■ 
 
 ANIMAL MECHANICS 
 
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 ifttraca, Nero IJark 
 
 BOUGHT WITH THE INCOME »"F THE 
 
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 THE GIFT OF 
 
 HENRY W. SAGE 
 
 1891 
 
QM 24.B43 ne " Un ' Ver8lty Ubrary 
 
 , .Animal mechanics, 
 
 3 1924 024 561 692 
 
Cornell University 
 Library 
 
 The original of this book is in 
 the Cornell University Library. 
 
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 the United States on the use of the text. 
 
 http://www.archive.org/details/cu31924024561692 
 
ANIMAL MECHANICS 
 
 BY 
 
 SIR CHARLES BELL, 
 
 K. G. H., F. E. S., L. & E. 
 AND 
 
 JEFFRIES WYMAN 
 
 A. M., M. D. H. C. 
 
 CAMBEIDGE 
 printrt) at Wyt IKitonsio* $ttss 
 
 1902 
 
PREFACE 
 
 These Papers are selections from the writings 
 of Sir Charles Bell [1774-1842] and Dr. Jeffries 
 Wyman [1814-1874]. They are memorable ex- 
 amples of careful observation, sound reasoning, 
 and clear description of the objects of which they 
 treat. 
 
 They are reprinted as worthy the serious con- 
 sideration of all those in preparation for their life- 
 pursuits. 
 
 MORRILL WYMAN. 
 
 Cambridge, 1902. 
 
CONTENTS 
 
 ANIMAL MECHANICS, OR PROOFS OP DESIGN IN 
 THE ANIMAL FRAME 
 
 INTRODUCTION 
 
 Liability to pain and injury proves reference of human body 
 to mind 1 
 
 Protection not absolute; strength and surroundings corre- 
 spond; to be compared with things of human invention 
 for our better understanding 2 
 
 A balance between the power of exertion, and capability of 
 resistance in the living body ; the analogy not perfect . . 4, 5 
 
 An improvement in architecture accompanied by observed 
 analogies in the animal body 5 
 
 The architecture and carpentry of the head; the skull has 
 two plates for the protection of the brain 6 
 
 The Eddystone lighthouse not formed on principles so cor- 
 rect as those of the bones of the foot; nor the king-post as 
 accurate as the hollow bones which support our weight . 6 
 
 The growth and removal of the elements of the body to be 
 another object of inquiry 7 
 
 CHAPTER I 
 
 ARCHITECTURE OF THE SKTJIX 
 
 Brain to be protected from sharp bodies as well as blows; a 
 soldier's cap has a leather lining and » cover of hair for 
 protection as well as ornament; an infant's skull is soft; 
 
 a man's hard 9 
 
 Joints of skull dovetailed — like a carpenter's box .... 12 
 
 Figure of bones of the head 13 
 
 Inclined rafters of a roof and bones of the head compared . 15 
 
vi CONTENTS 
 
 The several bones of the sknll; how begun; assumes the form 
 of an arch 17 
 
 The cheekbones arranged like the flying buttress of Gothic 
 architecture; when a man falls, these buttresses protect 
 him and prevent what is known as thrusts; see figures . 19, 20 
 
 Fig. 5, section of St. Paul's, engraved by Hooker .... 19 
 
 The joining of the bones is secured in another way; one 
 bone is divided at its edge to receive the next between its 
 two divisions 22 
 
 Interior of the skull shows groins like joints of two meeting 
 arches. The base of the skull is strengthened .... 23 
 
 CHAPTER II 
 
 MECHANISM OF THE SPINE 
 
 The column which sustains the brain-case — difference in 
 pliancy and joinings; elastic material between joints; no 
 
 two bones touch — protects nervous system 25 
 
 Bones of spine 26 
 
 Curve of spine — why so curved 27 
 
 Comparison of mast of ship to spine 28 
 
 Fig. 6, connection of spine with pelvis inclined ; like a ship's 
 mast bends backward 31, 32 
 
 CHAPTER III 
 
 OF THE CHEST 
 
 Union of the breastbone and ribs, the joinings, by means of 
 cartilage, — save from injury ; movements of the chest in 
 breathing, inspiration and expiration 36 
 
 CHAPTER IV 
 
 DESIGN SHOWN IN THE STRUCTURE OF THE BONES AND JOINTS 
 OF THE EXTREMITIES 
 
 Most perfect shape combining strength and lightness — com- 
 pare a reed or quill and a bone; observe least possible 
 expense of materials 38 
 
CONTENTS vii 
 
 Fig. 7, illustrating strain in a piece of timber 40 
 
 Fig. 8. Form of a hollow long bone ; difference between bones 
 of spine and extremities in their composition to resist pres- 
 sure, Fig. 9, and strain 41, 42 
 
 Bone of a draught horse differs in weight from the bone of a 
 running horse 43 
 
 Bones have earth for withstanding shocks, fibres for tough- 
 ness, and cartilage for elasticity 44 
 
 (Cancelli of bones, to be treated of elsewhere, p. 99.) 
 
 Fig. 10 illustrates bones as a buttress 46 
 
 Cuvier's "Comparative Anatomy of Bones," Sir Charles 
 Bell's "The Hand, its Mechanism and Endowment, as 
 evincing Design," 1834 47, 48 
 
 Comparative anatomist: the inferences from a single bone or 
 a tooth 49 
 
 Same process of reasoning will determine the existences of 
 a fowl, a bat, a lizard, or a fish — affords evidence of the 
 former existence of animals not now found on the earth . 50 
 
 OF STANDING 
 
 Compare the standing of a statue with that of a man — me- 
 chanical contrivance for standing 52 
 
 OF THE FOOT 
 
 There are thirty-six bones in the foot, with as many joints 
 and cartilages, and they all have their surfaces regularly 
 oiled; their ligaments described, and process of repair for 
 wear, and how well they wear 55 
 
 The movements of the foot in walking, Fig. 11 57 
 
 Fig. 12, illustrating the arch of the foot and the elastic liga- 
 ment to give it spring — notwithstanding these move- 
 ments, when standing the foot becomes immovable; knee 
 and hip joint explained 59 
 
 Fig. 13. How a bird sits on its perch without effort — pos- 
 ture of a soldier under arms, one of restraint and painful 
 — the order "stand at ease " is a relaxation of muscles, 
 and a sinking down on the left hip. Fig. 14 and its ex- 
 planation 60, 61 
 
 Still further explanation, Fig. 15 62 
 
viii CONTENTS 
 
 Attachment of muscles to the thighbone which give it stabil- 
 ity, Fig. 16 63 
 
 The greater breadth of the pelvis in women requires a greater 
 turning out of the toes, and consequently of the whole foot 64 
 
 Comparison of the form of the thighbone with the dishing of 
 a cart wheel, and the reason for it. See Fig. 17 ... 65 
 
 The thighbone most nearly perpendicular when it has the 
 most weight to bear, Fig. 18 66 
 
 CHAPTER V 
 
 OF THE TENDONS COMPARED WITH CORDAGE 
 
 Where nature has provided a perfect system of columns, 
 levers, and pulleys, she gives curiously constructed cords 
 for their movements ; she spins better yarns and they are 
 interwoven. See Fig. 19, A and B 70 
 
 As the methods of splicing and plaiting in the subdivision 
 of the rope make » texture stronger than the original 
 rope, so is the animal tendon made stronger by the inter- 
 weaving with another strand 71 
 
 Of the breaking of tendons in advanced life 72 
 
 CHAPTER VI 
 
 OF THE MUSCLES — OF MUSCULARITY AND ELASTICITY 
 
 The muscles, the only organs which properly have the power 
 of contraction 73 
 
 Movement of the blood in the arteries kept up by their elas- 
 ticity; the cause of elasticity unknown 74 
 
 Muscles have a tissue of nerves 76 
 
 Muscles of the forearm, Fig. 20; third kind, weight and 
 velocity are equivalent; Fig. 21, power lost and velocity 
 gained 77, 78 
 
 Same principle holds in animal machinery; by acquired 
 velocity we drive a nail — so of the fly-wheel. Fig. 22 and 
 Fig. 23, illustrations of principle 79, 80 
 
 Action of oblique muscles in drawing together ribs, Fig. 24 . 81 
 
 Fig. 27, illustration of bending foot on leg 83 
 
CONTENTS ix 
 
 Relations the belly and tendon of a muscle bear to each other 84 
 
 Fig. 28, rounding of muscles in action — exercise unfolds 
 muscular system — thighs, legs, and loins of a dancer . 85, 86 
 
 New fashions of gymnastics for children; to throw limbs 
 over a bar, to hang by the arms, feet, and knees of doubt- 
 ful utility; useful manual training much better — boys and 
 teachers have been ruptured 87, 88 
 
 Development of strength should be gradual, as in training 
 horses for the Derby 89 
 
 Reflecting on these many proofs of design, it is surprising 
 anatomy is so little cultivated by men of science .... 90 
 
 The human body a plan drawn in perfect wisdom; its con- 
 tinuance is by a power no less admirable than that which 
 rules the heavenly bodies 91, 92 
 
 CHAPTER VII 
 
 BOOKS 
 
 Clergymen may derive from animal mechanics a sure means 
 of enlightening the understanding, elevating the views, and 
 awakening the piety of their hearers. Lawyers may find 
 in these selections facts of use in jury-trials in cases of 
 damages for injuries received on railroads or defective 
 highways 94 
 
 Lord Brougham's Estimate of " Animal Mechanics "... 94 
 
 James Russell Lowell's sonnet to Jeffries Wyman .... 97 
 A Roman carpenter's shop in the Christian era 98 
 
x CONTENTS 
 
 ON THE CANCELLATED STRUCTURE OF SOME OF 
 THE BONES OF THE HUMAN BODY 
 
 Very little attention given in works on anatomy to this sub- 
 ject with reference to the weight they have to sustain . . 99 
 
 Sir Charles Bell's allusion to the direction of the cancelli 
 in the neck of the thighbone not satisfactory; those of the 
 astragalus and os calcis are accurately described and fig- 
 ured 100, 101 
 
 Inferences drawn from the direction of the cancelli are that 
 they are to sustain weight, and in some cases have re- 
 ference to the erect position which is naturally assumed by 
 man alone 103 
 
 I. VERTEBRAE 
 
 Their functions a"e the support of weight, and to constitute a 
 series of levers for the application of muscular force . . 103 
 
