871073 | Co-fine | Sine | 19.953421110.046579 14 9:953675 10.046325 3 9.953929|10.046071 9.95418310.045817 1 |9.954437|10.045562 0 | Co-tang. | Tangent. IM Degree 48. Сс 1 Degree 42. ! M Sine Ce-fine | Tangent Co-tang. I 0*9.8255119.871073 19.954437 10.045562160 189.825651|9.870960| |9.954691|10.045308159 29.8257919.870846 9.954945 10.045054 58 39.8259319.870732 9.955199 10.044800|57| 49.8260719.870618 9.955453 10.044546 56 59.826211|9.8.70504 9.955707 10.04429255 69.8263519.8703901 19-955961|10.044038154 79.8264919.870271 9.956215 10.04378453 89.8266319.870161 9.956469 10.043531 52 99.8267709.870047 9.956723 10.04327651 Fo 9.8269109.8699331 19.956977 10.04302350 119.827049 9.869818 9.95723110.042769149 129.8271899.869704 139.827328 9.869589 149.827467 9.869474 159.827606 9.869360 9.957485 10.04251548 9.957739 10.04226147 9.957993 10.042007 46 9.958246 10.04175345 169.827745 9.869245 179.827884 9.869130 19.95850010.041 500144 9.958754 10.04124643 189.828023 9.869015 9.959008 10.04099242 199.8281629.868900 9.956262 10.04073841 209.8283019.868785 9.959515 10.04048540 219.82843919.868670 229.8285789.868555) 239.8287169.868439) 24 9.8288559.868324 25/9.828993'9.868209 19.959769|10.040231139 9.960023 10.03997738 9.960277 10.039723 37 9.960530 10.03946936 19.960784/10.03921635 26 9.82913119.8680931 279.8292699.867978 289.8294079.867862 299.8295459.867747 3019.82968319.867631 | | Co-fine Sine 19.961038|10.038962134 9.961291 10.038608 33 9.961545 10.03845132 9.961799 10.03820131 9.96205210.03794730 Co-tang. Tangent. M Degree 47. Degree 42. MI Sine Co-fine I | Tangent Co-tang. 1 3019.82968319.867631| 19.962052/10.037947|30 3119.82982119.867515| 19.962306|10.037694129 3298299599.867399 9.96256010.03744028 339.8300969.867283 9.962813 10.037187|27 349.8302349.867167 9.963067 10.036933 26 359.8303729.867051 19.96332010.036680 25 3619.8305099.866935) 19.963574|10.036426|24 379.830646 9.866819 9.963827 10.03617323 389.8307849.866703 9.964081 10.03591922 399.8309219.866586 9.964335 10.03566521 4019.8310589866470 9.964588 10.03541220 4119.83119519.866353| 19.964842110.035158/19 429.8313329.866237 9.965095 10.034905 18 439.8314699.866120 19.965348 10.03465217 449.831606 9.866004 9.965602 10.034398 16 4519.83174219.865887 19.965855 10.03414415 469.83187919.865770 479.83201 59.865653 48 9.8321529.865536 499.832288 9.865419 sol9.83242519.8653021 $119.8325619.865185) 529.8326979.865068 $39.832833 9.864950 $49.832969 9.864833 59.833105/9.864716 5619.833241 9.864598 $79.833376 9.864480 589.833512 9.864363 599.83364819.864245 6a9.833783′9.864127 | Co-fine Sine 19.966109 10.033891|14| 9.966362 10.033638 13 9.966616 10.033384 9.966869 10.03313111 19.96712210.032878 10 19.967376|10.0326241 9 9.967629 10.0323711 8 9.967883'10.032117 7 9.968136 10.031864 19.968389 10.031611 19.968643 10.031357 4 9.968896 10.031104 3 9.969146 10.030851 9.969403 10.030597 19.969656 10.030344 0 Co-tang. Tangent | M Degree 47. Gc 2 พ Degree 43. # MI Sine Co-fine | Tangent | Co-tang 1 d9.833783′9.864127|| 19.969656|10.03034460 19.8339199.864010, |9.969909|10.030091159 29.8340549.863892 9.97016210.02983858 39.8341899.863774 9.970416 10.029584 57 49.8343249.863656 9.970669 10.02933156 519.83446019.863537 19.970922|10.029078 55 619.8345959.863419 9.971175 10.028827154 79.8347309.863301 9.971428 10.028571 53 89.8348659.863183 9.971682 10.028318 52 99.8349999.863064 9.971935 10.02806551 10 9.8351349.862946 19.972188 10.02781250 119.8352699.862827 19.972441|10.027559149 129.8355039.862709 9.972694 10.02730648 139.8355389.862590 9.972948 10.02705247 149.8355729.862471 9.973201 10.02679946 159.835806 9.862353 19.973454 10.026546145 1619.83594119.862234, 179.8360759.862115 19.973707110.02629344 9.973960 10.026040 43 189.835209 9.861996 9.974213 10.025987 42 199.8363439.861877 9.974466 10.02553341 2019.8364779.861757 9.974719 10.02528040 2119.83661119.861638 19.974973110.025027/39 229.836745 9.851519 9.975229 10.024774 38 239.8368789 861399 9.975479 10.024521 37 249.8370129.861280 9.975732 10.024268 36 259.837146 9.861161 9.975985 10.02401535 269.83727919.861041, 19.976238|10.023762|34 279.8374129.860921, 9.976491 10.02350933 289.8375459.860802 9.976744 10.02325632 299.8376799.860682 9.976997 10.02300331 3019 8378129.860562 9.977250 10.022750|30| Co-fine 1 Sine | Co-tang | Tangent [M Degree 46. Degree 43. 3119.8379459.860442 329.8380789.860322) 339 8382119.860202 Sine | Co-fine | | 309.8378129.860562 I Tangent Co-tang. \ 19.97725010.022 75 013 0 9.977503|10.022497 29 9.977756 10.022244 28 9.978009 10.02199127 349.8383449.86008 2 9.978262 10.021738|26| 359.8384779.859962 19.978515/10.02148525 3619.83860919.8598421 379.8387429.859721 389.8388759.859601 399.8390059.859580 409.8391409.859360 9.979768 10.02023224 9.979021 10.020979 21 9.979274 10.020726 22 9 979527 10.020473 21 9.979780 10.020220 20 4119.83927219.859239. 429.8394849.859118 439.8395369.858998 449.8396689.858877 19.980033|10.019967|19| 9.980285 10.0197148 9.980538 0.019461|17| 9.980791 10.01920916 459.839800 9.858756 9.981044 10.01895615 4619-8399329.858639 479.8400649.858514 489.8401969.858398 499.840428 9.858272 5019.8404599,858150) 9.98129710.01870314 9.981550 10.01845013 9.981803 10.0181971 9.982056 10.01794411 19.982309 10.017691 10 } 5119.840591|9.858029| 1529.84072219.857908 539.8408549.857786 9.98255210.017438) 9 9.98281410.017185 8 9.98306710.016933 7 549.8409859.857665 559.8411169.9575431 5519.841247,9.857421, 57 9.8413789.857300 589.8415099.857158 599.8416409.857056 609 8417719.856634| | Co-fine Sine I 9.983320 10.016680 6 9.98357310.01642; 5 9.983826|10.016174 9.984079 10.015921 3 9.984331 10.015668 2 9.984584 10.015416 1 19.98433710.015163 0 Co-tang. Tangent M Degree 46. Degree 44. Ml Sine | Co-fine | 09,84177119,856934) Tangent Co-tang. I 19,984837110,15162|60 19,841902 9,856812) 9,985090|10,014910159 29,8420339,856690 9,985343 10,014657 58 39,8421639,856 568 9,985596 10,01440457 49,8422949,856445 9,985848 10,0141$156 59,84242419,856323 19,986101 10,01389955 69,84255519,8562011 19,986354|10,013646|54 79,8426859,856078 9,986607 10,013393 53 8,9,84281519,855956 9,986859 10,01314052 99,8429459,855833 9,987112 10,012888 $1 109,84307619,855710 9,987365 10,012635|50 1119,84320619,855588 | 19,987618 0,01238249 29,8433369,855465 9,987871 10,01212948 139,8434659,855342 9,988123 10,011877 47 149,8435959,855218 9,988376 (0,01162446 1519,84372519,855096| 9,988629 10,01137145 199,8442439,854603 16,9,8438559,854973 179,8439849,854850 189,8441149,854727 9,989387 10,01061342 209,8443729,854480l 19,989893 10,01010749 19,988887 10,0г1118/44 9,989134 10,01086643 19,989640 10,01036047 219,8445029,85435 9,990145 10,009855139 £39,8446319,854233 9,990398 10,00960238 239,8447609,854109 9,990951 10,00924937 249,844889 9,853986 9,990903|10,009036|36| 259,8450189,8538621 9,99115610008844 35 269,8451479,8537381 - 19,991409|10,008592|34| 279,8452769,853614 |9,991662|10,008338 33 289,8454049,853590 9,99191410,c08086|32 299,8455339,853266 9,99216710,00783331 309,8456629,853242! |9,992420|10,00758030 Co-fine Sine | Co-tang. Tangent (M | Degree 45. Degree 44. M Sine | Co-fine. 3019,84566219,8532421 319,8457999,853118) Tangent Co-tang. 19,9924211000758c130 9,992672|10,007328 29 329,8459199,852994 39,846047 9,852869) 549,846175 9,852745 35/9,84630419,852620| 9,992925|10,007075 28 9,993178 10,006822 27 9,993430 10,006564|26 9,993683|10,006317|25| 369,84643219,842496 9,993936|10,006064|24 379,8465609,852371 9,994189|10,005811 23 389,8466889,852240 9,994441|10,005559|22| 399,8468169,852122 9,994694|10,005306 21 4019,8469449,851997 9,994947|10,005053/20 4119,8470719,851872| 9,99519910,004801|19 429,8471999,851747 9,99545210,00454818 439,8473279,851622 9,995701 10,004295 17 44 9,847454 9,851497 9,995957 10,004043|16| 4519,847582|9,851372] 9,996210|10,00379015 40 9,84770919,851246| 479,8478369,851121 489,8479649,850996 499,8480919,850870 509,8482189,8507451 9,996463 10,00353714 9,996715 10,00328513 9,996968|10,00303212 9,997220 10,002779′11 9,997473 10,00252710 519,84834519,850619| 9,99772610,002274 9 529,8484729,850493 9,997979 10,002021 8 539,8485999,850367 9,998231 10,001769 7 549,8487269,850242 9,998484 10,001516 6 5519,84885219,850116 9,998737 10,001263 5 569,84897919,849990 579,8491069,849864 589,8492329,849737 599,8493599,849611 6019,84948519,84948‹ 9,998989|10,001011 9,999242|10,001758 3 9,999495 10,000505 2 9,999747 10,000253 0000000|10,000000| | Co-fine | Sine || Co-tang. | Tangent. | M Degree 45. N Trigonom. Plate 60 70 Fig. 1 K تا دیگر B A D Fig. 2. Scale of Tangents Scale of Secants 60 50 40 50 30 20 45 80 40 ·60 150 30 40 30 20 10 20 10 Scale of Chords 20. 30- 4.0 50% 60! ་་་་་་ -20 +30 50 70 70 8080 до Scale of Sines 70 80 160 H Fig. 3. 200 86 60 40 20 Fig. 4. 2 4 6 8 K 500 L 400 CALE 50 Ꮐ 300 300 40+ F 4.00 A Simple or Plain Scale of Equal Parts A I S 30 E ·500 200 608 20 D AGON 10 C 700 100 "} 800 B A 900 K 20 20 40 40 موت 60 SA 80 I Fig. 5. 9 · 8 · 7 · 6 · 5 · 4 · 3 · 2 · 1 · Fig. 2. A 20 C E 40 G I 60 1. B D 20 F H 40 K M Go Fig. 6. k l m n o $ 12 b c d e f g h i t x efg A DI Trigon, Plate, 2. Ꭰ. B Fig. 7. 288.301 Fig. 9. 36 d. 521 m. 6f. C 114 d. 15m. 8f. Fig. 10 с Fig. 8. D 388.30m. C114 d. 15m. 27 d. 15 m. B 27d.15m B 11. Fig. 11 A B B A Fig. 12. B D A A Trigon, Plate. 3. BL Fig. 13 D B F E H Fig. 15 K Arch of of 80 degr. Arch of 48 8. Arch A 254 F F E A 2435. A Fig. 16 • 3477 35 degr A 20 f. Fig. 17 60 f. A C ୯ Fig. 14. B Fig. 18 c a B A B Ѣ Trigon, Plate. 4. A T W A Fig. 19 P: Fig. 20 B C Bb Fig. 21 Fig. 22 Fig. 24 A B b Fig. 23 a B D Fig. 25 E A B A a B Trigon. Plate 5. C Fig. 26 A a Fig. 27 B b 9. A Fig. 29 D Fig. 28 C b a d C Fig.30 B ib b B B Fig. 31 + A B С d E. Trigon Plate. 6. A M Fig. 32 D F E B a C d Fig. 33 m Fig. 34 a n C D Fig.35 B T A H Un 1 N B Trigon, Plate 7. Fig. 36 B Fig.37 B A с D P A: A d d F D E P Fig. 38. P E F P. H I 迟 ​Trigonom. Plate 8: a a Fig. 50 Fig.53 9 Fig. 51. f z b Fig 43 x 1 k 1 Fig. 48 Fig.: 44 Fig. 47 Y b Fig. 40 z 2 N M B: f Fig. 52. 1 Fig. 46 C X Fig 39 A + G D E P } m n 九 ​p Fig. 49. Fig. 42 Fig. 41 W m n Р all the Cutts to be folded out Fig. 45 THE Young Gentleman's MECHANICKS CONTAINING The more Uſeful and Eaſy ELEMENTS of Mechanicks, more properly fo called, of Sta- ticks, and Hydrostaticks. By EDWARD WELLS, D. D. Rector of Cotesbach in Leicester- Shire. 豬豬​粉 ​** sit si STS * SHE SKE LONDON, Printed for James Knapton, at the Crown in St. Paul's Church-Yard. 1713. 1 THE PREFACE. N Othing more needs be ſaid, to (hew the great Uſefulneſs of the Science, denoted by the general Name of Mechanicks, than that it teaches, and explains in a geometrical Manner, thoſe Principles, whereon is founded the Power or Force of the ſeveral Machines or En- gins, made use of either in Civil or Military Affairs; and alſo that it ex- plains in like manner the various Mo- tion of heavy Bodies, confider'd either in the Air or in the Water. The bare making of Machins is indeed an illi- beral or fervile Employ, and fit only for Perfons of the meaner Sort; whence Such Handy craft Perfons are fome- times called, by way of Degradation, (A 2) Mecha- The Preface. Mechanicks. But the Knowledge of the Principles, whereon depend mecha- nical Arts or Trade, is justly esteem'd a Liberal Science, not below the Stu- dy of Perfons of the highest Abilities and Rank. Forafmuch as this Sci- ence both gives a very confiderable In- fight into the Works of Nature; (not only with respect to Sublunary Bodies, but even to the Frame, Order, and Preſervation of the Celestial System;) and also may be infinitely ferviceable to the Concerns of Humane Life, by the Invention of new Machines or In- Struments especially if it be cultiva- ted by Perfons, who have both Abili ty of Parts to invent, and alfo Abi- lity of Pocket actually to experiment their Inventions, and by this Means to compleat and perfect them. For it is to be fear'd, that many an happy Invention has unfortunately mifcarried, becauſe the Inventer has not had a good Purſe, as well as a good Head. THE سمجھے 5 THE Young Gentleman's MECHANICKS. CHAP. I. Wherein are explain'd fuch Terms as relate to Mechanicks in general. T I. what, and HAT Art or Science, which teaches how to move any Mecha- given Weight, by any gi- nicks, ven Power we call in one why so cal Word (†) Mechanicks becauſe it is led. chiefly ſerviceable to the contriving of thoſe Machines or Engines, which are us'd ; (†) The Word Mechanicks is deriv'd from the Greek Word Maxa; from which is made likewife the corre fpondent Latin Word Machina; and from this is form'd our English Word Machine. From the fame original Greek Word is deriv'd alſo the Word Mechanism, i. e. the Arti ficial Contrivance of a Thing. (A 3) in The Young Gentleman's } 2. and a Pow- in the Concerns of Life, whether Civil or Military. By a Weight is underſtood in Mecha- A Weight, nicks any heavy Body; by a Power (*), whatever can move an heavy Body; tion, what and by Motion, Local Motion or the in Mecha- Change of Place. er,and Mo- nicks. 3. of Motion, what. The Axis of Motion is that right Line, The Axis round which a Body being mov'd, every and Center Point of the Body defcribes Circles, whoſe Centers are all in the ſaid right Line ; and the Mid-point of the Axis is called the Center of Motion. Thus Fig. 1 the Sphere or Bowl ADBE,being contriv'd to move round the right Line AB, the faid AB will be the Axis, and the Point C the Center of its Motion. 4. That right Line, wherein any Body or The Direc- Power endeavours to move, is call'd the tion of Mo- tion, what. Line of Direction, or fimply, the Directi- on of the Motion of the refpective Body or Power. And if a Body moves in a Curve Line, then the Direction of its Mo- tion in each Point of the Curve is the Tangent of the faid Point. AB is the Direction of the Thus Fig. 2, Weight A, and BC the Direction of the Power at C. (*) Hence any Weight or heavy Body is or may be e- fteem'd a Power, in reference to any other Weight or hea- vy Body, which it do's or can move. And Mechanicks. And Fig. 3, the Tangents TA, TB, TC, are reſpectively the feveral Directions of a Body mov'd round the Curve ABC, at the ſeveral Points A, B, and C. 5. a Body, That Force, which is in Bodies mov'd, and whereby they continually move, or The Mo- endeavour to move, is.call'd their Mo- mentum of mentum, and arifes from the Weight of what. (or Quantity of Matter in) the Body mov'd, and the Velocity or Swiftnefs wherewith it moves. The different Weight of Bodies arifes 6. from the different Quantity of Matter in The Weight the faid Bodies. Whence the Quantity proportio- of Bodies is of Matter in any Body may be eſtimated nal to their by its Weight. For instance, For instance, if a cubi- Matter. cal Inch of Lead be fix times heavier than a cubical Inch of Wood, it may thence be inferr'd, that the Quantity of Matter in ſuch a Piece of Lead is fix times as much, as the Quantity of Matter in a like Bulk of Wood. 7. Gravity, That Gravity or Weight, which arifes from the more or lefs Compactness of Specifick Matter naturally belonging to the ſeveral what. Species or Sorts of Bodies, is called their Specifick Gravity. Thus, although a Pound of Feathers be equal in Weight to a Pound of Lead, yet Lead is faid to be specifically heavier than Feathers, be- caufe there is not fo much Matter, nor confequently fo much Weight, in a Fea- (A 4) ther, . The Young Gentleman's 8. ther, as in a Piece of Lead of the fame Bulk with the Feather. Gravity or Weight being that, which Centrum caufes in Bodies a Tendency to move (if Gravium, not hinder'd by fome external Force) what. 9. of Gravity, what. • downwards, or towards the Center of the Earth; hence the Center of the Earth is ftil'd Centrum Gravium, or the Center to which heavy Bodies tend. The Center of Gravity in any Body is The Center that Point, through which a Plane paf- fing divides the Body into two Segments or Parts of equal Weight. It is this Cen- ter of Gravity, which is of chief Regard in Bodies, a Body being not properly faid to defcend or afcend, but when its Center of Gravity deſcends or af cends. 10. what. Velocity (which is the other Ingredi- Velocity, ent, that together with Weight makes up the Momentum of a Body) is that Affec- tion of Motion, which is meafur'd by comparing together the Length and Time of Motion. Thus Equal Velocity is that, whereby equal Length is pafs'd over in e- qual Time: Greater Velocity is that, whereby either a greater Length is paſs'd over in equal Time, or an equal Length in lefs Time: Lefs Velocity, when con- trariwife. Further, a Body that moves an hundred Yards, may be faid to move with double the Velocity of a Body, that moves Mechanicks. 9 moves but fifty Yards in the fame Time and with triple or thrice the Velocity of another Body, that moves but thirty- three Yards and one third in the fame Time ; and with quadruple or four- times the Velocity of a Body that moves but twenty-five Yards in the fame Time. And ſo on. II. a Body, The Momentum of a Body, arifing (as has been obferv'd §. 5,) from its Weight The Mo- and Velocity, may be known by multi- mentum of plying one of its Ingredients into the o- how to be ther. And confequently the different Mo- known. mentums of different Bodies may be known by multiplying the Weight of each Body into its refpective Velocity. Thus fuppofe the Weight of a Body A to be ten Pound, and of any other Body B to be four Pound; and the Velocity of B to be five times as much as that of A. The Momentum of A will be 10; viz. 10 Pound, the Weight of A, being mul- tiplied into 1 for its Velocity, (the Velo- city of A to B being fuppos'd as I to 5,) the Product will be 10 for the Momen- tum of A. And in like manner, 4 Pound, the Weight of B, being multiply'd into 5 as the Velocity of B. (for the Velocity of B to A is fuppos'd as 5 to 1) the Product will be 20 for the Momentum of B. Whence it appears that the Momentum of I B is 10 The Young Gentleman's 12. The Fun- Theorem nicks. B is double to that of A, being as 20 to 10. Hence is deduced the following Theo- rem, which may be ftiled the Fundamen- damental tal Theorem of Mechanicks, viz. When of Mecha Bodies have their Velocities reciprocally pro- portional to their Weights, their Momen- tum's will be equal. Let the Weight of a great Body A be 500 Pound, and the Weight of a little Body B be 50 Pound 5 and let their reſpective Veloci- ties be reciprocally proportional, (i. e. as the Weight of A is to that of B as 10 to 1, fo let the Velocity of B be to that of A as 10 to 1.) It will hence follow, that the Momentum of B will be juft equal to that of A. Namely, 500 Weight 1 Veloci- ty = 500 the Momentum of A; and 50 Weight * 10 Velocity 500 the Mo- mentum of B. 13. ral End gin's. X Hence it appears, not only that any The gene- little may have its Momentum equal to the and Effect Momentum of any great Body which is of Mecha- mov'd with a given Velocity; but alfo nical En. what Method is to be taken, in order to make it actually have fo; namely, by con- triving that the Velocity of the Power may be fo much greater than the Veloci- ty of the Body to be mov'd, as the Weight of the Body is greater than the Weight (or fomewhat equivalent there- to) of the Power. On which Account it is, that the foremention'd Theorem may be Mechanicks: 11 ! be juſtly eſteem'd the Fundamental Theo- rem of Mechanicks; forafmuch as there- on is founded the principal Mechaniſm or Contrivance of Machin's or mechanical Engin's, made ufe of to draw or raiſe heavy Bodies; the whole End and Ef- fect of theſe being to give fuch a Veloci- ty to the Power, or (which comes to the fame) ſo to diminiſh the Velocity of the Weight or heavy Body, as that the Momentum of the Power may be equal, or fomewhat exceed, the Momentum of the Body ſo to be drawn or rais'd. mechanical And this is what will be illuſtrated in 14. the fix following Chapters, in reference The fimple to the fix fimple and therefore primary Powers, fix Machin's, or (as they are otherwife cal- in Number. led) Mechanical Powers; to fome one or more of which may be reduc'd all o- ther mechanical Engin's. And I fhall ſpeak of them in the Order, wherein they here follow (*) reckon'd up, viz. I Vectis (*) Whereas fome reckon but five fimple Machines or mechanical Powers, comprehending the Balance under the Leaver; and others that reckon fix timple Machines, u- fually reckon the Balance as the firft, and the Leaver as the fecond; I have judg'd it more proper to agree with the latter, in reckoning fix fimple or primary Machines, and to fall in ſo far with the former, as to reckon the Leaver as the firſt, and the Balance as the ſecond fimple Machine, inaſmuch as the Leaver is a more fimple Machine than the Balance; 12 Mechanicks. i. Vedis or the Leaver. 2. Libra or the Balance. 3. Axis in Peritrochio or the Axle in the Wheel. 4. Trochlea or the Pulley. 5. Cochlea or the Screw. 6. Cuneus or the Wedge. Balance; and the Balance is no other than a particular Kind of Leaver. In like manner, whereas fome reckon the Wedge as the fifth, and the Screw as the fixth fimple Machine, I have rather follow'd them, who have inverted the faid Order, forafmuch as the Screw partakes more of the Faculty of the Leaver than the Wedge. I. A Leaver, what. CHAP. II. Of the Leaver. HE Leaver is fo call'd from the principal Uſe thereof, which is le- vare, i. e. to lift or raiſe up heavy Bo- dies. For the more eafy explaining the Mechaniſm thereof, it is here conceiv'd as a Line, which will not bend, and may be turn'd round about an unmoveable Point; which is therefore the Center of its Mechanicks. 13 its Motion, and rests upon fomewhat thence call'd the Fulcrum, i. e. Prop of the Leaver. Thus Fig. 4, AB is the Lea- ver, C the Center of its Motion, and F the Fulcrum or Prop. may 2. The main Doctrine of the Leaver Theorem the first. be comprifed under two Theorems, where- of the firft is this: The Space (or Arch) defcrib'd by each Point of a Leaver, and confequently the Velocity of each Point of a Leaver, is, as its Distance from the Ful- crum or Prop. For inftance, the Laver AB (Fig.4,) being mov'd from ACB to aCb, the Point A will defcribe the Arch Aa, and the Point B will deſcribe the Arch Bb; and by reafon of the like Sectors ACa and BCb, Aa is to Bb as AC to BC, that is, the Spaces defcrib'd by the Points A and B are as their Diſtances from C the Center of Motion, or (which comes to the fame) from F the Fulcrum. Now Powers being apply'd to the Points A and B, which draw the Arms CA and CB of the Leaver AB perpendicularly, the Spaces defcrib'd by them will be (not the Arches Aa and Bb, but (the Perpen- diculars AD and EB, theſe being the Meaſures of the Progrefs made by the Powers according to their reſpective Direction. But the Triangles ACD and BCE being equiangular, therefore (*) AD 14 Mechanicks. JA (*) AD is to BE as AC to BC or 4C to bć, that is, the Lengths gone over by the Powers according to their respective Directions, are as their Diſtances from C the Center of Motion, or (which comes to the fame) from F the Fulcrum. Now Velocity being (according to Chap. 1. S. 10) that Affection of Motion, which is meafur'd by comparing together Length and Time, and confequently (one Sort of) greater Velocity being that, whereby a greater Length is paft over in equal Time, as in the Cafe before us; hence it follows, that the Velocity either of the Point B, or of the Power apply'd thereto, is fo much greater than the Ve- locity of the Point A or the Power ap- ply'd thereto; (as the Arch Bb or the Line BE is greater than the Arch Aa or the Line AD; and confequently fo much greater) as BC or bC is than AC or aC that is, the Velocity of each Point in the Leaver, or of any Power apply'd thereto, is as its Diſtance from (C the Center of Motion, or from) F the Fulcrum (†). (*) By Theorem 9, of the Young Gentleman's Geo- metry. (†) For the Sake of fuch as may not readily apprehend the foregoing Geometrical Demonftration of the first Theo- rem, the fame is ſenſibly demonſtrated in Fig. 4, by actu- ally dividing BC, ¿C, Bb, and BE into fix equal Parts, each of the fame Length or Compafs as AC, aC, Aa, and AD re- Spectively. { The Mechanicks. 15 The Truth of the firft Theorem being 2. demonftrated and apprehended, it will Theorem the second. be eaſy to apprehend the Truth of the fecond Theorem, which is this: In a Leaver the Power, which is to the Weight (or Body) to be rais'd, as the Distance of the Weight (according to its Line of Direction) from the Fulcrum is to the Di- Stance of the Power (according to its Line of Direction) from the Fulcrum, will coun- terpoife or hold up the Weight; and there- fore being a little increas'd, will raiſe the Weight. For it has been fhewn under Theorem 1, that the Spaces defcrib'd by (the Powers apply'd to each End of the Leaver, i. e. by) the Power apply'd to one End and the Weight apply'd to the other, are proportional to their faid Diſtances from the Fulcrum; and confequently that their Velocities, be- ing proportional to the ſaid Squares, are alſo proportional to the laid Di- ftances. Wherefore if (Fig. 5) CA the Diſtance of the Weight from the Ful- crum be to CB the Diſtance of the Power from the Fulcrum, as the Power P is to the Weight W, it will follow, that likewife the Velocity of the Weight (1) Thus Fig. 5, Bb the Line of Direction of the Power is equidiftant from C to A4, the Line of the Weight's Di rection. will ** 16 The Toung Gentleman's 4. Theorem the second illuftrated by an Ex- ample. will be to the Velocity of the Power, as the Power is to the Weight. And con- fequently the Momentum of the Power will (by the Fundamental Theorem Chap. 1. S. 12) be equal to the Momentum of that Weight; and therefore the Power will be able to fuftain the Weight; and if it be but a little increas'd, (either by the Addition of fome new Force, or elſe by increasing its Diſtance from the Ful- crum) it will be able to raiſe the Weight. An Example will illuftrate the Matter. Let W the Weight of the Body to be rais'd be 120 Pound, and the Force of the given Power P be equivalent only to 20 Pound, and confequently the Weight be to the Power as 6 to 1. Wherefore P the Power being fo plac'd at B (Fig. 5) and W the Weight at A, as that BC may be fix times as long as AC, in fuch a Po- fition the Power will have a Force fuffici- ent to counterpoife, and fo hold up the Weights. For the Velocity of P to that of W being proportional to their Diſtan- ces from C, will be in this Cafe as 6 to I ; and confequently the Momentum of P, viz. 20 Pound x 6 Velocity = 120= 120 Pound × 1 Velocity, the Momentum of W. Wherefore the Power P (having a little new Force added to its own, or) being remov'd a little farther diſtant * from Mechanicks. if from C, viz. to b, and ſo having its Ve- locity a little more increas'd, it will raiſe W the Weight. For fuppofing bC to be to AC as 7 to 1, the Momentum of P will be 20 Pound × 7 Velocity 140; which is confiderably greater than the Momen- tum of Wat A, this being (as afore found) but 120. the ad exe Having thus fhewn the Truth of the 5. two foregoing Theorems, and thefe be- Theorem ing applicable to the other following me- preſs'd in chanical Powers, as well as to other Ca- short by. fes in refpect of the Leaver, it may be of Letters. Ufe to obferve here, that the Import of the fecond Theorem here laid down will for the future be exprefs'd in ſhort thus ; P: W:: CW: CP, that is, As much as the Force of the Power P is less than the Weight W, fo much lefs muft be CW the Diſtance of the Weight from the Fulcrum, than CP the Diſtance of the Power from the Fulcrum. And as this has been fhewn to hold good in refpect of the Leaver (as it is cal- led by fome) of the firft Kind, that is, when the Fulcrum is between the Power and the Weight; fo does it hold good al- fo in respect of the Leaver of the fecond Kind, when the Weight is between the Power and the Fulcrum, and alfo in the 5 Leaver of the third Kind, when the Pow- er is between the Weight and the Ful (B) crum. 6. The Kinds of Leavers. 