C 55. 4-oa ; G- a°i A /<*"& U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Survey Rockville, Maryland 20852 PREPRINT NATIONAL GEODETIC SURVEY DATA AVAILABILITY - EXPLANATION - APPLICATION Joseph F. Dracup National Geodetic Survey January 19 76 „0*- UT ' *^ NOAA--S/T 76-2132 NATIONAL GEODETIC SURVEY DATA AVAILABILITY - EXPLANATION - APPLICATION * Joseph F. Dracup Chief, Horizontal Network Branch National Geodetic Survey National Ocean Survey National Oceanic and Atmospheric Administration U. S. Department of Commerce Rockville, Maryland 20852 Introduction For more than 150 years, the Coast and Geodetic Survey collected and published data related to the oceans and the land. With the formation of the National Oceanic and Atmospheric Administration (NOAA) in October 1970', the Coast and Geodetic Survey became a major line com- ponent of this agency and was renamed the National Ocean Survey (NOS). This reorganization later included the transfer of the seismological and geomagnetic activities from NOS to the Environmental Research Laboratories (ERL), another mainline component of NOAA which is located in Boulder, Colorado, and the establishment within NOS of the Office of the National Geodetic Survey (NGS), the latter to include all geodetic functions of the former C&GS. In 1973, the seismological and geomagnetic functions were transferred to the U . S Geological Survey (USGS). However, the national data bank for geomagnetic data remained with NOAA and geomagnetic information is available from the National Geophysical and Solar-Terrestrial Data Center, EDS/NOAA, Boulder, Colorado 80302. The crustal movement studies which are performed by NGS will continue to be published and distributed by that office . Results of these studies and requests for geodetic data may be obtained from the Director, National Geodetic Survey Information Center, Rockville, Maryland 20852 > Routine C18. *This preprint is to be published in the NOAA NOS/NGS Technical Memorandum Series. 2 These organizational changes should have little effect on most users of geodetic control since these data will continue to be published and issued by the NGS. However, those surveyors and engineers who require information relating to seismic and magnetic data should refer their requests to the organizational components noted in the previous paragraph. NGS will provide, upon request, price lists for the geo- detic data and a selected group of publications. This information bulletin covers, in part, some of the material included in this paper, and in fact is perhaps more explanatory in some categories; but in general, its major content is directed to servicing procedures. AVAILABILITY AND EXPLANATION Publications Most bound publications are printed and sold by the Superintendent of Documents, Government Printing Office, and all requests should be directed to that agency and not to the NGS. If, however, a publication cannot be furnished by the GPO, it occasionally may be obtained from NGS stock. The Department of Commerce also main- tains Field Offices in most major cities, and these offices can usually furnish NGS publications in less time than that required to obtain them from the GPO. During its long history, the Coast and Geodetic Survey prepared more than 300 Special Publications dealing with all of the scientific disciplines in which this Bureau was involved. Many of the older publications are out of print and in numerous instances will not be reprinted because the contents have been superseded by later publi- cations or are of little present-day interest. The NGS does have file copies of those documents concerned with geodetic surveying and generally can furnish commercial - type copies of excerpts or occasionally even an entire publication; but such requests should be made only after receiving notification from the GPO that the publication is out of print. The NGS, as in the past, will furnish data and is always available for advice concerning technical matters, such as specifications, use of theodolites and electronic distancing equipment, computations, review of unsatis- factory closures between points established by this agency, etc. Also available from NGS are numerous papers, technical bulletins, data reports, and similar pamphlet-type publi- cations which have been prepared and issued over the years . Generally such material is limited in depth and scope but often appears in lists of references. For this reason, NGS has maintained a supply of the more popular ones and will reproduce a few copies of others upon request. The reference library of any surveyor or engineer who performs control surveys or employs the State Coordinate Systems should contain the following NGS and ACSM publications and papers. All are included in the more comprehensive Biblio- graphy which is given at the end of this paper, and for this reason, no further details other than the titles are given here . (i (2 (5 (4 (5 (6 (7 (8 (9 (10 (1.1 State plane coordinate projection tables for those states where projects would be undertaken. Tables of sines, cosines, and tangents (0° to 6°) for use in computing State coordinates on the Lambert system . The State Coordinate Systems (A Manual for Surveyors ) . Horizontal Control as Applied to Local Surveying Needs . Geodetic and Grid Angles Systems . State Coordinate Classification, Standards of Accuracy, and General Specifications of Geodetic Control Surveys Specifications to Support Classification, Standards of Accuracy, and General Specifications of Geodetic Control Surveys . Suggested Specifications for Local Horizontal Control Surveys. Standards and Specifications for Supplemental Horizontal Control Surveys . Definitions of Terms Used in Geodetic and Other Surveys . Electronic Distance Measuring Instruments. The impression may be gained from a cursory review of the reference material that the use of the State Plane Coordinate System involves very complex procedures. Such is not really the case - in the final analysis, State plane coordinates are really nothing more than an adaptation of the latitude and departure practices which have been in use for centuries. Numerous reasons have been given, during the last ^0 years, for not employing the State Plane Coordinate Systems. Some are quite valid, a lack of national network control, for example; but others, especially those related to scale factors, hold little water. The application of a scale factor is an arithmetical process, not an involved mathe- matical procedure. In those higher elevation sections of the country, the reasons given for not using the system include the reduction to sea level in addition to scale factors. The sea level reduction is also an arithmetical manipulation, and in fact, the two factors can often be combined, thus resulting in but a single computation to reduce each measured distance. Some surveyors and engineers contend the State systems are not adaptable to their projects because ground dis- tances are required in laying out structures, etc. This problem, of course, can be generally overcome by projecting the State plane coordinates to the average elevation and correcting for the average scale factor of the site. In a few projects examined by the author, this has been a needless exercise since the distance measurements made at the site for construction purposes either involved such short lengths or such inaccurate taping procedures as to negate the require- ment for project coordinates. Horizontal Control Data Early in the 1950' s, it