 Fig. 29, showing direction of cancelli in plan where the pres- 
 sure is greatest 104 
 
 H. NECK OF THE THIGHBONE 
 
 Whole weight of the head, trunk, arms, and pelvis rests on 
 the two heads of thighbones 105 
 
 Size of angle which the neck makes with the shaft of the 
 femur. Bourgery and Jacob's description of cancelli con- 
 fused ; in his Fig. 31 is represented an archway which does 
 not exist 107, 109 
 
 Author's views, with his cancelli, Fig. 30 110 
 
 Mr. Ward approaches nearer the truth, Fig. 31; but his repre- 
 sented archway does not exist Ill 
 
 The cancelli of the bones as braces 112 
 
 in. THIGH 
 Its structure and the braces which support it 114 
 
 IV. ASTRAGALUS 
 
 Sustains in each foot one half the weight of the body, or the 
 
 whole of it when it is supported on one foot 114 
 
 Description of astragalus 115 
 
CONTENTS xi 
 
 Fig. 32, section showing arrangement of cancelli in the as- 
 tragalus 116 
 
 V. OS CALCI8 
 
 Bone transmits whole body to the ground, and is also one 
 of the arms of a lever by which the body is raised from the 
 ground under the influence of muscular action .... 117 
 
 Fig. 33, two series of cancelli 117 
 
 The os calcis of man contrasts with that of other animals not 
 only in size, but in its internal arrangement, so that the 
 anatomist can determine ex calce hominem 118 
 
 The difference between hypothesis and fact in determining 
 final causes. Note by Cuvier 119 
 
 The peculiar structure of the neck of the thigh and of the 
 astragalus seems to exist in man alone 120 
 
 The structure of these bones in relation to locomotion . . 121 
 
 Conclusion that the human skeleton deviates widely from 
 that of all brutes 122 
 
 List of Scientific Papers and Works by Jeffries 
 Wyman 123 
 
ANIMAL MECHANICS 
 
 OR 
 
 PROOFS OP DESIGN IN THE ANIMAL FRAME 
 
 THE PERFECTION OF DESIGN IN THE BONES OF THE 
 HEAD, SPINE, AND CHEST, SHOWN BY COM- 
 PARISON WITH ARCHITECTURAL 
 AND MECHANICAL CON- 
 TRIVANCES 
 
 SIR CHARLES BELL, K. G. H., F. R. S., L. & E. 
 
 Published under the superintendence of 
 
 THE SOCIETY FOB THE DIFFUSION OF USEFUL KNOWLEDGE 
 
C. Bell, Del 
 
ANIMAL MECHANICS 
 
 INTRODUCTION 
 
 To prepare us for perceiving design in the 
 various internal structures of an animal body, we 
 must, first of all, know that perfect security 
 against accidents is not consistent with the scheme 
 of nature. A liability to pain and injury only 
 proves how entirely the human body is formed 
 with reference to the mind; since, without the 
 continued call to exertion, which danger and the 
 uncertainty of life infer, the development of our 
 faculties would be imperfect, and the mind would 
 remain, as it were, uneducated. 
 
 The contrivances (as we should say of things 
 of art) for protecting the vital organs are not 
 absolute securities against accidents; but they 
 afford protection in that exact measure or degree 
 calculated to resist the shocks and pressure to 
 which we are exposed in the common circumstances 
 of life. A man can walk, run, leap, and swim, be- 
 cause the texture of his frame, the strength and 
 power of his limbs, and the specific gravity of his 
 body are in relation with all around him. But, 
 
2 ANIMAL MECHANICS 
 
 were the atmosphere lighter, the earth larger, or 
 its attraction more ; were he, in short, an inhab- 
 itant of another planet, there would be no cor- 
 respondence between the strength, gravity, and 
 muscular power of his body, and the elements 
 around him, and the balance in the chances of life 
 would be destroyed. 
 
 Without such considerations the reader would 
 fall into the mistake that weakness and liability 
 to fracture imply imperfection in the frame of the 
 body, whereas a deeper contemplation of the sub- 
 ject will convince him of the incomparable perfec- 
 tion both of the plan and of the execution. The 
 body is intended to be subject to derangement 
 and accident, and to become, in the course of life, 
 more and more fragile, until, by some failure in 
 the framework or vital actions, life terminates. 
 
 And this leads us to reflect on the best means 
 of informing ourselves of the intention or design 
 shown in this fabric. Can there be any better 
 mode of raising our admiration than by compar- 
 ing it with things of human invention ? It must 
 be allowed that we shall not find a perfect ana- 
 logy. If we compare it with the forms of archi- 
 tecture — the house or the bridge are not built 
 for motion, but for solidity and firmness, on the 
 principle of gravitation. The ship rests in equi- 
 librium prepared for passive motion, and the con- 
 trivances of the ship-builders are for resisting 
 
INTRODUCTION 3 
 
 an external force ; whilst in the animal body we 
 perceive securities against the gravitation of the 
 parts, provisions to withstand shocks and injuries 
 from without, at the same time that the frame- 
 work is also calculated to sustain an internal 
 impulse from the muscular force which moves 
 the bones as levers, or, like a hydraulic engine, 
 propels the fluids through the body. 
 
 As in things artificially contrived, lightness 
 and motion are balanced against solidity and 
 weight, it is the same in the animal body. A 
 house is built on a foundation immovable, and 
 the slightest shift of the ground, followed by 
 the ruin of the house, brings no discredit on 
 the builder ; for he proceeds on the certainty of 
 strength from gravitation on a fixed foundation. 
 But a ship is built with reference to motion, to 
 receive an impulse from the wind, and to move 
 through the water. In comparison with the 
 fabric founded on the fixed and solid ground, it 
 becomes subjected to new influences, and in pro- 
 portion as it is fitted to move rapidly in a light 
 breeze, it is exposed to founder in the storm. A 
 log of wood, or a Dutch dogger almost as solid as 
 a log, is comparatively safe in the trough of the 
 sea during a storm, when a bark, slightly built 
 and fitted for lighter breezes, would be shaken to 
 pieces ; that is to say, the masts and rigging of 
 a ship (the provisions for its motion) may become 
 
4 ANIMAL MECHANICS 
 
 the source of weakness, and, perhaps, of de- 
 struction ; and safety is thus voluntarily sacrificed 
 in part to obtain another property of motion. 
 
 So in the animal body : sometimes we see the 
 safety of parts provided for by strength calcu- 
 lated for inert resistance ; but when made for 
 motion, when light and easily influenced, they 
 become proportionally weak and exposed, unless 
 some other principle be admitted, and a different v 
 kind of security substituted for that of weight 
 and solidity : still a certain insecurity arises from 
 this delicacy of structure. 
 
 We shall afterwards have occasion to show that 
 there is always a balance between the power of 
 exertion and the capability of resistance in the 
 living body. A horse or a deer receives a shock 
 in alighting from a leap ; but still the inert power 
 of resisting that shock bears a relation to the 
 muscular power with which they spring. And 
 so it is in a man : the elasticity of his limbs is 
 always accommodated to his activity ; but it is 
 obvious, that in a fall, the shock, which the lower 
 extremities are calculated to resist, may come on 
 the upper extremity, which, from being adapted 
 for extensive and rapid motion, is incapable of 
 sustaining the impulse, and the bones are broken 
 or displaced. 
 
 The analogy between the structure of the hu- 
 man body and the works of human contrivance, 
 
INTRODUCTION 5 
 
 which we have to bring in illustration of the de- 
 signs of nature, is, therefore, not perfect, since 
 sometimes the material is different, sometimes the 
 end to be attained is not precisely the same ; and, 
 above all, in the animal body a double object is 
 often secured by the structure or framework, 
 which cannot be accomplished by mere human 
 ingenuity, and of which, therefore, we can offer 
 no illustration strictly correct. 
 
 However ingenious our contrivances may be, 
 they are not only Hmited, but they present a 
 sameness which becomes tiresome. Nature, on 
 the contrary, gives us the same objects of inter- 
 est, or images of beauty, with such variety, that 
 they lose nothing of their influence and their 
 attraction by repetition. 
 
 If the reader has an imperfect notion of design 
 and providence from a too careless survey of ex- 
 ternal nature, and the consequent languor of his 
 reflections, we hope that the mere novelty of the 
 instances we are about to place before him may 
 carry conviction to his mind ; for we are to draw 
 from nature still, but in a field which has been 
 left strangely neglected, though the nearest to us 
 of all, and of all the most fruitful. 
 
 Men proceed in a slow course of advancement 
 in architectural, or mechanical, or optical sci- 
 ences ; and when an improvement is made, it is 
 found that there are all along examples of it in 
 
6 ANIMAL MECHANICS 
 
 the animal body, which ought to have been marked 
 before, and which might have suggested to us the 
 improvement. It is surprising that this view of 
 the subject has seldom, if ever, been taken seri- 
 ously, and never pursued. Is the human body 
 formed by an all-perfect Architect, or is it not ? 
 And, if the question be answered in the affirma- 
 tive, does it not approach to something like infat- 
 uation that, possessing such perfect models as we 
 have in the anatomy of the body, we yet have 
 been so prone to neglect them ? We undertake 
 to prove that the foundation of the Eddystone 
 lighthouse, the perfection of human architecture 
 and ingenuity, is not formed on principles so cor- 
 rect as those which have directed the arrange- 
 ment of the bones of the foot ; that the most 
 perfect pillar or kingpost is not adjusted with the 
 accuracy of the hollow bones which support our 
 weight ; that the insertion of a ship's mast into 
 the hull is a clumsy contrivance compared with 
 the connections of the human spine and pelvis ; 
 and that the tendons are composed in a manner 
 superior to the last patent cables of Huddart, or 
 the yet more recently improved chain-cables of 
 Bloxam. 
 
 Let us assume that the head is the noblest 
 part ; and let us examine the carpentry and archi- 
 tectural contrivances exhibited there. 
 
INTRODUCTION 7 
 
 But, before we give ourselves up to the interest 
 of this subject, it will gratify us to express our 
 conviction that the perfection of the plan of ani- 
 mal bodies, the demonstration of contrivance and 
 adaptation, but more than these, the proof of the 
 continual operation of the power which originally 
 created the system, are evinced in the property of 
 life, — in the adjustment of the various sensibili- 
 ties, — in the fine order of the moving parts of 
 the body, — in the circulation of living blood, — 
 in the continual death of particles and their re- 
 moval from the frame, — in the permanence of 
 the individual whilst every material particle of his 
 frame is a thousand times 1 changed in the pro- 
 gress of his life. But this is altogether a distinct 
 inquiry, and we are deterred from touching upon 
 it, not more from knowing that our readers are 
 not initiated into it, than from the depth and 
 very great difficulty of the subject. 
 