18 The Young Gentleman's ! 7. Pinchers, of Lea- vers. crum. For in a Leaver of the ſecond Kind, the Weight W at D (Fig. 6.) has (as is obvious) just the fame Effect, as it would have on the other Side of the Ful- crum and at the fame Diſtance from it, viz. at E. And in like manner the Pow- er P at D (Fig. 7.) has juſt the ſame Ef- fect, as it would have at E, CE being e- qual to CD. Wherefore the Leaver of the ſecond and third Kind being thus in effect no other than that of the first, the Mechaniſm of theſe depends on the fame Theorem or Rule, as the Mechaniſm of that, viz. P: W: CW: CP. To the Leaver of the firſt Kind are re- Seiffers, ferr'd Sciffers, Pinchers, Snuffers, and c. Kinds fuch-like Inftruments, they confifting as it were of two fuch Leavers join'd toge- ther, but acting contrary Ways; as may be eafily apprehended by Fig. 8 and 9. To the Leaver of the fecond Kind are re- ferr'd the Oars of a Boat, as alfo fuch Cutting-Knives as are fix'd at one End. To the Leaver of the third Kind may be referr'd a Ladder, lifted up between the two Ends, in order to rear it againſt at Wall. Laftly, an Hammer drawing a Nail is referr'd to a fourth Kind of Leaver, call'd a Bended Leaver. For the Nail is as the Weight at one End A, and the Hand of him that draws the Nail is as the Power at the other End B of the Lea- ver ? Mechanicks. 19- ver ; and the Point C (Fig. 10) is as the Fulcrum. And this fourth Kind of Lea- ver is likewife reducible to the First, the Weight or Nail at A having the fame Ef- fect, as if it were at a, Fig. 10. 1 8. proportio As a Weight carried on a Pole or Stick between two Perfons may alſo be referr'd How to to a Leaver of the ſecond Kind, fo it may weight or place a be of good Uſe to obferve, that agreea- Body on a bly to the foremention'd Theorem P: Stick or the like, fo W:: CW: CP, the Weight may be fo as to make plac'd, as that the Burden thereof fhall the Burden be proportion'd to the different Strengths nal to the of the two Perfons; Namely, by taking different Strengths P to denote the Strongest, W the Weak- of them eft, and C the Weight. For then the Im- that carry port of the faid Theorem will be this: the Stick- As much as the Strength of the Strongest P is greater than the Strength of the Weakeſt W, ſo much muft CW the Di- ftance of the Weight from the Weakeft, be greater than CP the Diſtance of the Weight from the Strongeft. For Exam- ple, fuppofe the Leaver or Stick PW (Fig. 11) to be divided into 18 equal Parts, and the Perfon at P to be twice as ftrong as the other at W, then C the Bo- dy to be carried muſt be plac'd at 6. For then the Diſtance CW will contain 12 of the equal Parts, into which the Stick is divided, and the Distance CP will con- tain but 6 of them 30 and fo CW 2CP, (B 2) and 20 The Young Gentleman's 9. The like explain'd as to draw- ing any Weight. and confequently the weakest Perfon at W will fuftain but half ſo much as the ſtrongeſt at P. In like manner, if the Bo- dy c were placed at 3, then the Perfon at P would fuftain 5 times fo much, as the other at W; becauſe then the Difpro- portion of the Diſtances would be as 15 to 3, cW containing 15 of the equal Parts, whereof cP would contain but 3. Laftly, if the Body c were placed at 9, that is, in the Mid-point of the Stick or Pole, then each Perfon P and W would bear equal Burden, becauſe the Diſtance 9P= Diſtance 9W. And the fame Theorem holds good in refpect of Drawing (as well as Carrying) any Burden. For (Fig. 12) let WC re- prefent the Pole of any Waggon or Coach, and AB the Crofs-bar, at whoſe Extremities are Spring-trees DE and FG, to which are to be faften'd the Horfes or the like. Becaufe A and B are equidiftant from C, therefore the Horfes at A and B will draw equal Weight. Whereas if one of the Spring-trees be faften'd at 1, then the ſaid Horfe would draw a fourth Part more of the Weight W, than the o- ther Horſe at B; forafmuch as the Di- ftance Ci is a fourth Part lefs than the Distance CB. And fo if one Horfe was faften'd to 2, he would draw twice as other at B; becauſe Ca much as the is Mechanicks. 20 is but the Half of CB. And fo on. 10. ticulars folv❜d. By the Mechaniſm of the Leaver may we alſo account for the Reafon, why it Other Par- is more difficult to lift up a Staff (or the like) of any Length, at or near one of its Ends, than nearer the Middle: Name- ly, becauſe the Momentum of any Thing fo fuftain'd increaſes proportionably to its Diſtance from its Fulcrum or Prop. And the fame is the Reaſon, why it is more difficult to lift up a long Staff or the like, at Arm's Length, or keeping the whole Arm from Hand to Shoulder ex- tended out, than when we bend the Arm at the Elbow. Namely, becauſe in the former Cafe the Shoulder is the Ful- crum, or Prop, in the latter Cafe the El- bow 30 and therefore in the former the Diſtance of the Weight from the Prop, is greater than in the latter. And fo much for the Leaver. (B 3) CHAP. 22 The Young Gentleman's I. The Beam of a Ba-· Lance no o- T CHA P. III. Of the Balance. HE Beam AB (Fig. 13 and 14) is the principal Part of a Balance, and is no other than a Leaver of the firſt ther than Kind, which (inftead of refting on a Fulcrum at C the Center of its Mo- tion) is held up from above by fome- what faſtened to C its Center of Mo- tion. a Sort of Leaver. 2. The Me- chanifm lance ex- plain'd in Hence the Mechaniſm of the Balance depends on the fame Theorem as that of of the Ba- the Leaver, viz. P: W:: CW: CP. Where, taking P to denote the known general. Weight, W the unknown Weight, and C the Center of the Balance's Motion, the Import of the Theorem is this: As much as the known Weight is less than the un- known Weight, (i. e. the Weight fought of the Body weigh'd) fo much will the Di ftance of the unknown Weight from the Cen- ter of Motion be less than the Distance of the known Weight from the Center of Moti- on, where the faid two Weights will counter- poife one the other ; and confequently the known Weight shew the Quantity of the un- known Weight. For Mechanicks. 23 ed. For Inftance, on the (*) Roman Ba- 3. lance or Steel-yard, (Fig. 13) the un- The Mecha- nism of the known Weight or Body to be weigh'd be- Roman Ba- ing apply'd to A, and the known Weight lances or P being mov'd up and down, nearer and Steel-yard particular- farther (from the Point C) upon the Arm ly explain- BC, and being found at the Diſtance 5 to counterpoife W the unknown Weight, thence it follows, (viz. becauſe the Di- ſtance CP is 5 times greater than the Di- ftance CW, or which is the fame, CA) that the Quantity of the unknown Weight W is 5 times as much as the Quantity of P the known Weight. And therefore, fuppofing P to be one Pound Weight, W will be five Pound Weight; or fuppofing P to be two or three Pound Weight, W will be reſpectively ten or fifteen Pound Weight. 4. But now, becauſe in a common Balance or a (†) Pair of Scales, (Fig. 14) the The Mecha- two Arms CA and CB of the Beam AB nim of the are (or ought to be) always of an equal Balance or Length; hence the Quantity of the of a Pair common of Scales, explain'de (*) This Sort of Balance is call'd the Roman Balance,from its being much us'd at Rome. And it is commonly call'd a Steel-yard, as being a Sort of Yard made of Steel. (†) So the Latins call this Libra or Balance by the pe- culiar Name of Bilanx (namely à binis Laucibus, i. e. from the two Scales belonging thereto) whence is made our English Word Balance. (B 4) known 34 The Young Gentleman's 5. Bare Weight is Strictly true Weight. known Weight P in one Scale muft in it felf be equal to the Quantity of the un- known Weight W put in the other Scale. And therefore the Quantity of the un known Weight on this Sort of Balance is found out, (not as on the Steel-Yard, by moving one and the fame Weight nearer or farther from C the Center of Motion, but) by putting in various Weights of known Quantity, 'till the known Weight counterpoifes the unknown; and there- by fhews the Quantity of the unknown Weight. For it is to be obferved, that the known Weight then fhews the exactly true Quantity of the unknown Weight, when the one counterpoifes the other. For the uſual Cuftom of making the Weight of the Thing fomewhat more than counterpoife the known Weight by which it is weigh'd, (even fo as to bring the Scale, wherein the Thing bought is put, to the Ground or the like) has aroſe from Tradesmen being willing to get Cu- ftomers, by allowing them fomewhat more than ftrictly true,or (as it is commonly and (*) properly enough call'd) bare Weight. And confequently, when we fay of a } (*) Becauſe hereby is denoted true Weight, confider'd barely as to Weight, without any refpect to Cuſtom, &c. Tradef A Mechanicks. 25 Tradefman, who is more free than ordi- hary in what he allows over bare Weight, that he makes good Weight, or better Weight than another, that makes only bare Weight; thereby is to be under- ftood, not that the Weight he makes is true, or truer than the other's, in reſpect of its intrinfick Quantity; but that it is good, or better than the other's, in reſpect of the Advantage accruing to the Buyer, by what is allow'd over bare or true Weight. to be in Æ. It is alſo not to be omitted, that as one 6. Body is faid to counterpoife (or to be of Standing equal Weight with) another, when they Weight, and being feverally apply'd to the two diffe- quilibrio, rent Arms of the Balance, the Beam lies what. (†) horizontally or equally level; fo this is call'd in our common Speech (not on- ly bare Weight for the Reafon afore af- fign'd, but allo) ftanding Weight, foraf- much as in this Cafe' the Beam ftands e- ven, neither Arm afcending or defcend- ing more than the other and for the fame Reafon the Bodies in this Cafe are faid by the Learned to be in Æquili- brio. ; (†) This is fhewn by the Piece of Iron CE, call'd the Tongue, being in a Line or directly between TX and TS. Laftly, 26 The Young Gentleman's 7. cover a falfe Ba- Lance or Scales. Laſtly, it is well to be obferv'd, that How to dif- the Truth or Exactneſs of (a common Balance or) a Pair of Scales greatly de- pending on its two Arms being of equal Pair of Length, as well as of equal Weight in themſelves, hence it follows, that if one Arm be longer than the other, it will be a falfe Balance, or not fhew the true Quantity of the unknown Weight, or (which is the fame) the true Weight of the Thing weigh'd. For inftance, fuppofe Fig. 14, the Arm AC to be divi- ded into ten equal Parts, and the other Arm BC to contain but nine fuch other Parts; and confequently AC to be longer than BC by a tenth Part. It will follow by the Fundamental Theorem (Chap. 1. S. 12, or which comes to the fame, by this Theorem, P: W:: CW: CP,) that a known Weight of nine Pound ap- ply'd to A, will have its Momentum e- qual to a Body of ten Pound Weight ap- ply'd to B; for 9 Pound x 10 Velocity =90 Momentum 10 Pound × 9 Velo- city,) and conſequently will counterpoiſe one the other in fuch a falfe Balance, though their Weights be not equal in themſelves. The Way to diſcover ſuch falfe Balances, is by changing the known and unknown Weight into the contrary Scales. For upon fuch a Change, the In- equality of the Weights will manifeft- X ly Mechanicks. 27 ly (*) appear; whereas in a true Balance or Pair of Scales, fuch a Change of the Scales will make no Difference, there be- ing no Difference in the Length of the Arms, and confequently no Difference in the Velocity of the known or unknown Weight, to which ever Arm they be ap- ply'd. (*) Namely, the Body being of 10 Pound Weight in ic ſelf, and when apply'd to A, its Velocity being in reſpect to the Velocity of the known Weight of 9 Pound in it felt, as 10 to 9, the Momentum of the faid Body will be (10 Pound 10 Velocity) 100; whereas the Momentum of × the known Weight will be (9 Pound × 9 Velocity =) 81. And confequently the known Weight will not counterpoife the Body by a great deal put in the Scale of the shorter Arm BC, though it did fo in the Scale of the longer Arm AC. 1 CHA P. IV. Of the Axle in the Wheel. T HIS I. fo called. Machine is fo called, as con- fifting principally of a Wheel BGHI, This Ma and a Cylinder or Axle ADEF. A- chine, why bout which Axle goes the Rope, which draws the Weight W, when the Axle is turn'd round by means of the Wheel; as Fig. 15. As 28 Mechanicks. 2. ing perpetu- Fulcrum. As the Balance is no other than a Lea- It is in ef- ver, particularly apply'd to finding out felt no o- ther than a the Quantity of an unknown Weight, fo Leaver, ca- this mechanical Power is no other than a pable of be- Leaver, apply'd to the fame Uſe as other ally turn'd Leavers are, (viz. to the railing up of round its great Weights) with this particular Ad- vantage added thereunto: Namely, where- as in the Leaver it ſelf the Motion can be continu'd only for fo fhort a Space Aa, Fig. 4 and 5) as is anfwerable to the little Distance CA between the Fulcrum and the Weight; in this Invention that Inconvenience is remedy'd, foraſmuch as by continual turning round the Wheel, and fo (together with it) the Axle, the Weight may be rais'd to any Height, as Occafion fhall require. 3. niſm ex- plain'd. As this Machine is no other than a Its Mecha- Leaver AB capable of being perpetually turn'd round, fo the Fulcrum of it or Center of its Motion is C, and the End B is that to which the Power P is to be apply'd, and A the other End, to which is to be apply'd the Weight W to be rai- fed. Hence the Mechaniſm of this En- gine depends on the fame Theorem, as that of the Leaver, viz. P: W:: CW: CP; that is with particular reference to this Machine; If as much as the Power is lefs in it ſelf than the Weight, fo much the Radius of the Axle be less than the C Radius Mechanicks. 29 Radius of the Wheel, (and confequent- ly fo much the Circumference of the Axle be leſs than the Circumference of the Wheel; and confequently fo much the (†) Velocity of the Weight apply'd to the Axle be less than the Velocity of the Power apply'd to the Wheel) by the Fun- damental Rule the Momentum of the Power will be equal to that of the Weight, and confequently the Power will counterpoife and fo hold up the Weight; and therefore the Power being a little in- creas'd will raiſe the Weight. > 4. An Obfer. The Momentum of the Power thus in- creafing according to the Difproportionation between the Circumference of the Wheel, and the Circumference of the Axle T hence it follows, that the Line of the Power's Direction must always touch the Circumference of the Wheel, fo as to make a(*)right Angle with the Ray, that fo the fame Diſtance between the Pow- er and the Center of Motion, and confe- quently the fame Momentum of the Pow- er, may be every where alike preſerv❜d ; (†) For the Weight, as is evident from the Make of this Machine, is rais'd up no more than is anfwerable to the Length of the Rope that goes round the Axle in one turn- ing round of the Wheel. (*) That is, fo as to be the Tangent of the Point of the Circumference it touches, according to Chap. 1. §. 4. which 30 Mechanicks. । which otherwife would not be fo. For fuppofing (Fig. 16) the Power P to be fo apply'd to any Spoke, viz. G, as that the Line of its Direction be GH, then the Diſtance of the Power is to be eſteem'd IC, and fo leſs than BC, and confequent- ly the Momentum of the Power will be fo much leffen'd, as IC is less than BC. Whereas if the Line of the Power's Di- rection were then the Momentum of the Power at C would be the fame as at > 5. To this third fimple Machine are re- Machines ferr'd the Crane Fig. 17, and all Engines and Inftru which confift of Wheels with Teeth, as ments refe- rable Fig. 18, and alſo the Machine repreſent- thereunto. ed Fig. 19, and the feveral other Inftru- ments repreſented Fig. 20, 21, 22, 23 24 and 25. In each of which A repre- fents the Place of the Weight, B the Place of the Power, and C the Center of Moti- on or Fulcrum. СНАР. Mechanicks. 31 T CHAP. V. Of the Pulley. I. what. HE Pulley is a Machine confifting of one or more little Wheels, a- A Pulley, bout which a Rope being put and (*) pull'd at one End, the faid Rope makes the ſaid Wheels turn round upon their proper Axles, and thereby at the fame time moves the Weight or Body to be drawn or rais'd, as Fig. 26, 27, 28. 2. If the Pulley it felf be faften'd up to fome Place or Mark H, and the Weight An upper W be apply'd to one End of the Rope, Pulley, and the Power P to the other, (as Fig. its Ufe ex- what, and 26,) then it is evident, that as much as plaind. the Weight W afcends, juſt ſo much the Power P defcends; and confequently that they both move with the fame Velocity. Wherefore in this Cafe the Force of the Power muſt in it felf be equivalent to the Weight of the Body rais'd, in order to (*) The Effect of this Machine being thus produc'd by pulling the Rope, hence it takes the Name of the Pulley á- mong us. make 32 The Toung Gentleman's 3. 'A lower Pulley, 1 make its Momentum equal to the Mo- mentum of the Body. And hence it fol- lows, that fuch a Pulley does not con- duce to the increafing of the Momentum of the Power, or (which comes to the fame) to the decreafing the Momentum of the Body or Weight to be rais'd; but only to the keeping of the Cords from fretting; and fo to the making them move more eaſily than otherwife they would. And, becauſe when there is Oc- cafion to apply ſeveral Pulleys together, fuch as are of this Sort, (or which the Ropes go over,) are plac'd uppermoſt ; hence theſe are diftinguifh'd by the Name of Upper Pulleys. But if (not the Pulley it felf, but) one End of the Rope be faſten'd to an Hook what, and H or the like, and the other End be pul-- its Ufe ex- led by the Power P, and the Weight W plain'd. hangs on to the Pulley, (as Fig. 27.) then it is evident, that in order to raiſe the Weight W one Foot, each Part AH and Bh of the Rope inuft be ſhorten'd one Foot, (reckoning downwards from the Hook H and its oppofite Point b) and confequently that in the fame Time the Power P must move two Foot. Where- fore in this Cafe the Velocity of the Pow er will be double to that of the Weight, and confequently if the Power be fub- duple to the Weight, that is, as I to 2, its Mechanicks. 33 Its Momentum will be equal to that of the Weight, and fo will ſuſtain the Weight. And therefore if the Power be a little increaſed, it will be able to raiſe the Weight. And the fame holds when there are two Wheels or Pulleys, one Upper and one Lower, as Fig. 28. If (as Fig. 29) there be three Wheels, and fo the Rope goes from Wheel to Wheel three times, viz. from A to B, and from C to D, and from E to F; and confequently in order to raiſe the Weight W one Foot, each of the three Parts AB, CD, and EF of the Rope muſt be ſhorten'd one Foot, which can't be done without the Power P mo- ving forward three Foot in the fame time ; in this Cafe the Velocity of the Power will be triple or thrice as much, as the Velocity of the Weight. And therefore, though the Power be to the Weight but as 1 to 3, yet its Momentum will be equal to the Momentum of the Weight, and fo will fuftain it; and if the Power be but a little increaſed, will raiſe the Weight. 4. Further of the fame. In like mariner it is evident from Fig. 30, that if there be four Wheels, and fo The fame the Rope goes four times frome Wheel to yer further exempli Wheel; then, while the Weight W is fyd. rais'd one Foot, the Power P will move forward four Foot; and confequently (C) (by 34 The Young Gentleman's relating to (by the fundamental Theorem) a Pow- er P, which is to the Weight W but as to 4, will have its Momentum equal to the Momentum of the Weight; and therefore being a little increas'd, will raiſe it. 6. Hence the Mechaniſm of the Pulley de- The general pends on this univerfal Theorem, viz. Theorem If a Power is to the Weight, as I to the the Pulley. Number of the Ropes (i. e. of the Parts of the Rope, viz. AH and Bh, Fig. 27, and 28; and AB, CD, EF, Fig. 29, and AB, CD, EF, GH, Fig. 30,) apply'd to the lower Pulleys, then the Power will be able to hold up the Weight the Weight; and there- fore being a little increas'd, will raiſe the Weight. 7. For Inftance, Suppofe the Weight to Examples. be rais'd 360 Pound, and the Power in it felf to be equivalent only to 180 Pound, (i. e. the Power to be to the Weight as 1 to 2.) therefore one lower Pulley (ei- ther with, as Fig. or without an up- per Pulley) will render the Momentum of the Power equal to that of the Weight, namely, by rend'ring the Velo- city of the Power double to that of the Weight. For 180 p. * 2 Velocity 360 Momentum 360 p. 1 Velocity. If the Power be to the Weight as 1 to 3, or e- quivalent only to 120 Pound, then there muſt be three Wheels, that fo the Velo- X city Mechanicks. 35 *1 * X city of the Power may be triple to that of the Weight; Namely, 120 p. × 3 Ve- 360 Momentum 360 p. × 1 And fo on. locity Velocity. ! CHAP. VI. Of the Screw. HE Screw, which makes here the TH 1. fifth fimple mechanical Power, is The Screw, a Right Cylinder, having feveral Rifings what. and Hollows alternately winding round it in a ſpiral manner. It confifts It confifts proper- ly of two Parts, one call'd the outward Screw, the other the inward; namely, becauſe the former receives the latter in- to it. Whence the inward Screw is o- therwiſe call'd the Male, and the out- ward the Female Screw. The Male or inward is denoted Fig. 31, by MS, the Female or outward by TS. 2. This Machine is chiefly us'd to fqueeze or prefs Things, and by that Means, in Its Uses: fome Cafes, to break Things. It is alfo fometimes uſed to raiſe up any Weight, as to thrust it forward. (C 2) For 36 The Young Gentleman's { 3. This in compound For the more eafie Ufe of this Ma- chine, (i. e. for the more eafie moving fome fort a the Male Screw through the Female, or Machine. the Female along the Male) it is uſual to apply thereto an Handle or round Stick, AB; and fo to the Power of the Screw to adjoin alſo the Power of the Axle with the Wheel: The Handle or Stick AB by its turning round, fupplying the Place of a Wheel, and the Cylinder of the Screw being as the Axle to the faid Wheel. So that this Machine is in fome fort a com- pound Machine. 4. " Now the Effect of this Machine de- The funda- pends upon the fame fundamental Theo- mental rem, as the other; which fundamental particular- Theorem particularly apply'd to the Fa- ly apply'd brick or Make of this Machine, ftands Theorem chine. to this Ma- thus: If, as the Compass defcrib'd by the Power in one Turn of the Screw, is to the Interval or Distance between any two imme- diate Spiral Windings (meafur'd according to the Length of the Screw) fo is the Weight or Refiftance to the Power; then the Power and the Refiftance will be equivalent one to the other, and confequently the Power be- ing a little increafed will move the Refi- fiance. 5. The fume further il lu rated or prov'd. For it is evident from the bare Infpe- &tion of this Machine, that in one Turn of the Screw, the Weight P (Fig. 33) is fo much lifted up, or the Refiſtance O (Fig. Mechanicks. 37 Fig. 31 and 32) is fo much remov'd, or the Thing to be prefs'd is ſqueez'd fo much cloſer together, as is EG the Di- ſtance between two immediate Spirals; and in the fame Time the Power (ap- ply'd to A or B) to be mov'd fo much, as is the Compaſs AB, defcrib'd by the faid Power in one Turn of the Screw. Wherefore the Velocity of the Weight (or whatever anſwers thereto) will be to the Velocity of the Power, as is the faid Di- ftance between the Spirals to the Com- pafs defcrib'd by the Power, in one Re- volution or Turning round of the Screw. And therefore by the fundamental Theo- rem, if as the Power is to the Weight, fo the Diſtance between the Spirals to the Compaſs deſcrib'd by the Power, the Power will have its Mo nent equal to the Moment of the Weight or Re- fistance. And therefore the tower, be- ing a little increas'd, will overcome the Refiftance. (C 3) CHAP. 2 38 The Young Gentleman's I. A Denniti- on of a Wedge, and its fe- veral Parts: 2. Its Effect accounted for by the fundamen- tal Theo- rem. TH CHAP. VII. Of the Wedge. HE Wedge is commonly made of Iron or fome harder Sort of Mat- ter, in Shape of a Prifm not very high, whofe oppofite Bafes are Ifofcelar Trian- gles. The Height of either of theſe Tri- angles is eſteem'd the Height of the Wedge, and the Bafis of either Triangle is eſteem'd the Thickness of the Wedge; and the right Line which joins together the Vertexes of both the Triangles is cal- led the Edge of the Wedge; and the Pa- rallelogram which joins together the Bafes of the two Triangles, is call'd the Back of the Wedge. The Effect of this Machine depends likewife upon the fame fundamental Theorem as the former which being particularly apply'd hereto will ftand thus: If the Power directly apply'd to the Back of the Wedge be to the Refiftance to be overcome by the Wedge, as the Thickness of the Wedge is to its Height; then the faid Power will be equivalent to the Refiftance; and therefore being increas'd will overcome it, That Mechanicks. 39 That Tenaciouſneſs or Firmnefs, where- 3. by the Parts of the Wood (or the like) The fame further il adhere one to the other, is the Refiftance luftrated,or to be overcome by the Wedge. Now it prov'd. is evident, that while the Wedge is drove into the Wood, the Way or Length which it has gone according to its own Propenfity, is (Fig. 34) BA; and in like manner DC is the Way or Length gone in the fame Time by the Impedi- ment, i, e. the Parts C and D of the Wood are ſo far divided aſunder. And accordingly as the Wedge is drove down further and further along its Height, fo the Parts C and D of the Wood are divi- ded more and more along the Thickneſs of the Wedge; and in the whole Pro- grefs proportionably, as is evident from the Nature of a Triangle. Whence it comes to pafs, that if as the Thicknefs of the Wedge (i. c. the Way of the Im- pediment, and confequently its Veloci- ty) is to the Height of the Wedge (i. c. the Way, and confequently the Velocity of the Power,) fo the Power to the Impediment or Refiftance, then the Mo- mentum of the Power and the Impe- diment will be equal the one to the o- ther; and confequently the Power be- ing increas'd will overcome the Refift- ance, (C 4) To 40 The Young Gentleman's 4. To the Wedge may be referr'd all Other In Edge-Tools, and Tools that have a firuments reducible to harp Point, in order to cut, cleave, the Wedge. flit, chop, pierce, bore, or the like: As Knives, Hatchets, Swords, Bodkins. 5. c. And thus I have gone through the fix fimple Machines, or primary mecha- nical Powers, fo far forth as feems re- quifite to the Defign of this Trea- tiſe. It remains only to obferve here, that Mechanicks as the Word Mechanicks in its largeſt what, in the Acceptation comprehends the whole Do- more re- ftrain'd Sense of the Word. &rine or Science of Local Motion; ſo in a reſtrain'd Senſe it is taken particularly to denote the Doctrine of Motion, as apply'd to Machines or mechanical En- gines, the more fimple of which we have here defcrib'd. CHAP } Mechanicks. 41 TH CHA P. VIII. of Staticks. 