was decided to lithoprint hori- zontal and vertical control data in a loose-leaf form rather than in bound volumes by States as had been the gen- eral practice previously. For this format, which became known as the ''lithos", separate listings for the geographic positions, plane coordinates by zones, and descriptions were required to complete the data for horizontal control points. Leveling data were issued by lines, and material involving several lines were often required to furnish the complete data for an area. As time passed, a tremendous amount of data was accumulated and it became obvious that this format was cumbersome and that a new approach to publishing the material was mandatory It was then decided to issue the data in 30 • by 30' quads, the advantages being that all data for a horizontal control point could be printed on a single sheet of paper and all the leveling control for an area of about 800 square miles could be assembled in a single volume. At this point in time, previously published adjusted geo- detic data for most States have been converted to the quad format. With rare exceptions, all new adjusted data are being prepared in this form. The New Adjustment of the North American Datum presently underway is scheduled for completion in 1983. Published data for this adjustment will be computer generated probably similar to the quad format. The diagrams for the quad format are on a 1:250,000 scale and show both horizontal and vertical control established by NGS, USGS, and any other Federal, State, or local govern- ment agencies whose data have been accepted for publication by NGS. The acceptance or adjustment of data published by NGS is made with the understanding that prescribed speci- fications for the stated standard of accuracy have been rigorously followed by the establishing agencies and this office (NGS) accepts no responsibility for the actual accuracy of these surveys. Diagrams: The State diagrams showing control established and/ or adjusted by NGS will continue to be published, one for the horizontal control and another for the vertical control (Figures 1 and 2). In those areas where the con- trol is congested, larger- scale diagrams, such as nautical base charts, supplement the State diagrams. The normal dimensions of the quad- format diagrams are 1° in latitude by 2° in longitude with the data assembled in 30' by 50* volumes. The horizontal and vertical control data are issued separately and designated as shown below: 26' 25 081 4 25 081 1 DIAGRAM NG 25 080 4 17-8 MIAMI 25 080 1 25 081 3 25 081 2 25 080 3 25 080 2 82' "of 6 25' 80* !•' * i! i! _J_ « J j L_iL_iL i L . _J L_ t i! I ii B f $ i — i i! I! i! i! i! i! «— | In a few instances along the coastlines the quad dimensions are 2° in latitude by 1 in longitude, and on other occasions to offset the need of an additional sheet, slightly larger than the normal size. Larger-scale "base maps are also used to supplement the regular quad diagrams in those areas where a large concentration of control exists . Control established or adjusted by the NGS is shown in black; that established, computed, and issued by the USGS in redi and data accepted by the NGS for publication in brown. The accuracy of the control is also indicated. A sample regular- size quad sheet is shown in Figure 3. Data Sheet Format ; An example of the new format horizontal- control data sheet is shown in Figure 4. This single -sheet type of listing replaces the multi-page tabulations pre- viously employed. In the old "litho" format, as noted previously, separate sheets were necessary for the listings of the various data, and for the example shown in Figure K, the user would have received as many as eight sheets of paper. Since much of the horizontal control data for a few States are still issued in the "litho" type format, examples and explanations of the data will be presented later. The form shown in Figure k is largely self-explanatory. Nevertheless, it is thought the following comments are necessary to assure the user a more complete understanding of the tabulated data: (1) Source - Archive number assigned to computations in which position was determined. Other source numbers are occasionally shown on data sheets which were prepared several years ago. These refer to projects in which the station was used as control, but this practice has been discontinued. (2) Field Sketch - A sketch is drawn for each project and filed by State and number. Sketches for projects which extend into more than one State are assigned to one of the States involved. There are no hard or fast rules in this regard, however. Usually only the sketch for the project in which the station was originally positioned is shown. The field sketch number and locality are omitted on the more recent tabulations . (3) Geodetic Positions -.Positions given to five decimal places of seconds are for computational purposes only and are not an indication of the accuracy of the point . 0>r J CO (MO ooP IHiHg W Q oss: sag teSSS *s 01 II h- ■ «; 8 lis -i II < s£ £ II O N a: O 3 u9 lis 5 ! * * o o ii c?o 4) m § o o 0» 0- o o I < < h-S |3o33 O.Q*-.m il'O^flO H«±> SEO H « o 3 aSh? H o e« *> h 3d ae -xos nQcomct dO> h a^-o «t.c a> hohko • Hfl d *-i o O O > to . +> KO Inm* •! "*H B t, O •) « 95 +> H H 0« • H • o M « e 29HSHI< QOHOS • «g <| §&§* l"3S fl .SS$2 gcSS . — - e «j o >« ■a ««h -«t) a i « ow •CO O-O ■q«)+>«0 HJelnS +» +>+> a • a +> i a^n«6Jh oo o o«.m o •OOO 3h H+» O fl T> OCCOMfl diaBM MO +>HHNe VlHtH^jjO M X COCO JJHH Si K 1 pit HO 6 CT]«H O UflU +»•< «u\ • «o+» HP. ct, no ti oa.edd3.piiH •* oico ;fr h m K . »m-h» en jq3aa.fi.atq f>»voo+> »d X haU'Vhj wC« hOhS«« XO aaoase _Ojq n ja - < AH •> o n o > «h«h 4CI< «t t) sso-. «•> oonejaoao hwohoo sbjs o ae SriMBUiafl ■Hja«JrH®j3 .... 3J3n Sh COX 35«10(-,C« Og OMS5BSBSBflJ3 COXA CO ► % Mtj*-i,a mo o nxop a a oh B5S35W ii Dak tJ^H«o^m< ■onuf • • • .<3w DA Do M« - H-0 a oi-i3cb5c6 • • • ••• o« • o e c|.g|S|««lf,H 0OO(«««KWW >gg >M « 5 p. ii!X»o fl o C itvS^H T%r; ® d a) © 4* U. It 31 &x^-:i If.li iii $lm ^ Eh 5c(.bh o)+» ja 55 P, ojoBh-h ^ |5l s ||j8- + .'S5 + ,g *gd 3flto5. S 1 11.1] co o t, (3 t- o d d e b-h q oh 9 .. -3 a I" £«£+>+> § 9 3 O H I U Si* H .H« ill ad t(J HO ,* 5^ h.S|R oS *S +.5": -^'O s jl COWH HHO+» H +» CO B HHH H OVO Vl T° ! \ 5 HH l\ 3 O > t 8 ss is O^ON 8: S 5 III s 9x1 v * : 0">* ^ OHH'* 5*-04N w ^ ' §gj^S s D . 8(3JCS <»»OVOH in CM O^ M s ■ * 1, ■^■H'^iH 53 is r HVO^S fOHHCg s < + \ I RES *¥ a| § 1 6 \ in CM % JB g a S S o 3SSS o "SfdoSi* r "gsil^jg slsl si ii (4) Elevations - Values shown to one decimal in meters and to even feet were probably determined from vertical angles (trigonometric leveling). Elevations given to two decimals in meters and one decimal in feet were generally determined in the course of a leveling project or from a spur line run by the horizontal control party from nearby bench marks. Elevations determined in such spur leveling usually "carry the notation """"WYE LEVELING." Those which have no check are so indicated and the source of the data, if other than the NGS, is also noted. Due to policy changes remarks concerning the elevations are not always shown on the latest listings. A few words of caution must be offered with respect to these values. Vertical angle elevations can be + 5 feet or more in error relative to leveling control in the general area and many of those elevations shown to two decimals in meters are unadjusted values. The principal reasons for tabulating these data are for use in