 1 The old philosophers gave out that the human body was seven 
 times changed during the natural life. Modern discoveries have 
 shown that the hardest material of the frame ia changing con- 
 tinually ; that is, every instant of time, from birth to death. 
 
CHAPTEK I 
 
 ARCHITECTURE OF THE SKULL 
 
 It requires no disquisition to prove that the 
 brain is the most essential organ of the animal 
 system, and being so, we may presume that it 
 must be especially protected. We are now to 
 inquire how this main object is attained. 
 
 We must first understand that the brain may 
 be hurt, not only by sharp bodies touching and 
 entering it, but by a blow upon the head which 
 shall vibrate through it, without the instrument 
 piercing the skull. Indeed, a blow upon a man's 
 head, J by - a body which shall cause a vibration 
 through the substance of the brain, may more 
 effectually deprive him of sense and motion than 
 if an axe or a sword penetrated into the substance 
 of the brain itself. 
 
 Supposing that a man's ingenuity were to be 
 exercised in contriving a protection to the brain, 
 he must perceive that if the case were soft, it 
 would be too easily pierced ; that if it were of a 
 glassy nature, it would be chipped and cracked ; 
 that if it were of a substance like metal, it would 
 ring and vibrate, and communicate the concussion 
 to the brain. 
 
ARCHITECTURE OF THE SKULL 9 
 
 Further thoughts might suggest that, whilst 
 the case should be made firm to resist a sharp 
 point, the vibrations of that circular case might 
 be prevented by lining it with a softer material ; 
 no bell would vibrate with such an incumbrance ; 
 the sound would be stopped like the ringing of a 
 glass by the touch of a ringer. 
 
 If a soldier's head be covered with a steel cap, 
 the blow of a sword which does not penetrate will 
 yet bring him to the ground by the percussion 
 which extends to the brain ; . therefore, the helmet 
 is lined with leather and covered with hair ; for, 
 although the hair is made an ornament, it is an 
 essential part of the protection : we may see it 
 in the head-piece of the Roman soldier, where all 
 useless ornament, being despised as frivolous, was 
 avoided as cumbrous. 
 
 We now perceive why the skull consists of two 
 plates of bone, — one external, which is fibrous 
 and tough, and one internal, dense to such a 
 degree that the anatomist calls it tabula vitrea 
 (the glassy table). 
 
 Nobody can suppose this to be accidental. It 
 has just been stated that the brain may be injured 
 in two ways : a stone or a hammer may break the 
 skull, and the depressed part of the bone injure 
 the brain ; whilst, on the other hand, a mallet 
 struck upon the head will, without penetrating, 
 effectually deprive the brain of its functions, by 
 
10 ANIMAL MECHANICS 
 
 causing a vibration which runs round the skull 
 and extends to every portion of its contents. 
 
 Were the skull, in its perfect or mature state, 
 softer than it is, it would be like the skull of a 
 child ; were it harder than we find it is, it would 
 be like that of an old man. In other words, as 
 in the former it would be too easily pierced, so, 
 in the latter, it would vibrate too sharply and 
 produce concussion. The skull of an infant is a 
 single layer of elastic bone ; on the approach to 
 manhood it separates into two tables ; and in old 
 age it again becomes consolidated. During the 
 active years of man's life the skull is perfect : it 
 then consists of two layers, united by a softer sub- 
 stance ; the inner layer is brittle as glass, and cal- 
 culated to resist anything penetrating ; the outer 
 table is tough, to give consistence, and to stifle 
 the vibration which would take place if the whole 
 texture were uniform and like the inner table. 
 
 The alteration in the substance of the bones, 
 and more particularly in the skull, is marvel- 
 lously ordered to follow the changes in the mind 
 of the creature, from the heedlessness of child- 
 hood to the caution of age, and even the help- 
 lessness of superannuation. 
 
 The skull is soft and yielding at birth ; during 
 childhood it is elastic, and little liable to injury 
 from concussion ; and during youth, and up to 
 the period of maturity, the parts which come in 
 
ARCHITECTURE OF THE SKULL 11 
 
 contact with the ground are thicker, whilst the 
 shock is dispersed towards the sutures (the seams 
 or joinings of the pieces), which are still loose. 
 But when, with advancing years, something tells 
 us to give up feats of activity, and falls are less 
 frequent, the bones lose that nature which would 
 render concussion harmless, and at length the 
 timidity of age teaches man that his structure is 
 no longer adapted to active life. 
 
 We must understand the necessity of the double 
 layer of the skull, in order to comprehend an- 
 other very curious contrivance. The sutures are 
 the lines of union of the several bones which 
 form the cranium* and surround and protect the 
 brain. These lines of union are called sutures 
 (from the Latin word for sewing), because they 
 resemble seams. If a workman were to inspect 
 the joining of two of the bones of the cranium, 
 he would admire the minute dovetailing by which 
 one portion of the bone is inserted into, and sur- 
 rounded by, the other, whilst that other pushes 
 its processes or juttings out between those of the 
 first in the same manner, and the fibres of the two 
 bones are thus interlaced, as you might interlace 
 your fingers. But when you look to the internal 
 
 1 Cranium, from a Greek word signifying a helmet. The cra- 
 nium is the division of the skull appropriated to the protection 
 of the brain ; it consists of six bones — the frontal (or forehead) ; 
 two parietal (walls or side bones) ; the occipital (back of the 
 head) ; and two temporal (or temple) bones. 
 
12 ANIMAL MECHANICS 
 
 surface, you see nothing of this kind ; the bones 
 are here laid simply in contact, and this line by 
 anatomists is called harmonia, or harmony : archi- 
 tects use the same term to imply the joining by 
 masonry. Whilst the anatomists are thus curi- 
 ous in names, it is provoking to find them negli- 
 gent of things more interesting. Having over- 
 looked the reason of the difference in the tables 
 of bone, they are consequently blind to the pur- 
 pose of this difference of the outward and inward 
 part of a suture. ' 
 
 Suppose a carpenter employed upon his own 
 material, he would join a box with minute and 
 regular indentations by dovetailing, because he 
 knows that the material on which he works, from 
 its softness and toughness, admits of such adjust- 
 ment of its edges. The processes of the bone 
 shoot into the opposite cavity with an exact re- 
 semblance to the foxtail wedge of the carpenter 
 — a kind of tenon and mortise when the pieces 
 are small. 
 
 But if a workman in glass or marble were to 
 inclose some precious thing, he would smooth the 
 surfaces and unite them by cement, because, even 
 if he could succeed in indenting the line of union, 
 he knows that his material would chip off on the 
 slightest vibration. The edges of the marble 
 cylinders which form a column are, for the same 
 reason, not permitted to come in contact; thin 
 
ARCHITECTURE OF THE SKULL 
 
 13 
 
 plates of lead are interposed to prevent the edges, 
 technically termed arrises, from chipping off or 
 splitting. 
 
 Now apply this principle to the skull. The 
 outer softer tough table, which is like wood, is 
 indented and dovetailed; the inner glassy table 
 has its edges simply laid in contact. It is morti- 
 fying to see a course of bad reasoning obscure 
 this beautiful subject. They say that the bone 
 growing from its centre, and diverging, shoots its 
 fibres betwixt those which come in an opposite 
 direction; thus making one of the most curious 
 provisions of nature a thing of accident. Is it 
 not enough to ask such reasoners, why there is 
 not a suture on the inside as well as on the out ? 
 
 The junction of the bones of the head gener- 
 ally being thus ex- 
 act, and like the most 
 finished piece of cab- 
 inet work, let us next 
 inquire, whether 
 there be design or 
 contrivance shown in 
 the manner in which 
 each bone is placed 
 upon another. 
 
 When we look 
 upon the side of the skull thus, the temporal 
 suture betwixt the bones A and D is formed in 
 
 Fig. 1. 
 , The parietal bone. B. The fron- 
 tal bone. C. The occipital bone. 
 D. The temporal bone. E. The 
 sphenoid bone. 
 
14 ANIMAL MECHANICS 
 
 a peculiar manner ; the lower, or temporal, bone 
 laps over the superior, or parietal, bone. This, 
 too, has been misunderstood : that is to say, the 
 plan of the building of the bones of the head has 
 not been considered ; and this joining, called the 
 squamous 1 suture, which is a species of scarfing, 
 has been supposed a mere consequence of the 
 pressure of the muscle which moves the jaw. 
 
 Dr. Monro says, " The manner how I imagine 
 this sort of suture is formed at these places, is, 
 that by the action of the strong temporal muscles 
 on one side, and by the pressure of the brain on 
 the other, the bones are made so thin that they 
 have not large enough surfaces opposed to each 
 other to stop the extension of their fibres in 
 length, and thus to cause the common serrated 
 appearance of sutures; but the narrow edge of 
 the one bone slides over the other." 
 
 The very name of the bones might suggest a 
 better explanation. The ossa parietalia 2 are the 
 two large bones in a regular square, serving as 
 walls to the interior or room of the head, where 
 the brain is lodged. — See A in the foregoing 
 figure. 
 
 Did the reader ever notice how the walls of a 
 house are assisted when thin and overburdened 
 with a roof? 
 
 1 From squama, the Latin for a scale, the thin edges lying over 
 each other like the scales of a fish. 
 
 2 From the Latin word paries, a wall. 
 
ARCHITECTURE OF THE SKULL 15 
 
 The wall plate is a portion of timber built into 
 the wall, to which a transverse or tie-beam is 
 attached by carpentry. This cogging, as it is 
 termed, keeps the wall in the perpendicular, and 
 prevents any lateral pressure of the roof. 1 We 
 sometimes see a more clumsy contrivance, a clasp, 
 or a round plate of iron, upon the side of a wall ; 
 this has a screw going into the ends of a cross- 
 beam, and by embracing a large portion of the 
 brick-work, it holds the wall from shifting at this 
 point. Or take the instance of a roof supported 
 on inclined rafters, AB: — 
 
 Fig. 2. 
 