1. what. HE Word Staticks denotes in the Greek Language the Science or Do- Staticks, &trine of Weights, and confequently in its largest Acceptation, is of the fame Ex- tent with Mechanicks in the largeſt Senfe thereof, both comprehending the whole Doctrine or Science of Motion with refe- rence to the Weights of Bodies; and fo being fynonymous Words, or Words of the fame Import. But as the Word Me- chanicks in a reſtrain'd Senfe is taken to denore more particularly the Doctrine of Motion and Weights in reference to Me- chanical Engines; fo the Word Staticks in a reſtrain'd Senfe is taken to denote more eſpecially that Part of the Doctrine of Motion, which arifes from the Weight of natural Bodies confider'd in themfelves or compar'd together, and which confe quently has not at leaſt ſo immediate a reſpect to mechanical Engines. In this Chapter therefore I fhall take notice of fuch Particulars as relate to Staticks in its reſtrain'd Senſe, and are agreeable to the Defign of this Treatife. It 42 The Young Gentleman's 2. Bodies It is then obfervable in the firſt Place, The Motion that the natural Motion of heavy Bodies of heavy (i. c. That Motion of them downwards, which arifes from the natural Principle of wards is their Gravity or Weight) is found by uniformly accelera- Experience to be a Motion uniformly acce- ted. lerated, i. e. a Motion which acquires in down- ༡. equal Times equal Degrees of Velocity. For when an heavy Body defcends, the fame Gravity, which gave it a Motion downwards at first, will all along conti- nue to act alike upon it, and ſo to give it in the ſecond Inftant of Time a Moti- on equal to what it gave it at the firſt, and again in the third Inſtant or Minute to give it likewife a Motion equal to that at firſt, So that at the third Minute the Sum of the whole Motion will be the Triple of the first; and fo at the fourth Minute the Sum of the whole Motion will be Quadruple to what it was at the first. And fo the Degrees of Motion, or Velocity of the Body moved, will always increaſe, as does the Time wherein it moves. Hence it comes to pafs, that the Spa- The Spaces ces, through which Bodies defcend in thro' which their Fall, are as the Squares of the Times Bodies fall, are as the they take up in Falling, always account- Squares of ing from the Beginning of the Fall. For bercin Inftance, if a Body be ten Minutes a fal- they fall. ling, and the firft Minute it falls a Mile, the fecond Minute it will have fall'n four he Time Miles, } Mechanicks. 43 Miles, and the third Minute nine Miles; and fo on: According to which Proportion at the tenth Minute, the Body will have fall'n an hundred Miles. Whence it ap- pears, that if the Times be taken in the arithmetical Progreffion of natural Num- bers, viz. 1, 2, 3, 4, 5, &c. the spa- ces defcrib'd in thoſe Times, reckoning from the Beginning of the Motion, will be as 1, 4. 9. 16, 25, &c. This is wont to be demonſtrated or at leaſt illuſtrated, by confidering (Fig. 35.) AB to repre- fent the first equal Part of Time, and BC to reprefent the first Degree of Velocity acquir'd in the first Part of Time: And likewife BD (AB) to reprefent the fe- cond equal Part of Time, and FE (=BC -DF) the fecond Degree of Velocity, ac- quir'd in the fecond Part of Time, and e- qual in it felf to that Degree of Velocity acquir'd in the first Part of Time: and con- fequently AD to reprefent two equal Parts of Time, and DE to reprefent two equal Degrees of Velocity. Wherefore the Tri- angle ABC will reprefent the Space gone thro' in AB, the first equal Part of Time, with the Velocity BC; and the Triangle ADE will reprefent the Space gone thro' in AD two fuch equal Parts of Time, with the Velocity DE (the Double of BC.) But the faid fimilar Triangles ABC and ADE are (by Theor. 10 of Young Gen- tleman's 44 Mechanicks. 4. the Fall of der'd in Part of Time di- it felf. tleman's Geometry) as the Squares of their homologous Sides AB and AD; that is, the Spaces gone through in the Times AB and AD are as the Squares of the faid Times. Thus (Fig. 35) ADE is actually divided into four Parts, each equal to ABC. Hence it is obvious, that the Spaces The Spaces defcrib'd or gone through by a Body in deferib'd by its Fall, in each (equal Part or) Minute bevy Bo- of Time, are according to the Series of dies, confi- the natural Numbers, 1, 3, 5, 7, 9, &c ; each equal thefe being the Differences of the squares I, 4, 9, 16, &c. Thus if a Body falls ftinctly by One Mile in the firſt Minute, and four Miles in the ſecond Minute, it will there- fore, during the fecond Minute, confi- der'd diftinctly from the first, fall three Miles. And in like manner, if a Body falls at the End of two Minutes four Miles, and at the End of three Minutes nine Miles, it will, during the third Mi- nute confider'd by it ſelf, fall five Miles, and ſo five Times as far as it did the firft Minute. 5. How to find, what Space a Body will go thro' in a given Time. Hence it is obvious, that the Space gone through in a determinate Time by any Body being known, thereby may be found out, what Space it will go through in a given Time う ​viz. by find- ing a fourth Proportional. For Exam- ple, fuppofe a Body to fall twenty-four Foot Mechanicks. 45 : Foot in one Minute, and it be requir'd to tell, How far the fame Body will fall in the fame Medium in Three Minutes ; the Anſwer will be, 216 Foot. For as I to 9 (i. e. as the Square of one Minute is to the Square of three Minutes) fo is 24 (the Space gone through in the firſt Minute) to 216, which therefore is the Space the Body will go through in three Minutes. 6. what Time Body will take up in defcending ven Spase. thro' a gi- In like Manner, the Time being known, wherein an heavy Body defcends through To find, a determinate Space, it is obvious to find, a in how long Time it will defcend thro' an- other given Space, viz.by finding a fourth Proportional. For Example, fuppofe a Body has taken up one Minute in falling twenty-four Foot, and it be requir'd to tell, what Time it will take up in falling 216 Foot in the fame Medium; the An- fwer will be three Minutes. For as 24 to 216 (ie. as the first Space given is to the ſecond Space given) fo is the Square of the given Time to 9 the Square of the Time requir'd, which therefore is three Minutes. As a Body in falling acquires equal Degrees of Velocity in equal Times, fo on the contrary, in rifing it lofes equal Degrees of Velocity in equal Times. For the Gravity of the Body thrown up con- tinually drawing it downwards, its Moti- On 7. of the Af- cent of Bo- dies. 46 The Young Gentleman's on upwards will continually decreaſe, in proportion to the Force downwards pro- duc'd in equal Times by the Gravity of the Body. But it has been fhewn afore (§. 2.) that the Motion downwards is u- niformly accelerated; and therefore the Motion upwards must be uniformly re- tarded. Whence it follows, that fuch a Body goes through the fame Spaces in e- qual Times, in rifing as it does in falling, but in an inverted Order. Namely, if the Body be five Seconds in rifing to the Height of twenty-five Foot, and the Space afcended through the first Second of Time be nine Foot, the faid Body during the fecond Second of Time, will afcend through a Space of feven Foot; and in the third Second a Space of five, and the fourth a Space of three, and in the fifth and laſt a Space of one Foot. Then it will be as it were in Equilibrio, i. e. the Impetus upwards being now juft equal to the Impetus downwards, the Body will neither rife nor fall for fome Time. After which it will begin to fall in the like inverfe Proportion viz. fo as that the first Second it will fall a Foot, the fecond three Foot, the third five the fourth ſeven, and the fifth and laſt nine Foot, thus taking up five Scones of Time to defcend twenty five Foot, as it took up the fame Time to afcend twenty-five Foot. By Mechanicks. 47 rife up a Height, By the fame Principles it comes to 8. paſs, that the Force which a Body ac- Why Bodies quires in falling, will make it rife up a- gain to the gain to the fame Height which it fell fame from. For Inſtance, fuppofe (Fig. 36) from which the (†) Pendulum, i. e. the Body or they tell. Weight fafter'd to one End A of the String AB, whoſe other End is faſten'd to the fix'd Point C, as the Center of its Motion: Suppofe, I fay, the Body to fall from D to A, it will rife again to E, which is of an equal Height with D. For divide DA into any Number of equal Parts, fuppofe three, markt a, b, c, and EF into as many markt d, e, f, E. the foregoing Principles it is obvious, that whatever Force or Degree of Velo- city the Body acquires by its Gravity in deſcending from D to a, it will acquire twice as much in defcending from a to b and thrice as much in defcending from b to c; with which triple Force it will be- gin to aſcend from c towards d. C But in afcending from c to d the Body will by its Gravity drawing downwards lofe one of the three acquir'd Degrees of Velocity or Force; and in afcending from d to f it will loſe two of the faid acquir'd De- By (†) It is fo call'd from the Weight's hanging on the Thread or Wire, to which it is faften'd; the Latin Word Fendulus denoting any Thing that thus hangs. grees 48 The Young Gentleman's * 9. The Refift- ance of the Air not con- fider'd in the fore, mention'd Cafes. 10. grees, the Force of Gravity downwards at f being double to its Force at d, and fo deftroying two of the acquir'd Degrees of Velocity or Force, wherewith the Bo- dy at c began to afcend. And likewiſe at E, the Force of Gravity downwards will be triple to that at d, and ſo deſtroy all the three acquir'd Degrees of Force, wherewith the Body began at c to af cend: And therefore the Body will af cend no higher, but begin to fall down- wards again towards e or A. But now it is to be obferv'd, that in this and the foregoing Cafes, the Refift- ance of the Air, wherein the Bodies are conceiv'd to move, is not confider'd which is the Cauſe why the foregoing Theorems will not exactly agree with Ex- periments; and particularly as to the Pendulum, which, by means of the Re- fiftance of the Air, does not return ex- actly to the fame Height from which they fell, and confequently have not a perpe- tual Vibration or Motion forwards and backwards, but ſtand ſtill in fome Time. Abſtracting from or fetting afide this Pendulums Refiftance of the Air, it follows from afcend and the foremention'd Principles, that the defcend thro' equal Pendulum does afcend and defcend thro' Spaces in e- the equal Spaces DA and AE in equal Times. To which I ſhall here add as worth remarking, that the Longitudes qual Times, &c. of Mechanicks. 49 of Pendulums are as the Squares of the Times, wherein. they perform their Vibra- tions. II. dies de- ter of Gra As Gravity is that natural Principle which caufes Bodies to defcend, fo no How the Body will defcend, but when its Center Fall of Bo- of Gravity can defcend. Thus the in- pends on clin❜d Body ABDE, (Fig. 37.) which is their Cen- fet on the Horizontal Plane HP, cannot vity. fall toward the Part D, to which it in- clines, becauſe by fuch a Change of Situ- ation its Center of Gravity C would riſe; as may be known by defcribing from A (as the Center) the Arch CF, which is the fame, as C the Center of Gravity would make about the Point A, if the Body ABDE could fall; for it is evident. that one Part of that Arch rifes above the Point C, and confequently the Cen- ter of Gravity in fuch a Cafe muft for fome Time afcend of its own Accord, which is contrary to the Nature of heavy Bodies. Infrated. But on the contrary, the inclin'd Body II. ABDE (Fig. 38) mult of neceffity fall The fame towards the Part D, which it inclines to, further il- becauſe its Center of Gravity C may de- ſcend in fuch a situation; as will appear by drawing as afore) from A through C the Arch CF, which is the fame that will be defcrib'd by C the Center of Gravity about A, when the Body ABED falls (D) For : 50 The Young Gentleman's 13. of Bodies Standing firmly. 14. For all the Points of the ſaid Arch fall below the Point C. Hence it appears, that to have a Body keep firm upon any Thing, that fupports it, and is not it felf inclin'd, the right Line CF drawn from the Center of Gra- vity in the faid Body toward the Center of the Earth, and wherein the ſaid Body endeavours to defcend (i. e. in fhort the Line of Direction) must neceffarily fall in fome Part of the Bole or Foot AB of the ſaid Body ; as Fig. 37. Otherwiſe, if the Line of Direction CG falls without the Bafis, the Body will neceffarily fall down, as in Fig. 38. Whence it follows, that by how much Further of lefs the Bafis of a Body is even though the fame. it be not inclin'd, fo much more eaſily will it be mov'd out of its Place; becauſe the leffer Change of Pofition is capable to make the Line of Direction be without its Bafis or Foot. Which is the Reafon that a Bowl rolls eafily upon a Plane, and that a Needle will not ftand upon its Point. It is obvious, that agreeably to what has been faid, it follows alfo, that the wider the Foot of a Body is, the more firmly will it ftand, becauſe fo much the greater Change is neceffary to cauſe the Line of Direction to fall with- out the Foot of the faid Body. I' Mechanicks. 51 1.5. It appears alſo from what has been faid, that if the Plane OP, which fuftains of the Sli- ding and the Body ABDE (Fig. 39) be inclin'd, Falling of that Body will flide, when its Line of Bodies. Direction CG falls upon any Part of its Baſe AD And that a Body abde will fall, when its Line of Direction out the faid Bafe ad. 1 cg falls with- Whence it follows, that a Bowl fet up- 16. on an inclining Plane, as the Roof of an Further of Houfe, will roll off it, becauſe its Line the fame. of Direction not being perpendicular to the Plane, (but to the Horizon,) can- not pass through its Foot where it touches the Plane, it being almoſt an indivifible Point. 17. bends, vie when he ris It is remarkable, that we naturally obferve this Law of Staticks, we are Why a Man here ſpeaking of, to keep our felves from falling. Thus, when we would rife from fes from a a Seat, we bend our Body, by thruft- Seat ing forward our Head and Back HB, and putting backwards our Feet and Legs FK (Fig. 40) fo as the Line of Directi- on LG of our Center of Gravity may paſs through our Footing F or Bafis. And it is obvious, that if we bend not enough, we fall backwards or towards B; but if we bend too much, we fall forwards or towards F or K. (D 2) In 52 The Young Gentleman's 1 18. In like Manner, when we go up Stairs, Why a Man as we lift one Foot up, fo we bend our ward when Body forward, that we may (both go up he goes up eafier, and alfo) may preſerve our ſelves leans for- Stairs. 19. mon Pof- tures ac- from falling beckwards, by having the Line of Direction of our Center of Gravity too far from our Footing, which in this Cafe is chiefly the Foot lifted up upon the Stair, when we are get ing up. On the fame Account it is, that when Other com- a Man carries a Burthen on his Back, he leans forward; but if he carries a counted for. Burthen before him, he leans backward. If he carries it with his right Hand, he leans to his Left ; if with his left Hand, he leans to his Right. Namely that hereby he (may not only more eafily carry the Burden, but alfo) nay pre- ferve himſelf from falling that Way which the Burden' he carries, pulls him. 20. The like And that we learn this, not from Reaſon, but rather from natural Inſtinct, Rules ob.. is evident, not only from Mens doing fo Jerv'd by irrational without knowing the Reafon of it, but Creatures. alfo from irrational Creatures doing the like. For a Goofe going through a Barn or other Door, be it never to high, does thruft forth, and fo downwards his Head, not becauſe he is afraid of ſtriking it Mechanicks. 53 * but it againſt what is ſo much above it, but) in conformity to this Law of Staticks. Namely at a Barn Door there is ufually a Threshold or the like, to be gone o- ver. Wherefore the Goofe having put one Foot on the Threfhold, thrufts forward his Head, that his Center of Gravity may not be too far behind his Feet, and ſo pull him backwards that by thruſting his Head and Neck fo far as is requifite beyond the Threſhold, the Direction of his Center of Gravity may be brought fo near to his Footing, as that he may go over the Threſhold more easily, and without falling either backward or forward. So that it appears, the Gooſe is not to be laugh'd at for fo doing, but rather they, who neither know the Reafon of his ſo doing, nor at leaſt that he does no other than they do themſelves in like Cafes. And this is fuf- ficient to our Defign, to have taken no- tice of concerning Staticks, fo call'd in a more reſtrain'd or proper Senfe. (D 3) CHAP. 54 The Young Gentleman's 45 I. Hydrofta- T CHA P. IX. ? Of Hydroftaticks. HO' the Word Staticks, both as to its own literal Import, and alſo in ticks,what its largest Acceptation, denotes the Sci- ence of the Weights of Bodies in gene- ral, whether fluid (or liquid) or not flu- id, and whether weigh'd in the Air or Water; yet it is ufual to reftrain Staticks in a more appropriated Senfe to denote the Science of the Weights only of folid (or not fluid) Bodies, and that too when weigh'd in the Air; and to give the pe- culiar Name of (*) Hydrostaticks to that Part of Staticks largely taken, which treats of the Weight of fluid or liquid Bodies, efpecially of Water, and of fo- lid Bodies put into (†) liquid Bodies, e- Specially into Water. The (*) It is a Greek Word, compounded of sanny. the Science of Weights, and dwg, Water. (t) There is this Difference between a fluid and a liquid Body. A Fluid is a Body, whofe Parts are eafily fepára- red, and being feparated join together immediately, as fif Mechanicks. 55 4 A ; nor ry Theo- rems or The primary Property of heavy Flu- 2. ids are thefe; that if an heavy Fluid The prima- ABCD (Fig. 41) be, either not prefs'd at all, or equally prefs'd from above; its Properties of Fluids. upper Surface AB will lie horizontal or level. And if the ſaid Fluid be diſturb- ed, it will by its own Gravity return to the fame Level of its upper Surface. For the lower Particles of the Fluid will not, by Reaſon of their Gravity, afcend up- ward of themſelves, to raiſe any Part of the faid Surface above the other can the upper Particles of the Fluid de- fcend, fince there is no Room for them, in the lower Part of the Veffel, it being taken up by other Particles of equal Weight. And therefore if there be no Preffure at all from above, or an equal Preffure, then there is nothing to diſturb or alter the Level of the upper Surface. But if it be diſturb'd, the fluid will re- turn to its Level, becauſe the higher Part HI (Fig. 41) being heavier, will partly deprefs the Particles under it, and will partly run down into the lower Part Air, Flame, Water, Oil, and other Liquors. A Liquid is a Body whofe Parts are alfo eafily feparated, and again come together immediately, and withal will continually flow or fpread themſelves, 'till their upper Surface becomes level, as Water, Oil, but not Flame. Hence it appears, that all Liquids are Fluids, but all Fluids are not Liquids. (D 4) and ·56 The Young Gentleman's 3. and that fo long, as any one Part of the Surface is higher than the others. If the Fluid (Fig. 42) be from above Further of unequally prefs'd, it is obvious, that the the fame. Part thereof AE, which is moft prefs'd, will defcend, the Particles fo prefs'd, thrusting out of their Places the other Particles, that are either not prefs'd at all, or lefs prefs'd; which therefore will afcend to HI in proportion to the De- fcent FG of the Particles prefs'd AE, Namely, as the Part prefs'd AE is equal to the Part not or lefs prefs'd EB, fo the Afcent EH or BI will be aqual to the Defcent AF or EG. What has been faid of the upper Sur- face AB, holds good of any other Paral- lel Surface within the Fluid, as EF Fig. 43. Namely, if it be equally prefs'd by the upper Part of the Fluid, and withal by any Thing elſe fwimming either on the Top or within the Fluid, it will re- tain its horizontal Situation or Level. But if it be any where prefs'd more than in other Parts of it, there it will fink, the Parts of it which are lefs prefs'd af- cending as that defcends. And from what has been hitherto faid, are inferr'd the following Propofitions, as fo many Corollaries. If Mechanicks. 57 the first. If an heavy Body EFHB (Fig. 44) 4. Iving upon a Fluid AB, be of an equal Corollary Weight with the Air that takes up an e- qual Space AHEG, the Surface AB of the Fluid will retain its Level, as being eve- ry where equally prefs'd. 5. If the Body EFIK (Fig. 45) be lighter than the Air which takes up the like Corollary the second. Space, then the faid Body, and the Par- ticles of the Fluid under it, will afcend, 'till the Aggregate (of the Body IKEF and of the Parts EFHB of the Fluid fo af- cending, viz.) IHBK be of equal Weight with the Air, that takes up the like Space GAHI. .For then the Surface AB will be equally prefs'd every where, both in AH and HB. 6. the third: If the Body EFAB, (Fig. 46,) be hea- vier than the Air of a like Bulk, then Corollary the Body will fwim in the Fluid, de- fcending fo far into it, 'till the Aggre- gate (of the Air GEIK and the Fluid IKAH, viz.) AHEG, which take up to- gether like Space with the faid Body, be of equal Weight with the Body. For the Surface AB will become equally prefs'd, both in AH and HB. If the Body EGDF (Fig. 47) be hea- 7. vier (not only than the Air, but also) Corollary the fourth than the Water (or other Fluid) that takes up a like Space HCGE, then the Body will fink down quite to the Bottom CD, 58 The Young Gentleman's A 8. Corollary CD, there being nothing to counterpoiſe or bear it up, 'till it comes to the Bot- tom. For the Body being fuppos'd to be put on the upper Surface AB, and to lie upon the Part IB thereof, it being heavi er than a like Bulk of Air, the Part of the Fluid IBDE will be more prefs'd thereby, than the other Part of the Flu- id AIEC by the Air, and therefore the Particles in IBDE will defcend. And in like Manner when the Body is come to GF, it being heavier alfo than a like Bulk AHGI of Water, it will ſtill prefs the Parts of the fluid Water GF more than are thoſe that are under GH, and therefore will caufe the Parts under GF ftill to give way, 'till it comes to the Bot- tom CD. Upon the fame Principles, if a Body GHIK (Fig. 48) be immerg'd into the the fifth. Fluid, and be (of equal Weight with fo much EFGH of the Fluid as takes up the like Space, i. e. in ſhort, be) of the fame fpecifick Gravity with the Fluid, then the ſaid Body will ſtay where it is plac'd in the Fluid, without either rifing or fink- ing. For the Surface EI being equally prefs'd all along, the faid Body cannot rife. And the Surface FK being all along equally prefs'd, neither can the faid Body fink. But Mechanicks. 59 But if the faid Body be fpecifically lighter than the Fluid and confequently the Bulk GHIK be lighter than the Bulk EFGH, it evidently follows, that the Surface FK will be more prefs'd in FH than in HK, and confequently the Body GHIK will be thruft up and rife ftill high- er and higher for the fame Reaſon, 'till it comes to fuch a Situation, as that it is of equal Gravity with fo much Air (which is in this Cafe fuppos'd fpecifically lighter than the Body) and fo much of the Flu- id, as take up equal Space with it; (as is reprefented Fig. 46) according to S. 6. But lastly, if the Bodv be of the fame Specifick Gravity with the Air, then it will rife juft to the very Top of the Flu- id; as is repreſented Fig. 44. according to S. 4. 9. der Water. From what has been faid, it is eaſe to account for feveral Occurrences in Flu- Why a Buc- ket of Wa- ids, as particularly in Water; of which ter has lit- the more remarkable or common fhall be tle or no Weight une taken Notice of. Hence then it is eaſie to tell, why we don't feel the Weight of the Bucket and the Water in it, when we draw Water, 'till it begins to rife out of the Water. Namely, becauſe fuppofing the Bucket with the Water in it to be reprefented, Fig. 48, by GHIK, it being of the fame † Gra- 60 The Young Gentleman's IS. Why the Depths of ; (†) Gravity with the like Bulk of Water EFGH, the Surface FK will be equally prefs'd, both in FH, and HK ; and there- fore the Bucket of Water can't defcend, but is held up by the Water under it and confequently the Weight of it is no more felt, than is a Weight which is counterpois'd by an equal Weight upon a Balance. And the fame holds all the while the Bucket is drawing up to the Surface AB. Where it, and the Water in it, coming into the Air ſo much ſpeci- fically lighter than the Water or Wood, c. of the Bucket, the Air can't ſuſtain it, and fo the Weight of it muſt be ſuſ- tain'd then by him that draws up the Bucket. On the fame Principles the Reafon, why one cannot fathom the Depth of the Sea in fome Places, is this: Becauſe tho' fome Seas cannot be the Plummet or Lead made ufe of be fpe- fathom'd. cifically heavier than Water, yet the Line to which the Plummet is faſten'd, is (in this Cafe) fpecifically lighter than the (+) The Water in the Bucket is certainly of the fame Specifick Gravity with the Reft of the Water. And the Bucket, if all of Word, is much lighter. And if other- wife, the fpecifick Lightness of the Wood does reduce the fpecifick Gravity of the Iron about the Bucket, almof to an Equilibrium with the Water. Water, f Mechanicks. 61 1 Water. Wherefore when the Depth is fo great, that fuch a Quantity of Line is requir'd, as that the Weight of the Line and Lead together is no greater than the Weight of a like Bulk of Water, then the Lead or Plummet will fink no deeper; and confequently will not fhew the Depth of the Sea in that Place. II. According to the fame Principles we may eafily tell, why one Liquor will fwim Why fome upon another, or remain at Top without Liquors Swim upan mixing, if it be pour'd on gently; as Oil others. in reſpect of Water; and Water in re- ſpect of Quickfilver. Namely, becauſe Oil is fpecifically lighter than Water, and Water than Quickfilver. 12. Why Ships, that fail is the Ocean, ter. Hence likewife it ceafes to be a Won- der, that a Ship, which has fail'd in the Open Seas, has funk and been loft in the Mouth of a River of fresh Water; name- fink in ly, becauſe Sea-water is much heavier fresh - than freſh Water. And therefore though the Ship with its Burden was lighter than a like Bulk of Salt-water, and fo was fuftain'd by the Salt-water in the Sea, yet it was heavier than a like Bulk of frefh Water, and therefore funk in the River. It is obvious, that for the fame Rea- fon any Ship or Boat will draw more Water (that is, though it does not fink quite down to the Bottom, yet will fink deeper) in freſh Water than in Salt-wa- ter. More- * 61 The Young Gentleman's 13. that will (wim for Some time, finks after- wards. Moreover the Reafon, why a Log of Why Wood, Wood, that has been fwimming a long time upon Water, will fink at laft, is this, viz. becaufe fuch a Piece of Wood may be of the fame or greater fpecifick Gravity than Water, fetting afides the Pores of the Wood; but by reaſon of its Pores, the Air which fills the faid Pores and the Wood together, make up one Whole lighter than an equal Bulk of Wa- ter, and therefore the Wood will not fink at firft. But after fome Time the Water being got into the Pores, and fo the Air excluded, then the Water in the Pores and the Wood make up one Whole hea- vier than the Water of a like Bulk, and fo muſt fink according to the Principles of Hydroſtaticks aforemention'd. 14. fwim,when From which Principles it follows alfo, Why hollow that although a Lump of Brafs or Iron Weffels of Brass or I- or other Metal will fink in Water, as be- ron will ing fpecifically heavier, yet a Kettle or the like of Brafs or Iron (c.) will not fink but fwim; becaufe the Kettle with the Air contain'd in its Hollow, make up one Whole, which is much lighter than an equal Bulk of Water. Lumps of the fame Metal will fink. It follows alfo, that a Body will weigh 15. A Body will lefs in Water than in Air, by juft fo weigh less much as is the Weight of an equal Bulk thanin air. of Water. Whence it comes to pafs, that in Water, two Pieces of Metal of different ſpecifick Gravi- Mechanicks. 