reducing electronic distance measurements and to furnish elevation control for those projects where accuracy is not critical. Whenever a project involves the need for accurate ele- vations, the State or quad diagrams should be examined to ascertain the availability of leveling control in the immediate area and then a request made to the appropriate agency for the data. (5) State Coordinates - The "X" coordinate is the value in feet which is referenced east or west of a selected meridian which has been designated as the central meridian for a particular zone. In order to keep the coordinates positive, a large constant value is assigned to the central meridian and in the State system the computed coordinate (X 1 ) is added to this constant value when the point is east of the central meridian and subtracted when west of this meridian. For the example shown, the central meridians for both zones have assigned values of 500,000.00 feet. The station is therefore 159,^10.80 feet east of the central meridian for the. west zone and 159,733.54 feet west of the east zone central meridian. The "Y" coordinate is the distance in feet north of some parallel of latitude which is below the southernmost extremity of the zone and generally assigned a numerical value in feet of 0.00. (6) 9 (or Aa. angle) - The angle between the geodetic and grid meridian and often referred to as the mapping angle. 12 These angles are applied with the opposite sign to geo- detic or astronomic azimuths to obtain plane (grid) azimuths. In this example, the coordinates are computed on the transverse Mercator projection and the mapping angles are identified as Aa (delta alpha) angles. Similar values on the Lambert projection are referred to as 6 (theta) angles. Another term, the (t-T 1 ) or second term correction may be computed and applied as an additional refinement, but generally it is quite small and usually can be ignored. However, the computations are rather simple (see reference no. :>, page ^ ) and where significant, they should be applied to the azimuths and angles in those projects where a high accuracy is required. Astronomic azimuths should also be corrected for the deflection of the vertical at the point of observation when such azimuths are to control higher grade projects. This correction is known as the Laplace correction and can amount to as much as 20" in the conterminous United States, but generally is considerably smaller. Values of 5 to 7 ' are not uncommon, however. The NGS will furnish estimated corrections upon request. Since these estimations involve, in many cases, a review of the local topography, reasonably accurate positions of the points from which the observations were made are required. Scaled values from USGS topographic sheets are usually satisfactory for this purpose. (7) Geodetic and Plane Azimuths - For the more recent listings, the number of azimuths listed is limited to those required to compute the azimuths of the marks and objects given in that portion of the description or recovery notes known as the "box" or "box score". In earlier versions, all geodetic azimuths and distances from the station were shown, but the revisions of these data necessary to keep the listings up-to-date became too much of a costly burden and the practice was discontinued. It was felt that with the availability of electronic computers, these data could be easily computed and their elimination from the format would cause little inconvenience. (8) Descriptions and Recovery Notes - Anyone using a station to control a survey should verify the descriptive and observational data contained therein to insure that a recovery has been made. Any discrepancies should be reported to the NGS or the establishing agency if the data were not obtained from NGS. 13 The "DIRECTION" shown in the box does not refer to a compass bearing but to the angular direction from the initial point taken in a clockwise manner. The direction to the initial point is usually assigned a value of 0° 00 ■ 00" 0. The angles between any of the other points are obtained by differencing the directions involved. All points shown in the box, with the possible exception of the initial point, were visible at tripod height at the time the descriptive information was prepared. When the initial station carries the notation VG (visible from ground), it too can be observed from tripod height. (9) Additional Explanatory Notes - When a point has been determined by procedures which do not provide a check, the notation "NO OBSERVATIONAL CHECK ON THIS POSITION" appears under the Source . The agency making the observations, if other than the NGS, is identified by the statement "Observations by " which immediately follows the station name. Other appropriate comments are added below the azimuths when considered necessary to explain particular circumstances. In general, only the date of establishment is shown but on occasion, especially in crustal movement areas where new positions have been determined, the original date and date of the new observations used in the new position determination are noted. "Litho" Type Format : The old style horizontal control listings, commonly called "lithos", involve, as noted previously, separate sheets for the geographic positions, plane coordinates, descriptions and recovery notes (see Figures 5* 6, and 7). There were some advantages to this format such as the availability of all geodetic azimuths and lengths and the data were assembled in a more orderly fashion with regard to the actual route of the survey and the area covered; but these advantages were more than off- set by the numerous sheets of paper that were required to complete the compilation of the data for a point. In the early forms used for this type of listing there were other disadvantages; the order of accuracy, for example, was not indicated but generally it could be ascertained by a review of the data as follows: lh in 15 ^ I en iii Sc z Q a: o o u z < -J Q. in \ti. —rr n; 5 I g il i i! ■Ht- ^3 1i i i i a a 8i I 5; 1 ; I ! $ *1 4 ! ml H M! I<3 I Oj OT ^j 1 fil 1 0): «a i j I! ! ■4-i- .1 ! ! si i 33 I 3 3 I : IT* ! ! HJi I J i 1 .8 i Si ri - — i — j. i ■ •* O: | to! 10- 3^ fii ! I XI i 1 1 8 g| £ I S J Si-, jSigi Si i g ^ til i A i I : Si I S| j 13! ! VD lb UNITED STATES COAST AND OEODBTIC SURVEY Deso-lptlons of Triangulatlon Stations Shady to Lily, Florida . WOODS (Marlon County, Fla.,H.C.IY.,1933)--Thla atatlon Is about 4.S miles S of the oourthouse In Ocala, and about 250 yarda W of the Orange Avenue msoadam road, on land owned by W.E. Woods, who lives about 0.2 mile S of the W side of the road. The station Is on enolosed timber land, about 200 yards W of a partly built rook foundation, on which Mr. Woods Intends to build a house. It Is on the highest part of the hill, about 75 yards N of the edge of the oleared, cultivated land. The station Is 41 feet W of a biased oak tree, and the mark projeots 8 Inches. SurfBoe, underground, referenoe and azimuth marks are stand- ard bronze disks set In conorete as described In notes la, 7a, and 11a. Deference mark No.l Is ESE of the station, 10 feet from the road leading to the station and 13 feet WNW of a pine tree whloh is slightly to the right of an exteneion of the line between the station and the reference mark. The mark projeots 8 Inches. Referenoe mark No. 2 Is SW of the station, and about 30 feet from the edge of the clearing. The mark projects 8 Inches. The azimuth mark Is N of the station, 33 feet E of the oenter line of the Orange Avenue road, and projects 8 inches. The mark is 0.4 mile N of the entrance to the Btatlon, and 2.2 miles S of the point where the turn into Orange Avenue is mads. To reach from the courthouse In Ocala, go S 1.8 miles to the Orange Avenue cross road, turn right (S) and go 2.6 miles to the rock foundation mentioned above. Turn In here and follow the dim road around the foundation to the top of the hill, and the atatlon. A 116-foot tower was erected first, but the line to MARTEL was obstructed by a ridge about 1/2 mile W. A 136-foot tower was neoessary to clear the line. OBJECT DISTANCE DIRECTION HOTEL feet o 00'00!0 R.M.No.l 134.72 81 SO 55.4 R.M.No.2 129.68 182 43 11.2 Az.Mk. (Approx.) 