 Were they thus, without further security, placed 
 upon the walls, the weight would tend to spur or 
 press out the walls, which must be strong and 
 heavy to support the roof ; therefore, the skeleton 
 of the roof is made into a truss (for so the whole 
 joined carpentry is called). The upper cross-beam, 
 marked by the dotted lines C, is a collar-beam, 
 connecting the rafters of the roof, and stiffening 
 
 1 In the second Treatise on Heat, the reader will find an ac- 
 count of the manner in which the expansion of iron by heat, and 
 its subsequent contraction on cooling, is used in order to cog great 
 buildings. 
 
16 ANIMAL MECHANICS 
 
 them, and making the weight bear perpendicu- 
 larly upon the walls. When the transverse beam 
 joins the extremities of the rafters, as indicated 
 by the lower outline D, it is called a tie-beam, and 
 is more powerful still in preventing the rafters 
 from pushing out the walls. 
 
 Now when a man bears a burden upon his head, 
 the pressure, or horizontal push, comes upon the 
 lower part of the parietal bones, and if they had 
 not a tie-beam, they would, in fact, be spurred 
 out, and the bones of the head be crushed down. 
 But the temporal bone D, and still more, the 
 sphenoid bone E, by running across the base of 
 the skull, and having their edges lapping over 
 the lower part of the great walls, or the parietal 
 bones, lock in the walls as if they had iron plates, 
 and answer the purpose of the tie-beam in the 
 roof, or the iron plate in the walls. But the con- 
 nection is at the same time so secure, that these 
 bones act equally as a straining--piece, that is, as 
 a piece of timber, preventing the tendency of the 
 sides of the skull to each other. 
 
 It may be said, that the skull is not so much 
 like the wall of a house as hke the arch of a 
 bridge : let us then consider it in this light. 
 
 We have here the two parietal bones, separated 
 and resting against each other, so as to form an 
 arch. In the centering, which is the wooden 
 frame for supporting a stone arch while building, 
 
ARCHITECTUKE OF THE SKULL 17 
 
 there are some principles that are applicable to 
 the head. 
 
 We see that the arch formed by the two parie- 
 tal bones is not a 
 perfect semicircle : 
 there is a projec- 
 tion at the centre 
 of each bone ; the 
 bone is more con- 
 vex, and thicker 
 at this part. 
 
 The cause as- 
 signed for this is, that it is the point from which 
 ossification begins, and where it is, therefore, 
 most perfect. But this is to admit a dangerous 
 principle, that the forms of the bones are matter 
 of chance : and thence we are left without a 
 motive for study, and make no endeavor to com- 
 prehend the uses of parts. We find that all the 
 parts which are most exposed to injury are thus 
 strengthened, — the centre of the forehead, the 
 projecting point of the skull behind, and the 
 lateral centres of the parietal and frontal bones. 
 The parts of the head which would strike upon 
 the ground when a man falls are the strongest, 
 and the projecting arch of the parietal bone is a 
 protection to the weaker temporal bone. 
 
 If we compare the skull to the centering, where 
 a bridge is to be built over a navigable river, and 
 
18 ANIMAL MECHANICS 
 
 consequently where the space must be free in the 
 middle, we find that the scientific workmen are 
 careful, by a transverse beam, to protect the points 
 where the principal thrust will be made in carry- 
 ing up the masonry : this beam does not act as a 
 tie-beam, but as a straining-piece, preventing the 
 arch from being crushed in at this point. 
 
 The necessity of strengthening certain points 
 is well exhibited in the carpentry of roofs. In 
 
 this figure it is clear, 
 that the points A A 
 s*j will receive the pres- 
 sure of the roof, and 
 if the joining of the 
 puncheons 1 and raf- 
 ters be not secure, it will sink down in the form 
 of the dotted line. The workmen would apply 
 braces at these angles to strengthen them. 
 
 In the arch, and at the corresponding points 
 of the parietal bones, the object is attained by 
 strengthening these points by increase of their 
 convexity and thickness ; and where the work- 
 man would support the angles by braces, there are 
 ridges of bone in the calvaria 2 or roof of the skull. 
 If a stone arch fall, it must give way in two 
 places at the same time ; the centre cannot sink 
 
 1 The puncheons are the upright lateral pieces, the rafters are 
 the timbers which lie oblique, and join the puncheons at A A. 
 
 2 From the Latin calva, or calvaria, a helmet. 
 
AKCHITECTUKE OF THE SKULL 
 
 19 
 
 unless that part of the arch which springs from 
 the pier yields ; and in all arches, from the imper- 
 fect Roman arch to that built upon modern prin- 
 ciples, the aim of the architect is to give security 
 to this point. 
 
 In the Roman bridges still entire the arch rises 
 high, with little inclination at the lower part ; and 
 in bridges of a more modern date we see a mass 
 of masonry erected on the pier, sometimes assum- 
 ing the form of ornament, sometimes of a tower 
 or gateway, but obviously intended at the same 
 time, by the perpendicular load, to resist the 
 horizontal pressure of the arch. If this be omit- 
 ted in more modern 
 buildings, it is sup- 
 plied by a finer art, 
 which gives security 
 to the masonry of 
 the pier (to borrow 
 the terms of anat- 
 omy), by its internal 
 structure. 
 
 In what is termed 
 Gothic Architecture, 
 we see a flying but- 
 tress, springing from 
 the outer wall, car- 
 ried over the roof of 
 the aisle, and abutting against the wall of the 
 
20 ANIMAL MECHANICS 
 
 upper part, or clerestory. From the upright part 
 of this masonry a pinnacle is raised, which at first 
 appears to be a mere ornament, but which is 
 necessary, by its perpendicular weight, to coun- 
 teract the horizontal thrust of the arch. 
 
 By all this we see, that if the skull is to be 
 considered as an arch, and the parietal bones as 
 forming that arch, they must be secured at the 
 temporal and sphenoid 1 bones, the points from 
 which they spring. And, in point of fact, where 
 is it that the skull yields when a man falls, so as 
 to strike the top of his head upon the ground? 
 — in the temples. And yet the joinings are so 
 secure that the extremity of the bone does not 
 start from its connections. It must be fractured 
 before it is spurred out, and in that case only does 
 the upper part of the arch yield. 
 
 But the best illustration of the form of the head 
 is the dome. 
 
 A dome is a vault rising from a circular or 
 elliptical base ; and the human skull is, in fact, 
 an elliptical surmounted dome, which latter term 
 means that the dome is higher than the radius 
 of its base. Taking this matter historically, we 
 should presume that the dome was the most diffi- 
 
 1 In the Greek, sphenoid, — in the Latin, cuneiform, — like a 
 wedge, because it is wedged among the other bones of the head ; 
 but these processes, called wedges, are more like dovetails, which 
 enter into the irregularities of the bones, and hold them locked. 
 
ARCHITECTURE OF THE SKULL 21 
 
 cult piece of architecture, since the first dome 
 erected appears to have been at Kome, in the reign 
 of Augustus — the Pantheon, which is still entire. 
 The dome of St. Sophia, in Constantinople, built 
 in the time of the Emperor Justinian, fell three 
 times during its erection : and the dome of the 
 Cathedral of Florence stood unfinished 120 years 
 for want of an architect. Yet we may, in one 
 sense, say that every builder who tried it, as well 
 as every laborer employed, had the most perfect 
 model in his own head. It is obvious enough 
 that the weight of the upper part of the dome 
 must disengage the stones from each other which 
 form the lower circle, and tend to break up their 
 joinings, and consequently to press or thrust 
 outwards the circular wall on which it rests. No 
 walls can support the weight, or rather, the lateral 
 thrust, unless each stone of the dome be soldered 
 to another, or the whole hooped together and 
 girded. The dome of St. Paul's has a very strong 
 double iron chain, linked together, at the bot- 
 tom of the cone ; and several other lesser chains 
 between that and the cupola, which may be 
 seen in the section of St. Paul's engraved by 
 Hooker. 
 
 The bones of the head are securely bound to- 
 gether, so that the anatomist finds, when every- 
 thing is gone, save the bone itself, and there is 
 neither muscle, ligament, nor membrane of any 
 
22 ANIMAL MECHANICS 
 
 kind, to connect the bones, they are, still, securely 
 joined, and it requires his art to burst them asun- 
 der ; and for this purpose he must employ a force 
 which shall produce a uniform pressure from the 
 centre outwards 5 and all the sutures must receive 
 the pressure at one time and equally, or they will 
 not give way. And now is the time to observe 
 another circumstance, which calls for our admira- 
 tion. So little of accident is there in the joining 
 of the bones, that the edge of a bone at the suture 
 lies over the adjoining bone at one part and under 
 it at another, which, with the dovetailing of the 
 suture, as before described, holds each bone in its 
 place firmly attached ; and it is this which gives 
 security to the dome of the cranium. 
 
 If we look at the skull in front, we may con- 
 sider the orbits of the eye as crypts under the 
 greater building. And these under-arches are 
 groined, that is to say, there are strong arched 
 spines of bone, which give strength sufficient to 
 permit the interstices of the groinings, if I may 
 so term them, to be very thin. Betwixt the eye 
 and the brain, the bone is as thin as parchment ; 
 but if the anterior part of the skull had to rest on 
 this, the foundation would be insufficient. This 
 is the purpose of the strong ridge of bone which 
 runs up like a buttress from the temple to the 
 lateral part of the frontal bone, whilst the arch 
 forming the upper part of the orbit is very strong : 
 
ARCHITECTURE OF THE SKULL 23 
 
 and these ridges of bone, when the skull is formed 
 with what we call a due regard to security, give 
 an extension to the forehead. 1 
 
 In concluding this survey of the architecture of 
 the head, let us suppose it so expanded that we 
 could look upon it from within. In looking up 
 to the vault, we should at once perceive the appli- 
 cation of the groin in masonry ; for the groin is 
 that projection in the vault which results from 
 the intersection of two arches running in different 
 directions. One rib or groin extends from the 
 centre of the frontal bone to the most projecting 
 part of the occipital foramen, or opening on the 
 back of the head ; the other rib crosses it from 
 side to side of the occipital bone. The point of 
 intersection of these two groins is the thickest 
 and strongest part of the skull, and it is the most 
 exposed, since it is the part of the head which 
 would strike upon the ground when a man falls 
 backwards. 
 