63 Gravities, fuppofe one of Gold and the other of Silver, which fhall be of equal Weight in the Air, will not be ſo in the Water, that Metal whofe fpecifick Gra- vity is greateſt, (viz. the Gold) lo- fing less of its Weight in the Water than the other (viz. the Silver,) be- cauſe it takes up the Room of a lefs Bulk of Water. , If (Fig. 49) a Fluid, particularly (Viercury or) Quickfilver contain'd in the Tube CD preffes on the Part C of the Surface AB, more than the Air preffes on the other Parts, C will defcend, and the Quickfilver run down out of the Tube, 'till what is left CI in the Tube preffes C, juſt as much as the other Parts are preſs'd by the Air. And then no more will run out of the Tube, becauſe of the equal Preffure in all Parts of the Surface AB. Where it is to be noted, that the Weight of the Quickfilver CI is equivalent to the Weight of a Column of Air, extended from the Surface AB up to the Top of the Atmoſphere, and of the fame Bafis or Diameter of the Tube CD. } 16. Why a Flu- Tube will Stand up higher than Fluidwick. id in a the ſame out the Tube. 17. id will rife to Why a Flu the fame Height in a floping Tube, as in And it is obfervable (Fig. 50) that the Quickfilver will rife up juft to the fame Height in the oblique or floping Tube EG, as it does in the upright Tube DC, although the Quick-filver EF in the Tube EG be more, and confequently an upright heavier, 6A The Toung Gentleman's 18. heavier, than the Quickfilver CI in the Tube CD. The Reafon whereof is this, that as much as the Quickfilver EF is more than the Quickfilver CI, fo much greater is the Bafis E than the Bafis C, (this being equal to the Bafis of the Cy- linder EK, wherein the Quickfilver EH will be found to be juſt ſo much as the Quickfilver EF, by reaſon of the two Tubes EK and EG being Cylinders of Equal Height upon the fame Bafes, and therefore Equal one to the other.) Now it is obvious that fuppofing the Bafis E to be Twice as big as the Bafis C, and confequently the Quickfilver EH in the Tube EK (or the Quicksilver EF in the Tube EG) to be Twice as much as the Quickfilver CI in the Tube CD, it evi- dently follows that as the Quicksilver CI do's equiponderate to a Column of Air of the fame Bafis C, fo the Quick- filver EH (or EG) which is the Dou- ble Quantity of Ci, do's but equipon- derate to a Double Quantity of Air, i. e. to a Column of Air, whofe Bafis E is the Double of the Bafis C. Since according to the Rules of Sta- Further of ticks, Bodies gravirate or weigh hea- the fame. vier in a Perpendicular. than in any Oblique or floping Situation, it may be ask'd, why the Quickfilver EH gravi- tating or prefling upon the Bafis E more, than Mechanicks. 65 than do's the Quickfilver EF, (that be- ing perpendicular to E, this oblique.) the Quickfilver do's not defcend lower in the Tube EK, and afcend higher in the Tube EG. The Reafon then is this, that as much as EH preffes downwards more than EF, fo much do's the Force at E, which (arifes from the Preffure of the Air on the other Parts of the Surface AB, and) fuftains the Quickfilver in each Tube, prefs upwards more in the up- right, than in the oblique Tube; and both for the fame Reaſon, viz. becauſe the Preffure, whether upward or down- ward, is in the Tube EK perpendicular, whereas in the Tube EG it is oblique, and therefore not fo great. Now the Force at E, which holds up the Quick- filver in the upright Tube; being as to Effort fo much greater than the Force at E which holds up the Quickfilver in the oblique, as the Weight of the Quick- filver in the upright Tube, is greater than the Weight of the other; it fol- lows, that the faid Force at E acting upwards according to the Perpendicular EH, is as able to fuftain the Quickfilver in the upright Tube, as is the fame Force acting upwards according to the oblique Line EF to fuftain the fame Quantity of Quickfilver in the oblique Tube. And therefore the Quickfilver in the (E) 66 The Young Gentleman's 19. of the Fluid. the upright Tube will not defcend low- er by Running any of it out of the faid Tube, nor will the Quickfilver in the oblique Tube afcend any higher, by any more Running into it: but the Quickſilver in both Tubes will keep at an equal Height. And the fame will hold as to any o- The Shape ther Tube (or Veffel) of any other of the Vef- fel makes Shape: Namely, the Height of the Quick- no Diffe filver will be the fame in any Veffel, as rence as to it is in a Cylinder of the fame Height the Rifing and Bafis with the Veffel. Thus, for Inftance, Fig. 51, the Height of the Quickfilver is the fame, both in the round-headed Tube DEHF, and the fharp-headed KLB, as it is in the Cy- linder infcrib'd in the former, viz. CI, or the Cylinder BLOP, circumfcrib'd a- bout the latter. For as to the round- headed Tube DEHF, as much of the Quickfilver as lies without the Cylinder CI, is fuftain'd not fo much by C, as by the Parts MT and NS of the Tube's Head which are under them, and no more of the Quickfilver is properly or directly fuftain'd by C, than what lies within the Cylinder CI. And confequently the Effect will be the fame, as if the Quickfilver was put in the Cylinder CI. As 1 Mechanicks. 64 20. As to the tharp-headed Veffel LBK, and the Cylinder BLOP, the Quickfilver Further of the fames will likewiſe rife as high in the one as the other. For as to fo much of the faid Veffel, as allows a free Afcent from the Surface AB, the Quickfilver will there rife to its juft Height CI, for the fame Reaſon as it will rife to the fame Height in the Cylinder BLOP. As to the other Parts of the faid Veffel, where the Quickfilver is hinder'd by the Sides of the Veffel to rife up to the Height CI, as much as is there wanting in the Weight of the Quick-filver, which is over the refpective fubjacent Parts of the Surface AB, fo much is fupply'd by the Sides of the Veffel. For although the Sides of the Veffel do not prefs downwards as a contrary Force, yet they keep the Quick- filver from being thruft Higher by the Force that preffes upwards. And confe- quently the feveral Parts of the Sides may be look'd on as fo many Impedi- ments, which are equivalent to the Weight of fo much Quickfilver, as would be contain'd between the refpective Parts of the Sides, and the Parallel to I. And fo the Surface AB will be equally preſt all along under the Veffel B. & (E 2) The 68 The Young Gentleman's 21. Why the Fluid rifes The Preffure of the Air being that which makes the Quickfilver rife in the higher in a Tube; it follows, that the greater is the The at the Preffure of the Air, the higher will the the Quickfilver rife; which is the Reaſon, Top of a that the Quickfilver will rife higher in Mountain. the fame Tube at the Bottom of a Moun- Bottom, them at 22. of the Weather- Glaís. tain or confiderable Hill, than at the Top. Namely, becauſe the Column of Air pref- fing the Surface AB will be ſo much longer at the Bottom, than at the Top of the Mountain, as is the Height of the Mountain; and confequently the faid Column containing fo much more Air, will prefs fo much more. So as to the (*) Barometer or Weather- Glafs, the Quickfilver rifes and falls in the Tube, as the Air is heavier or lighter, and fo more or lefs preſſes the Quickfilver that is in the Well (as it is call'd) of the Barometer. And thus far is agreed by all: but what it is that cauſes the Air to be fometimes heavier, fometimes lighter, is not fo agreed. That the Vapours do not, (as is, or has been, commonly fuppos'd,) increaſe the Gravity of the Air, feems more than (*) It is fo call'd as being a Meaſure of the Weight of the Air, the Word Begs fignifying Weight, and uergov a Measure, in the Greek Tongue. probable Mechanicks. 69 probable on this Account: Namely, that when the Vapours are in the lower Re- gion of the Air, as in rainy Weather, than the Air is lighteft, as appears by the Falling of the Mercury (or Quick- filver) in the Barometer. And when the Vapours are in the middle Region of the Áir, (i. e. when the Clouds are high.) they do not increaſe the Preffure of the Air. For although the Air be heavier then, it is not becauſe the Clouds are high; but the Clouds are high, becaufe the Air is heavy. For when the Air near the Earth is more denfe than ufual, then it becomes heavier than the Va- pours, which therefore muft afcend, and at last fettle in that Region of the Air, which is of the fame Gravity with them- felves. If the Vapours were the Caufe of Increaſing the Air's Gravity, there muſt be as many Vapours in the Air at a Time, as are equal in Weight to three Inches of Mercury, for fo much we find the Mercury rifes or falls in the Weather- Glaſs. Now Mercury is about 14 Times heavier than Water, and confequently there must be in the Air at once fo many Vapours, as are equal in Weight to a Column of Water of 42 Inches in Height, and whofe Bafis is equal to the Surface. of the Earth; which is much more than falls down in Rain, during a whole Year. (E 3) For 79 The Young Gentleman's 23. The prova ble Cante of the Ri- fing and For a whole Year's Rain do's not fill a Veſſel above 14 or 15 Inches high, as is obferv'd in the Hiftory of the Royal Socie ty at Paris. The Reason then, why the Air is heavier at one Time than another, arifes more probably from there being more Air on that Part of the Earth's Surface, when the Air grows heavier. And this proceeds from Winds. For Example: If Weather the Wind, which is nothing but a Stream Glass. of Air, thould blow on any Place, and Falling of the Mercu- ry in st 24. Of the Si- as'd to the Air thus mov'd fhould be kept in that Place by Mountains or Hills: or, if two contrary Winds fhould blow on the fame Place; in either Cafe the Air will be heaped up in the Middle; and confequently there being more Air its Gravity will be increas'd. But if the aforefaid Circumftances, or the like do not happen in any particular Country, then the Air which is over it, will grow lefs in Quantity, and confequently ligh- ter. Whence it is probable, that the Winds are the Caufes of the Variation of the Air's Gravity. It was afore (§. 16.) intimated, that phon, or what has been faid in that and the fol Inftrument lowing Paragraphs concerning Mercury draw off or Quickfilver, holds true likewife in refpe&t of other Fluids. But the fore- quors out of mention'd Affections have been illuftra- Wine or c- ther Li Vaffelis 1 ted Mechanicks. 71 ted, particularly as to Quickfilver, foraf- much as it is that which is us'd in Wea- ther-Glaffes, wherein the faid Affections are more frequently feen by Us: It be- ing the Defign of this Treatife by the Laws or Principles of Mechanicks to ex- plain chiefly fuch Things as more fre- quently occur in common Ufe. On which Account I fhall add here the Ex- plication of the Effect of the Siphon, (or Inftrument us'd by Vintners, &c. in drawing off Wine, or the like,) accor- ding to the forementioned Principles of (Mechanicks, or, more particularly of) Hydrostaticks. It is then obvious, that (Fig. 52.) the Air being fuck'd out of the Siphon at E, the Wine (or other Li- quor) in the Veffel ABFG will be thruſt up by the Preffure of the Air upon the Surface AB, into the other End H of the Siphon apply'd to the faid Surface. And the Wine will be thruft upwards in the Siphon, 'till the Weight thereof comes to an Equilibrium with the Preſſure of the external Air, fuppofe 'till it comes to the Height CI. If therefore the Top D of the Siphon be not higher than I, the Wine will rife to the faid Top of it 33 and there finding a Vent or Paffage down the other Leg DE of the Siphon, it will go that way, and fo run out at E; con- tinuing fo to do, the Caufes ftill conti- (E.4) nuing, 72 The Young Gentleman's : 25. The Me- chanism of a common nuing, 'till the Veffel is emptied. But it is to be obferv'd, that the Mouth E of the Siphon must be lower than the Mouth H. For elfe, E and H being e- qually prefs'd by the Atmoſphere, if the Leg DE be but of an equal Length with DH, and confequently the Fluid in one Leg of equal Gravity, with the Fluid in the other; the Fluid would ftay in the Siphon, not moving one Way or the other, without fome other external Force befide the Air. And by Parity of Rea- fon, if DE be shorter than DH, and fo the Fluid contain'd in DE of leſs Weight than that in DH, the Fluid would run (not from H to E, but) from E to H, the Air coming up at E, and thruſting the Fluid forward the contrary Way. This would happen, except at leaſt the Siphon be fo wide, as that the Air may afcend by the Sides of the Fluid, while the Fluid it felf defcends in DE. Proceed we next to explain the Me- chaniſm of a Common Pump (Fig. 53) by the Principles of Hydroftaticks. The Pump, ex- Handle KL being thruft down, the Sucker plain'd. GF is drawn upwards from E, and toge- ther with it the Air that lies upon it. Wherefore the Water at the Bottom, be- ing without the Hollow of the Pump at A and B prefs'd by the Air, but within the Hollow of the Pump at C being not Cat Mechanicks. 73 (at leaſt, not ſo much) prefs'd by the Air, will therefore afcend from C to D, and thruſting open the Valve E, (as ha- ving no Weight or Preffure upon it,) will afcend ſtill higher to the Bottom of the Sucker, as meeting with no Preffure from above, and being continually prefs'd up- wards from Beneath. The Water ha- ving thus fill'd the hollow Part EF of the Pump, and the Sucker FG (by lifting up the Handle KL) being forced down- wards, do's force alfo downwards the Water under it between F and E, and by this Means forces down and keeps fhut down the Valve E. Wherefore the Water between E and F being thus prefs'd by the Sucker; and having no Paffage downwards through E, it lifts up the Valve G of the Sucker FG, this be- ing the only Way it can make for it felf. The Water thus arifing above the Sucker, is together with it (the Valve G being kept down by the Weight of the Water lying upon it, fo that the Water can't run back that way again; and the Han- dle KL being thruft downwards again) lifted upwards: where finding an open Paffage, it runs out at the Mouth H of the Spout, other Water afcending up in the mean while through D, when the Sucker is drawn up. continually, as long as the (as afore,) And thus Handle is lifted 74 The Young Gentleman's * Wells will Pump- Wells. lifted up and down, and confequently the Sucker is mov'd up and down, the fame Cauſes being thus continued. 26. It is obvious from the Principles of Why fome Hydrostaticks afore laid down, that the not be made Distance between the Water at G in the Well, and the Valve E, (or Bottom of the Sucker when at the Lowelt, viz. at E,) must not be greater than the Alti- tude, whereto the Preffure of the Air is fufficient to make the Water rife, which is found by Experience to be about 33 Foot. Hence fuch Wells, as have their Water lying fo deep, as that (a Pump can't be made, but) the Diftance will be greater than the aforefaid Altitude, can't be Pump-Wells, but muſt be Draw-Wells, i. e. can't have their Water drawn up by a Pump, but by a Bucket and Rope. 27. I ſhall conclude this Chapter, with The Tide fhewing how that Rifing and Sink- by the Prin- ing of the Sea-Water, which we call ciples of the Tide, (and which has been of Hydrofta- old obferv'd, but is by none of the ticks. old Philofophers, as I know of, tole rably accounted for,) may be very na- furally accounted for by the Princi- ples of Hydrostaticks, after fuch a man- ner as is very eafy to be compre- hended. The 1 Mechanicks. 75 28. Tide al- ways comes The Moon's Orbit being over thoſe Parts of the terraqueous Globe, which Why the lie between the Tropicks, and where are the largeſt Seas, as the paffes over to Us from theſe Seas, the preffes (thofe Particles of the South, Matter which are next under Her, and they the next underneath, and fo the whole intermediate Air, and thereby at laft) the Water of the Sea, and ſo cauſes the faid Water to rife, on each Side of that Part of the Sea which lies under her Orbit, that is, toward the North and South Parts of the World. Hence to us who live in the northern Parts of the World, the Tide always comes from the South, because the Moon's Orbit is South of us. And on the like Account, the Tides comes from the North, to thofe who live in the fouthern Parts of the World, becauſe the Moon's Orbit is North of them. alfo, that the Tide muſt come fo much ſooner or later to any Place, as it lies more or leſs diſtant from the Tropicks, or that Track of the Sea which is under the Moon's Orbit. And hence it is evident 29. Why the The Tide being thus caus'd by the Preffure of the Moon, it plainly follows, that becauſe the Moon comes every Day to the Meridian of any Place fifty Mi- nutes later than the Day before; there- nutes La- fore the Tide likewiſe muſt fall every Day Tide comes fifty Mi- there for than out fifty the Day Minutes afore. 76 The Young Gentleman's 30. Why the Tide is fix Hours co- and fix Hours go- ing out. Minutes later every Day, than the Day before, in Refpect of any particular Place. Alfo, becauſe the Moon is fix Hours in coming from the Horizon of any Place to its Meridian, therefore (it is ob- ming in, vious, that) the Tide muſt be fix Hours coming in. And in like manner, becauſe the Moon is fix Hours in going from the Meridian to the Horizon of any Place, therefore the Tide muſt be the fame Time in going out. Where it is obvi- ous, that as the Preffure of the Moon begins in respect of any particular Place, fo foon as the comes to its Horizon; fo her Preſſure continually increaſes 'till fhe comes to the Meridian of that Place, and confequently the Tide rifes ftill higher and higher, 'till fhe comes to the faid Meridian. Which as the Moon leaves again, fo her Preffure decreaſes, and confequently the Tide finks lower and 31. Why the Tides are Bigger at the Change and lower. Moreover it being agreeable to the Laws of Staticks, (as is found by Expe- riments,) for heavy Bodies to gravitate fo much more, as they are nearer to the Full of the Center of the Earth; hence the Reafon, Moon, than why the Tides are Bigger at the New at other and Full Moons, than at the Quarters, Parts of the Month. is easily to be affign'd; namely, the Moon's being at her Change and Full C mearer Mechanicks. 77 nearer to the Earth, than at her Quar- ters. the Change about the Equinox's other Parts Again it is obferv'd, that as the Tides 32. at the Change and Full of the Moon are Why the bigger, than at any other Time of the Tides at Month; fo the Tides at the Change and and Full of Full of the Moon about the Equinox's the Moon are bigger, than thofe at any other Time of the Year. Which may be accounted are bigger, for by the Moon's being then over the than at Middle Part of the Ocean, which is un- of the Year. der the Celeſtial Equator, and confe- quently by its Preffure thereon making a greater Quantity of Water recede to each Side, viz. Northward and South- ward, than when the preffes on one Side of the Equator, and fo not in the Middle of the Ocean. be Two It remains to be obferv'd, that it is 33. demonftrable (†) by the Principles of Why there Staticks, that the Moon do's cauſe (the Tides in Sea to fwell, or in one Word) the Tide, every twenty-five not only in that Part of the Sea which Hours. fhe is over, but alfo in the Part oppofite thereto. And hence it comes to paſs, (†) Such as would have a more accurate Account of the Tide, let him confult Newton's Phyf. Mathem. Lib. 3. Prof. 24 & 37, and Numb. 16. of the Philofoph. Tranfa&t. Lond. 1666; as alfo Gregory's Aftron. Phyf. and Geom. Lib. 4. Prop. 65. I have here contented my felf with a more general Account, as being more Easy to be under. ftood. that 78 The Young Gentleman's, &c. 1 1 34. that there be two Tides every twenty five Hours; namely, becauſe in that Time the Moon going from any Meri- dian, returns to it again; and confe- quently caufes one Tide, while fhe is in the upper Hemifphere, and another Tide while the is in the lower Hemifphere. And thus I have taken Notice of fo much of Mechanicks (in general, or in- cluding Mechanicks, Staticks, and Hy- drostaticks properly fo called,) as is an ſwerable to the Defign of this Trea tife. FINI S i Mechan, Plate, 1. Fig. 1. A D C E B Fig. 2. B a A D A F A Fig. 4. 4 T Fig. 3. B T T B Ъ E B 6 A Fig. 5 3 P: 20Pound 120 Pound W a A F 2 4 • 5 6 Mechan. Plate, 2. Fig. 6 Fig. 7 E Fig. 8 W C P W P B ATA D b ப D B ... E Fig 10 Fig. 9 b TAT B F OO. A a A Fig. 11 C P + 1 2 3 4 5 7 8 9 10 11 12.13 14 15 Fig. 12 A LE B Fig. 13 '8 6 7 4 3 2 1 W 3. B Fig. 14 K X C B w 16 17 1 W B Mechan, Plate. 3. } H IB I K Fig. 15 E A F Fig. 16 D P.. Fig. 17 A I: W C A W B Fig. 18. Mechan. Platé 4. W B W с Fig. 19 A B A Fig. 21 Fig. .bd B A B •B A Fig. 22 B A A Fig. 23 B. B A A 玉 ​A Fig. 24 ..B 20 B Fig. 25 Fig. 26 S Mechan, Plate 5. Fig. 27 Ph 2H A B A... ·B P Fig. 28 Fig. 29 h F P H B A B E D W Fig. 31 B M A F S TAX P F B ल A Fig. 30. H Mechan, Plate. 6. Fig. 33 P Fig. 32 B M E Fig. 34 C B E Fig. 36 f L B A C A A Fig. 35 B D E F D D C C F Fig. 37 E H A B Mechan, Plate.7. } * Fig. 38 Fig. 39 E A D E b a F P H G A B д HT I B Fig. 4! A H Fig. 40 Fig. 42 I H B A F I M.. Mechan Plate.7. Fig. 38 D E Fig. 39 A B b F P H G A HB P д H Fig. 40 B K A Fig. 41 H Fig. 42 I H.. E B A F с D C I H: B Mechan Plate ´8, Fig. 43 Fig. 44 A E B I A Fig. 46 D } H G H Fig. 47 Fig. 45 I F G K E B A B D Fig. 48 D A B E F Ι A E I B H F K מי D C A C E Fig. 49 Fig.50 K I H F D A B A K O P I Fig. 51 S M N A D I B B Mechan, Plate. 9. K Fig.53 Fig.52 I A A E A B H ית F G B THE Young Gentleman's OPTICKS: CONTAINING The more Ufeful and Eaſy ELEMENTS of Opticks, more properly fo called, of Catoptricks, Dioptricks, and Perfpective. By EDWARD WELLS, D. D. Rector of Cotesbach in Leicester- ſhire. LONDON, Printed for James Knapton, at the Crowu in St. Paul's Church-Yard. 1713. THE PREFACE. A S Vifion or Sight is the most useful and pleasant Senfation of the Body, fo Opticks must confequently be very useful and pleasant, as not only explaining the Manner of Viſion in a Geometrical Way, but also by the fame Principles teaching how to ſupply or re- medy the feveral Defects of the Sight, by the Help of pro- per Inſtruments, ſuch as Spec- (F) tacles, The Preface. tacles, Microſcopes, Telef copes, &c. Add bereto, that to this Sci- ence is owing the Invention of Several Inftruments, which ferve to pleaſe and divert the Mind by curious and furprizing Ope- rations; fuch as are the Dark- Chamber, the Magick-Lan- tern, &c. All which are ac- counted for in the following Treatiſe. * THE - : 83 THE Young Gentleman's OPTICK S. CHA P. I. of Opticks in general. T what, 言​。 HE Word Opticks, as it lite- rally fignifies in the Greek Opticks in Tongue any Thing that relates general, to the Sight; fo in its largeſt Acceptation it is ufed by the Learned. to denote the whole Compafs of Science or Knowledge (Phyfical as well as Mathe- matical) relating to Vifion or Sight. 2. call'd, It is now agreed by the Learned, that Vifion is caus'd by the Eye's receiving in- Opticks, to it Rays, which iffue from the Object properly fo feen. Thefe Rays, if they pafs from the whats Object to the Eye through a Medium all (F 2) along હૈ $4 The Young Gentleman's ! 3. Catop- tricks, what. along of the fame Nature, diffuſe them- felves all along after the fame Manner by right (becauſe the ſhorteft) Lines. Whence this Sort of Viſion is call'd Direct Viſion ; and the Word Opticks is taken in a more reſtrain❜d Senfe, to denote that Part of Opticks in general, which treats of direct Vifion. If the Rays come not directly from the Objects to the Eye, but fall first up- on fome impenetrable Body, and are thence reflected or beaten back to the Eye, then the Vifion is called Reflex Vi- fion; and not the Object it ſelf, but its Image is feen. A rough Surface fo breaks and ſcatters the Rays, that they render no Image at all, or at beft but a very im- perfect Image, of the Object; and there- fore thoſe Bodies, which are capable of being moſt poliſh'd, or made moſt ſmooth, make the beſt Reflexion. Such is Glaſs, us'd therefore now-a-days for Looking- glaffes; but Glafs being of it felf pellu- cid or tranfparent, there is ufually put,on the Back-fide of Looking-glaffes, Quick- filver to render it impenetrable by the Rays. Before Looking-glaffes were in- vented, the Ancients made ufe of polifh'd Metal; and fuch a Piece of Metal, made uſe of to ſee one's felf in, the Greeks cal led KάTOTTO; and from thence that Part Κάτοπτρον of Opticks in general, which treats of reflex Opticks. 85 reflex Viſion, is diftinguiſh'd by the Name of atoptricks. what. If the Rays of the visible Object pafs 4. through different Mediums, fo that they Dioptricks are more or leſs diffus'd in the one than in the other, then each Ray will be re- fracted or broken in one Medium, from that right Line wherein it diffus'd it ſelf in the other Medium; whence this is cal- led Refracted Viſion. Thus a Ray paffing out of Water into the Air appears refrac- ted, i. e. broken or bent, from that right Line it made in the Water. And becauſe the Knowledge of refracted Viſion is moſt uſeful in order to the making of Telef- copes, and fuch other Inftruments ; by looking through which, Objects are more clearly feen; hence that Part of Opticks in general, which treats of refracted Vi- fion is diſtinguiſh'd by the Name of Diop- tricks, Aiorov being a Word capable of denoting in the Greek Language any In- ftrument made for to look through. 5. To the foremention'd Parts of Opticks in general, may be added Perspective, or Perfpec the Art of repreſenting vifible Objects in tive, what. a Picture, juſt as they appear to the Eye. This Art is fo call'd, becauſe the Picture is to be fuppos'd between the Eye and the Object, and tranſparent that ſo the Object may be ſeen through its the Word perfpicere in the Latin Tongue (F 3) 86 The Young Gentleman's ; Tongue fignifying to fee through a Thing I hall ſpeak of each of the forementi- on'd ſeveral Parts of Opticks, fo far as is requifite to the Defign of this Trea- tife after that I have here adjoin'd the Definitions or Explications of fuch Terms or Words, as are of principal Ufe in Op- ticks; as alfo fuch Theorems, as are a- greeable both to the Principles of Geo- metry and Experience, and therefore are us'd as Axioms in demonftrating the The- orems of this Treatife relating to Catop tricks and Dioptricks. DEFINITIONS. 1. A Radiant is whatever fends forth Rays from its feveral Points. Hence not. only the Object, fuppofe a Candle, is called the Radiant; but alſo its Image, fuppofe the Image of a Candle feen in a Glafs, is call'd fo likewife. As is alfo the Image of an Image, and fo on Where note, that for Diftin&tion's Sake, the Object is ufually ſpecify'd by the Name of the prime (or primary) Radiant. And fo the immediate Image of an Ob- ject may be diftinguifh'd by the Name of a fecond Radiant; the Image of the faid Image, by the Name of the third Radi- ant, and fo on; that which is feen by the Eye being always diftinguishable (where Opticks. 87 (where there are many Images) by the Name of the last Radiant. 2. Parallel Rays are fuch, as keep all along at an equal Diſtance one from the other. 