0.4 mile 340 54 28.2 OBJECT DISTANCB WOODS feet R.M.No.l (S) 114.06 R.M.No.2 (W) 180.05 DI RECTI OH 0°00'00!0 197 57 45. 306 35 66. WHITE (Marlon County, Pla.,H.C.W.,1933)--Thls station Is about 13 miles SSW of Ocala, In open timber land and on the highest point of a ridge. Surface, underground, reference and azimuth marks are stand- ard bronze disks set In concrete as described in notes la, .7a and 11a. Reference mark No. 2 la N of the atatlon and projeots 7 Inches. Reference mark No.l Is SW of the station end projects 8 lnohes. The azimuth mark Is about 0.2 mile N of the station, 174 paces SE of the two blazed trees marking the trail, 37 paces S of the sand road and projects 10 Inches above the ground. To reaoh from Ocala follow U.S. Highway 441 to the intersection with Orange Avenue, which Is about 0.2 mile S of the Seaboard Air- line railroad underpass. Follow Orange Avenue S 10.4 miles to Danks Corner. There la an old church on the W side of the high- , way and a small store on the E side. Turn W on a sand road and go 1.1 miles to a road leading SW through the woods) there Is a oross road at 1.0 mile. Follow the road SW 0.7 mile to a E-W road at the SE corner of a oleared field and wire fenoe. Turn W and go 3.7 miles to two blazed trees on the S side of the road. One tree Is a pine and the other Is an oak. Turn 3 and follow the blazed trail 0.25 mile to the station on the ridge. The mark Is 24 feet SW of a blazed pine tree, 18 feet S of a 10-foot stump, 30 feet N of a leaning oak tree and projeots 5 lnchss above the ground. OBJECT DISTANCE DIRECTION STOKES feet COO'OOlO R.M.No.2 178.62 43 33 24.0 R.M.No.l 199.72 292 46 46.8 Az.Mk. (Approx.) 0.2 mile 68 48 28.9 Height of telescope above station mark - 116 feet. LUCIUS (Marlon County, Fla. , H. C. W. ,1933)—Thls station Is about 11 miles S of Ocala, 3.7 miles by road SW of the Belleview railroad station, 0.2 mile N of the macadam road leading from Belleview SW to the Orange Avenue macadam road, on the highest point of a hill, in open timber land and on property which has been taken over by the State for taxes. The mark is about 250 paces E of the farmhouse owned by Mr. C.E. LucIub, 276 feet E of the private road leading from the highway to the farmhouse, 22 feet SE of an oak tree marked with a triangular blaze and 19 feet NE of a large oharred stump. The mark projects 5 inches above the ground. • Surface, underground, reference and azimuth marks are stand- ard bronze disks set in ooncrete as described in notes la, 7a and 11a. Reference mark No.l Is N of the station, 96 feet E of the private road and projects 12 inches above the ground. Reference mark No. 2 is S of the station and projects 12 Inches above the ground. The azimuth mark is 0.15 mile S of the station, 36 feet N of the "center line of the macadam road, 27 feet W of a ooncrete culvert and proJeot3 12 inches above the ground. To reach from Ocala follow U.S. Highway 441 S about 3 miles to the Junction with a macadam road called Orange Avenue. Thia is about 0.3 mile S of a Seaboard Airline Railroad underpass. At the Junotlon there is a filling station on either side of U.S. Highway 441. Turn right and follow Orange Avenue 9.4 miles to crossroads. A maoadam road leads E and a graded sand road W. Turn E and follow the macadam road 2.5 miles to the private road leading N to the Luolus's home. Follow this road N 0.2 mile to a blazed oak tree at the point where the road swings sharp left. Turn right and go 276 feet to the station. OBJECT DISTANCE DIRECTION WHITE feet COO'OOSO R.M.No.2 180.00 22 31 42.2 Large White Bldg.(S) 2.5 miles 228 26 R.M.No.l 144.09 273 53 21.9 Az.Mk. (Approx.) 0.15 mile 273 46 57.6 Unpalnted bungalow (S) 0.2 mile 317 13 Height of telescope above station mark - 116 feet. LUCIUS (Marion County, Pla.,H.C.W. ,1933) J. S.B.,1936)~Station mark, reference and azimuth marks reoovored in good condition. Reference mark No.l la S of the station instead of N as originally described. Reference mark Ho. 2 is W of the station instead of 3 as originally described. The azimuth mark is S of the station as desoribed. There is an srror in mileage In describing how to reaoh the station from Ocala. It should be made to read as followsi To reach from Ocala, follow U.S. Highway 441 S about 2.0 mllea or 0.2 mile S of the Seaboard Airline Railroad underpass to road forks at a filling station on either side of U.S. 441. Here U.S. 441 bears left and a macadam road called Orange Avenue tums right (3). Turn right and follow Orange Avenue 9.4 miles to crossroads. A macadam road leads E and a graded sand road W. Turn E and follow the macadam road 2.5 miles to the private road leading N to the Luclua ' home. Follow this road N 0.2 mile to a blazed oak tree at the point where the road swings sharp left. Turn right and go 276 feet to the station. LUCIUS (Marion County, Fla. ,H.C.W.,1933;E.B.L., 1937)— Station was recovered approximately as dsscrlbed. Marks in good oondltlon and undisturbed. Correoted description as followsi About 11 miles S of Ocala, 3.5 miles SW of Belleview, 0.2 mile N of the macsdam rood leading W from Belleview (at Junctions of U.S. Highways 441 and Florida 23) to Orange Ave. At the highest point of a smsll hill, in open timber land which has been taken for taxes. The mark Is 200 yarda E by N of C.E. Lucius ' home. 270 feet ENE of sand road leading to the Luoius home. 19 feet N of a fire blackened atump, 3 feet high, 22 feet SB of an oak tree marked with a triangular blezo. Mark, note lb, projeots 6 inohes. Reference mark No.l is S of station, note lib, and projeots Reference mark No. 2 is a standard disk sot In oonorete as da.icrlhed In note lib, is W of the station, 30 yards E of the conter line of the sand road. It. projeots 12 inches. WHITE (Marlon County, Fla. , F.C .W. ,1933;E.B.L. ,1937 )— Station, reference and azimuth marks recovered as described and in good oondltlon. TURNER (Citrus County. Fla lng on W side of Wlthlacoochee Turners Camp. It Is 121 feet palmetto on high-water line on edge of live oaks. Mark proje Surface, underground, ref G.L.A., 1934)— Station is in oleer- Rlver, and about 0.5 mile N of of road, 163 feet W of prominent bank of river, 170 feet S of ence and azimuth marks are stand- oncreto ao described in notes lb, 7a and lib. Reference mark No.l Is 7.5 feet E of road, 93 feet W of high- water line, 52 feet S of palmetto. Mark projects 3 inches. Reference mark No. 2 is 9.5 feet S of twin-oak in N edge of clearing, 102 feot W of road at entrance to woods, 146 feet W of high-mater line, and projects 6 lnchos. Azimuth nark Is 3 feet NW of wire fence, 8 feet SW of 12- lnoh ash, 55 feet HE of 12-lnch sweet gum tree in fenoe oorner, 160 feet E of road, and projects 4 Inches. To reach from courthouse In Inverness, go NW on U.S. High- way 41 (Main Street) 0.66 mile; turn