 What is termed the base of the skull is strength- 
 ened, if we may so express it, on the same prin- 
 ciple : it is like a cylinder groin, where the rib 
 of an arch does not terminate upon a buttress or 
 pilaster, but is continued round in the completion 
 
 1 Although they are solid arches connected with the building 
 of the cranium, and bear no relation to the surfaces of the brain, 
 the early craniologists would have persuaded us that their forms 
 correspond with the surfaces of the brain, and indicate particular 
 capacities or talents. 
 
24 ANIMAL MECHANICS 
 
 of the circle. The base of the skull is irregular, 
 and in many places thin and weak, but these 
 arched spines or ribs give it strength to bear those 
 shocks to which it is of course liable at the join- 
 ing of the skull with the spine. 
 
CHAPTER II 
 
 MECHANISM OP THE SPINE 
 
 The brain-case is thus a perfect whole, secure 
 on all sides, and strengthened where the exposure 
 to injury is the greatest. We shall see, in the 
 column which sustains it, equal provision for the 
 security of the brain ; and, what is most admira- 
 ble, there is an entirely different principle intro- 
 duced here ; for whereas in the head, the whole 
 aim is firmness in the joinings of the bones, in 
 the spine which supports the head, the object to 
 be attained is mobility or pliancy. In the head, 
 each bone is firmly secured to another; in the 
 spine, the bones are not permitted to touch : there 
 is interposed a soft and elastic material, which 
 takes off the jar that would result from the con- 
 tact of the bones. We shall consider this subject 
 a little more in detail. 
 
 The spinal column, as it is called, serves three 
 purposes : it is the great bond of union betwixt 
 all the parts of the skeleton ; it forms a tube for 
 the lodgment of the spinal marrow, a part of the 
 nervous system as important to life as the brain 
 itself; and lastly, it is a column to sustain the 
 head. 
 
26 ANIMAL MECHANICS 
 
 We now see the importance of the spine, and 
 we shall nest explain how the various offices are 
 provided for. 
 
 If the protection of the spinal marrow had 
 been the only object of this structure, it is natural 
 to infer that it would have been a strong and 
 unyielding tube of bone; but, as it must yield 
 to the inflections of the body, it cannot be con- 
 stituted in so strict an analogy with the skull. 
 It must, therefore, bend; but it must have no 
 abrupt or considerable bending at one part ; for 
 the spinal marrow within would in this way suffer. 
 
 By this consideration we perceive why there are 
 twenty-four bones in the spine, each bending a 
 little ; each articulated or making a joint with its 
 fellows ; all yielding in a slight degree, and, con- 
 sequently, permitting in the whole spine that flex- 
 ibility necessary to the motions of the body. It 
 is next to be observed that, whilst the spine by 
 this provision moves in every direction, it gains a 
 property which it belongs more to our present 
 purpose to understand. The bones of the spine 
 are called vertebrae ; at each interstice between 
 these bones, there is a peculiar gristly substance, 
 which is squeezed out from betwixt the bones, 
 and, therefore, permits them to approach and play 
 a little in the motions of the body. This gristly 
 substance is inclosed in an elastic binding or 
 membrane of great strength, which passes from 
 
MECHANISM OF THE SPINE 27 
 
 the edge or border of one vertebra to the border 
 of the one next it. When a weight is upon the 
 body, the soft gristle is pressed out, and the 
 membrane yields : the moment the weight is re- 
 moved, the membranes recoil by their elasticity, 
 the gristle is pressed into its place, and the bones 
 resume their position. 
 
 We can readily understand how great the influ- 
 ence of these twenty-four joinings must be in 
 giving elasticity to the whole column ; and how 
 much this must tend to the protection of the 
 brain. Were it not for this interposition of elas- 
 tic material, every motion of the body would pro- 
 duce a jar to the delicate texture of the brain, 
 and we should suffer almost as much in alighting 
 on our feet as in falling on our head. It is, as 
 we have already remarked, necessary to interpose 
 thin plates of lead or slate between the different 
 pieces of a column to prevent the edges (techni- 
 cally called arrises) of the cylinders from coming 
 in contact, as they would, in that case, chip or 
 split off. 
 
 But there is another very curious provision for 
 the protection of the brain : we mean the curved 
 form of the spine. If a steel spring, perfectly 
 straight, be pressed betwixt the hands from its 
 extremities, it will resist, notwithstanding its elas- 
 ticity, and when it does give way, it will be with 
 a jerk. 
 
28 ANIMAL MECHANICS 
 
 Such would be the effect on the spine if it 
 stood upright, one bone perpendicular to another ; 
 for then the weight would bear equally ; the spine 
 would yield neither to one side nor to the other ; 
 and, consequently, there would be a resistance 
 from the pressure on all sides being balanced. 
 We therefore see the great advantage resulting 
 from the human spine being in the form of an 
 italic s. It is prepared to yield in the direction 
 of its curves ; the pressure is of necessity more 
 upon one side of the column than on the other ; 
 and its elasticity is immediately in operation with- 
 out a jerk. It yields, recoils, and so forms the 
 most perfect spring ; admirably calculated to carry 
 the head without jar, or injury of any kind. 
 
 The most unhappy illustration of all this is the 
 condition of old age. The tables of the skull are 
 then consolidated, and the spine is rigid : if an 
 old man should fall with his head upon the car- 
 pet, the blow, which would be of no consequence 
 to the elastic frame of a child, may to him prove 
 fatal ; and the rigidity of the spine makes every 
 step which he takes vibrate to the interior of the 
 head, and jar on the brain. 
 
 We have hinted at a comparison betwixt the 
 attachment of the spine to the pelvis and the in- 
 sertion of the mast of a ship into the hull. The 
 mast goes directly through the decks without 
 touching them, and the heel of the mast goes into 
 
MECHANISM OF THE SPINE 29 
 
 the step, which is formed of large solid pieces of 
 oak timber laid across the keelson. The keelson 
 is an inner keel resting upon the floor-timbers of 
 the ship and directly over the proper keel. These 
 are contrivances for enlarging the base on which 
 the mast rests as a column : for as, in proportion 
 to the height and weight of a column, its base 
 must be enlarged, or it would sink into the 
 earth ; so, if the mast were to bear upon a point, 
 it would break through the bottom of the ship. 
 
 The mast is supported upright by the shrouds 
 and stays. The shrouds secure it against the 
 lateral or rolling motion, and the stays and back- 
 stays against the pitching of the ship. These 
 form what is termed the standing rigging. The 
 ' mast does not bear upon the deck or on the beams 
 of the ship ; indeed, there is a space covered with 
 canvas betwixt the deck and the mast. 
 
 We often hear of a new ship going to sea to 
 stretch her rigging ; that is, to permit the shrouds 
 and stays to be stretched by the motion of the 
 ship, after which they are again braced tight : 
 for if she were overtaken by a storm before this 
 operation, and when the stays and shrouds were 
 relaxed, the mast would lean against the upper 
 deck, by which it would be sprung or carried 
 away. Indeed, the greater proportion of masts 
 that are lost are lost in this manner. There are 
 no boats which keep the sea in such storms as 
 
30 ANIMAL MECHANICS 
 
 those which navigate the gulf of Finland. Their 
 masts are not attached at all to the hull of the 
 ship, but simply rest upon the step. 
 
 Although the spine has not a strict resem- 
 blance to the mast, the contrivances of the ship- 
 builder, however different from the provisions of 
 nature, show what object is to be attained ; and 
 when we are thus made aware of what is necessary 
 to the security of a column on a movable base, we 
 are prepared to appreciate the superior provisions 
 of nature for giving security to the human spine. 
 
 The human spine rests on what is called the 
 pelvis, or basin ; — a circle of bones, of which the 
 haunches are the extreme lateral parts ; and the 
 sacrum (which is as the keystone of the arch) may 
 be felt at the lower part of the back. To this 
 central bone of the arch of the pelvis the spine is 
 connected ; and, taking the similitude of the mast, 
 the sacrum is as the step on which the base of 
 the pillar, like the heel of the mast, is socketed 
 or mortised. The spine is tied to the lateral parts 
 of the pelvis by powerful ligaments, which may 
 be compared to the shrouds. They secure the 
 lower part of the spine against the shock of lat- 
 eral motion or rolling ; but, instead of the stays 
 to limit the play of the spine forwards and back- 
 wards in pitching, or to adjust the rake of the 
 mast, there is a very beautiful contrivance in the 
 lower part of the column. 
 
MECHANISM OF THE SPINE 
 
 31 
 
 Fig. 6. 
 
 The spine forms here a semicircle which has 
 this effect : that, whether by the exertion of the 
 lower extremities, the 
 spine is to be carried for- 
 ward upon the pelvis, or 
 whether the body stops 
 suddenly in running, the 
 jar which would neces- 
 sarily take place at the 
 lower part of the spine 
 A, if it stood upright 
 like a mast, is distributed 
 over several of the bones 
 of the spine, 1, 2, 3, 4, 
 and, therefore, the chance 
 of injury at any particular part is diminished. 
 
 For example, the sacrum, or centre bone of the 
 pelvis, being carried forward, as when one is 
 about to run, the force is communicated to the 
 lowest bone of the spine. But, then, the surfaces 
 of these bones stand with a very slight degree of 
 obliquity to the line of motion ; the shock com- 
 municated from the lower to the second bone of 
 the vertebrae is still in a direction very nearly per- 
 pendicular to its surface of contact. The same 
 takes place in the communication of force from 
 the second to the third, and from the third to the 
 fourth ; so that before the shock of the horizon- 
 tal motion acts upon the perpendicular spine, it 
 
32 ANIMAL MECHANICS 
 
 is distributed over four bones of that column, 
 instead of the whole force being concentrated 
 upon the joining of any two, as at A. 
 
 If the column stood upright, as indicated at 
 C D, it would be jarred at the lowest point of con- 
 tact with its base. But by forming a semicircle 
 A B, the motion which, in the direction E F, would 
 produce a jar on the very lowest part of the col- 
 umn is distributed over a considerable portion of 
 the column A B ; and in point of fact, this part 
 of the spine never gives way. Indeed, we should 
 be inclined to offer this mode to the consideration 
 of nautical men, as fruitful in hints for improv- 
 ing naval architecture. 
 
 Every one who has seen a ship pitching in a 
 heavy sea must have asked himself why the masts 
 are not upright, or rather, why the foremast 
 stands upright, whilst the main and mizzen masts 
 stand oblique to the deck, or, as the phrase is, 
 rake aft or towards the stern of the ship. 
 