3. Diverging Rays are fuch, as being produced both Ways, concur or meet in one Point that Way, which is contrary to their Motion. Thus Fig. 10, the Rays. AD, AB, and AF, which are fuppos'd to come from A, are diverging Rays. 4. Converging Rays are fuch, as being produced both Ways, concur the fame Way they move. Thus Fig. 11, the Rays ED, OB, and HF, which are conceiv'd to move toward a,, are converging Rays. N. B. Parallelifm, Divergency, and Convergency are to be underſtood of Rays. of the fame Point.. * 5. The Focus is that Point, where the Rays of the fame Point being produced concur. Thus Fig. 10, A is the Focus of the diverging Rays AD, AB, and AF and a is the Focus of the converging Rays, ED, OB. and HF. Whence it is obvious, that the Focus of parallel Rays. muſt be conceiv'd to be at an infinite Di- ſtance, i. e. at ſo great a Diſtance, as that the Rays of the fame Point, though they are ſtrictly diverging or converging, yet diverge or converge fo very little, (at leaft in respect of that Length and Porti- (F 4) on { 88 The Young Gentleman's 1 > on of them, wherein they are confider'd,) as that they may be look'd upon as pa- rallèl, 6. The Angle of Incidence is naturally and ſo properly the Angle ABC (Fig. 8.) comprehended between the incident Ray AB and the Surface BC which it (incides or) falls upon. But the Angle ABC be- ing always the Complement of the An- gle ABP to a Right; and becauſe what is to be prov'd of the Angle ABC may be primarily, and fo more cafily prov'd, of the Angle ABP, hence for Conveniens cy fake Writers of Opticks do ufually take ABP for the Angle of Incidence, and agreeably define it to be the Angle comprehended under the incident Ray AB, and a right Line PB perpendicular to B the Point of Incidence. Agreeably alfo hereto, 7. A Reflex Angle is that, which is comprehended under the reflex Ray BE and the forefaid Perpendicular PB, viz. the Angle EBP Fig. 8: Though more properly or naturally EBG be the Angle of Reflexion. 8. A Refracted Angle is that, which is comprehended under the refracted Ray BG and the Perpendicular KF or BF, (Fig.) viz, the Angle GBF. 9. By Opticks. 89 9. By Inflection, as a general Word, is denoted either Reflection or Refraction. And confequently both the reflecting Sur- face BC (Fig. 8) and the refracting Sur- face BD (Fig.) are ftiled inflecting Surfaces. And both a reflected Ray BE (Fig. 8) and a refracted Ray BG (Fig. ) are comprehended under the Name of in- flected Rays. AXIOM S. 1, A Ray of Light falling perpendicu- larly on an inflecting Surface, either goes forward in a right Line, or is reflected in- to its felf. Thus (Fig. ) the Ray AC is to be conceiv'd as reflected by the re- flecting Surface BD into it felf. And the Ray AD (Fig. ) is to be conceiv'd to pafs forward beyond the refringent Sur- face BD in a right Line DE or DN. 2. The Inflection of any Ray is per- formed in a Surface perpendicular to the inflecting Surface. Thus (Fig. ) the Ray AB is reflected into BE in the Surface BCDE perpendicular to the reflecting Sur- face BC. And likewife (Fig. ) the Ray AB is refracted into BG in the Sur- face BGND perpendicular to the re- fringent Surface BD. And note, that the faid Surface wherein any Ray is in- flected, 90 The Young Gentleman's Fig. 1. flected, is thence ftil'd the Plane of In- flection. 1 CHAP. II. Of Opticks properly fo call'd, or Direct Vision, THEOREM I. THE fione HYVIN A HE Eye is always placed in the Center of its own Sphere of Vi- Demonftration. At what Diſtance fo- ever; fuppofe Oa, the Eye O can fee one Way, it is felf-evident, that the fame Eye, if by no means hinder'd, can fee at the fame Diſtance any other Way, viz. towards bit can fee at the Distance Ob; towards c at the Diſtance Oc, and fo quite round. Wherefore the ſeveral Di- ftances Oa, Ob, Oc, &c. being equal one to the other, and all proceeding from the fame Point O, it follows that they are the Rays of a Circle, whofe Center is O, and Circumference abcdefgh. Whence al- fo it follows, that the faid right Lines Oa, Ob, Oc, &c. are the Rays likewiſe of a j Sphere Opticks 918 Sphere generated by the Turning of the foremention'd Circle round about any of its Diameters, fuppofe ae, as an Ax- is; and confèquently that. O the Eye will be the Center of the ſaid Sphere: Q- E. D. Corel, r. As it is evident from what has been faid, that could the Eye be placed where it might fee every Way, the Space, which would then fall within its Sight, would repreſent an entire Sphere; fo it follows, that by the Interpofition of the Earth, the Space or Compafs of actual Vifion, even when the Eye has a full View, is equal but to an Hemifphere. Namely, fuppofing ae to reprefent the up- per Surface of the Earth whereon the Eye is placed, the Extent of actual Viſion will be equal to the Hemifphere Qabcde, the Line EE denoting the Horizon or the Boundary of the Sight downwards.^.90 Corol 2. From this Theorem it follows alſo, that whatever Portion of the Hea- vens, (whether All abcde, or only Part: of it, as bd, or bc, &c.) is feen by usit appears as a Portion of the eoncave Sur- face of a Sphere. Corol. 3. Becauſe the Sun and Moon': and Stars are beyond the Extent of di- ftinct Vision, and confequently the Eye can't difcern, how far one is more diſtant from it than the other; hence it comes to país, 92 The Young Gentleman's paſs, that the Sun, Moon, and Stars, do appear to us, as all fituated in the Surface aceg of one and the fame Sphere Oaceg, and fo equally diftant from us, though they are in reality at ſeveral Di- ftances from us. Corol. 4. So much of the Heavens as is feen by us, viz. abcde, appearing of a ſpherical Figure only for the Reaſon contain'd in this Theorem; it thence fol- lows, that the Body of the Heavens may be of a Quadrilateral Figure, as ABCD, or of any befides a Spheri- cal. Scholium. This first Theorem with its Corollaries is of good Uſe to prepare young Students for Aftronomy. And I have choſen to place this Theorem under direct Viſion, partly becauſe it will ſo be the more easily understood, and partly becauſe, (though it be not one Homo- geneous Matter contain'd in the Expanfe or Space which we call Heaven, and con- ſequently what we ſee therein at any confiderable Distance, we fee not by di- rect, but refracted Viſion, yet) it comes to the fame in refpect as to the Cafe be- fore us, whether Things in the Heavens. are viſible to us by direct or refracted Vi- fion. THEO Opticks. 93 THEOREM II. The Eye can ſee at one View (i. e. at Fig. 2. one Time and Place) no more Objects, than whoſe Rays fall within the Com- paſs of a Semicircle, to which the Eye, or rather its Pupil, is the Center. Dem. For the Eye ocaf can fee only thoſe Objects, whofe Rays, paffing thro' O its Pupil, reach to its Retina or Optick Nerve placed at the Bottom of the Eye. But now it is evident from the bare In- ſpection of Fig. 2. that no Ray can en- ter the Pupil O, but what falls within the Semicircle DHE, whofe Center is Q. For fuppofing a Ray to pafs along ED the Diameter of the Semicircle, it will paſs over the Pupil O, and not enter it. And confequently all Rays falling with- out the faid Semicircle, will much lefs enter the Pupil. Q. E. D. Corol. Rays of Light (as well as other Things, whether natural or artificial) ha- ving a greater or lefs Force, as they are leſs or more oblique, it follows that ſuch Rays as pafs through the very Middle of the Semicircle DHE, are of moſt Efficacy in caufing Viſion, as entring the Pupil of the Eye perpendicularly, and confequent- ly falling perpendicularly upon the Reti- na at the Bottom of the Eye. Thus a the 94 The Young Gentleman's ! Fig. 2. the Image of the Object A will be painted moſt lively and diftinctly on the Retina. The Image b and g of the Objects B and G will be painted lefs lively and diftin&t than the former Image 4, as being made by oblique Rays: but alike lively and diſtinct in reſpect of one another, as being made by the Rays Bb and Gg equally oblique and more lively and diſtinct than the Images c and fof the Objects C and F, becauſe the Rays Bb and Gg are leſs oblique than the Rays Ce and Ff. Schol. Agreeably hereto we find by Experience, that we ſee moſt diſtinctly fuch Objects, as (ceteris paribus) are ex- actly before our Eyes. And upon this Account it is, that, in all the feveral Parts of Opticks largely fo called, prin- cipal Regard is to be had to fuch Rays, as enter the Eye perpendicularly. THEOREM III An Object appears greater or lefs, ac- cording as it is feen under a greater or lefs Angle. Demonft. Let the Lines AB and CD (as they are of equal Length, fo) repreſent two Objects of equal Bignefs. It is evi- dent that the Angle AOB, under which is ſeen the Object AB, is only a Part of the Angle COD, under which is feen the Ob. Opticks. 95 3 C Object CD. It is alſo evident, that the Rays AO and BO being extended be- yond the Pupil of the Eye ODC will fall respectively upon the Points a and b of the Retina in the Bot- tom of the Eye; and likewife the Rays CO and DO being extended beyond O, will fall upon the Points c and d of the Retina. Whence it follows, that ab the Image of the Object AB will be fo much in proportion lefs than the Image cd of the Object CD, that is, the Obje& AB will appear to a Spectator fo much leſs than the Object CD, (though they be both of an equal Bigneſs in reality,) as the Angle AOB is lefs than the Angle COD. Q. E. D.: Schol. Hence it appears, why the Dif- Fig. 4: tance between the fame two Objects A and B appears to be greater or leſs, ac- cording as the Diſtance of the Spectator from the faid Objects is greater or lefs; namely, becauſe the Diſtance AB between the ſaid two Objects is feen under an An- gle proportionably greater or lefs, as the Diſtance of the Eye from the faid Objects is leffer or greater; that is, the Angle AOB is proportionably greater than the Angle AEB, as the Distance OD is lefs than the Diſtance ED. And confequent- ly (according to this Theorem III.) the Diſtance AB will appear fo much in pro- 1 } portion 96 The Young Gentleman's Fig. 5. portion greater to a Spectator at O, than at E. THEOREM IV. The Rays of an Object being admitted through a narrow Hole, do therein croſs one the other, ſo as that the Image made by the ſaid crofs Rays will be inverted in reſpect of its Object. Ray Bb, they muſt being extended be- And therefore the 3 Demonft. The Ray A proceeding from the Point A of the Object or Arrow AB, being (in dire& Vifion) a right Line, and fo likewiſe the croſs one the other, yond the Hole O. upper Point A of the Arrow AB will be- come the lower Point a of the Image ab and the lower Point B of the Arrow AB will become the upper Point b of its Image ab.And the like will hold as to all the inter- mediate Points, (except the very middle Point C, which being perpendicular or in a right Line with O, its Image c will like- wife be the middle Point of the Image ab) and confequently the Image ba will be inverted in refpect of its Obje& AB. Q. E. D. Schol. 1. Agreeable hereto are Expe- ments of this Nature. Namely, a Room being darken'd by putting together its Window-fhuts, and a fmall Hole being made with a common Gimblet or Nail- paffer Opticks 97 paffer in one of the Window-fhuts, and the Glaſs of the Window being remo- ved from before the Hole by open- ing the Cafement or the like fuch Objects as are without, and fo fituated as that their Rays will pafs through the Hole, will appear upon a Sheet of white Paper, held on the Inſide overa- gainſt the Hole, in an inverted Manner according to this Theorem. And the nearer the Paper is held to the Hole, fo much leſs will the Image be; becauſe as much leſs as the Rays Aa and Bb are ex- tended beyond O the Hole or Point of their Meeting, fo much lefs is the Dif tance between them: Namely, the Dif tance cd is less than the Diſtance ab, and confequently the Image of the Object (ſuppoſe the Arrow) AB will appear lefs on the Paper held at the Diſtance cd from the Hole, than if the Paper be held at the Diſtance ab. 2. And the fame has been found, by Experiments made for this Purpoſe, to hold good in refpect of the Eye it felf, this being as it were a ſmall dark Cham- ber, into which are let pafs through the Pupil the Rays of outward Objects, which paint their Images on the Retina in the Bottom of the Eye, agreeably to this Theorem, that is, in an inverted Man- ner with reſpect to its Object. As is il (G) luftrated 98 The Young Gentleman's luftrated Fig. 6, which reprefents an Eye having on its hinder Part a little Piece of each of its Coats or Skins cut away, 'till you come to the vitreous Humour. A Candle being held before the Eye, and a Piece of white Paper being apply'd to its hinder Part prepared as aforemention'd, the Image of the Candle has been found to be made on the faid Paper in an in- verted Manner; All other Rays of Light being kept from falling on the Paper by dark'ning the Room where the Experi- ment was made. Concerning which more ſhall be ſaid in Chapter IV, foraſmuch as the Rays paffing through the Humours of the Eye are refracted, and confequent- ly it is requifite to underſtand the Laws of Refraction, before we can underſtand aright, how Viſion is caus'd in the Eye. And for the fame Reafon I omit here faying any thing of the Ufe of ſpherical Glaffes in the Hole to a dark Cham- ber, for rendring the Images more lively and diſtinct. 3. I fhall add here (as being of great Uſe for the clearer Underſtanding of what has been or fhall be faid in this Treatife of Opticks) a Defcription of the feveral Parts of an Eye, reprefented Fig. 7, where A denotes the Chryftalline Humour, B the Vitreous, C the Aqueons: D the Cornea Tunica; E the Retina E the Retina; F the Coat Opticks. 99 Coat call'd Choroides; G the Coat call'd Sclerotica, being a Part of the Dura Mater continued about the Ball of the Eye on its inner Part; H the Optick Nerve without the Ball of the Eye; I the Coat or Skin call'd the Uvea; K the Hole of the U vea, call'd in one Word the Pupil. It remains only to obſerve further, that moſt, if not all the Particulars taken no- tice of in this Chapter, belong not to di rect Vifion alone, but are applicable alfo to reflected and refracted Viſion ; which we proceed to ſpeak of in their Órder. СНАР. III. Of Catoptricks, or Reflex Viſion. THEOREM I Fa Ray AB of Light be reflected by a Fig. 81] plain Surface GC, the Angle PBE of Reflexion will be equal to the Angle PBA of Incidence. Demonft. Draw BP, and alfo AC, per- pendicular to GC. The Medium GCde being fuppos'd homogeneous to (i. e. of the fame Nature with) the Medium (G 2) EBCD, J The Young Gentleman's 100 EBCD, it follows that all the Rays com- prehended between AB and AC, and which take up or ſpread all over the right Line BC, were they not hinder'd (by GC the reflecting Plane) from paffing thro' the Medium GCde, would therein diffufe themſelves after the fame Manner, as in the other Medium EBCD, that is, (the right Line AB being continued to e, and AC to d,) at the Diſtance Be they would diffuſe or ſpread themſelves all over de. And whereas the reflecting Plane BC does neither increaſe nor diminiſh the ſpread- ing of the Rays, but only turns them back into the fame Medium they were in afore; hence it is obvious, that after the Reflection the Rays will fpread them- felves in the fame Manner, asthey would have ſpread, had they not fell upon the Surface GC, but (that being remov❜d) gone on in the fame homogeneous Medi- um. But in that Cafe, at the Diſtance Be, the Rays would (as is afore fhewn) ſpread themſelves all over ed. fore in the Diſtance BE Be, they will fpread themſelves all over DE-De: and confequently the Figure BCDE will be in all Reſpects like and equal to the Figure 'BCde; and indeed is no other than the Figure BCde reflected, or turn'd about (as it were) half round upon BC. Where- fore, if from the equal Angles EBC and Where- eBC Opticks. 10.1 F *BC there be taken away the right Angles PBC and pBC, there will remain the An- gles EBP and eBp equal one to the other. But ABP eBp, therefore ABP=EBP. Q. E. D. Corol. 1. Hence the Angles EBG and ABC (which, as has been Defin. 6 and 7 obferv'd, are more properly call'd the Angles of Incidence and Reflection) are equal one to the other. Namely, be. cauſe PBG PBC, and PBE=PBA, therefore (PBG-PBE=)EBG=(PBC -PBA=)ABC. Cor. 2. If the reflex Ray BE be taken for the Incident, then the incident Ray AB will be its Reflex. Cor. 3. If the Angle PBE PBA, or GBE CBA, then BE is the Reflex of AB. Schol. What has been prov'd as to a Fig. 9. reflecting Plane GC, the fame holds good also in respect of any reflecting Curve Sur- face PQ. For the Inclination or Directi- on of the Curve, at B the Point of In- cidence, is the fame with the Inclination of the Plane DE that touches it there. And therefore the Reflection following always the Inclination, will be the fame, whether it be fuppos'd to be made by B as a Particle of the Curve Surface PBQ, or of the Plain DBE. And the fame holds good as to refracting Surfaces. (G 3) THEO. - 102 The Young Gentleman's Fig, 10. THEOREM II. At what Diſtance CA an Object A is placed before a reflecting Plane CF (whe- ther of Metal or Glafs, &c.) at the fame Diſtance Ca will a the Image of the Object appear behind the ſaid reflec- ting Plane, each Diſtance CA and Ca be- ing meaſur'd upon one and the fame Per- pendicular to the faid Plane, viz. upon Aa. Demonft. Let AD, AB, and AH be Rays proceeding from the Object (or a- ny Point of the Object) A; and let DE, BO, and FH be their refpective reflex Rays. It is evident, that theſe being ex- tended beyond CF (i. e. behind the re- flecting Plane) will all meet in a, which therefore will be the Focus of the ſaid Rays, and confequently the Place where the Image of a will appear. But now the Angle aDC EDF, and EDF ADC by Theorem I. of this Chapter; where- fore aDC=ADC. And becauſe in the Triangles ACD and CD, the Angle ADC=aDC, and alfo ACD=aCD, and the Side CD is common to both Trian- gles, therefore CA-Ca. And after the very fame Manner may it be provid, that in the other Triangles, ACB and CB, as alfo ACF and CF, the Di- ftance Opticks. 103 ſtance CA of (any Point in the Object, and (*) confequently of all) the Object A is equal to the Diſtance Ca of the Image a. Q. E. D. Corol. 1. Hence it follows, that fuppo- fing the reflex Ray OB to be that which comes to the Eye plac'd at O, though all the rest of the Looking-glaſs or other re- flecting Plane, CF be cover'd (or taken away) but the Part B, yet the Image a will be ſeen by the Eye; whereas if the Part B be hid, and all the reft uncove- red, the Image can't be feen by the Eye at O. Cor. 2. After the fame Manner as Ob- jects are inclin❜d towards the reflecting Plane, will alſo their Images be inclin'd, And confequently in fuch a Plane or Looking-glafs plac'd horizontally, Objects will appear inverted, or with their upper Parts downward. Cor. 3. Becaufe B AB, therefore @O=AB+BO, that is, the Diſtance of the Image from the Eye is equal to the (*) Namely, as the vifible Object is conceiv'd to con fift of feveral Radiant Points, fo the Image of the whole Object is made up of all the Images of the feveral Radi- ant Points, taken together, as is more fully illuftrated by Fig. 11 and 12, of which fee more in the following Scholium. (G 4) inci- 104 The Young Gentleman's incident Ray and reflected Ray taken to gether. Cor. 4. Whatever has been faid of the Image of any Object or prime Ra- diant, the fame holds true alfo of the Image of an Image, Whence arifes the multiplying of Images by Means of two or more reflecting Planes duly pla- ced. Wherein this is moft remarkable, the Diſtance of every Image is equal to the Ray propagated from the prime Ra- diant to the Eye, through all the inter- mediate Reflexions. { Schol. It is obfervable, that by this Theorem, the Focus A of Rays AD, AB, and AF falling on the reflecting Plane CF being given; thereby may be found the Focus a after Reflection; name- ly, by drawing AC perpendicular to CD, and extending it to a fo, as that Ca may be equal to CA. For then a will be the Focus fought. Schol. 2. For the Sake of fuch as may not fo readily apprehend from Fig ro,' how the Image of a whole Object is ſeen by Reflection, I have therefore added Fig. 11 and 12. In each of which AB de- notes a Crofs, and ab its Image ſeen by the incident Rays reflected to the Eye at E by the reflecting Plane CF. Namely, Fig. fhews exprefsly, how the Rays AG and Opticks. 105 and BI that come from the two Extremi- ties aB of the Object are reflected to the Eye, and fo caufe the Image of A and B to appear at a and b; and Fig. 12 fhews how in like Manner the Images of the Points D and H of the Object appear at d and b; namely, in both Figures the I- mages appear, where the reflex Rays EG and EI being extended, meet with the Perpendiculars Aa. Bb, Hb, and Dd; and where Ca CA, Fb FB, Ch⇒CH, and Fd=FD. And the fame may be ſhewn. as to any other Points. THEOREM III. If a reflecting Glafs (or other Surface) Fig. 13. BD be ſpherical, either concave or con- vex, and the Object E be far distant from the Glafs; its Image will, to the Eye placed in the Axis AB of Radiation, appear at C the Middle of the Semidia- meter AB of the Glafs. But if the Ob- Fig. 14, ject E be not far diftant, then its Image 15, 16. will, to the Eye in the Axis, appear at that Place C, where (BC: CA:: BE: EA, that is, where) the Diſtance of the Image from B the Vertex of the Glafs will be to its Diſtance from A the Center of the Glafs, as the Diſtance of the Object from the faid Vertex is to its Distance from the faid Center. I 106 The Young Gentleman's Fg. 13. I have choſen to comprehend all that relates to reflecting fpherical Glaffes, with reſpect to the Eye placed in the Axis of Radiation, under one Theorem, that thereby may the more eafily be diſcern'd the uniform Manner, whereby Viſion is perform'd in fuch Cafes. In reference to which it is to be ob- fery'd, that (although in the Figures be- longing to this Theorem, the Point D be placed at fome confiderable Diſtance from B, for the more diftinctly perceiving the Demonſtrations, yet) D is to be fuppos'd very near to B, becauſe otherwife the Re- flex CD of the Incident Ray ED will not affect the Eye placed in AB. For the re- flex Rays of all fuch Rays as fall more remote from B, will pafs by on one Side of the Pupil of the Eye, and fo contri- bute nothing to the Sight of the Image. Add hereto, what has been obſerv'd in the Corollary of Theorem 2, Chap. 2, Hence Notice is here taken only of fuch Rays as fall upon the Glafs very near to its Vertex B. Theſe Particulars being premis'd, I come now to the Demonftra- tion of this Theorem, in refpect of its four principal Cafes following. Cafe 1. When the Object is far diftant from, the Glaſs, ſo that the Rays coming from any one Point thereof may be con- ceiv'd parallel one to the other, as well as Opticks. 107 In as to the Axis AB, as the Ray ED. fuch a Cafe the Image will appear, to the Eye placed fomewhere in the Axis, at C the Middle of the Semidiameter of the Glaſs, For bifect AB in C, and draw AD and CD, and produce them on the other Side of BD the Glafs. Becauſe the Point D is look'd to be ſo very near to B, as in a Manner to coin- cide with it, therefore we may alſo look upon CD=CB; and by Conftruc- tion CA CB, therefore CA-CD, and confequently the Angle CAD CDA. But the Angle CAD-EDA the Angle of Inci- dence of the Ray ED, (for AD is perpen- dicular to the Surface of the ſpherical Glaſs,) wherefore the Angle CDA is e- qual to the Angle of Incidence of ED, and therefore (by Cor. 2, Theorem I. Chap. 3.) DC is the Reflex of the Incident ED upon the Concave Surface of the Glafs BD. And the like may be demonſtrated as to the Convex Surface of the Glafs BD. For, becauſe the Angle EDA=eDO, and CDA NDO, therefore the Line DN will be the Reflex of the Ray eD, and being produced backwards (or on the Concave Side of the Glafs) will touch AB alfo at C. And what has been de- monftrated of any Ray ED taken at plea- fure, the fame holds true of all Rays in the fame Circumſtances. Wherefore Rays parallel J 108 The Young Gentleman's Fig. 14. parallel to AB, and whoſe reflex Rays contribute to the Sight of the Image, if they fall upon a Concave Glaſs, after their Reflexion will concur at C; and from thence diverging again, will render the Image viſible at C, to the Eye placed fomewhere in AB. And the reflex Rays of fuch parallel Rays, as fall upon a Convex Glaſs, do diverge from C, and confequently render the Image vifible at C, to the Eye plac'd in AB produc'd on the convex Side of the Glaſs, that is, if D be the incident parallel Ray, ND will be the Convex, which will form the I- mage at C. Q. E. D. Corol. Hence, and from Corol. 2. Theo- rem I. of this Chapter, it follows, that Rays diverging from C and reflected by a Concave Surface, or converging at C and reflected by a Convex Surface, are parallel to AB; that is, if CD be the In- cident, DE is the Reflex; or if ND be the Incident, De is the Reflex. Cafe 2. If the Object E be not far dif tant from BD the Glaſs, and fo the Rays proceeding from any fingle Point thereof are (not parallel, but) diverging, then the Image will, to the Eye in the Axis, appear at that Place C, where BC: CA :: BE: EA. And this ſhall be demonſtra- ted first in reſpect of Concave Glaffes, and when the Diſtance of the Object is greater Opticks. 109 greater than half the semidiameter of the Glaſs. For let the Point C be ſo taken in AB, as is requir'd; and draw AD and CD. Becauſe (for the Reaſon above- mention'd) ED EB, and CD=CB, therefore by Conſtruction CD (=CB) : CA :: DE(=BE): EA. Wherefore al- ternately CD: DE:: CA: EA. And fo by (Prop. 3. Euclid. 6.) the Angle ADE ADC. But ADE is the Angle of In- cidence of the Ray ED therefore (by Corol. 2. Theorem I. of this Chapter) DC is the Reflex of the Ray ED. And ED being taken at Pleaſure, it follows that the Focus of all other Rays diverging from E will, after their Reflection by a concave Glaſs, be at C, and confequent- ly the Image of the Object will appear at C, to the Eye placed in the Axis (AB produced, or) EB. Q. E. D. ; Cor. 1. Hence C will be the Focus of Rays eD converging to E in the like Cir- cumſtances, and reflected by a ſpherical convex Reflecter. Cor. 2. Hence and from Cor. 2. Theo- rem I. of this Chapter, if CD be the Inci- dent, DE will be the Reflex; and if ND be the Incident, De will be the Re- flex. Cafe 3. And the fame holds true, when Fig. 15. the Diſtance of the Object is lefs than half the Semidiameter of the Glaſs. For " in 110 The Young Gentleman's Fig. 16. S in AB extended, let C be taken accord- ing to the Prop. be requir'd; and let AD and CD be drawn and produced as alſo let ER be drawn parallel to CD. The Arch BD being as Nothing, there- fore ED=EB, and CD=CB. Whence ED: EA :: CD: CA; and fo (by Rea- fon of DC being parallel to ER) ED: EA:: ER: EA. Wherefore ER=ED, and the Angle ERD=EDR. But EDR is the Angle of Incidence of ED, and ERD=NDA its Altern, therefore (by Cor. 2. Theorem I. of this Chapter,) DN is the Reflex of the Incident ED. And ED being taken at pleaſure, it is manifeſt, that all Rays proceeding from E, and re- flected by a concave Glafs, being extend- ed backwards, will concur in C; and confequently the Image of the Object will appear at C, to the Eye placed in the Ax- is. Q. E. D. Corol. 