right on paved street and follow macadam road to its end and continue on sand road, follow- ing main-travelled way for a total distance of 7,7 idles to Turner's Camp on Wlthlacooche River. Just before entering oamp turn left at large pine tree and follow dim trail through fer.oed lane for 0.6 mile to olearlng on left and station. DIRECTION 0°0O'0O!0 79 22 12.7 220 01 48.4 Az.Mk. (SSE) 0.15 mile 254- 02 34.6 A 126-foot tower saw stations CASSA and LIVEOAK, but failed to see LECANTO. TURNER (Citrus County, Fla. ,0.L.A.,1934jE.B.L., 1937)— Station and all marks recovered as described and in good oondltlon. Additional doscrlption followsi Station is on ths W shore of the Wlthlaoooohee River, near the N tip of a small triangular clearing, on a slight rise at the N end of a double row of palmettoea, 60 feet N of the taller of two palm treea, 62 feet W of a 4-foot burned out snag, about 65 yards E of edge of river swamp, about 90 yarda W of the high- wator line of W bank of river. Mark projeots 4 Inches. OBJECT DISTANCE CHASSA feet R.M.NO.2 (N) 168.26 R.M.No.l (ESE) 152.56 Figure 7 IT WILDWOOD (Sumter County, Fla., E.B.L., 1937)— Station is about 2.7 miles by road WNW of Wlldwood, near the house of and on timber land owned by Mr. Caruthers. Mark lies 22 feet E of oenter line of woods road and 22 feet SW of triangular blaze on 22-inch pine. It projeots 2 inches. Surface, underground, referenoe and azimuth mark* are stand- ard bronze disks set in concrete as desoribed in notes la, 7a and 11a. Referenoe mark No.l ia located NW of the station, 6 feet SSB of a 20-inch pine, and 17 paces W of the center line of the woods road. It projects 4 Inches. Reference mark No. 2 lies S of the station, 10 yards B of tha oenter line of the woods road and 8 feet ESB of a 16-lnch pine tree. It projects 4 Inches. Azimuth mark lies on the dirt road 0.46 mile W of the lane leading to the Caruthers dwelling. The mark is 8 yarda H of tha osnter line of the road and 65 yards B of a sand oross road. It la 45 yards NNE of a small pond and projeots 6 lnohes. To reaoh atatlon from Junction of Routes 23 and 36 In Wild- wood go W on Routs 36, 2.2 miles to a sand T-road going N. Turn N and go 0.45 mile to point where road turns W, oontlnua M past Caruthers dwslling and through gate into woods. Station lias 98 yards N of gate on E side of woods road. OBJECT DISTANCE DIRBCTIO" SUMPTER feet 0*00 'OOlO Ae.Mk°* (Approx.) o'.S mile 72 84 64.6 R.M.No.l 91.69 128 00 48 Height of light above station mark • 34.7 meters. 31 meters. First-order - azimuths to hundredths of seconds, logarithms of the distances in meters to seven places, and the distance in meters to two decimal places. Second-order - azimuths, logarithms, and distances to one less decimal or significant figure than for first- order points. Since surveys made to third-order accuracy were also listed in the same manner, it is occasionally difficult to determine the accuracy of a particular point. Any problems which may arise in this regard would generally be in the coastal regions because units other than geodetic parties may have performed the surveys. Geodetic parties seldom, if ever, perform surveys to less than second-order specifications, except to locate certain structures. But photogrammetric or hydrographic support units often establish control only to the accuracy required for the particular project involved and these accuracies may be third-order or even less on occasion. Data for surveys made to less than third -order require- ments are not published, however. In those cases when the accuracy of the control is an important consideration in a project requirement and there are any doubts whatsoever in this regard , the NGS should be consulted prior to beginning field operations. A further discussion of the accuracy of the control will be made later. Intersection points such as water tanks, church spires, etc., with very rare exceptions are always located to third- order accuracy. No check points in this listing format are given to hundredths of seconds in position and to even feet for. the State plane coordinates . Field Positions : At the conclusion of a field project, lists of geographic positions computed from the unadjusted observations and lists of descriptions and recovery notes are prepared and published. The listing format is very similar to the "litho" type and all the data are printed on yellow colored paper (Figures 8 and 9). These positions must be employed with care since the values, regardless of the number of decimal places shown, have not been processed in any manner to remove or distribute the closures other than those involved in the triangles. The general practice is to initiate the computations from one published line and proceed in a continuous operation without 18 \ 1 \ \ i \ \ v £3 tx> to © r- vO en WACO o -4 O CM C-CM cm m so o cn-o OJ o CM CM o to CM o O CM CM O c- in en cm O rH in o enc- o en r-i O OCX to en CM en O vO en to H o O r-i cm rH o o vO o o to o o C- O O O Ovo rH C- r-so cm o r-i r-i r-i in c^- to c^ -^ in rH r-i tsj «* co <« CM o o eg « * r. w id ^ e-< 2 a \ \ ^ V \ in en en m to r-i r-i en rH O Q vO O m to o mrH i& ii CM rH in o -*«n rH en in in C^VO CM -* ^ CM CM en en CM CM O r-i r-i r-i O m vO vO CM m tO O in o vn o HsO en CM O H m 2* H o en CM O CM CM r-i O UN en en vO m J 4 m in 4H H to C-- 3$ oc^- >n cm r-i in c*- to \ \ ^ ^ \ F-N en \ \ ^ i ^ l ^ \ O-* o o to in o- o enr- ^3 vO in O O o in to mto cm en enc-rH r> in sO o vO to r-i O in r- (V04 o enr/- r-i cm CM to r> oc- o rH in en o en en cm mrH rr\r-i S3 into O »A ^ \ O en -J -^ o to into -*to in cm to o in o \ \ OCM enc— ^ CM en -* vO CM vO r-i r^^ &\ .v^ \\ r-i O O CM O to en \ o a-. M U \ en % 19 \ R o o o t- H o o o rH rH 2: § 3 o OQ o \ a c oi " <« '•> * • h -'1 • -h o a o -v) is i* tj c ti 4* n o >>.« ;: o t> oi -o a; >. v. . « . o -.'; t -\ v. i.', 4 ' s. ~: r*i o v p *' p p u> ♦-» ^ xi vt o a p ri -u c- it '.. >: y J-. ',' . li xi » u c-- U u <.. a ii d r: D »( .: noiiOu-iN hko« > a .c o a .c v. c .-I r- >, ■) ii a 3 (. o o .•* v. i: r. a c t: -i p a -o o 1 >n ~ o o «j o a w io *> o •« a-i>o*' «.-: a :-.- *> >. u,-.h ..••.. m c »< « q p i • c o OOP - O ft o .-i p c a C C "J o n .h p c o o a -* p . ojo • S D ") Q < 3 t0 (h -P O P. O I c £ «i s n o 3 o H o > .c -m r> Q a . ' O tf c c ocx> a o o j ) CO > * % a 3t)aooo c v. £ a a m^-o o -h m o m . O rHWOr-PWC^ Dl"-!l J-, 01 4) -P .-I a G } rf i,Orf£ o a v> h£ ofl«3N ««fl«f< ••a 4JHJV-. 01£KI>iH(J»Nt)Jl o OCCMPOO.CICOO eg ii c cm oaa.(lhMlHHhC600 ■ U «l 3Hw • K gOOHXOII(£ S--l0)O^iP^iC M !( « O ia U ho .c \ «>.p d >> Odpm nisKoitti v< +> t> v. « v o .c -p o, ±> u p o x -h cmn 4) 3 no hov-o m-ce :>j 1 *>-fr*u*-<'S)xunv x • • s c « -h co o) «4-i 0.0 J a *j -P p +> -p a o ^J *» v. -P -P I o«i o tihhSG N 3 la 4) nil () s^ss Moj i>-ao ikmh 03 «5 « as P-t> OO. acOP- 5 ; 3 .5 hi? x: ^1 j -p v. 3 ' ii 1= O .H OU3- c h a o jc 1 i>- 4) n c <: £ to 4J i* o a) n a) £ >AC0 3 £ O M 4-> M 5 T3 O •»■< a w) »-p c co o< S C 3P ONM ii„o 11 kh 00 -ogto : o h 1 M b£i o a 1 vr\og l>-i>- >>^IVA co • . . . .0 I O i-i o-vrv ~~\ — r M 4) O 01 4) a £ U *-l tt)4J ..