 The main and mizzen masts incline backwards, 
 because the strain is greatest in the forward pitch 
 of the vessel; for the mast having received an 
 impulse forwards, it is suddenly checked as the 
 head of the ship rises ; but the mast being set 
 with an inclination backwards, the motion falls 
 more in the perpendicular line from the head to 
 the heel. This advantage is lost in the upright 
 position of the foremast, but it is sacrificed to a 
 
MECHANISM OF THE SPINE 33 
 
 superior advantage gained in working the ship ; 
 the sails upon this mast act more powerfully in 
 swaying the vessel round, and the perpendicular 
 position causes the ship to tack or stay better ; 
 but the perpendicular position, as we have seen, 
 causes the strain in pitching to come at right 
 angles to the mast, and is, therefore, more apt to 
 spring it. 
 
 These considerations give an interest to the 
 fact, that the human spine, from its utmost con- 
 vexity near its base, inclines backwards. 
 
CHAPTER III 
 
 OF THE CHEST 
 
 In extending the parallel which we proposed 
 between the structure of the body and the works 
 of human art, it signifies very little to what part 
 we turn ; for the happy adaptation of means to 
 the end will everywhere challenge our admiration, 
 in exact proportion to our success in comprehend- 
 ing the provisions which Supreme Wisdom has 
 made. We turn now to a short view of the bones 
 of the chest. 
 
 The thorax, or chest, is composed of bones and 
 cartilages, so disposed as to sustain and protect 
 the most vital parts, the heart and lungs, and to 
 turn and twist with perfect facility in every motion 
 of the body ; and to be in incessant motion in the 
 act of respiration, without a moment's interval, 
 during a whole life. In anatomical description, 
 the thorax is formed of the vertebral column, or 
 spine, on the back part, the ribs on either side, 
 and the breastbone, or sternum, on the forepart. 
 But the thing most to be admired is the manner 
 in which these bones are united, and especially 
 the manner in which the ribs are joined to the 
 
OP THE CHEST 35 
 
 breastbone by the interposition of cartilages, or 
 gristle, of a substance softer than bone, and more 
 elastic and yielding. By this quality they are 
 fitted for protecting the chest against the effects 
 of violence, and even for sustaining life after the 
 muscular power of respiration has become too 
 feeble to continue without this support. 
 
 If the ribs were complete circles, formed of 
 bone, and extending from the spine to the breast- 
 bone, life would be endangered by any accidental 
 fracture ; and even the rubs and jolts to which 
 the human frame is continually exposed would be 
 too much for their delicate and brittle texture. 
 But these evils are avoided by the interposition 
 of the elastic cartilage. On their forepart the 
 ribs are eked out, and joined to th^ breastbone by 
 means of cartilages, of a form corresponding to 
 that of the ribs, being, as it were, a completion of 
 the arch of the rib, by a substance more adapted 
 to yield in every shock or motion of the body. 
 The elasticity of this portion subdues those shocks 
 which would occasion the breaking of the ribs. 
 We lean forward, or to one side, and the ribs 
 accommodate themselves, not by a change of 
 form in the bones, but by the bending or elasticity 
 of the cartilages. A severe blow upon the ribs 
 does not break them, because their extremities 
 recoil and yield to' the violence. It is only in 
 youth, however, when the human frame is in per- 
 
36 ANIMAL MECHANICS 
 
 fection, that this pliancy and elasticity have full 
 effect. When old age approaches, the cartilages 
 of the ribs become bony. They attach themselves 
 firmly to the breastbone, and the extremities of 
 the ribs are fixed, as if the whole arch were 
 formed of bone unyielding and inelastic. Then 
 every violent blow upon the side is attended with 
 fracture of the rib, an accident seldom occurring 
 in childhood or in youth. 
 
 But there is a purpose still more important to 
 be accomplished by means of the elastic structure 
 of the ribs, as partly formed of cartilage. This 
 is in the action of breathing, or respiration ; espe- 
 cially in the more highly raised respiration which 
 is necessary in great exertions of bodily strength, 
 and in violent exercise. There are two acts of 
 breathing — expiration, or the sending forth of 
 the breath ; and inspiration, or the drawing in 
 of the breath. When the chest is at rest, it is 
 neither in the state of expiration nor in that of 
 inspiration ; it is in an intermediate condition 
 between these two acts. And the muscular effort 
 by which either inspiration or expiration is pro- 
 duced is an act in opposition to the elastic pro- 
 perty of the ribs. The property of the ribs is 
 to preserve the breast in the intermediate state 
 between expiration and inspiration. The muscles 
 of respiration are excited alternately, to dilate or 
 to contract the cavity of the chest, and, in doing 
 
OP THE CHEST 37 
 
 so, to raise or to depress the ribs. Hence it is, 
 that both in inspiration and in expiration the 
 elasticity of the ribs is called into play; and, 
 were it within our province, it would be easy to 
 show, that the dead power of the cartilages of the 
 ribs preserves life by respiration, after the vital 
 muscular power would, without such assistance, be 
 too weak to continue life. 
 
 It will at once be understood, from what has 
 now been explained, how, in age, violent exercise 
 or exertion is under restraint, in so far as it de- 
 pends on respiration. The elasticity of the car- 
 tilages is gone, the circle of the ribs is now un- 
 yielding, and will not allow that high breathing, 
 that sudden and great dilating and contracting 
 of the cavity of the chest, which is required for 
 circulating the blood through tbe lungs, and re- 
 lieving the heart amidst the more tumultuous 
 flowing of the blood which exercise and exertion 
 produce. 
 
CHAPTER IV 
 
 DESIGN SHOWN IN THE STB.UCTUEE OF THE 
 BONES AND JOINTS OF THE EXTREMITIES 
 
 That the bones, which form the interior of 
 animal bodies, should have the most perfect shape, 
 combining strength and lightness, ought not to 
 surprise us, when we find this in the lowest vege- 
 table production. 
 
 In the sixteenth century, an unfortunate man 
 who taught medicine, philosophy, and theology, 
 was accused of atheistical opinions, and con- 
 demned to have his tongue cut out, and to suffer 
 death. When brought from his cell before the 
 Inquisition, he was asked if he believed in God. 
 Picking up a straw which had stuck to his gar- 
 ments, " If," said he, " there was nothing else in 
 nature to teach me the existence of a Deity, even 
 this straw would be sufficient ! " 
 
 A reed, or a quill, or a bone, may be taken to 
 prove that in Nature's works strength is given 
 with the least possible expense of materials. The 
 long bones of animals are, for the most part, 
 hollow cylinders, filled up with the lightest sub- 
 stance, marrow ; and in birds the object is attained 
 
BONES AND JOINTS OF THE EXTREMITIES 39 
 
 by means (if we may be permitted to say so) still 
 more artificial. Every one must have observed, 
 that the breastbone of a fowl extends along the 
 whole body, and that the body is very large com- 
 pared with the weight : this is for the purpose 
 of rendering the creature specifically fighter and 
 more buoyant in the air ; and that it may have a 
 surface for the attachment of muscles, equal to 
 the exertion of raising it on the wing. This com- 
 bination of lightness with increase of volume is 
 gained by air-cells extending through the body, 
 and communicating by tubes between the lungs 
 and cavities of the bones. By these means, the 
 bones, although large and strong to withstand the 
 operation of powerful muscles upon them, are 
 much lighter than those of quadrupeds. 
 
 The long bones of the human body, being 
 hollow tubes, are called cylindrical, though they 
 are not accurately so, the reason of which we 
 shall presently explain ; and we shall, at the same 
 time, show that their irregularities are not acci- 
 dental, as some have imagined. But let us first 
 demonstrate the advantage which, in the struc- 
 ture of the bones, is derived from the cylindrical 
 form, or a form approaching to that of the cyl- 
 inder. If a piece of timber supported on two 
 points {Fig. 7) bear a weight upon it, it sustains 
 this weight by different qualities in its different 
 parts. For example, divide it into three equal 
 
40 ANIMAL MECHANICS 
 
 parts (A, B, C) : the upper part A supports the 
 0tei»»» -««»« weight by its solid- 
 
 ^w^W^^WSl^SlS^S^TO ty anc ^ resistance 
 
 A to compression ; the 
 lowest part B, on the 
 other hand, resists 
 by its toughness, or 
 
 adhesive quality. Be- 
 Fig. 7. . Z 1 J . 
 
 twrxt the portions 
 
 acting in so different a manner there is an inter- 
 mediate neutral, or central part C, that may be 
 taken away without materially weakening the 
 beam, which shows that a hollow cylinder is the 
 form of strength. The writer lately observed a 
 good demonstration of this : — A large tree was 
 blown down, and lay upon the ground ; to the wind- 
 ward, the broken part gaped ; it had been torn 
 asunder like the snapping of a rope : to the lee- 
 ward side of the tree, the fibres of the stem were 
 crushed into one another and splintered ; whilst 
 the central part remained entire. This, we pre- 
 sume, must be always the case, more or less ; and 
 here we take the opportunity of noticing why the 
 arch is the form of strength. If this transverse 
 piece of timber were in the form of an arch, and 
 supported at the extremities, then its whole thick- 
 ness, its centre, as well as the upper and lower 
 parts, would support weight by resisting compres- 
 sion. But the demonstration may be carried 
 
BONES AND JOINTS OF THE EXTREMITIES 41 
 
 much farther to show the form of strength in the 
 bone. If the part of the cylinder which bears 
 the pressure be made more dense, the power of 
 resistance will be much increased ; whereas, if a 
 ligamentous covering be added on the other side, 
 it will strengthen the part which resists extension : 
 and we observe a provision of this kind in the 
 tough ligaments which run along the vertebrae of 
 the back. 
 
 When we see the bone cut across, we are 
 forced to acknowledge that it 
 is formed on the principle of ^ft. 
 
 the cylinder ; that is, that the /giplllillfev. 
 material is removed from the ,J|iJp!^ll|l|i 
 
 centre, and accumulated on the c j|jj| ~ia lj|j| 
 
 circumference {Fig. 8). We ^mm^-smSm 
 find a spine, or ridge running *tmtm00^ 
 along the bone, which, when -pie. 8. 
 
 divided by the saw in a trans- 
 verse direction, exhibits an irregularity, as at A. 
 