1. Hence if CD be the Incident on a ſpherical Convex Reflecter, De will be the Reflex, and fo the Image will ap- pear at E. Cor. 2. Hence and from Cor. 2. Theorem I. of this Chapter, if ND be the Incident, DE will be the Reflex; and if eD be the Incident, DC will be the Reflex. Cafe 4. The like holds good in reſpect of convex Glaſſes. For in AE let C be taken according to the Proportion re- quir'd Opticks. ΙΙΙ quir'd in this Theorem, or (which comes to the fame) fo as that AC: CB :: AE : EB, and let CD be drawn and extended; and parallel thereto let ER be drawn, 'till it meets in R with AD produced. The Arch BD being as Nothing, therefore CD=CB, and ED=EB. And therefore AC: CD::AE: ED. AE: ED. But becauſe the Triangles ACD and AER are equiangu- lar, therefore AC: CD :: AE: ER; and fo AE: ED:: AE: ER; and therefore ER ED. And confequently the Angle (ERD, or its Altern, and fo Equal) NDR EDR the Angle of Incidence of ED. Wherefore DN is the Reflex of the Incident ED. But ED being taken at pleaſure, it is evident, that all the Rays diverging from E, and entring the Eye placed in the Axis, after they are reflec- ted by the convex Surface BD, will di- verge from the Focus C; and confe- quently the Image of the Object E will appear at C to the Eye fo placed. Q E. D. Coroll. Hence if ND be the Incident, DE will be the Reflex; and if in a con- cave Reflecter eD be the Incident, DC will be the Reflex; or if CD be the Incident, De will be the Reflex. Schol. From this Theorem is deduced the Way of finding the Focus of paral- lef 112 The Young Gentleman's • lel or other Rays, falling upon fpheri- cal Surfaces, after their Reflection, viz. The Focus C of fuch parallel Rays ED after Reflection is found by bifect- ing the Semidiameter AB of the Sphere in C. And the Focus C of other Rays falling upon a ſpherical Surface, is found after Reflexion, by taking C fo, as that BC: AC::BE:AE. And thus it has been fhewn, both by Way of Theorem and Problem, where the Image of an Object will appear in a- ny ſpherical Glafs, (or other like reflect- ing Plane) to the Eye placed in the Axis of Radiation. And this is fufficient to our preſent Purpoſe, not only becauſe moſt optical Inftruments are made after this manner, but alſo becauſe the Image, only in this Situation of the Eye, appears fo lively and diftinct, as to deferve the Name of an Image. Hitherto both Object and Image have been denoted only by fin- gle Points, as being fufficient to illuſtrate what has been afore deliver'd. I now proceed to ſpeak of Object and Image sonfider'd as Lines or Surfaces. THEO Opticks. 113 THEOREM ÍÍ. The Image CT of a radiant plain Sur- face FE, made by a ſpherical Glaſs BD, Fig. 17 is alſo a plain Surface. From A the Center of the Glafs, draw AE perpendicular to FE, and meeting the Glafs in its Vertex B. And (according to Theorem III, of this Chapter) let C be the Image of the Point E, through which draw parallel to FE the Plane CT. In the Plane CT will appear the Image of the Plane FE made by the Glaſs. Thus let AF be the Ray, drawn from any other Point F of the radiant Plane FE to the Center of the Glafs, and meet- ing with the Glaſs in D, and the Plane CT in T. And by Conſtruction let CD be the Reflex of the Incident ED and ; let the Reflex of the Incident FB be BH, meeting the Ray FD in H. Now, be- cauſe we fuppofe in the prefent Cafe the Angle FAE to be fmall, therefore the Arch BD will be alſo ſmall, and in effect no other than a little or fhort right Line. And the Circumference of the Circle de- fcrib'd with the Diameter BF will pafs through the Points D and E, becauſe the Angles FEB and FDB are right. Whence the Angles BFD and BED being in the fame Segment, are equal. And when the Angles at Aare Verticals or the fame, (H) it & 18. 114 The Young Gentleman s it will follow that FBA=EDA. And (becauſe by Theorem I, of this Chapter) ABH-FBA, and ADC=EDA, there- fore ABH EDC. Whence the Trian- gles ABH and ADC are equiangular, and fo fimilar. Wherefore AB: AH:: AD: AC; and whereas ABAD, there- fore AH-AC. But by reaſon of the Smalneſs of the Angle CAT, we may look upon AT-AC. and therefore we may alſo look on AHAT. But H is the Image of the Point F in the radiant Plane, whence the faid Image is plac'd in the Plane CT. And the fame may be fhewn the fame Way as to the Image of any o- ther Point in the Plane FE. Wherefore the Image of the Plane FE is placed in the Plane CT. Q. E. D. ་ If the radiant Plane be far diftant, then the Images of feveral radiant Points will be (by Theorem III, of this Chapter) in the Mid-points of the ſeveral Semidi- ameters of the Glafs tending to the faid radiant Points, that is, the Image of a radi- ant Plane far diftant will have the Figure of a ſpherical Surface concentrical to the Glafs. But becauſe the faid Radiant is (ac- cording to our Suppoſition) feen under a fmall Angle, that fmall Portion of a ſphe- rical Surface, which is taken up by the faid Image, will ſcarcely differ from a plain Surface, to which AB is perpendicular. Whence Opticks. 115 Whence this Theorem holds good in all Cafes for the Demonſtration will ferve for any other Cafe, as well as thoſe two reprefented in Fig. 17 and 18. Cor. If the Angle EAF be too great, the right Line AH will be fenfibly leſs than AT. Whence an Obje& being ſeen under fuch an Angle, its Image, if made by a concave Glafs, will appear concave; if made by a convex Glafs, will appear convex.. THEOREM V. The Object HF, and its Image bf, are Fig. 19 ſeen under equal Angles HBF and hBf x 29. from the Vertex B of the reflecting Curve BD, whether convex (as Fig. 19) or con- cave (as Fig. 20) Demonft. Draw AE perpendicular to HF, (which by Theorem IV, of this Chap- ter, will confequently be perpendicular to hf.) and meeting the reflecting Curve BD at B. Draw alfo BF, BH, Bƒ, Bh, and Ff, which laft will pafs through the Cen- ter A; forafmuch as according to our Suppofition the Image of every Point is placed in the Axis of Radiation. In like Manner the Points H, A, and b will be in the fame Axis. Now by Theorem III, of this Chapter, BE: EA:: BC: CA. Wherefore BE: BC:: EA: CA. But (by BC::EA: reafon of the equiangular Triangles AEF and ACf) EA: "CA :: EF: Cf. Where- (H 2) fore 116 The Young Gentleman's fore BE: EF :: BC: Cf And whereas the Angles BEF and BCƒ are right, there' fore the Angle EBF-CBf. And in like Manner the Angle EBH-CBb. Wherefore HBF=bBF. Q. E D Corol. The Obj‹ & FH (if it be a Line) and its Image fb are one to the other, as their Diſtances from the Vertex, BE and BC. But if the Oje& be a Surface, it and its Image will be one to the other, as the Squares of their Distances aforefaid. Whence, the Distance of the Object and the Image from the Reflecter being given, thereby is given alſo the Ratio or Proporti- on of the Image to the Obje&. And in like Manner may be found the laſt Image of an Obje&, when it is propagated by ma- ny Refle&ters. Laftly, it is evident, that the fame will hold true in all re- fpecs, if fb be the Object, and HF the Image. Schol. By what has been faid, it is ea- fie to account for and illuſtrate the Parti- culars relating to Images made by fphe- rical Reflecters. Of which the more re- markable are thefe that follow, viz. 1. If the Refle&er be concave, and the Diſtance BC of the Object hf from B the Vertex of the Reflecter, be lefs than half the emidiameter, then Its Image HF will appear beyond or behind the Reflec- ter, and in a right Pofition, (as in a plain Re- Opticks. 117 Reflecter, namely the upper Part of the Object will appear the upper Part of the Image; the lower Part of that, the low- er Part of this. c) and as the Obje&t is placed nearer or farther from the Reflec- ter, within the Diſtance of the Semidia- meter, fo will the Image be nearer or far- ther from the fame, and appear lefs or more magnify'd. All which Particulars will be illuftrated by comparing together Fig. 19 and 21 and 22. Namely in Fig. 21, the Obj-& bf being placed a fourth Part BC of the Semidiameter BA from the reflecting Concave BD and in Fig. 19, the Object hf being placed a third Part BC of the Semidiameter BA from the fame concave Reflecter, it is evident that in the former the Image HF (as well as the Object hf) is nearer to the Reflecter, and lefs proportionably, than in the lat- ter. And in both Figures the Image ap- pears in a due Pofition, viz. F is on the fame Side of the Axis AB as f, and Has h. And therefore if f be the upper and h the lower Part of the Obje&, F will be likewiſe the upper, and H the lower Part of the Image. Laftly, it is evident, that in both Figures bf and HF, i. e. the Object and its Image, are one to the other, as their Diſtances from the Vertex BC and BE; viz. in Fig. 19, BC: BE::1:3:: bf: HF. And in Fig. 21. BC: BE 2:: bj: HF. (H 3) ::1: 3. It 312 The Young Gentleman's 2. It is evident from comparing toge- ther Fig. 19 and 22, that if the Reflec- ter be convex, and fo HF the Object, and hf its Image, then likewife the Image will appear in its due Pofition; and alfo as the Obje& is brought nearer to the Refle&er, fo will the Image come nearer. But in this a convex Reflecter differs from a concave, viz. that (whereas in a con- cave, the nearer the Object hf is to the Vertex B, the lefs will the Image HF ap- pear, as is evident from comparing, as has been faid, Fig. 19 and 21, on the contrary) in a convex, the nearer the Ob- ject HF is to B the Vertex, the greater will the Image hf appear, as is evident from comparing Fig. 19 and 22. It is al- fo remarkable, that be the Obje& HF re- moved never fo far diftant from the re- flecting Convex beyond the half Semidia- meter, yet its Image will fix it felf at the half Semidiameter. 3 If the Refle&er be a Concave, and the O ject HF be more diftant from it than the length of the Semidiameter AB, (as Fig 20 and 23) then the Image hf will be more diftant from it than the half Semi- diameter,and yet lefs than the whole Semi- diameter, that is, it will appear in the Air between the Object and the Reflecter; and alſo it will appear in an inverted Poſition, that is, the Point F and its Image f will ap pear Opticks. 119 Pear on contrary Sides of AB the Axis, as will the Point H and its Image h; (and fo of any other Point of the Object, and its Image,) whence it F be the upper or right Hand Part of the Objc&, f will be the lower or left hand Part of the Image, &c. Likewiſe it is evident from compa- ring Fig. 20 and 23, that in this Cafe, as the Obj.& HF is remov'd farther from the Reflecter, fo its Image bf will come nearer and appear lefs; and on the con- trary, as the Object comes nearer, the Image will go off farther, (and appear bigger) 'till they meet one the other at the Center A. In like Manner if fb be the Obj&, then HF will be the Image; the Affctions whereof are eafie to be ac- counted for from what has been faid. It is alſo obfervable that if the Object HF be remov'd fo far from the Reflecter, as that the Rays of it falling near the Vertex B of the Reflecter, may be efteen,'d pa- rallel to AB, then (according to the for- mer Part of Theorem II, of this Chapter) the Image bf will appear at the Mid point of the Semidiameter of the Reflecter. And if the Sun be the faid far diſtant Object, then the Place of the Image (or Mid-point of the Semidiameter) will be the burning-point of the Reflecter, if it be confiderably larger than the Image of the Sun. But if a lucid Body, as a Candle, (H 4) be 126 The Young Gentleman's be plac'd in the faid Mid-point of the Semidiameter, it will caft a Light to a great Diſtance. Diſtance. Add as in this Cafe, no- thing but Light will appear on the Sur- face of the Reflecter; fo when other Ob- jects are placed at the half Semidiameter, nothing but their Colour will appear on the Surface of the concave Reflecter. 4. It is obfervable, that fuppofing the Object to ſtand ſtill, and the Eye to change its Place, the fame Alterations will be produc'd in refpect to the Image, as if the Object had chang'd its Place in a cor- reſpondent Manner. 5. It is evident from Fig. 19-23, that a reflecting Concave magnifies, that a reflecting Convex leffens an Object. Namely, if in the faid Figures BDG be confider'd as a Concave, then hf will be the Object and HF the Image, which is in all the faid Figures much larger than hf the Object. But if DBG be confider'd as a Convex, then HF will be the Ob ject, and hf the Image, which is in all the ſaid Figures much leſs than HF. 6 It is obfervable, that cylindrical Re- flecters, whether concave or convex, muſt render the Image deform'd. For a Cy- Jinder being generated by the Motion of a right Line round two parallel Circles, hence fuch a Reflecter muſt partake, part- of the Properties of a plain Reflecter, partly Opticks. partly of a ſpherical. Of that, in re- fpect of its right Lines, in Longitude; of this, in reſpect of its circular Lines, Round-ways. Hence the Longitude or Height of an Object being repreſented justly, as by a reflecting plain Surface; but its Latitude magnify'd or diminiſhed, ac- cording as the Reflecter is a Concave, or Convex; the Image appears difproporti- onable. But on the fame Account, if a Picture be drawn proportionably bigger in breadth than in Length, its Image will be reprefented by a reflecting Cylinder in its jult Dimenſions. Which is illuſtrated Fig 24, 25, 26. Namely, in Fig. 24, is drawn the Picture in its juft Dimenfi- ons, and divided into Parallelograms. In Fig. 25 are drawn as many circular Lines, as there are (in Fig. 24) horizon- tal Lines parallel one to the other, viz, 7; all the faid circular Lines being con- centrical to the circular Bafis of the Cy- linder C; and diftinguifh'd proportiona- bly by right Lines drawn a-crofs them in- to as many Divifions, as the Ficture (Fig. 24) is divided into Parallelograms: So much of the Picture, as is contain❜d in each Parallelogram being to be drawn in each of the foremention'd Divifions anfwering thereunto. Which being done, and the reflecting Cylinder being plac'd on C, the Image of the Picture will appear in the faid $22 The Young Gentleman's faid Cylinder according to its juft Dimen- fions, but less than the Picture, if the re- flecting Cylinder be convex ; which is ge- nerally us'd in this Cafe, and is reprefent- ed Fig. 26. ter. Laftly, It remains only to obferve, that by the foregoing Theorems may be found fuch a Pofition of the Radiant, as that the faid Radiant may have a given Pro- portion to its Image made by the Reflec For Inftance, let BD (Fig. 27) be the Refle&er, and the given Proportion be that of BA to AM. If the Obje& be a Line, bifect BM in E, and by Theorem III, of this Chapter find the Focus Can- fwering to the Focus E, which C will be the Place of the Radiant. For becauſe BC: CA :: BE: EA; therefore BC: BC+CA :: BE: BE+EA; that is (be. caufe BE=EM) BC: BA:: BE : AM and therefore BC: BE:: BA: AM. But by the Corollary of this Theorem V, BC is to BE, as the radiant Line in C is to its Image in E therefore the Radiant Line in C, is to its Image made by BD in E, as BA to AM, i. e. in the Proportion gi- ven. If the Radiant be a Surface, then inſtead of AM, a right Line muſt be taken, to which BA has a fubdulicate Ratio of that which it has to AM. And this is fufficient to our Defign, concerning Ca- toptricks or reflex Vifion. ; ; CHAP. Opticks. 123T > 1 CHA P. IV. of Dioptricks, or Refracted Viſion. THEOREM I. Fa Ray AB of Light be refracted by Fig. 28, the plain Surface BD of a Medium of 29. different Thickneſs, the right Sine of ABK the Angle of Incidence will, in reſpect of the fame different Mediums, always have the fame (Ratio or) Proportion to the right Sine of GBF the Angle of Refrac- tion, however the Ray AB be inclin❜d to the Surface BD. Demonft. Let BG be the Refract of the Ray AB, whether AB paffes out of a thinner Medium into a thicker, (as Fig. 28) or out of a thicker into a thinner, (as Fig. 29.) Now as the Light proceed- ing from A, and contain'd between AB and AD, will be diffus'd within the Me- dium DK all over BD; fo after it has en- ter'd the new Medium DG, it will at the Length of BG diffuſe it ſelf all over GN: Whereas had the fame Medium DK been con- 72 4 The Young Gentleman's continued on each Side of BD, the Light at the Length of BC (=BG) would have been diffus'd all over CE. But in both Ca- fes (namely, whether the Medium DG be different from or the fame with the Me- dium DK) FN=ME, and conſequently both the faid Lines may be look'd upon, as not at all depending on the (*) Facili- ties of the Medium's, and fo of no Confi- deration in the prefent Cafe. Wherefore GF (i. e. GN-FN) and CM (i. e. CE -ME) are to be look'd on, as the genu- ine Effects of the Facilities of the two Me diums DG and (DC, or which is the fame) DK; that is, GF is to CM, as the Facility of the Medium DG is to the Fa- cility of the Medium DC or DK. But CM is the right Sine of the Angle (CBM) ABK, which is the Angle of Incidence of the Ray AB; and according to the fame Semidiameter, GF is the right Sine of GBF the Angle of Refracti- on of the fame Ray AB. Wherefore fince the Angle DAB (=ABK) is taken at pleaſure, the like will hold good of a- ny other Angle ; that is, in the Refrac- tion of any Ray AB, let it fall how it will on the Plain whereby it is refracted, the Sine of the Angle of Incidence is to (*) This Word is us'd to denote the feveral Virtues, which different Mediums have to diffuſe the Light. the Opticks. 125 the fine of the Angle of Refraction, as the Facility of the Medium DK is to the Facility of the Medium DG, whereby the Ray AB is refracted into BG. But in respect of the fame Mediums. the Thick- neffes of the Mediums, and the Facilities thence arifing, and their Ratio will abide the fame. Wherefore in the Refraction of any Ray, the Sine of the Angle of In- cidence always keeps, with refpect to the fame Mediums, the fame Ratio or Pro- portion to the Sine of the Angle of Re- fraction. Q. E. D. Corol. 1. If BG be the refracted Ray of the Incident AB, the reft remaining the fame, BA will be the refracted Ray of the Incident GB. Cor. 2. The refracted Ray BG of any Incident AB is rightly affign'd, when the Sine CM (of the Angle CBM) ABK the Angle of Incidence, is to the Sine GF of the Angle GBF contain'd under the af- fign'd Ray BG, and the right Line BM perpendicular to the refracting Surface BD, as the Facilities of the given Medi- ums are one to the other. Namely, this Corollary is no other than the Converſe of this first Theorem. Schol. 1. In a Ray's paffing out of a thicker Medium into a thinner (as Fig. if it be fo inclin'd to the refracting Sur- face, that GF (which is to CM, as the Faci- 126 The Young Gentleman's Facilities of the given Mediums) does ex ceed the Semidiameter BC; then the in- cident Ray AB will have no refracted Ray, (after the Manner of an impoffible Cafe in a geometrical Problem ;) that which ought to be the refracted Ray not entring the thinner Medium DG, but be- ing reflected by its Surface, according to Theorem I. of Catoptricks. And this Caſe is illuftrated Fig. 30. Schol. 2. When a Ray of Light paffes out of the Air into Glaſs, it is obferv'd that the Sine of the Angle of Incidence is to the Sine of the Angle of Refraction, as 3 to 2 in whole Numbers; and in paf- fing from the Air into Water, I is to R, (by which Symbols henceforward is de- noted the Ratio of the Sine of the Angle of Incidence to the Sine of the refracted An- gle, which meaſures the Refraction) as 4 to 3. And on the other hand, in the paffing of the Ray out of Glafs into Air, I will be to R as 2 to 3 ; and in its paffing out of Water into the Air, I will be to R as 3 to 4. Whence the Reason is manifeft, why a Ray paffing out of Glafs, and falling on the Surface of the Air fo, as to make the Angle of Incidence more than about 42 Degrees, will not enter into the Air, but is reflected by its Surface. Namely, be- cauſe 2 : 3 :: 42: 63; that is, the Ra- tio fefquialtera (as it is called) of 42 is 633 Opticks. 127 63; and confequently the right Line GF, which is to denote the faid Ratio of the Sine of 42 Degrees muft exceed the Ray, this being the Sine only of 60 Degrees. In which Cafe the Ray is reflected accord- ing to Schol. I. Schol. 3. It is demonftrable that if Rays diverging (Fig. 30 and 31) from E, and refracted by the Surface BD, do diverge from C, the Mediums being tranf- pos'd, but the fame intermediate Surface BD remaining, the Rays converging to E, will after Refraction converge to C. Wherefore what fhall be demonftrated in the following Theorems concerning di- verging Rays, may alfo be apply'd to converging Rays. THEOREM II If an Object E be feen through diffe- Fig. 30, rent Mediums BDA and BDO, the Image & 31. of the faid Object will appear, at that Place C in the right Line EB (perpendi cular to the plain Surface BD of the re- fracting Medium, whether thicker or thinner) where CB : EB :: I: R, that is, where the Diſtance of the Image from the plain Surface of the refracting Medium is to the Diſtance of the Obje& from the faid Surface, as the Sine of the Angle of Inci- 128 The Young Gentleman's M Incidence is to the Sine of the Angle of Refraction. Demonft. Let ED be any Ray of the Object E falling upon the Surface BD. Thro' D draw AO parallel to EB. Join C and D, and produce CD to F. Thoſe Rays only being here (as well as in the foregoing Chapter) confider'd, that fall near EB the Axis of Radiation, and wherein the Eye is fuppos'd to be plac'd, it follows (for the Reafons mention'd in the foregoing Chapter) that we may look on ED=EB, and CD=CB. Where- fore CD: ED::1: R. I: But CD is to ED, as the Sine of the Angle BED or its Equal EDA, to the Sine of the Angle BCD or its Equal ODF. Therefore the Sine of the Angle EDA is to the Sine of the Angle ODF, as I to R. But EDA is Í the Angle of Incidence of the Ray ED, therefore ODF is the refracted Angle an- fwering thereto; that is, DF is the re- fracted Ray of the incident Rav ED. And the ſame may be fhewn of any other Ray diverging from E. Wherefore C will be the Focus of all Rays diverging from E and refracted by ED. that is, the Image of the Object E will appear after Refraction at C. Q. E. D. Cerol. Opticks. 129 A S Theo Corol. 1. Hence and from Cor. I, rem I, of this Chapter it follows that (cæteris paribus) Rays in the Medium BDO converging to C, will after Refrac- tion' converge to E. And if the Medi- ums be tranfpos'd, then from hence and Schol. 3, Theorem I, of this Chapter it fol- lows, that Rays in the Medium BDO converging to E, will, after Refraction, converge to C; and that parallel Rays will, after Refraction at the plain Sur- face of any Medium, ftill continue rallel. pa- Corol. 2. If BDA be Water, and BDO Air, then CB : EB :: 3 : 4. Whence it comes to pafs, that Water appears not to be fo deep, as it really is, by a fourth Part: But if BDA be Glafs, then CB : EB.:: 2 : 3. Schol. From this Theorem is deduced the Method of finding the Focus C of Rays refracted by a plain Surface, viz. by drawing EB perpendicular to the re- fracting Surface DD, and therein taking C fo, as that CB :: EB :: I: R. THEOREM III. If the Surface BD of the Medium of Fig. 32, different Thickness be fpherical, and the 33. Object E be very far diftant, then its I- mage will, to the Eye plac'd in AB the (D) Axis 130 The Young Gentleman's $1 Fig. 34, 35, 36, 37. Axis of Radiation, and parallel to the incident Rays, (as ED,) appear in that Place C of the Axis AB produced as there is Occafion, where BC: CA::I: R. But if the Object E be not very far di- ftant, then its Image will, to the Eye placed in AB produced if there be Occafi on, appear in that Place C of AB, where the Ratio compounded of the Ratio's of EA to AC and of CB to BE is equal to the Ratio of I to R. (*) Demonft. The first Part of this Theo- rem (as it relates to Objects at ſo great diftance from the refracting Surface BD, as that the Rays proceeding from each fingle Point therein, may, confider'd by them- felves, be eſteem'd parallel one to the o- ther, fo it) is thus demonftrated. Let ED denote any Ray falling on BD, and draw AD and CD, and produce them. The Sine of the Angle BAD or its Equal EDO is to the Sine of the Angle CDA (or its Complement to two Right) as CD to AC, or (by reafon of the Smalnefs of the Arch BD) as CB to AC, that is, by (*) I have comprehended all here relating to refracting fpherical Surtaces under this one Theoreni for the like Reafon, as I comprehended all relating to reflecting fphe- rical Surfaces under one Theorem; and alſo that the Har- mony between reflected and refracted Viſion may the bet ter appear. Con- Opticks. 131 Conftruction, as I to R. But EDO is the Angle of Incidence of the Ray ED, there- fore DC is its refracted Ray. In like manner may it be fhewn, that any o- ther of the parallel Rays proceeding from (any Point of) the Object E after Refraction will pass through C. There- fore C will be the Focus of all fuch Rays, or which is the fame, at C will appear in this Cafe the Image of an Object very far diftant. Q. E. D. The latter Part of this Theorem is thus demonſtrated. Let ED be the incident Ray; draw AD and DC, and through C draw CH parallel to AD, and meeting ED in H. By reafon of the ſuppos'd Smalness of the Arch BD, we may look on CD CB, and ED EB. Wherefore CD=CB, ED—EB. the Ratio of I to R is equal to the (Ratio of EA to AC and the Ratio of CD and ED together; that is, by reafon of AD being parallel to CH, is equal to the Ra- tio of CD to ED and the Ratio of ED to DH together, or which is the fame, to the) Ratio of CD to DH. But CD is to DH, as the Sine of the Angle (DHC, or its Complement to two right,viz.ADH=) EDO is to the Sine of the Angle (DCH =) ADC, or in fome Cafes to the Sine of the Complement of ADC to two Right. Wherefore EDO being the Angle of In- cidence of the Ray ED, it follows that I (1 2) is 132 The Young Gentleman's Fig. 32. is to R, as the Sine of the Angle of In- cidence of ED to the Sine of the Angle ADC. Wherefore (by Theorem I, of this Chapter) DC is the refracted Ray of the incident Ray ED. And ED being taken at pleaſure, it is evident that C will be the Focus of all Rays proceeding from E after their aforefaid Refraction ; and 'confequently at C will appear the Image in fuch Cafes. Q. E, D. · 瑞 ​From the first Part of this Theorem and the Corollary of Theorem I, arife fe- veral Corollaries; among which we fhall here take notice of theſe following, viz. Corol. 1. Rays ED in the Air parallel to AB the Axis, after their Refraction at the ſpherical convex Surface DB of Glafs, do converge to that Point, C, whofe Di- ftance BC from the Vertex. B is equal to 3AB, three Semidiameters of the Sphere. Corol. 2. Rays ED in Glafs parallel to the Axis, after their Refraction at the ſpherical convex Surface of the Air, do diverge from C that Point, whofe Di- ftance BC from the Vertex, is equal to (3AB or) the Diameter of the Sphere: as Fig. 33. … Corol. 3. Rays eD in the Air parallel to the Axis, after Refraction at DB the concave Surface of the Glafs, do di- verge from C a Point three Semidia- meters Opticks. 133 meters 3 AB diſtant from the Vertex as Fig. 32. Corol. 4. Rays eD in Glafs parallel to the Axis, after Refraction at a ſpherical concave Surface of Air, do converge to Ca Point diftant from the Vertex B the Diameter of the Sphere (*): that is, BC= 2AB, as Fig. 33. Corol. 5. In all the four Cafes, which are the Converſe of thoſe mention'd in theſe four Corollaries, the Rays after Re- fraction will become parallel to (the Ax- is, i, e. to) a right Line drawn through the radiant Point and the Center of the Sphere. As to the latter Part of this Theorem, there are eight principal Cafes relating thereto, which may all be demonftrated after the fame Manner, as thofe four of them, which are here mention'd, as be- ing fufficient to our Purpofe; and are ex- prefs'd by Fig. 34, 35, 36, 37. Of which Fig. 34 and 35 relate to Rays pro- ceeding out of a thinner into a thicker Medium, the other two, Fig. 36 and 37, to Rays proceeding out of a thicker Me- dium into a thinner. And in both Cafes the former Figure relates to concave Re- fringents, the latter to convex. And in Fig. 36, is reprefented the Cafe, wherein the incident Ray ED is not refracted, but reflected into DC, according to what (13) was 134 The Young Gentleman's I was obferv'd above, in Schol. 