■O £tl 0£t) « ?4) o c use j wt: jJ3U)wuia tc-dotD-po -p m c -Haa- -A ' o waoo cp j5»ojS4>M*;*j ,H P 4) >-• P<» 01O M 4) a 4) O O iHjSrliAO*) 4)X:«0 30.J334> Si 4-.tC-^u^tt)a PUa H frUnV.!] o«) M own Ms. ewe oio vo n-dai O03amQ(»-i Qo^o- a ^ijso-ri-jpacp • 4>c^ ^^ooo-oo aoNpo rt»H3 OOJCO »(>£ C--J g'-ja^rHiUH <„Hi.cot:.E.Hf-i ta 3ijrtpr^op^.o .sjoocxoa oo^tn r-i ,-1 <\ji, ^ m v. 0)3 a a »>xj -o-jcotu p\4)l!Pi:04) JT I OHliirttltH^Hrf C 3 C Tl h c o ■-< ax) o -h •-< -a 4) ■ d-P o 3 CO. c pa 1 C U O 4) MP o m.c a rH a o ( n £ >> < Kh^n «l i"S S S 3? °i-, .i «) - • c> U • -P M • C - 4) <„ MMowaaocaoviXv.o <« «ii(M>oa»«Bnoii o a4>- c ° oav. MHMV.P4) or magnetic tape. A sample listing is shown in Figure 10. Astronomic data are available for more than 2,000 stations in the U. S. and territories. The data are maintained in a card file, one card for each station. Copies of the cards are furnished on request, and contain final results in latitude, longitude, and azimuth; precision figures; and deflections of the vertical where available. A sample data card is shown in Figure 11. Much of these data are now available on computer listings. Anyone considering the observation of astronomical azimuths should consult the following references prior to initiating operations. Further details with respect to the authors and sources will be found with the list attached to this paper. IS! 1) Astronomical Azimuths for Local Control 2) Ephemeris Time and Universal Time 22 3 3 3 o a x 3X1. I- 3 < Z < -I D > UJ a o m ;> o o *- UJ O i/1 «* t/1 t/1 ■Q OJ UJ ac O wo CJ VI UJ o CD Ct 4 a u. o UJ > a UJ CD CJ z o < > UJ -1 z 3 a. >- UJ u 3 IS z o -j o 3 t- 3 3 3 U DQ X a jj J. jj z JJ J. at - ct u >- « a. u z >- a. u z 4 1/5 < >- - hi < UJ - UJ X IN D IN CT o p-l a IN ■a- o CD 1 D CO N do 1NJ m u m in >u INI tr M O - M cr CJ CJ 00 1 o o 00 IN 00 n j N N n N D 3 M N CJ O o C CO N OO M m O M m CO IN o IN r\j rg -> J 1 so » N m O n IN O m o IN PI (N IN O in IN O 00 1 oo IN 00 rg o n N N N n ■1- N ao cj DO OO N uu N in O IN IN r- 1NI o •c •T IN sr IN IN IN 3 CO CO oo IN o n IN m ~f f~ n IN + ■J O V IN N O >T m u so oo IN OO IN m cr IN lO IN ♦ o co n ■3" IN pi rsi O tr eo o> oo k\j r> o IN *> IN ♦ 3 CT <-> O OO 0> OO IN 2 hi o ui N o IM * ■J- IN CJ 0U CP IN CO IN 3 in o N !N l«l o 00 I*! 3 OB C N X^ 4j o Jl M «o m rvi id IT + N IN O fi OJ IT- CO O n o n IN rn r> o INI XJ l_> ST l"tl CJ 1 o IN O li> a ^0 (M ro r- O 00 00 N ^ - o rsi in UO rvj m CM o m OJ •T (M fN (J CN o m rs) CNJ IN O o PI 00 CM m O 0 CN «r CN CJ PI o 1 fl CN in CN O rn o + o CM CJ «T fNI CJ fcr- 00 CO IT r» O + cr co IT CJ ■*■ «c tj CM CO CO I'd -v o m r- <* * CO CN CT '_■ 1''- r> ■: ' CN 00 1 PI 00 + NOAA form 76-49 U.S. DEPARTMENT OF COMMERCE OCEANIC AND ATMOSPHERIC ADMINISTRATION Quad. . 29O8I2 siate . Florida L. S. Baker ASTRONOMY, ABSTRACT OF RESULTS LATITUDE station . . .PAV9RETTA 1954 chief of Party observer. R. . B.._Gassett Date 26 Sept . 1962 PRELIMINARY FI^AL INSTRUMENT n6. CHRONOMETER MOT Mean Observed Latitude ?9.\ .22 .' 06 .51. ..".,* 0.08 . . .T ? 4 J_31l4 _ . Reduction to Sea Level ( m.). .Q«QQ. , No. of Observations Variation of PoleC. . I ,0 ,1968. BIH - .10 Eccentric Reduction— in Latitude . . . .TY?.?4- O ' " Astronomic Latitude ( A ) 29 22. Geodetic Latitude (0 G ) ?9 °. 22 ' . . . " . . 04. 404 .....7897 ( Accepted. . 16 j Rejected Q . . in Longitude +1.24 06.72 * .0,08. .wM?::±::m* A *:::. Deflection in the Meridian ( A - g) . .-. +2 • 42 (X .) 8l 11 06 .809 (A G ) Remarks: N 0ne + .007 + .102 FAVORETTA 1934 LONGITUDE Station Observer.. R:.B..GaSSett PRELI ( Time ?! . 2/P ^ L - , ,r, L. S. Baker .Chief of Party Date* 0ct ' ^62 FINAL INSTRUMENT NO. 44 s .29& S .008 T-4 33114 CHRONOMETER NO. 7897 Mean Observed Longitude 81 11 Eccentric Reduction— in Longitude^ Variation of PoleC.vI.vO.a968. BIH Astronomic Longitude (A A ) 81 11 Geodetic Longitude (A G ) bl . .11. Deflection in Longitude (A A — A G ) Deflection in Prime Vertical (A A — A G ) Cos cf> " " NO. OF SETS 04.47 ~ 0.12 4 +l;2h in Latitude . +P.-.? 1 . ... . + .91 o5:v2' ± o:i2 Cos0 .8715 06 .809 (0 . ) . 29 ° . 22 '04 . 404 -1.09. None -.003 + .102 FAVORETTA 1934 Station . Observer. .?... C .. Howes < .N. E . Matlock S. C. Miller "i48 05"'" Mark WELCOME 3 Date_...^..l?.??*;.l?.62 Chief of Party. Mean Obserred Azimuth Diurnal Aberration Elevation of mark ( m. ) Eccentricity Variation of Pole C .1 .0 .1968 BIH o Astronomic Azimuth (a A ) 148 05 . . . .Instrument_No. . 05.66 ± 0'.'24 T-3 53077 No. of Observations Accepted . . ?1 (A A -A G ). . T 1 .'??.. . . ,(A A -A G )Sin<£. +P.-3.2. . / Rejected .0.00 Sin 0. ...49.04 Cos0.... -99 (0 6 ) • • ?9 .°. . 22 .'. .04 . 404 . -.'97. . (A G > . . §?-.°. . A 1 . .'. .96 r?&9 05.91 ± 0.24 (q.) .....° ' "... -0.53 («»-a 8 ).; Cot . Laplace Azimuth. . . . 14$ 05'. ...95:58; _ (a A -a G ) Cot Remarks: None x - -.042 y = +.110 Figure 11 24 ACCESSION NUMBERS 8'/ 2 A l^D^ Vol. 18,19 G-12984 A -3047 JSCOMM-DC 34242-P71 Vertical Control Data Quad Type Format : Figures 12, 13, and 14 illustrate the format used in tabulating Vertical Control Data on the quad system. The line numbers do not correspond to those shown on the State leveling diagrams or necessarily the same as that assigned when the line continues into adjacent quads. In crustal movement or subsidence areas, several elevations identified by the year in which the observations were made are often listed for each bench mark. Listings by Lines : In some States and localities within States which have not been completely converted to the quad-type publication, leveling control is published by lines whose numbers correspond to those shown on the State leveling diagrams. This format is quite similar to the quad type and no examples will be shown here . In the oldest listings there may be no route sketch included and the elevations are often tabulated with the bench mark descriptions rather than in separate lists. Also, for all types of listings which follow this general format, when a line extends into another State,, the line number may not be identical. Field Elevations : Unadjusted field elevations are generally available shortly after the completion of a project. These data, as for any material that has not been verified or adjusted In the office, must be used with due caution. Accuracy of Horizontal Control Stations The accuracy of control points published as part of the national network is noted* on the listings of geographic positions or the data sheet for each point or can be ascertained. With few exceptions, stations forming the basic network have been established by one federal agency (the Coast and Geodetic Survey, now the National Geo- detic Survey, NOS) and since about 19^0 the standards and specifications employed have been continually upgraded for first- and second-order surveys. At the present time, all primary arcs and area networks are accomplished to first-order (1:100,000) standards. On occasion, supplemental surveys may be performed to second-order class I (1:50,000) standards, and in rare instances to 3econd-order class II (1:20,000) criteria. 25 as 5 s o a: o> o^ 1 (D bO lit '^ :■ :■ 26 > »°8 seas D K M O O eC O CH ii < _ ( pJ! -H 3 o o £ otno p -^> o o o o o ^££ PUJ s n e & j & < 0) ^o » y o 1.1 cogg |B§ ■P H CO •■ o I s ! o > Kb o ° u^ mHO .1 ra d co >>H < tjj< r^OT o o <" u c c * h ""' co Ll) > •a -p >h CD .o w •a o S> ~ g I- C ■* H CO in o •* en co h roco too r- m co tooioicoo o'oi co coooco ICJtO tONtO tO tO MHCJMOJ a to * o pl, u O ON CO H CO to o> co r*- cm to r~ to m cr> k) H to h ^ i^iOcnaiM cm i-i c O r- to in t^ to go -«* r- co co r- in OO-*m > t, c ft >v=f in — pco OdjHomai coioQ- ociQhEtji £Oi:ro x:c>>ood -m; HO103 t to S cu co ftS c t°H ro.c.c ro t3OO>><0. 