 The section of this spine shows a surface as 
 dense as ivory, which is, therefore, much more 
 capable of resisting compression than the other 
 part of the cylinder, which is common bone. This 
 declares what the spine is, and the anatomists 
 must be wrong who imagine that the bone is 
 moulded by the action of the muscle, and that the 
 spine is a mere ridge, arising by accident among 
 the muscles. It is, on the contrary, a strength- 
 
42 
 
 ANIMAL MECHANICS 
 
 Fig. 9. 
 
 ening of the bone in the direction on which the 
 weight bears. If we resume the experiment with 
 the piece of timber, we shall learn why the spine 
 is harder than the rest of the bone. If a portion 
 of the upper part of the timber be cut away, and 
 a harder wood inserted in its place, the beam 
 
 will acquire a new 
 power of resisting 
 fracture, because, as 
 we have stated, this 
 part of the wood 
 does not yield but by 
 being crushed, and 
 the insertion of the harder portion of wood in- 
 creases this property of resistance. With this fact 
 before us we may return to the examination of 
 the spine of bone. We see that it is calculated to 
 resist pressure, first, because it is farther removed 
 from the centre of the cylinder ; and, secondly, 
 because it is denser, to resist compression, than 
 the other part of the circumference of the bone. 1 
 This explanation of the use of a spine upon a 
 bone gives a new interest to osteology. 2 The 
 anatomist ought to deduce from the form of the 
 spine the motions of the limb ; the forces bearing 
 
 1 As the line A B extends farther from the centre than B C, 
 on the principle of a lever, the resistance to transverse fracture 
 will be greater in the direction A B than B C. 
 
 2 Osteology, from the Greek words, signifying discourse on 
 bone, being the demonstration of the forms and connection of the 
 different bones. 
 
BONES AND JOINTS OF THE EXTREMITIES 43 
 
 upon the bone, and the nature and the common 
 place of fracture : while, to the general inquirer, 
 an agreeable process of reasoning is introduced 
 in that department, -which is altogether without 
 interest when the " irregularities " of the bone 
 are spoken of, as if they were the accidental con- 
 sequences of the pressure of the flesh upon it. 
 
 Although treating of the purely mechanical prin- 
 ciple, it is, perhaps, not far removed from our 
 proper object to remark, that a person of feeble 
 texture and indolent habits has the bone smooth, 
 thin, and light; but that Nature, solicitous for 
 our safety, in a manner which we could not anti- 
 cipate, combines with the powerful muscular frame 
 a dense and perfect texture of bone, where every 
 spine and tubercle is completely developed. And 
 thus the inert and mechanical provisions of the 
 bone always bear relation to the muscular power 
 of the limb, and exercise is as necessary to the 
 perfect constitution of a bone as it is to the per- 
 fection of the muscular power. Jockeys speak 
 correctly enough, when they use the term " blood 
 and bone " as distinguishing the breed or gene- 
 alogy of horses ; for blood is an allowable term 
 for the race, and bone is so far significant, that 
 the bone of a running horse is remarkably com- 
 pact compared with the bone of a draught horse. 
 The reader can easily understand, that the span 
 in the gallop must give a shock in proportion 
 
44 ANIMAL MECHANICS 
 
 to its length; and, as in man, so in the horse, 
 the greater the muscular power the denser and 
 stronger is the bone. 
 
 The bone not being as a mere pillar, intended 
 to bear a perpendicular weight, we ought not to 
 expect uniformity in its shape. Each bone, ac- 
 cording to its place, bears up against the varying 
 forces that are applied to it. Consider two men 
 wrestling together, and then think how various 
 the property of resistances must be : here they are 
 pulling, and the bones are like ropes ; or, again, 
 they are writhing and twisting, and the bones 
 bear a force like the axle-tree between two wheels ; 
 or they are like a pillar under a great weight ; or 
 they are acting as a lever. 
 
 To withstand these different shocks, a bone 
 consists of three parts, the earth of bone (sub- 
 phosphate of lime) ; fibres to give it toughness ; 
 and cartilage to give it elasticity. These ingre- 
 dients are not uniformly mixed up in all bones ; 
 but some bones are hard, from the prevalence of 
 the earth of bone; some more fibrous, to resist 
 a pull upon them ; and some more elastic, to resist 
 the shocks in walking, leaping, etc. But to re- 
 turn to the forms : — Whilst the centre of the 
 long bones is, as we have stated, cylindrical, their 
 extremities are expanded, and assume various 
 shapes. The expansion of the head of the bone 
 is to give a greater, and consequently a more 
 
BONES AND JOINTS OF THE EXTREMITIES 45 
 
 secure surface for the joint, and its form regu- 
 lates the direction in which the joint is to move. 
 A jockey, putting his hand on the knee of a colt, 
 and finding it broad and flat, augurs the perfec- 
 tion of the full-grown horse. To admit of this 
 enlargement and difference of form, a change 
 in the internal structure of the bone is neces- 
 sary, and the hollow of the tube is filled up with 
 cancelli, or lattice-work. These cancelli of the 
 bone are minute and delicate-like wires, which 
 form lattice-work, extending in all directions 
 through the interior of the bone, and which, were 
 it elastic, would be like a sponge. — This more 
 uniform texture of the bone permits the outer 
 shell to be very thin, so that whilst the centre of 
 the long bones are cylinders, their extremities are 
 of a uniform cancellated structure. But it is per- 
 tinent to our purpose to notice, that this minute 
 lattice-work, or the cancelli which constitute the 
 interior structure of bone, have still reference 
 to the forces acting on the bone; if any one 
 doubts this, let him make a section of the upper 
 and lower end of the thighbone, and let him 
 inquire what is the meaning of the difference in 
 the lie of these minute bony fibres, in the two 
 extremities ? He will find that the head of the 
 thighbone stands obliquely off from the shaft, 
 and that the whole weight bears on what is termed 
 the inner trochanter ; and to that point, as to 
 
46 ANIMAL MECHANICS 
 
 a buttress, all these delicate fibres converge, or 
 point from the head and neck of 
 the bone, which may be rudely 
 represented in this way. 
 
 We may here notice an opin- 
 ion that has been entertained, in 
 regard to the size of animals. It 
 is believed that the material of 
 bone is not capable of support- 
 Fig. 10. i n g a creature larger than the 
 
 elephant, or the mastodon, which is the name of 
 an extinct animal of great size, the osseous re- 
 mains of which are still found. This opinion is 
 countenanced by observing that their bones are 
 very clumsy, that their spines are of great thick- 
 ness, and that their hollow cylinders are almost 
 filled up with bone. 
 
 It may be illustrated in this manner : — A soft 
 stone projecting from a wall may make a stile, 
 strong enough to bear a person's weight ; but if 
 it were necessary to double its length, the thick- 
 ness must be more than doubled, or a freestone 
 substituted ; and were it necessary to make this 
 freestone project twice as far from the wall, even 
 if doubled in thickness, it would not be strong 
 enough to bear a proportioned increase of weight : 
 granite must be placed in its stead ; and even the 
 granite would not be capable of sustaining four 
 times the weight which the soft stone bore in the 
 
BONES AND JOINTS OF THE EXTREMITIES 47 
 
 first instance. In the same way the stones which 
 form an arch of a large span must be of the hard- 
 est granite, or their own weight would crush 
 them. The same principle is applicable to the 
 bones of animals. The material of bone is too 
 soft to admit an indefinite increase of weight; 
 and it is another illustration of what was before 
 stated, that there is a relation established through 
 all nature, and that the very animals which move 
 upon the surface of the earth are proportioned to 
 its magnitude, and the gravitation to its centre. 
 Archdeacon Paley has with great propriety taken 
 the instance of the form of the ends of bones, as 
 proving design in the mechanism of a joint. But 
 there is something so highly interesting in the 
 conformation of the whole skeleton of an animal, 
 and the adaptation of any one part to all the 
 other parts, that we must not let our readers re- 
 main ignorant of the facts, or of the important 
 conclusions drawn from them. 
 
 What we have to state has been the result of 
 the studies of many naturalists; but although 
 they have labored, as it were, in their own depart- 
 ment of comparative anatomy, they have failed 
 to seize upon it with the privilege of genius, and 
 to handle it in the masterly manner of Cuvier. 
 
 Suppose a man ignorant of anatomy to pick 
 up a bone in an unexplored country, he learns 
 nothing, except that some animal has lived and 
 
48 ANIMAL MECHANICS 
 
 died there ; but the anatomist can, by that single 
 bone, estimate, not merely the size of the animal, 
 as well as if he saw the print of its foot, but the 
 form and joints of the skeleton, the structure of 
 its jaws and teeth, the nature of its food, and its 
 internal economy. This, to one ignorant of the 
 subject, must appear wonderful, but it is after 
 this manner that the anatomist proceeds : let us 
 suppose that he has taken up that portion of bone 
 in the limb of the quadruped which corresponds 
 to the human wrist ; and that he finds that the 
 form of the bone does not admit of free motion 
 in various directions, like the paw of the carnivo- 
 rous creature. It is obvious, by the structure of 
 the part, that the limb must have been merely for 
 supporting the animal, and for progression, and 
 not for seizing prey. This leads him to the fact 
 that there were no bones resembling those of the 
 hand and fingers, or those of the claws of the 
 tiger; for the motions which that conformation 
 of bones permits in the paw would be useless 
 without the rotation of the wrist — he concludes 
 that these bones were formed in one mass, like 
 the cannon bone, pastern bone, and coffin bones 
 of the horse's foot. 1 
 
 1 For these are solid bones, where it is difficult to recognize 
 any resemblance to the carpus, metacarpus, and bones of the 
 fingers ; and yet comparative anatomy proves that these movable 
 bones are of the same class with those in the solid hoof of the 
 
 helium of Linnaeus. 
 
BONES AND JOINTS OF THE EXTREMITIES 49 
 
 The motion limited to flection and extension 
 of the foot of a hoofed animal implies the absence 
 of a collar bone and a restrained motion in the 
 shoulder joint ; and thus the naturalist, from the 
 specimen in his hand, has got a perfect notion 
 of all the bones of the anterior extremity ! 
 The motions of the extremities imply a condition 
 of the spine which unites them. Each bone of 
 the spine will have that form which permits the 
 bounding of the stag, or the galloping of the 
 horse, but it will not have that form of joining 
 which admits the turning or writhing of the 
 spine, as in the leopard or the tiger. 
 