1 and 2 of Theorem I, of this Chapter, Schol. 1. From the former Part of this Theorem is deducible the Way, how to find the Focus of parallel Rays falling on ſpherical Glaffes, viz. by taking C in AB fo,as that BC: CA::I: R. And from the latter Part of this Theorem is dedu- ced the Way, how to find the Focus of diverging Rays falling upon a fpherical Glafs, viz. by taking C in AB fo, as that the Ratio compounded of the Ratio's of EA to AC, and CB to BE may be equal to the Ratio of I to R. Schol. 2. If the Mediums propos'd be Air and Glaſs,and the Ray falls out of the Air upon the Glafs (as Fig.34 and 35) then the Focus C may be very eafily found, namely, by making EA : AB; : EC: BC. For by tripling the Antecedents, EA; (AB=) AD : ; 3EC: (BC=) DC. But EA is to AD as the Sine of the Angle EDO is to the Sine of the Angle DEA; and 3EC is to DC, as the Triple of the Sine of the Angle EDC or HDC is to the Sine of the Angle DEA. Wherefore the Sine of the Angle EDO is the Triple of the Sine of the Angle HDC, and confe- quently is to the Sine of the Angle ADC, as 3 to 2. Therefore DC, or De lying in the fame direct Pofition, is the Refract of the Ray ED falling out of the Air upon Glafs. When * Opticks. 135 When the Ray paffes from Glaſs into the Air (as Fig. 36 and 37.) then the Focus may be found, according to the fame Principles, by taking C fo, as that EA: AB:: EC: BC. Schol. 3. By what has been faid un- Fig. 36. der the foregoing Theorems, there being given one Focus of a given Lens, the other may be found. Where it is to be noted, that by a Lens is denoted a (dia- phanous or) tranfparent Body (fuch as Spectacles, Burning-glaffes, &c.) of a different Thickneſs from the ambient Tranſparent, terminated by two Surfaces, which are either both ſpherical, or the one plain and the other ſpherical. A right Line perpendicular to both its Sur- faces, is call'd the Axis of the Lens. The Points, where the Axis interfects the Sur- faces, are call'd the Vertex's; one the Vertex of Incidence or Immerſion, the o- ther of Emersion, accordingly as it is in that Surface, on which the Rays first fall, or through which they pafs out again. The Thickness of the Lens, is the Diſtance between its Vertex's. To which add, that where more than one Lens is us'd, that which is next to the Object, is thence call'd the Object-Lens; and that which is next to the Eye, is thence diftinguiſh'd by the Name of the Eye-Lens. (I 4) Now 136 The Young Gentleman's Fig. 38. Now if the Focus before Incidence or Immerfion be given, and the Focus after Immersion be fought; let there be found first the Focus of the Rays after their Re- fraction at that Surface of the Lens, on Fig. 38. which they first fall; and this is done by Theorem II, if the Surface of the Lens be plain; but if it be fpherical by Theo- rem III, namely, by the former Part of it, if the Rays are parallel; and by the latter Part, if diverging or (*) converg- ing. Having thus found the Focus of the Rays after Refraction at the firft Surface of the Lens, (that is, while they pafs through the Lens, whence the faid Fo- cus is call'd the Focus of Tranfition) in like Manner may be found their Focus after Refraction at the ſecond Surface of the Lens, or rather at that Surface of the ambient Medium, which is contigu- ous to this fecond Surface; that is, the Focus after Emerfion. If there be more than one Lens pro- pos'd after the like Manner is the O- peration to be carried on in refpect to each. (*) Namely, according to what has been obferv'd of Converging Rays in Schol 3. of Theorem I. of this Chap per. } In Opticks. 137 In like Manner, there being given the Focus of one given Lens or more, there- by may be found the Focus before Inci- dence, that is, the optical Inftrument being given, thereby may be determin'd the Diſtance of the viſible Object. THEOREM IV. The Image CT of a radiant plain Sur- Fig. 39. face EF, made by a refracting Surface · BD, whether plain or fpherical, will be alſo a plain Surface. Demonft. Let A be the Center of BD the refracting Surface, and AE be perpen- dicular to EF, meeting with BD in B. Let C be the Focus of the Rays diverging from E and refracted by BD. From F, any Point taken at Pleaſure in the radi- ant Plain draw, FA meeting with BD in D, and the Plain CT in T. The Ray DC will be the Refract of ED; and let BH be the Refract of FB. Becauſe the Angle EAF is fuppos'd to be ſmall, there- fore the Arch BD may be look'd on as a ſhort right Line; and a Circle drawn with the Diameter BF will pals through the Points D and E, becauſe of the right Angles BEF and BDF. Whence the An- gles EBF and EDF, (viz. the Angles of Incidence of the Rays FB and ED) being in the fame Segment, are equal; and con- fequently 138 The Young Gentleman's ſequently their refracted Angles ABH and ADC will be equal. Therefore by rea- fon of the equal Angles at A, the Trian- gles BAH and DAC are equiangular, and BA is to AH as DA to AC; and, where- as BA DA, therefore AH-AC. But becauſe the Angle EAF or TAC is very fmall, therefore (in a manner) AT=AC; and therefore AH may be look'd on as e- qual to AC, that is, the Focus of the ra- diant Point F, is placed as near as may be in the Plane CT. And the Point F being taken at pleaſure, it holds good al- fo in all other Points of the Plane EF, that their Focus's, are in the Plane CT; that is, that the Image of the radiant Plane EF will in this Cafe be alſo a plain Surface. Q. E. D. Corol. 1. Hence it follows, that the I- mage of the radiant Plane EF, whereto the Axis of the Lens is perpendicular, will alſo be a Plane parallel to the for- mer. For the Image CT is to be con- ceived as the plain Surface, which fends forth Rays upon the fecond Surface of the Lens. Corol. 2. If the Angle EAF be too great, fo that AT is fo much longer than AC, as not to be capable of being e- fteem'd equal thereto, then the Image of the Plane EF will be concave towards A, if BD be the convex refracting Surface of a thick- Opticks. 139 } a thicker Medium, or the concave refrac- ting Surface of a thinner Medium; and on the contrary. THEOREM V. The Angle fGb, under which the Image Fig. 38. fCh appears from G the Vertex of Emerfi- on, in a Lens, is equal to the Angle FBH under which the Object appears from B the Vertex of Incidence in a Lens. Demonft. Let GB be the Axis of the Lens, and perpendicular to the vifible Plane or Object FEH at E, and confe- quently (by Corol: 1, Theorem IV,) per- pendicular to its Image fCh. Draw BF, BH, Gf, and Gh. Of the innumerable Rays flowing from the Point F, and af- ter Refraction at the Lens again united at f the Image of the Point F, let two be chofen, whereof one FB meets the Lens at Bits Vertex of Incidence, and being there refracted tends to p the Fo- cus of Tranſition in reſpect of F; and be- ing again refracted at L tends towards f The other Ray FD being first refracted at D, tends directly to p, 'till paffing out of the Lens at G the Vertex of Emerfion, it is there refracted again, and thence pro- ceeds directly to f. The Angle of Inci- dence of the Ray DG is DGB, and its Refract is CGf; and the Angle of Inci- dence 149 The Young Gentleman's dence of the Ray LB, which would (by the Corollary of Theorem I,) be refracted into BF, is the Angle LBG, and its Re- fract EBF. Now becaufe the right Lines PB and pG are to be efteem'd equal, (by reafon that the Thickneſs of the Lens is not to be confider'd,) therefore the Sines of the Angles DBG and LBG being pro- portional to the faid Lines pB and pG, and confequently the Angles themfelves DGB and LBG, and therefore their re- fracted Angles CGf and EBF will be e- qual. In like manner it may be prov'd, that the Angles CGh and EBH are equal. Therefore the Angles FBH and fGh are equal. (And the like may be fhewn in any other Cafe.) Q. E. D, Corol. Hence it follows, that a radiant Line is to its Image made by a Lens, as the Diſtance of That from the Vertex of Incidence is to the Diſtance of This from the Vertex of Emerfion, or (the Thick- nefs of the Lens being not regarded) as their Diſtances from the Lens. But if the Radiant be a Surface (the homologous Lines will keep in the fame Ratio, but) the faid Surface will be to its Image (in the ſaid Ratio duplicated, or) as the Squares of their Diſtances from the Lens. Hence may be determin'd the Ratio, which the laſt Image, (i. e. that which is immedi- ately feen by the Eye) made by the Means of Opticks. 141 of one Lens or more, has to the viſible Object, whoſe Image it is. Schol. From what has been faid, may be accounted for and illuſtrated the Affec- tions of (or feveral Particulars relating to) refracting Surfaces, whether plain or fpherical. Among which Affections the more remarkable are thefe that fol- low, viz. 1. If the prime Radiant or Object be Fig. 40. far diftant, and the Surface PCQ of the Lens be plain, the Surface PDQ be of Glaſs and convex, and the ambient Bo- dy be the Air, then (by Corol. 4, Theorem III) Db will be equal to the Diameter of the Sphere PDQ; (for by Axiom 1, the Rays parallel to BC pafs through the plain Surface PCQ, whereon they fall perpendicularly, without being refrac- ted :) and confequently by Theorem IV and V, fbe will be the Image of the far diftant Objec, from which proceed the Rays FBE; and therefore the ſaid Image will appear in an inverted Situation with refpect to its Object: Namely, the Point F of the Object, and the correfpondent Point f of the Image, will be on different Sides of Bp the Axis; and fo of the o- ther Points B and b, E and e. And therefore, if F be the lower Part of the Object, f will be the upper Part of the Image; and fo as to the reft agreeably. 2. But 142 The Young Gentleman's Fig. 41. Fig. 42. Fig: 43. of Burn- ing-glaf 1es. 2. But if the Surface PCQ be convex, and PDQ plain, then (by Corol. 1, Theo- rem II, and Corol. 1, Theorem III of Diop- tricks) Cb will be equal to the Diameter of the Sphere PCQ,`and a third Part of the Thickness of the Lens over. Or neg- lecting the Thickneſs of the Lens, (as is ufual in the Object Lens of a Telef cope,) in this as well as the former Cafe, and confequently in general of any plain convex Lens, it may be faid, that the I- mage of an Object far diftant, made by fuch a Lens, will be equal to the Diame- ter of the Sphere. 3. If the Lens PQ be of Glafs, and e- qually convex on both Sides, then (by Corol. 1. Theorem III, and Theorem IV of Dioptricks) Db will be equal to the Se- midiameter of either Sphere. Laftly, in a whole Glafs Sphere, the Image of an Object far diftant will appear at the Di- ftance of half the Semidiameter from the Sphere: For in this Cafe Regard muſt be had to the Thickneſs of the Lens. 4. In all theſe or the like Cafes, if the Sun be the far diftant Radiant or Obje&, and the Lens be confiderably larger than the Sun's Image, in the Place of the I- mage will be the Burning point: And a- ny fuch convex Lens will burn ftronger than a concave Reflecter (cæteris pari- bus) 1 Opticks. 143 bus) by reaſon more Rays are loft by the latter than by the former. with Con- 5. If in the foremention'd Place of the of Dark- Image there be placed a lucid Body it felf; Lanterns then the Image of the faid Body will ap- vex Glaf pear at a great Distance ; that is, the ſe:.' faid lucid or fhining Body will caft a Light at a great Diſtance, fo as that Things fo far diftant may be clearly ſeen by the faid Light. And this is the Manner, whereby a Candle, put into a Dark Lan- tern with a convex Chryftal, gives a Light at fo great a Diſtance as ufual as 6. If the Radiant or Object be not afore) far diftant, but yet is more diftant from the Lens than is the Place where would appear the Image of a far diftant Object; befides the Affection aforemen- tion'd, (viz. that the Image will appear inverted) there will be in this. Cafe alſo theſe other Affections. Namely, as the Radiant comes to the Lens, the Image will go from it, and contrariwiſe 'till the Radiant being come into the Place, where would appear the Image of a far diſtant Radiant, its own Image becomes far diftant. All which Affections may be obferv'd in a Dark-Chamber, into which Objects at feveral Diſtances fend their Rays through a convex Lens or Glafs. The Place of the Image of each Radiant Object may be diftinctly known, by ob- ferving 144 The Young Gentleman's Of a Ma- tern. ferving where the Image of the faid Object does appear moſt diftinctly on a Sheet of White Paper or the like. 7. And on theſe fame Principles de- gick Lan pend the Mechanifm of (what is call'd) a Magick-Lantern; namely, whereby the Images of little Pictures are repreſent- eds on a white Wall or the like. Fig. 44, & 45. ..8. If the Radiant be nearer to a con- vex Lens, than the Place where would appear the Image of a far diftant Radi- ant or Object, then its Image will appear on the fame Side of the Lens with the Object it felf; and its Place may be de- termin'd from the given Place of the Ra- diant, as afore. The Image in this Cafe will always appear in the like Situation with the Object, and greater than it; and if the Object comes to the Lens, the I- mage will alfo; if that goes from the Lens, this will alfo; only the Image will in both Cafes move quicker. 9. If the Lens be concave, then (by the refpective Corollaries of Theorem III of Dioptricks) the Image ebf made by a plain concave Lens, PQ, will be diftant the Diameter of the Sphere PDQ, and will be erect or in the like Pofition with the Object, and on the fame Side with the Object reckoning from the Vertex D. If the Surface PCQ be alfo concave, and the Object not far diftant, its Image may Opticks. 145 may be determin'd after the like Method, by finding (according to Theorem IV of Dioptricks) the Image of that Point of the Object which is fituated in the Axis of the Lens. In refpect to which Image, befides what has been already faid, it is to be obſerv'd, that it will together with the Object come to or from the Lens, but flower. 10. Further, it is here obfervable, that of Telef on the foremention'd Theorems depends copes, Mi- croſcopes, the Mechaniſm or Contrivance of the fe- and Spec- veral optick Inftruments, made ufe of to tacles. help the Eye, or to fupply the ſeveral Defects of our Sight. For, as the Eye is a natural Organ or Inftrument, defign'd to this End, namely, that on the Bottom thereof may be painted the diftant Ima- ges of cutward Objects; ſo it is manifeft that one and the fame Eye can fee diftinct- ly only at a certain Diſtance from the vi- fible Object. Could the Eye always place it felf at fuch a Distance from the Object, as is neceffary to diftinct Vilion, then (fuppofing the other Requifites to Sight to be given, fuch as a due Degree of Light, &c.) the Eye might always fee diftinct- ly. 'Tis true indeed that the Diſtance re- quifite to diftin&t Viſion is not rigidly de- termin'd to one fingle Point, but admits of fome Latitude; forafinuch as the fame Eye can fo alter its Figure according to (K) the 146 The Young Gentleman's the various Diſtance given, that it may be look'd on not as one Eye but ſeveral., But then, fince this Latitude of Distance is contain'd within certain Bounds, be- yond which the Eye can by no natural Means fee diftinctly, hence arifes the Need of artificial Inftruments. And any Lens, or ſpherical reflecting Glafs, is fuffi- cient to remedy this; forafmuch as there- by the Image of fuch an Object, as we can't come to as we would, may (by Help of the Theorems above demonftra- ted) be brought near us, fo as that we may have a diſtinct View thereof. of this Kind are thoſe fingle Glaffes, us'd by fuch as can't fee well at a common Diſtance, and apply'd by them to one of their Eyes, when they would difcern the Face or Picture of a Perfon (or the like) that is farther diftant from them than they can diftinctly fee with the bare Eye. As the Word Telefcope does in the Greek Tongue denote an Inftrument which helps us to fee far off, fo thefe Gingle Glaffes may be call'd fingle Teleſcopes, to diftin- guish them from fuch Teleſcopes as are made of two or more Glaffes. And 11. But becauſe (befide diftin& Vifi- on) it is often requifite in humane Affairs, that the more minute Parts of an Object fhould be diſcern'd; and becauſe it is found by Experience, that an Object which Opticks. 147 • { } f } < 3 { which appears under a lefs Angle than of one Minute, appears but as a Point, or fo as that its Parts can't be diftinguiſh'd one from the other: Hence it often comes to pass, that the Obje&t being brought fo near to the Eye, as that its Particles to be examin'd may be feen under a fenfible Angle, thereby the Object it felf becomes too near to the Eye, fo as not to be with- in the Bounds requifite to diftinct Viſion. This Inconveniency, when alone, may al- fo be remedied by any given Lens or re- flecting Glaſs; forafmuch as the Image of the faid Object (*) may by the faid Lens or Glaſs be reprefented (in any gi- ven Meaſure, i. e.) fo as to have any gi- ven Ratio or Proportion to its Object. (*) How this may be done in refpect of a reflecting Glafs, is fhewn above in Schol 7, to Theorem V, or laft of Catoptricks. How the fame may be done in refpect of a Lens or retracting Glafs, fhall be here fhetvn. Let a Glafs Lens be given (Fig. 45) the Semidiameter of whofe fore- Fig. 46. moft Surface is AB, the Semidiameter of the hindermoft Surface CB. Draw CM as you pleafe, and let the Ratio affign'd be fuch as ought to be between the homologous Lines of the Radiant and its Image, and be denoted by the Ratio of MD to DC. Draw AM, whereto through B draw the Parallel BE, meeting CM in E; ME doubled will be the fought Diſtance of the Radiant from the Lens. And after the fame Manner may be found, in refpect of any given Lens, the Pofition, or Place where any Radiant is to be put, that (its Image made by the Lens may be equal to a given Figure, which is fimilar or like to the Radiant, i.. in fhort, that) the Radiant may have a given Ratio (to its Image made by the Lens. (K 2) And 1 148 The Young Gentleman's Fig. 46. And of this Kind are thofe fingle Glaffes us'd to ſee the Shape or Parts of ſmall Infects, and the like, and thence call'd Microſcopes, the Word importing in the Greek Language an Inftrument, where- by we fee Small Things. To theſe may be referr❜d Spectacles, of which more by and by. But if both the foremention'd Inconve- niencies concur, then they are not to be remov'd but by the joynt Help, either of a Lens and Reflecter together, or elſe of more than one Lens, or laftly of more than one Reflecter. And how Inftru- ments confifting of two or more of thefe are made, fhall be next illuftrated. 13. Let R denote the Object given, S the given Angle under which the Object is to be reprefented, D the given Di- ftance of the Sight, and L the given Di- ftance of the Eye from the Lens. Make the Triangle AOB, fo as that the vertical Angle at O may be equal to the given Angle S, and OE the Perpendicular from the Vertex to the Bafis may be equal to the given Line D. If you'd have the middle Point of the Object be in the Axis of the Lens or Reflecter, (which is moft convenient for Practice) the Trian- angle AOB must be made an Ifofceles. Take OV L, and at V place a Lens or Re- Opticks. 149 J 5 Reflecter fo, as that its Axis may fall in with OE. A Then having E thus given for one Fo- cus of the Lens or Reflecter, by the re- ſpective Theorem III of Catoptricks or Dioptricks or their Scholium, find the o- ther Focus e; namely, that fo taking e for the Focus before Incidence, E may be the Focus after Inflection at the Lens or Re- flecter. Through e draw aeb parallel to AEB, meeting with Va and Vb (drawn through V, and parallel to VA and VB) in a and b. It follows from Theorem V, of Catop- tricks or Dioptricks (refpectively, as you calculate for a reflecting or refracting Glaſs,) that if aeb be the Radiant, AEB will be its Image. Wherefore if the Ob- ject given R, (which is here fuppos'd to be near at hand) and a fecond Lens or Reflecter be ſo plac'd, according to Schol. 7, Theorem V of Catoptricks, or accord- ing to the Note before added to Schol. II of this Theorem V of Dioptricks,) that the Image of the Object made by this fecond Lens or Reflecter, may appear just in the Place, Situation, and Bignefs of aeb there will be thus made fuch a Microf- cope as is requir'd. For aeb will be the Image of the given Object R, the Image of which Image, and that feen by the Eye, will be AEB. And this will appear (K 3) ذ under 150 The Young Gentleman's under the Angle AOB equal to the given Angle S; and in the Diſtance OE equal to the given Distance D, and confequent- ly will appear diftinct; and laftly, the Diſtance of the Eye from the Lens or Re- flecter next to it in V, will be equal to L, the given Diſtance in this refpect. And fo the Inftrument will be in all Refpects fuch as is requir'd. 14. If the Inftrument be made for the Eye of an aged Perfon, then the right Line OE becomes infinite, and confe- quently the Point e is to be found by Theorem III of Catoptricks and Dioptricks. As for the reſt of the Work, it is the ſame as afore. If the Object propos'd to be diſtinctly feen be far diftant, then having all (as a- fore) given, but the Angle S, a Telef- cope may be made fit for the Purpoſe thus. In a right Line extended toward the re- mote Object propos'd, take from O for- ward OE and OV equal to the given D and L; and in V place a Reflecter or Lens having its Axis in VE. The Focus E of the Lens or Reflecter plac'd at V be- ing thus given, find the other Focus e, namely, that this being taken for the Focus before Inflection, E may be the Focus after Inflection. In the right Line OE fo place a fecond Lens or Reflecter, having alfo its Axis in OE, that the I- mage Opticks. 151 3 mage of the propos'd Object made there- by, may appear in the right Line aeb perpendicular to OF; and fo there will be made fuch a Telefcope as is requir'd. For the first Image of the far diftant Obje& propos'd will be in aeb and the Image of this Image will be in AEB, the Distance of which AEB from O is by Conftructi- on equal to the given D, and conſequent- ly diftinct to the Eye; and. alfo the Di- ftance of the Eye from V is equal to the given L. And from hence may be found the Angle, under which the laſt Image is feen. 16. By the Help of three or more Lens's or Reflecters, an Inftrument may be made to repreſent even a far diftant Object un- der a given Angle. Namely, let any one Lens or Reflecter form the Image of the Object propos'd; and then with the o- ther two make (as afore) a Microſcope, repreſenting the firft Image (as being a given Radiant nigh at hand) according to the Conditions propos'd; and fo there will be made fuch a Teleſcope as is re- quir'd. In like Manner, a Microſcope be- ing made of three Lens's or Reflecters, by adding a fourth it will become a Telef cope. In all which Cafes is known the Ratio or Proportion, which the Image ſeen by the Eye has to the Obje&, or (which comes to the fame) the Proporti- (K 4) Oil, ; * 152 The Young Gentleman's Fig. 48, & 49. on, which the Angle under which the faid Image is feen, has to the Angle un der which the Object is ſeen without the Inftrument, (which, in refpect to far diſtant Objects, is as the Diſtances of the Lens's or Reflecters from the common Fo- cus e.) And confequently from hence. (according to the Corollary of Theorem IV, Chap. III and IV,) may be computed how much the Inftrument does help the Sight. 17. I fhall next adjoin fome Obferva- tions in reference to a dark Chamber, as was abovemention'd in Schol. 2, Theorem IV, Chap. II. Namely, it was there ob- fervid, that Rays let into a dark Cham- ber through a naked little Hole, will paint the Images of their respective Ra- diants on a Sheet of white Paper held a- gainst the Hole. To which it is here to be added, that the fame will be done thro' a much larger Hole, if a Lens or ſpheri- cal Glafs be placed therein, with this Dif- ference, that the Images of outward Ob- jects will be painted much more lively and diftinctly this Way than the other without a Lens; which is thus account- ed for. Through the little Hole (Fig. 48) muft neceffarily pafs fewer Rays from the outward Objects than through a much larger Hole (Fig. 49.) And not on- 17 fo, but thofe fewer Rays, which pafs through Opticks. 153 through the bare Hole are difpers'd ; whereas by a convex Lens or Glafs all the Rays proceeding from any one Point of the Object, are united again at a certain Diſtance, and fo render. the Image much more lively and diftin&t, than the other Way, This is illuftrated Fig. 48 and 49. Whence it is alfo obvious, why in both Cafes, the farther the Paper is held from the Hole, the bigger the Image will appear; as alfo why the farther the outward Objects are from the Hole, the lefs their Images will be; and why the Image made by a Glafs will appear moſt diftinctly at the Diſtance ac (Fig. 49) with other fuch like Particulars. 18. But it is obfervable, that in both Cafes, either with or without a Glafs, the Image will appear inverted in respect of the Object, as has been afore obſerv- ed under Theorem IV, Chap. II, and is e- vident from Fig. 48 and 49. And from Fig. 48 it is evident, that when the Image as is painted erect on the Bottom of the Eye, then the immediate Radiant abc it felf is feen inverted by us; and on the contrary, when the Image abc is painted inverted on the Bottom of the Eye, then we ſee the immediate Radiant ABC e- rect. For as in the faid Figure the fe- cond Image aby is erect in the Eye, fo if the Eye were put in the Place of the Pa- per, 154 The Young Gentleman's per, the firft Image abc would be pain- ted therein inverted, in reſpect of the Object ABC. 19. This being fo, the Manner how that Senſation, which we call Vifion, is. perform'd, feems to be the fame, as that wherby a blind Man by the Thruſt of the End of feveral Sticks against his Hand, can thereby diftinguifh, which Stick thrufts from above, which from below. Namely, fo by the Senfation caus'd by the Ends a and b of the Rays Aa and Bb and Cc, touching the Retina, we are na- turally endued with a Faculty of readily diſtinguiſhing, from whence each Ray proceeds, viz. that the Ray Aa, as touch- ing the lower Part of the Retina, does proceed from the upper Point A of the Object; and the Ray Cc as touching a the upper Point of the Retina, does pro- ceed from the lower Point c of the Ob- ject; and the Ray Bb as touching b, the Middle of the Retina, does proceed from B the Middle of the Object. And confe- quently we are enabled to judge of the Situation of Things aright, by receiving their Rays after fuch a Manner as (it ap- pears from the forefaid Experiments) we do: Which is the fame as to ſay, that we fee Things in their Erect or due Si- tuation, by having their Images painted on the Retina in an inverted Manner and Opticks. 155 and contrariwise, we fee Things invert- ed, by having their Images painted on the Retina in an erect Manner. cles. 20. I ſhall now, in the last Place, ex- of Specta- plain the Mechanism of Spectacles, or how they come fo to help the Eye. It is then evident from the Rules of Dioptricks, that convex Glaffes turn the Rays in- ward, or towards the Axis of the Glaſs and the more convex they are, ſo much the more inward the Ray is turn'd. It is al- fo found by Obfervation or Experiments, that the Chryſtalline Humour has the fame Effect as a convex Glaſs. Where- fore, when the Surface or Coat of the Fig. 56. Chryſtalline Humour is of fuch a due Convexity, as that it makes the Rays of the feveral Points of an Object to unite again in fo many feveral Points juſt up- on the Retina, then Vifion is duly per- form'd, as Fig. 50. 