01 II c ■ K) COIOIO INHNN H CMNCM INtOOIN en NNN.. O OOOiOcO co to co CO (C co CO t HU OUOMM HCMCMMM HON ( 27 o o CM CO o S8S <\i oo o r-l o o Eh W H 9CU 3 O-OO p 3 0)1->CL. «) -CH • fc. & s O CM o. o*>.cs:a-{Jis:voai 9JP O MP C 3 -H p fc. O.U-H P O co c o fc. cu 41.CM J3-C >0 P t j= tttf^il • ft P 01 OX 3 H^HTJ «*> « O ■H O C fc. -C CO e ciuep § n -g-o°5- 11 C5 4J J CO £ r- fc. CO tn.aj ■: * ~ CO r u-\ 41 -t fc, CO O C-J CO O H 0) -to «J a > .o « oi .c C001"0ft-H>,t04>ti4>i +JO M«£ 41-H CO j CfcpHU 4> „ S O O fc, -H fc, ft 1 ~ rH C O H : JC -o 1 CO C -P , «j i » 0) *j co j l,» . *>h e ni «) O 2 S •> -H.C ft [ C « S 4> B -PrH 5 5 t ft co ti l (I».1XH41C£ rH-H .p • CO M.P ■HQ fc. O -H a o -o cocm ^m a -c o to CO D-H O *3 o -h c o e «coU w '"e*' H HSO. C-h 4>u-\< m iH 6 <« = O r. • o 4> ° CJ 5 -H -P OON IB- * *> «> Cc\ p, ■5 1 "5 = urn ciCo' ; jo o j-paor-iJ!, S S - c r O C«-H m . ;5;o;t,t>i3<« , -p C Ss rH « 3 ft o' g». lot OH * ftp p U CO PI p 4) CO P -H M • 4> ' fc, e rH no. c-<« j O O -H 01 O < 9HQ fc. .* C CM O p . DrlO^ 01 O P C p J< SOP 4)n coo4>3c»4i a) en co js «: rH s: bej-s^p ^m 2 J^ 41 CO P 4) •- co « 4) 2 O O c I3IJ a CJ.HP«0 2C1 o a . o p W O r-| CO t, ^H J, S C « P tOO 4) §rH J< bJBS, ■j=«»0JO41 CO CO J3 ft «-* 3 I o fct o : r-i-a ^■o « -H - O I • C O >. J U XS ->flTi a) j« ' OD«4 P ft t, O 3 01 -1-01 co ■ 03 -cm 41 <« a ! J CO 13 -a O ti' o-c a p« t. J 041CM OPO 01POP coox;o]i>«i«liiActii) o» ssco co -ox:so> o s bomio -ocmpjCpo » ■= C *J3 •«* « Up £> s ', =H ««-H S 00 <«cp«c8jOj-; Ja U P 41 3 ft S f. 4>ooi.*oo41>.O C COO MC«H B.4 V«! 41 CO >.-H ok) . c ^P^PCV^Si - 41 CO . rl HI P CO CM X C I s ►. • CO£ C J= fci p CM CO p -rt t> -O < .0 CM 41 fc. rH C0H J= O C fc. O C P p P-H/041PT3 coBC c0413toc-CCGfc.CDO.0J cuco *> e 11 41 c t. ?r 1 3 O P jC-O CO 41 tbc p 41-H 3 fc. pSJ „J-o-Eg C0COt..C 41 pfc,p |»S°Ss > ,>4'^P*JP-03« $ cs5sS^? t *' H '0«H10J10 -- : •^•;*o.afcioisoftc«o 5 II (5 5 I O 3 > 41 ^ 41 bO I J? .(N^fcu 10 3 rHpdl in 5 p> . -jc p So Lj •oncJXiiHi.t) ^ TT 41 11 412PO. 41-H 4) l3 c 3<0.0 5-.o5 -H.Jcft;. g « 3 cu CO r<" a » u o = J4lgo_OC|H^ PC P-CC S T3 B 3 tbp "*> 41 CO CO O H ^BSI om^ ; i; : 2 : u > aio«i '( S^Sp-S CO O J3 rH 4) fc. aj 03 ,'M Prior to this time, most basic area networks were estab- lished to standards approaching first-order; but due to the lack of sufficient scale and a very slight reduction in the specifications, this work has been class!' field as second-order. There is little doubt that with the introduction of a few measured distances the majority of these area nets can be upgraded to minimum first-order standards. As presently adjusted, however, the relative accuracy of many stations may barely meet the listed standard and in some isolated instances perhaps less. Where such conditions exist, the cause in almost every case can be traced to the piecemeal manner in which the network was adjusted. Plans are underway for a new adjustment, and these results will much better reflect the excellent quality of the observations. For many years, in an effort to provide the local surveyor or engineer with convenient control, a large number of stations, supplemental to the basic net, was established along highways or other easy- to- reach locations. The observations involved with these points are generally of the same precision and quality as the basic stations and acceptable geometry was usually obtained; however, no effort was made to establish continuous chains. As a result, stations located quite close to one another, but not connected, may have relative accuracies somewhat less than the stated standard. At the time much of this work was accomplished, few local practi- tioners had the equipment or trained personnel to meet even these lessened standards, and there did not seem to be any reason for concern about the possible less -than - desirable relationship of these points. About a decade ago, however, with the increased use of electronic dis- tancers and quality theodolites at all levels of the surveying profession, it was realized this practice could no longer be tolerated and a decision was made to connect all points which were within a specified distance. This specification is known as the 20$ rule and is rather rigorously followed. Essentially the rule states that a connection will be made between two points whenever this distance is 20$ or less than the total distance along the shortest directly connected route between the points. For example, in Figure 15, VERONA should have %een connected to KOLLATH because this distance is less than 20$ of the shortest directly connected route, KOLLATH -HILT + HILT- VERONA. Similarly, a connection SAUK-MARXVILLE should 29 have been made since this distance is less than 20$ of the sum of the distances SAUK-REUTER + REUTER-R0BS0N + ROBSON-MARXVILLE . When a survey is made between two unconnected stations, an evaluation such as this should be made. Should the distance be greater than 20$ of the route as described above, satisfactory results will usually be obtained, but should it be less, there is a good chance that excessive closures may result. MERRIMAC HILT MINIX KOLLATH PITCHBURG (USGS) ROBSON Figure 15 REUTER AUK MARXVILLE Another method for evaluating the control in a locality is to measure lines of the network at every opportunity. By comparing these measurements with computed or published distances, the scale differentials can be determined, and often a better understanding of the traverse closures can be obtained. Whenever difficulties are encountered, the agency that published the data should be consulted . Often a review of the computations or a check of the field records can resolve or at least clarify a problem. On occasion, re- visions will be made to the published data when serious distortions in the network are uncovered by additional observations. When these recomputations are made, obser- vations secured by other organizations, private and public, will be included providing these data are furnished and were obtained by acceptable survey practices. 30 APPLICATION Geodetic data have numerous applications , some having little to do with surveying per se, but no effort will be made here to expound on this subject except to note that the results of geodetic operations affect most everyone's daily life in one way or another. The pub- lications given in the Bibliography contain numerous examples of the application of geodetic data. In a short presentation such as this paper, it is thought the pos- sible solution to a particular problem is more worthwhile than an enumeration of the attributes of geodetic control data. Accordingly, one of the major user complaints is the lack of orientation at a station site or the blockage of the lines of sight to the azimuth mark or some other point which could be used to provide orientation. On these occasions, the only solution would seem to be astronomical observations. In many instances, however, a variety of "tricks of the trade" can often be employed and the astronomic work may not be necessary. Figures 16, 17, and 18 and the accompanying text describe some of the methods that have proven successful. In addition to these procedures, there are numerous other geometrical and trigonometrical innovations that can be employed by imaginative surveyors. These practices would not be sug- gested for surveys where results better than 1:15,000 are expected, but could be used in higher grade surveys as a check providing good quality orientation has been introduced elsewhere in the traverse . In the examples shown in Figures 16 and 17, A is a point on a traverse terminating at control point FIXED. The line between FIXED and its azimuth mark is obstructed. An intersection point may be substituted for the azimuth mark in the example shown in Figure 17. Since this point would not normally be occupied, extra care must be exercised in making the observations, however. In this case a check of sorts would be obtained by using the traverse distance A to FIXED in the computation and comparing the computed distance between FIXED and the intersection point with that obtained from the published data. The triangle closures should seldom exceed 5" , 31 FIXED Azimuth Mark Refer to Figure 16 (1) Measure distance shown by two parallel cross hashes . (2) Measure angle at A. (5) Compute angle at Azi- muth Mark by side- angle-side computation. (k) To obtain the azimuth A to Azimuth Mark, apply computed angle at Azimuth Mark to grid (plane) azimuth FIXED to Azimuth Mark. In this example, the computed angle would be subtracted. Figure 16 FIXED Refer to Figure 17 (1) Observe angles as indicated by full lines - no distances are necessary (assume a distance for one line and compute other lines). (2) Compute angle at FIXED between Azimuth Mark and A by side-angle-side computation and use to determine the azimuth FIXED to A. Azimuth Mark Figure 17 32 In the example shown by Figure 18, A is a point on a traverse terminating at control point FIXED (l). No azi muth control is available at FIXED (l), but orientation can be obtained at FIXED (2). FIXED (l) and FIXED (2) are not intervisible, of course; however, the azimuth could be carried between the points through one or more intermediate points . FIXED (2) Azimuth Mark (1) (2) Observed angles as indicated; no distances between FIXED (1) and FIXED (2) are required. Starting with the grid azimuth FIXED (2)-Azimuth Mark, compute the grid azimuth FIXED (l)-A using the observed angles. The distribution of the azimuth closure should be made from FIXED (2) through FIXED (l) to azimuth control. 33 BIBLIOGRAPHY , Classification, Standards of Accuracy, and General Specifications of Geodetic Control Surveys, Federal Geodetic Control Committee, February 1974. Available from NGS , Control Leveling, USC&GS Special Publication No. 226.* , Horizontal Control Data, USC&GS Special Publica- tion No. 227 .* , Magnetic Surveys, USC&GS Serial No. 718.* , Manual of Second-and Third-Order Triangulation and Traverse, USC&GS Special Publication No. 145.* , Plane Coordinate Systems, USC&GS Serial No. 562.* , Sines, Cosines, and Tangents, 0°-6°, for use in computing Lambert plane coordinates, USC&GS Special Publication No. 246.* , Specifications to Support Classification, Standards of Accuracy, and General Specifications of Geodetic Control Surveys, Federal Geodetic Control Committee, January 1976. Available from NGS. , State Plane Coordinate Projection Tables (Available for all states except Alaska. Computations for Alaska are made using the 2^-minute intersection tables, USC&GS Publication 65-1, Part 49 for zone 1, Part 50 for zones 2-9, and Part 51 for zone 10.*) USC&GS Special Publications.* Tables are also available for most U. S. Possessions. , Use of Coast and Geodetic Survey Data in the Surveys of Farms and Other Properties, USC&GS Serial No. 347.* Adams, 0. S., Azimuths from Plane Coordinates, USC&GS Serial No. 584.* °idams, 0. S., and Claire, C. N., Manual of Plane Coordinate Computation, USC&GS Special Publication No. 193.* Baker, L. S., Specifications for Horizontal Control Marks, ESSA Technical Memorandum C&GSTM-4.* * Available through the Superintendent of Documents, Government Printing Office, Washington,' D. C. 20402 . 54 Brittain, J. H., Computation of Traverse by Plane Coordinates, USC&GS Serial No. 624.* Brit tain, J. H., Control Surveys and Their Uses, USC&GS Serial No. 583.* Claire, C. N., State Plane Coordinates by Automatic Data Processing, ESSA (C&GS) Publication 62-4.* Dracup, J. F., Application of National Geodetic Survey Practices to Local Control Surveys, New England Section ACSM Workshop, Rockport, Maine, November 1975- Available from NGS . Dracup, J. P., Fundamentals of the State Plane Coordinate Systems, presented to the 25th Annual Surveyors Institute, University of Wisconsin, Madison, Wisconsin, December 1973. Available from NGS. Dracup, J. F., and Kelley, C. F., Horizontal Control as Applied to Local Surveying Needs, ACSM Publication. Dracup, J. F., Suggested Specifications for Local Horizontal Control Surveys, ACSM Technical Monograph No. CS-1. Revised April 1973- Dracup, J. F., Standards and Specifications for Supplemental Horizontal Control Surveys, ACSM Proceedings, ACSM-ASP National Convention, Washington, D. C, 1970. Dracup, J. F., Kelley, C. F., Lesley, G. B., and Tomlinson, R. W., Surveying Instrumentation and Coordinate Computation Workshop Lecture Notes, ACSM Publication. Dracup, J. F., The Alaska Coordinate Systems, presented to the Alaska Surveying and Mapping Convention, Anchorage, Alaska, February 1975. Available from NGS. Dracup, J. F., Trilateration - A Preliminary Evaluation, ACSM Proceedings, ACSM-ASP Fall National Convention, Denver, Colorado, October 1970. Dracup, J. F., Use of Control for Land Surveys, presented at the Arkansas Association of Registered Land Surveyors - Arkansas Section ACSM, 5th Annual Convention, Hot Springs, Arkansas, April 1972. Available from NGS. Gossett, F. R., Manual of Geodetic Triangula t ion, USC&GS Special Publication No. 247.* Holdahl, J. H. and Dubester, D. C., A Computer Program for Traverse Adjustment Using Plane Coordinates, ACSM Proceedings, ASP-ACSM National Convention, Washington, D. C., March 1971. Documentation available from NGS. 35 PENN STATE UNIVERSITY LIBRARIES ADDD07DTm333 Hoskinson, A. J. and Duerksen, J . A . , Manual of Geodetic Astronomy, USC&GS Special Publication No. 237.* Kaufman, H. P., The ABC of Triangulation Adjustment, USC&GS Publication G-45. Available from NGS . Kelley, C. F., What Data? ACSM Proceedings, ASP-ACSM Fall National Convention, San Francisco, California, September 1971. Meade, B. K., The Practical Use of the Oregon State Plane Coordinate System, Proceedings of the 1964 Surveying and Mapping Conference, Oregon State University, Corvallis, Oregon, also available from NGS. Mitchell, H. C, Definitions of Terms Used in Geodetic and Other Surveys, USC&GS Special Publication No. 242.* Mitchell., H. C., Use of State Plane Coordinates in Route Surveying, USC&GS Publication 1950. Available from NGS. Mitchell, H. C. and Simmons, L. G., The State Coordinate Systems (A Manual for Surveyors), USC&GS Special Publication No. 235. Revised June 1974.* Poling, A. A. Jr., Astronomical Azimuths for Local Control, Surveying and Mapping, Vol. XXVII, No. 4, also available from NGS. Poling, A. C, Elevations from Zenith Distances (Vertical Angles), USC&GS Publication G-56 . Available from NGS. Rappleye, H. S., Manual of Geodetic Leveling, USC&GS Special Publication No. 239-* Rappleye, H. S., Manual of Leveling Computation and Adjustment, USC&GS Special Publication No. 240.* Reynolds, W. F., Manual of Triangulation Computation and Adjustment, USC&GS Special Publication No. lJ&J* Rice, D. A., Ephemeris Time and Universal Time, Surveying and Mapping, Vol. XIX, No. 3. Simmons, L. G., Geodetic and Grid Angles - State Coordinate Systems, ESSA Technical Report C&GS J>6 .* Tomlinson, R. W. and Burger, T. C., Electronic Distance Measuring Instruments, ACSM Technical Monograph No. CS-2. Revised March 1975. Thorson, C. W., Second-Order Astronomical Position Deter- mination Manual, USC&GS Publication 64-1.* * U.S. GOVERNMENT PRINTING OFFICE: 1976- 210-801/172 36