21. But when the Chryftalline Humour is not convex enough, but too flat, (as it Fig. 51. grows through Age,) then the Rays paf- fing through it are not united foon e- nough, i. e. are not united at the Retina, but their Point of Union is further be- hind the Retina, and confequently then the Eye can't fee duly or diftinctly, but only confuſedly, the Objects, from whence proceed the Rays. Wherfore to help this, convex Glaffes, (call'd Specta- cles) 156 The Young Gentleman's cles) are us'd, whereby the Rays are made to unite in their proper Place, or at the Retina. In order thereto, the more flat the Chryftalline Humour is, that is, the more aged the Perfon is, the more convex must the Spectacles be. 22. On the other Hand, if the Surface of the Chayſtalline Humour be too con- Fig. 52. vex, (as is the Cafe of fhort-fighted Per- fons.) then the Rays are thereby united too ſoon, or before they come to the Re- tina, and fo Viſion is not duly perform'd. Hence fuch Perfons hold Things very near to their Eyes, to fee them the better, becauſe (according to the Rules of Diop- tricks) the nearer the Object is to the (Lens, or in this Cafe) the Chryſtalline Humour, the further will be the Union of its Rays on the other Side. Hence al- fo concave Spectacles helps fuch Perfons Sight, by making the Rays unite in their proper Place, viz. at the Retina. Hence, laftly, fuch Perſons ſee better and better, as they grow elder; becauſe the Chryſtal- line Humour grows more and more flat, or less convex; fo as to come but to a due Convexity in their old Age: Which by the way is the Reaſon, that fuch People, as are fhort-fighted when Young, want not Spectacles when they are Old. And this is fufficient to our Purpofe concerning Dioptricks. CHAP, Opticks. 157 CHAP. V. Of Perſpective. I. N Perſpective the chief Things (befide the Eye and the Object) to be con- Definitions fider'd, and therefore explain'd, are thofe of Terms which are contain'd in the following De- Perſpective finitions. us'd in 2. metrical The (†) Geometrical Plane is a plain Surface parallel to the Horizon, and pla- The Geo- ced lower than the Eye, in which we plane, imagine the viſible Objects without any what. Change, (except it be reducing a great Figure into a ſmall one,) and upon which the Situation of the Object to be repre- fented in Perſpective is defcrib'd. 3. The Situation (call'd alfo the Ich- nography or Plan) of an Object is its The Situa- Orthographical Projection upon the tion of an Object, wh.it. (†) It is alfo called the Bafis. This and the following Planes, c. here denoted, are not reprefented in Figures or Cuts, they being not cafie to be fo apprehended by young Students; but they may be more eafily apprehended by the bare Imagination, or elfe by actually placing fo ma- ny Plains in ſuch a Manner. (*) geo- 158 The Young Gentleman's 4. The Pic ture, what. The 5. (*) geometrical Plane, or, that Figure which is defcrib'd upon the Gemetrical Plane, when from all the Points of the Object right Lines are drawn perpendicu- lar to the faid Geometrical Plane. Thus the (Plan or) Situation of a right Cylin- der is a Circle, and the Situation of a right Cube is a Square. The Picture is a plain Surface, fup- pos'd as tranfparent as Glafs, and al- ways plac'd at fome Distance between the Eye and the Object, to repreſent in it the Object in Perfpective; whence the Picture is alfo call'd the Perspective Plane. 1 The Picture ftands (uſually (†) per- pendicular) upon the geometrical Plane. Ground- Whence the common Section of the Pic- line, what. ture and the geometrical Plané, is call'd the Baſe of the Picture, or the Bafe-line, and alſo the Ground-line. 1 (*) If the Orthographical Projection be (not upon the geometrical Plane, but) upon a Plane parallel to the Pic- ture, then it is call'd Front; and if it be upon a Plane pa- rallel to the vertical Plane (defcrib'd §. 11) it is term'd Profil. (†) Sometimes the Picture is inclin'd to the geometrical Plane or Horizon, and has alſo a curve Surface, as when the Surface of an arch'd Roof is to be drawn. But this being not common, the Picture is look'd upon throughout this Chapter as a Plane perpendicular to the geometrical Plane or Horizon. The Opticks. 159 6. zontal The Horizontal Plane is a plain Sur- face parallel to the Horizon, and which The Hori is conceiv'd to pass through the Eye, and Plane, to be perpendicular to the Plane of the what. Picture. 1 zontal The Horizontal Line is that right Line, 7. in which the horizontal Plane and the The Hori- Plane of the Picture interfect, and which Line,what. therefore is parallel to the Ground- line. 8. The Prin- The Principal Ray is a right Line drawn from the Eye, perpendicular to cipal Ray, the Plane of the Picture, which there- what. fore muſt run along the horizontal Plane. The Point of Sight, call'd alſo the Principal Point, is the Point where the of Sight, Picture is cut by the principal Ray, what. which muſt neceffarily be in the horizon- tal Line. 9. The Point 10. of Dif- The Point of Distance is a Point in the horizontal Line, whofe Distance from The Point the Point of Sight, is equal to the Length of the principal Ray. The Vertical Flare is a plain Surface, which going along the principal Ray, is perpendicular to the Horizon, and fo to the geometrical Plane, and alfo to the Picture: The common Section of the Pic- ture and vertical Plane being call'd the Vertical Line, and being alfo the Mea- fure of the Height of the Eye; and the common.Section of the geometrical and vertical ( tance, what. 1.1. The Verti- cal Plane and Line, whit • 160 The Young Gentleman's 12. vertical Planes being call'd the Line of Station. The Repreſentation or Appearance of a- The Ap- ny Point of an Object is that Point, where pearance, the Picture is cut by a right Line drawn of a Point, from the Eye to the Point propos'd of the Object. what. 13. dental Point, what. The Accidental Point of a right Line is The Acci- the Point, where the Picture is cut by a right Line drawn from the Eye parallel to the Line propos'd. Whence it is eafie to conclude, that all Lines, which are paral- lel to the Picture, have no accidental Point; and that all other Lines, which are parallel one to another, have the fame accidental Point. It is alfo obferv- able, that all right Lines, which are per- pendicular to the Picture, have the prin- cipal Point for their accidental Point ; and that all thofe, which make an half- right Angle with the Picture, have one of the Points of Diſtance for their acciden- tal Point. 14. Obferva- bles from what bar been faid. It is alſo obfervable from what has been faid, that all the Parts of an Object, which are lower than the Eye or horizon- tal Plane, ought to be reprefented in the Picture below the horizontal Line. And on the contrary, all above the horizon- tal Plane, or higher than the Eye, ought to be reprefented in the Picture above the faid horizontal Line. In like Manner, all thofe Opticks. 161 "S hoſe Objects, which with refpect to the Eye are on the right Hand of the verti- cal Plane muſt in the Picture be repre- fented on the right Side of the vertical Line; and fuch as are on the Left, muſt be reprefented on the left Side of the ſaid vertical Line. the Picture, In order to perform any Operation, 15. the Sheet of Paper, which you would How to de- work upon, muſt be divided into two Paper the fcribe on Parts, by the Line AB (Fig. 53) which Plane of will repreſent the Ground-line. The up- thei per Part of the Paper, viz. ABDD, muft be taken for the Plane of the Picture cal Plane. and the lower Part ABYZ of this Paper Fig. 53. for the geometrical Plane. ; and the Geometri- find or fet Distance. The next Thing is to know, (under 16. what Angle the Picture ought to be feen, How to that whatever is reprefented therein may off the appear in juft Proportion, and may eafi- Points of ly be taken in by the Eye at one View ; that is in fhort,) how far the Points of Diſtance ought to be from the Point of Sight. Let there be propos'd a Square, which takes in all that you would repre- fent in Perſpective. And let the Ground- line AB be of equal Length with one Side of the Square propos'd. Wherefore, if the Eye of the Spectator was at G, he could not fee the two Ends A and B, be- cauſe the Eye could fee, (f) at most, but (†). According to Theorem II, of Chip. II. (L) fo * 162 The Young Gentleman's 17. fo much as is comprehended under the right Angle GHI. But if the Eye were at K, it could fee the Ends A and B, be- cauſe the Angle AKB is leſs than a Right, viz. 80 Degrees. And the Eye would fee the Ends A and B better at L, and better yet at M, where the Angle AMB is 60 Degrees. And from fuch a Diſtance the Objects (to be repreſented in Perfpec- tive, and contain'd in the foremention'd Square) may be feen in Perfection, the viſual Angle AMB being neither too great nor too little. The Angle ANB would alfo be very well. Wherefore having bifected AB in F, and from F drawn the Line FV perpendicular to DD for the vertical Line, and confequently V being the viſual Point or Point of Sight, from the faid Point V fet off the Diſtance ((*) FK_or rather FL, or) FM, or FN on each side upon the horizontal Line DD, viz. to D and D, which will be the Points of Diſtance requir'd or fought. And this may be look'd on as a gene- A general ral Maxim, viz. that the Distance be- cerning the twixt the Point of Sight V and the Points Rule con- Jame. (*) If the Diſtance VD were lefs than FK, then the Per- ípective Square ABCE (concerning which fee §'17) would appear irregular, becaufe it would be fren under an ob. tule, and fo too great an Augle. of Opticks. 163 of Diſtance D and D muſt be (at leaſt) equal to FA or FB. And it will not be amiſs to let this Diſtance be ſomewhat greater. And, if in this Cafe the Plane of the Picture be not wide enough to receive two Points of Diſtance, there mut only one be mark'd; and the prin- cipal Point or Point of Sight V may be plac'd on one side, as Fig. 59, &c. 18. The Points of Distance D and D (Fig. 53) being found, draw the Lines AV The Per- ſpective and BV, as alfo AD and BD. And the Square, Figure ABCE will be the Appearance (in what. the Picture) of the Square, propos'd to be repreſented in Perſpective; which Ap- pearance of the faid Square is in fhort call'd the Perspective Square. 19. How to find the Pic- ture the Ap ven in the Proceed we now to the Reprefentation (in the Picture) of Points, Lines, and Planes. And first, how to find in the in Picture the Repreſentation or Appear- pearance of ance of a Point given in the geometrical a Point gi- Plane. From C the given Point (Fig. geometrical 54) let fall upon the Ground-line AB the Plane. Perpendicular CE; and from the Point Fig. 54 E draw to the principal Point V the Line VE. Upon AB fet off EF (or EA) CE; and then draw FD (or AD either of) which will upon VE give at c the Ap- pearance of the given Point C. (L2) C Second- 164 The Young Gentleman's 20. To find in the Picture the Appear. Secondly, how to find in the Picture the Appearance of a right Line given up- on the geometrical Plane. Suppofe MN Fig. 55 and 56) to be the right Line gi- ven. Find (as afore) the Appearance of geometrical the Point M, viz. at m, and then the Plane. Appearance of the Point N of the given Fig. 55, Line MN, viz. at n. Then join ance of a right Line given in the 56. 21. the Picture and n, the Line mn will be in the Picture the Appearance of MN the Line propo· fed (*). When the Line given on the geometri- To find in cal Plane is (not a right Line, but) a the Aptear- Curve Line, then from feveral Points of ance of a it draw Perpendiculars to the Ground- eurve Line line; by means of which, and what has geometrical been faid, may be found in the Picture given on the Plane. the Appearances of all thofe ſeveral Points, which being join'd by a curve Line, that Curve will be the Appearance of the Line propos'd. (*) That every Thing you defign to reprefent in Per- fpective, may appear in juft Proportion, it is requifite fometimes to have the Eye at a great Diſtance from the Picture, which may hinder from marking either Point of Distance upon the horizontal Line. In which Cafe you muft mark only half of the Diſtance of the Eye from the Picture upon the horizontal Line, as (Fig. 57) from V to Q, which will reprefent one of the Points of Diſtance. And then you muſt only ſet off half the Perpendicular HI upon the Ground-line AB, from I to P. Then draw QP, and the Point b will be the Appearance of H the Point pro- pos'd. 1 Thirdly, Opticks. 165 22. the Pille gure given Plane. Thirdly, To find in the Picture the Appearance of a plain Figure given on To find in the geometrical Plane, fuppofe the Square the Appear- CEGH Fig. 58. Find the Appearance ance of a (as has been afore fhewn) of its four an- plain Fi- gular Points C, E, G and H; which will in the geo- be c, e, g and h. Join the faid (laft) metrical Points, and the Perfpective Square cegh will Fig. 58, be the Appearance of the given Square 59. CEGH, when feen foreright, or when the Line KL, of the given Square falls in with VF the vertical Line. If the given Square be all on one Side of the vertical Line VF, (as Fig. 59) then the Perſpec- tive Square cegh (in Fig. 59) will be the Appearance of the given Square CEGH. Where alſo it is to be noted, that the Appearance g of the Point G may be A Remark. found alſo after this Method. in the Ground-line AB take at pleaſure, and draw BV. BM equal to the Perpendicular IG, and draw MD, which upon the Ray VB will give the Point N. Through which NC being drawn parallel to AB, will upon the Ray VI give the Point requir'd g And this Method may be uſed, when the Perpendicular IG is fo long, that the Length thereof can't be fet off upon the Ground-line AB wlthin the Picture. 23. Namely, Namely, Fig. 59. the Point B Then fet off In the fame Manner may be found in 24. the Picture the Appearance of any other Another plain Remark. 166 The Young Gentleman's 25. Pilure the plain Figure, viz. Triangle, Pentagon, Heptagon, &c. Namely, by distinctly finding the Appearance of each angular Point of the plain Figure propos'd, and then joining the Appearances fo found by right Lines. It fhall here be only obſerv'd farther Fo find in a in reference to plain Figures, that to find Appearance in the Picture the Appearance of a Cir- of a Circle cle given in the geometrical Plane, there given in the muſt be defcrib'd about it a Square, as geometrical Plane. (Fig. 60,) the Square EFGH about the Fig. 60. Circle ILKM. One Side of the Square, viz. EF (or GH) muſt be parallel to the Ground-line AB, and confequently the o- ther Side EH (or FG) must be perpendi- dicular to AB. Draw the two Diagonals EG and FH, which interfecting at O the Center of the Circle, will give upon IKL, M the Circumference of the Circle, theſe four Points, P, Q, R and N. Then find in the Picture the Appearance of the Square EFGH, which will be the Per- fpective Square efgh, and alfo the Appear- ances of the Points L, Q, K, R, M, N, I and P, which will be in the Perfpec- tive Square the Points l, q, k, r, m, n, i and P. A Curve drawn through theſe laft Points will determine the Appearance of IKLM the Circle propos'd. Where note, that the Appearance of the Circle will alſo be a true Circle, if the Circle • pro- 1 Opticks. 167 *** Propos'd be ſeen fore-right, that is, if its Line (*) LM, being perpendicular to AB, make one right Line with VF the vertical Line. But if the Circle propos'd IKLM be fituated (as Fig. 61,) then its Ap- pearance will be (as there) elliptical. 26. fent aFloor Proceed we now to fhew, how to re- preſent in Perfpective a Floor of equal To repre- Squares feen fore-right, without a geo- of equal metrical Plane. Divide the Ground-line Squares AB (Fig. 62) into as many equal Parts right. as you pleaſe, each of which will repre- Fig. 62 (*), To have the Appearance of a Circle in the Picture, to be likewiſe a Circle, the Diſtance between the Eye and the Picture muſt be of a determinate Length, which may be found thus. Having produc'd the Side of the circum- fcrib'd Square EFGH, 'till it meets at right Angles with the horizontal Line DD ia a Point as S, draw SL, and cut off from it SCSV, and the remaining Part LC (of SL) wil be the Diſtance between the Eye and the Picture, or VD equal to the ſaid Diſtance. If VD be given, and you would find VE (or the Distance between the horizontal Line DD and the Ground-line AB, that is) the Height of the Eye requifite, that the Appearance may be alfo a true Circle; the rectangular Triangle SVL fhews, that the Square of the Line EL (or of the Ray of the given Circle IKLM) muſt be taken from the Square of the Line LS, and the Side ES of the remaining Square will be the Height re- quir'd. Note further, that the Perfpective Square efg being found, the Mid-point X of the Line mL (or ml) will be the Center of the Perspective Circle; upon which there- fore Center the faid Circle may be drawn without any more ado, or without finding the Points 1, q. k, &c. Laftly, note, that in Fig. 60, the Perpendiculars Ef and TN are not fet off on the Ground-line AB, partly to avoid Confuſion by defcribing the Arch of many Circles, partly and chief- ly, because it is evident (from the fecting off FK and QR) that EL-El and TF TK. fent feen fore. 168 The Young Gentleman's 27. ſent the Side of a Square. Draw through each Point of Divifion to the principal Point V, as many right Lines or Rays, the two laſt of which will be VA and VB. Then draw the Ray AD (or BD ;) which will cut the foregoing Rays in Points, through which you must draw Parallels to the Ground-line AB. The laſt of theſe Parallels will be EF, which will have its Divifions equal between G and H. And the like equal Divifions may be continued from G to E, and from H to F, in order to draw through theſe new Points of Divifion, from the principal Point V, other Rays which will upon the Lines DA and DB meet the foregoing Parallels reſpectively belonging to them. Thus you'll have in Perfpec- tive all the squares, which can be com- prehended in the Space ABFE. And if you would have more, draw DE, which will cut all the Rays that proceed from V in Points, thro' which (as afore) you muſt draw Parallels to AB, the laſt of which will be KL. And fo, go on as a- fore. If ! you would reprefent in Perfpective a Toreprefent Floor feen fore right, and containing e- a Floor of qual Squares feen Cornerwife, work thus. The Side AB of the fquare Floor being determin'd upon the Ground-line AB, de- ſcribe the Appearance of the fquare Floor, Equal Squares feen Cor- determin'd ner-wife. Fig. 63. by Opticks. 169 叉 ​by drawing from the two Ends A and B of the Side given, to the principal Point V, the Rays VA and VB; and to the two Points of Distance the Rays DA and DE. Theſe Rays will cut the former in the Points E and F, which being join'd, the Line EF will be parallel to the Ground- line; and ABEF will be the Perſpective Square. Having divided AB (or the Side of the Perfpective Square) into e- qual Parts, to each Point of Diſtance D, draw Rays through each Polnt of Divi- fion; which Rays by their common In- terfections, will form the Appearances of the Squares feen Corner-wife. With which Squares it will be eafie to fill the Perfpe&ive Square ABFE, becauſe all the Rays that proceed from the two Points of Diſtance, divide equally in the fame Points the Side EF parallel to AB; which is alfo divided equal- ly and in the fame Points, by the faid Rays which go from the two Points of Diſtance. 28. lent a Floor To repreſent in Perfpective a Floor made of equal Squares feen fore-right, To repre- and encompaſs'd with a Border or Frame, of Shares without a geometrical Plane; work thus. feen fore- Divide the Ground-line AB into as many right, and Parts, alternatively equal and unequal, fed with a encompaj. as you would have Squares and Borders, Border. at the Points 1, 2, 3, 4, 5, 6, 7, 8. Fig. 54. (M) From 1.14 170 The Young Gentleman's 29. To repre- ſent a Floor of equal Squares feen Cor- From all theſe Points draw Rays to V; the first Ray will be VA, the laſt VB. Then draw the Ray DA, which will cut thofe that go from V in Points, through which you muſt draw Parallels to AB the laſt of theſe Parallels will be EF, which terminates the Perfpective Square ABFE. And ſo you will have the Re- preſentation of the Floor requir'd. And you may continue it, if you draw ano- ther Ray through the Point E and the Point D; and then proceed to work as afore. To repreſent ſuch a Floor as is laſt mention'd, but feen corner-wife, work thus. Divide the Ground-line AB into Parts as afore, viz.alternatively equal and unequal. Then draw thro' the Points of and with a Division, to the Points of Diſtance, Rays or Lines; which will (as afore) termi- nate in the reſpective Square, this allo being to be defcrib'd as is afore taught. ner-wife, Border, bc. Fig. 65. one or 30. Laſtly, It is obfervable, that if you An useful defcribe Squares given in a geometrical Way to re- Plane, then the Ground-line AB muſt be preſent in Perfpective divided into Parts equal to the Sides of the given Squares. And the littlePerfpec- tive Squares, not only will be the Ap- pearances of thofe in the geometrical Plane, but alſo may be very uſeful to re- preſent in Perspective one or more Fi- gures made up of feveral Lines; as for moré Fi- gures. Inftance, Opticks. 171 * Inſtance, a fortified Polygon. Namely, the faid Polygon (or Wall of a fortified Town) being deſcrib'd on the geometri- cal Plane with the Squares, it will not be difficult to defcribe the fame likewife in Perſpective with the Squares of the Pic- ture, drawing fuch a Part of it in each Square of the Picture, as is deſcrib'd in the correſpondent Square of the geome- trical Plane. All which will be fuffici- ently illuſtrated by a bare Sight of Fig. 66. 31. thod. And in like Manner, Fig. 63, if up- on AB a Square be drawn in the geome- A like Me trical Plane, as ABGH, whofe Reprefen- tation is the perfpective Square ABEF; and that Square ABGH on the geometri- cal Plane be divided into other little Squares by Lines parallel to the Diago- nals AG and BH, the faid Square ABGH may be made uſe of, to put or repreſent in Perſpective ſeveral Things at once, the Draught of the faid Things being de- fcrib'd upon the ſaid Square. 33. clufion And thus I have taken notice of fo much of Perſpective, as is agreeable to The Con- the Defign of this Treatife. And there- fore ſhall here put an End to this Trea- tife of Opticks. FINI S. ERRATA to Trigonometry. AGE 7. Line 33. For fit for Use. Read not fit for Use. p. și l. 33. f. to ax. PAGE r. — tux p. 19. 1. 5. f. ΤΟ ĘD 2 B-D 3. r. --=D. p. 30. 1. 13. f. CA. г. 2 EA. p. 35. 1. 22. f. E=350. г. B=35 degr. p. 42. l. 13. f. CA —–793. t. CA=793. P. 44. 1. 6. t. Arch (BA. 1. Angle CBA. p. 51. 1. ult. f. Line BA. 1. Line 85. p. 54. 1. 16 f. Angles meet. r. Angles, 'till they meet. p. 55. 1. 13. f. at M. r. at N. ibid. 1. 19. f. at N. r. at M. p. 56. l. 1. f. at the End m. r. at the End n. ibid. 1. 4. f. as the End n. r. at the End m. p. 65. l. 1. f. fo that. I. ſo ſhall. p. 82. 1. 22. f. to 99. г, to 89. ' PA • ERRATA to Mechanicks. AGE 6. Line 14. For contriv'd. Read conceiv'd, p. 16. 1. 21. f. little may. 1. little Body mag. p. 13. 1. 12. f. Laver. T. Leaver. ibid. 1. 26. f. bust (the. x. but) the. p. 51. 1. 21. f. faid Squares. r. faid Spaces. ibid. penult. f. is equidiſtant from C to Aa, r. is fix times as diſtant from Cas is As. p. 17. l. 1. f. to b. v. to B. ibid. 1. 3. f. ¿C. r. BC. ibid. I. 7. £. (this being. r. this being p. 20. ult. t. G2 1. C2. p, 3º. 1. 10. f. were. r. were FD. ibid. 1. 11, f, at C r. ar G, ibid. 1. 12. f. at r. at B. p. 31. 1. 12. f. or Mark. I. or Hok. p. 34. 1. 23. f. as Fig. 1. as Fig. 28, 29, 30. ibid. 1, 24- £. Pulley) r. Pullen as Fig. 27.) p 35. 1. 19. f. by TS. 1. by FS. p. 47. 1.15. f. d, e, f, E. By. r. d, c, f. By. p. 5o. 1. 6 f CE. t. CG. p. 56. 1. 14. F aqua!. t. equal. p. 57. 1. 18, £. EFAB. r. EFHB. p. 65. 1. 17. £. How the г. Now the. 1. ERRATA to Optické. PAGE 87. Line 14. For Fig. 11. Read Fig. 10 p. 88. ult. £. (Eig. ) r. (Fig. 28.) p. 89.1. 5, 7.17, 25. f. (Fig. ) r. (Fig. 28.) ibid. 1. 14. 27. f. (Fig. ) r. (Fig. 8) ibid. 1. 16. f. Surface BD. r. BC. p. 102. 1. 11. £. AH. 1, AF. p. 107. 1. 8. 1. ss look'd to be, x. is look'd on to be. p. 108. 1. 14. f, the Conver. 1. the Reflex, p. 110. 1. 2. E to the Prop. be requir'd. I. to the Proportion here required. p. 113. l. 1. f. Theor. II. 1. Theer. IV. ibid. 1. penult. f. And when, r. And whereas, p. 114. 1.4. f. EDG. 1. ADC. p. 116. l. 5. f. hBF. r. hBf. p. 117.1. ult. f. 2: lf, r. 4 : lif. p. 122. 1.29. fubdulicate, r. fubuduplicate. p. 125. I, 20. £. (of the Angle (BiViS). I. of the Angle (CBM). ibid. 1. ante penult t. (as Fig. ) r. (es Fg. 29) p 126. 1. 1o. f. Fig. 35. r. Fig 35. p. 132. I. 27. f. 3 AB. r. 2 AB. p. 133. l. 28. f. Coneasic, & Corvex, ibid. 1. 29. f. Convet, f. Concave. ibid. 1. 30. t. Fig. 36. r. F.g. 35, and 36. p. 141. 1 2. f. Bp. r. Bb. p. 148. in Ma gin, f. Fig. 46. r. Fig. 47. p. 151. 1. 3. E. OF x. OE. P, $56. 1, 8, F. Chayſtalını, t. Chryſtaline. In Aftronomy, Page 63. Line 15. Read, Three Diameters of the Moon. In Chronology, Page 33 After thefe Words, (in the last two Lines of the Text,) viz. and in the Calendar adjoining to this Treatife; add as follows: Or else the Golden Numbers are call'd the Prime, as denoting Luna Prima or the Firl Day of the New Moon; according to which way of speaking the Full Moon is frequently fil'd Luna Quarto-decima, as falling on the fourteenth Day after the New Moon inclufively. JUL 7 1920 A B Optick Plate Fig. 1. E b a h Fig. 2 D d b E Fig. 3. 1 C B H A C D F D Optick Plate 2. b یک C Fig. 5. FB I- Fig. 4 Fig. 6 M n Fig. 7 K C F B G H E I Um ID B A Optick Plate 3: Fig. 8. P E D E A C G B Fig. H 10 e р A A D C a I I I P Fig. 9. B Fig.11. • Fig. 13 E D. B. Fig. 12 B A B H D I' I G I 1 1 I h E IE A Fig. 14 B B Optick Plate 4 R Fig.15 A E B N Fig. 16 I B N F E F Fig. 17 NA B Fig. 18 D B I H C A Fig. 20 H E F H F C D A B H E H Fig. 21 H h B f Fig. 22 Fig. 23 A E f Fig. 24 D • B IB. C A if Optick P.5. Fig. 26 TM K Fig. 27 Fig. 28 B B Fig. 25 M Johan A N. Optick Plate 6. Fry 30 A E K LA C Fig 31. Fig.32 D Fig. 29 B D B B D F N I lo F C 'M E E Fig.36 Fig.33 H B D C Fig.34 A Fig.35 HɅ e B B H Fig.37 A A B E F E H ell E F Fig. 38 Fig.39 B D B D B e C Fig. 40 E P H B T C H h Fig. 41 p: P E E b B B F Fig. 43 P E B F E P b B b F Q b 2 Fig. 42 Fig 44 e +Um Optick Plate 7. E Fig. 45 e Fig. 46 " Р B b ୧ M B F Fig 47 E A A A Fig. 48 B ct P R+ H N E D H Fig. 50 A E A R A Fig. 47 S I • E Fig. 49 F D Optick Plate 8. D Fig. 53 A H Y N Fig. 51. • • Fig. 52. V D Fig.54. D N A B H с D V Fig 55 m A M D Q Fig. 56 D Fig.57 A m -B A- B I: P M Hi.. B -B Optick Plate 9 F A D V Fig. 58 A E H K Y I Fig.59. I H M 凶 ​C I G B N I B .... N Optick Plate 10 + A E I ev H N Fig. 60. D T P M V D :m X k. N R ୧ f F •B K Optick Plate Plate 11. D Fig. 61. A I P : I સ h. m. 1. H M D V 9 K Fig. 62 स. E k K 9 P B D H B Optick Plate 12 D A H Fig. 63. V \F. D B Optick Plate 13. V Fig. 64 E 2 A 1 3 4 5 6 7 D Fig. 65. A E V D 8 B D B Optick Plate 14 V ·Fig. 66. A • • D + • > • 1716 UNIVERSITY OF MICHIGAN 3 9015 06387 4385