 And now he comes to the head : the teeth of 
 a carnivorous animal, he says, would be useless 
 to rend prey, unless there were claws to hold it, 
 and a mobility of the extremities like the hand, 
 to grasp it. He considers, therefore, that the 
 teeth must have been for bruising herbs, and the 
 back teeth for grinding. The socketing of these 
 teeth in the jaw gives a peculiar form to these 
 bones, and the muscles which move them are also 
 peculiar ; in short, he forms a conception of the 
 shape of the skull. From this point he may set 
 out anew, for by the form of the teeth, he ascer- 
 tains the nature of the stomach, the length of the 
 intestines, and all the peculiarities which mark a 
 vegetable feeder. 
 
 Thus the whole parts of the animal system are 
 
50 ANIMAL MECHANICS 
 
 so connected with one another, that from one 
 single bone or fragment of bone, be it of the jaw, 
 or of the spine, or of the extremity, a really accu- 
 rate conception of the shape, motions, and habits 
 of the animal may be formed. 
 
 It will readily be understood, that the same pro- 
 cess of reasoning will ascertain, from a small por- 
 tion of a skeleton, the existence of a carnivorous 
 "animal, or of a fowl, or of a bat, or of a lizard, or 
 of a fish ; and what a conviction is here brought 
 home to us, of the extent of that plan which 
 adapts the members of every creature to its proper 
 office, and yet exhibits a system extending through 
 the whole range of animated beings, whose mo- 
 tions are conducted by the operation of muscles 
 and bones. 
 
 After all, this is but a part of the wonders 
 disclosed through the knowledge of a thing so 
 despised as a fragment of bone. It carries us 
 into another science ; since the knowledge of 
 the skeleton not only teaches us the classification 
 of creatures now alive, but affords proofs of the 
 former existence of animated beings which are 
 not now to be found on the surface of the earth. 
 We are thus led to an unexpected conclusion 
 from such premises : not merely the existence of 
 an individual animal, or race of animals; but 
 even the changes which the globe itself has un- 
 dergone in times before all existing records, and 
 
I, 
 
 BONES AND JOINTS OF THE EXTREMITIES 51 
 
 before the creation of human beings to inhabit 
 the earth, are opened to our contemplation. 
 
 OP STANDING 
 
 This may appear to some a very simple inquiry, 
 and yet it is very ignorant to suppose that it is 
 so. The subject has been introduced in this 
 fashion : — " Observe these men engaged in rais- 
 ing a statue to its pedestal with the contrivances 
 of pulleys and levers, and how they have placed 
 it on the pedestal and are soldering it to keep it 
 steady, lest the wind should blow it down. This 
 statue has the fair and perfect proportions of the 
 human body ; to all outward appearance it ought 
 to stand." 
 
 In the following passage, we have the same 
 idea thrown out in a manner which we are apt to 
 call French. Were a man cast on a desert shore, 
 and there to find a beautiful statue of marble, 
 he would naturally exclaim, — " Without doubt, 
 there have been inhabitants here : I recognize the 
 hand of a famous sculptor : I admire the delicacy 
 with which he has proportioned all the members 
 of the body to give them beauty, grace, and ma- 
 jesty, to indicate the motion and expression of 
 life." But it may be asked, what would such a 
 man think if his companion were to say, — " Not 
 at all, no sculptor made this statue ; it is formed, 
 to be sure, in the best taste, and according to the 
 
52 ANIMAL MECHANICS 
 
 rules of art, but it is formed by chance : amongst 
 the many fragments of marble, there has been 
 one thus formed of itself. The rain and the 
 ■winds have detached it from the mountain, and a 
 storm has placed it upright on the pedestal. The 
 pedestal, too, was prepared of itself in this lonely 
 place. True, it is like the Apollo, or the Venus, 
 or the Hercules. You might believe that the 
 figure lived and thought ; that it was prepared to 
 move and speak; but it owes nothing to art; 
 blind chance has placed it there." 1 
 
 The first passage suggests the conviction that 
 the power of standing proceeds not from any 
 symmetry, as in a pillar, or from gravitation 
 alone. It, in fact, proceeds from an internal pro- 
 vision, by which a man is capable of estimating, 
 with great precision, the inclination of his body, 
 and correcting the bias by the adjustment of 
 the muscles. In the second passage, it is meant 
 to be shown, that the outward proportion of 
 the form bears a relation to the internal struc- 
 ture ; that grace and expression are not superficial 
 qualities, and that only the Divine Architect 
 could form such a combination of animated ma- 
 chinery. 
 
 We shall consider how the human body is pre- 
 pared by mechanical contrivances to stand up- 
 right, and by what fine sense of the gravitation 
 
 1 Demonstration de V Existence de Dieu, par Fenelon. 
 
BONES AND JOINTS OF THE EXTREMITIES 53 
 
 of the body the muscles are excited to stiffen the 
 otherwise loose joints, and to poise the body on 
 its base. 
 
 OF THE FOOT 
 
 Let us take the arrangement of the bones of 
 the foot, according to the demonstration of the 
 anatomists. 
 
 They are divided into the tarsus, which is com- 
 posed of seven bones, reaching from the heel to 
 the middle of the foot. The metatarsus, which 
 consists of five long bones laid parallel to each 
 other, and extending from the tarsus to the roots 
 of the toes. The bones of the toes are called 
 phalanges, from being in the form of a phalanx. 
 
 There are in all thirty-six bones in the foot ; 
 and the first question that naturally arises is, 
 Why should there be so many bones ? The an- 
 swer is, In order that there may be so many 
 joints ; for the structure of a joint not only per- 
 mits motion, but bestows elasticity. 
 
 A joint then consists of the union of two bones, 
 of such a form as to permit the necessary motion : 
 but they are not in contact : each articulating 
 surface is covered with cartilage, to prevent the 
 jar which would result from the contact of the 
 bones. This cartilage is elastic, and the 'cele- 
 brated Dr. Hunter discovered that the elasticity 
 was in consequence of a number of filaments closely 
 compacted, and extending from the surface of the 
 
54 ANIMAL MECHANICS 
 
 bone, so that each filament is perpendicular to 
 the pressure made upon it. The surface of the 
 articulating cartilage is perfectly smooth, and is 
 lubricated by a fluid called synovia, signifying a 
 mucilage, a viscous or thick liquor. This is vul- 
 garly called joint oil, but it has no property of 
 oil, although it is better calculated than any oil 
 to lubricate the interior of the joint. 
 
 When inflammation comes upon a joint, this 
 fluid is not supplied, and the joint is stiff, and 
 the surfaces creak upon one another like a hinge 
 without oil. A delicate membrane extends from 
 bone to bone, confining this lubricating fluid, and 
 forming the boundary of what is termed the 
 cavity of the joint, although, in fact, there is no 
 unoccupied space. External to this capsule * of 
 the joint, there are strong ligaments going from 
 point to point of the bones, and so ordered as 
 to bind them together without preventing their 
 proper motions. From this description of a single 
 joint, we can easily conceive what a spring or 
 elasticity is given to the foot, where thirty-six 
 bones are jointed together. 
 
 An elegant author has this very natural remark 
 on the joints : — "In considering the joints, there 
 is nothing, perhaps, which ought to move our 
 gratitude more than the reflection, how well they 
 wear. A limb shall swing upon its hinge, or 
 
 1 From capsula, a little case, or box. 
 
BONES AND JOINTS OF THE EXTREMITIES 55 
 
 play in its socket, many hundred times in an 
 hour, for sixty years together, without diminution 
 of its agility, which is a long time for anything to 
 last, for anything so much worked and exercised 
 as the joints are. This durability I should attrib- 
 ute, in part, to the provision which is made for 
 the preventing of wear and tear : first, by the 
 polish of cartilaginous surfaces ; secondly, by the 
 healing lubrication of the mucilage ; and, in part, 
 to that astonishing property of animal constitu- 
 tions, assimilation, by which, in every portion of 
 the body, let it consist of what it will, substance 
 is restored and waste repaired." — Palby. 
 
 If the ingenious author's mind had been pro- 
 fessionally called to contemplate this subject, he 
 would have found another explanation. There is 
 no resemblance betwixt the provisions against the 
 wear and tear of machinery and those for the 
 preservation of a living part. As the structure 
 of the parts is originally perfected by the action 
 of the vessels, the function or operation of the 
 part is made the stimulus to those vessels. The 
 cuticle on the hands wears away like a glove ; but 
 the pressure stimulates the living surface to force 
 successive layers of skin under that which is wear- 
 ing, or, as the Anatomists call it, desquamating ; 
 by which they mean, that the cuticle does not 
 change at once, but comes off in squamce, or 
 scales. The teeth are subject to pressure in chew- 
 
56 ANIMAL MECHANICS 
 
 ing or masticating, and they would, by this action, 
 have been driven deeper in the jaw, and rendered 
 useless, had there not been a provision against 
 this mechanical effect. This provision is a dispo- 
 sition to grow, or rather to shoot out of their 
 sockets; and this disposition to project balances 
 the pressure which they sustain ; and when one 
 tooth is lost, its opposite rises, and is in danger 
 of being lost also, for want of that very opposi- 
 tion. 
 
 The most obvious proof of contrivance is the 
 junction of the foot to the bones of the leg at 
 the ankle-joint. The two bones of the leg, called 
 the tibia and the fibula, receive the great articu- 
 lating bone of the foot (the astragalus) betwixt 
 them. And the extremities of these bones of the 
 leg project so as to form the outer and inner 
 ankle. Now, when we step forward, and whilst 
 the foot is raised, it rolls easily upon the ends of 
 these bones, so that the toe may be directed ac- 
 cording to the inequalities of the ground we are 
 to tread upon ; but when the foot is planted, and 
 the body is carried forward perpendicularly over 
 the foot, the joint of the leg and foot becomes 
 fixed, and we have a steady base to rest upon. 
 We next observe, that, in walking, the heel first 
 touches the ground. If the bones of the leg were 
 perpendicular over the part which first touches 
 the ground, we should come down with a sudden 
 
BONES AND JOINTS OF THE EXTREMITIES 57 
 
 jolt, instead of which we descend in a semicircle, 
 the centre of which is 
 the point of the heel. 
 And when the toes 
 have come to the 
 ground we are far 
 from losing the ad- 
 vantages of the struc- FlG " u ' 
 ture of the foot, since we stand upon an elas- 
 tic arch, the hinder extremity of which is the 
 heel, and the anterior the balls of the toes. A 
 finely formed foot should be high in the instep. 
 The walk of opera dancers is neither natural nor 
 beautiful ; but the surprising exercises which they 
 perform give to the joints of the foot a freedom 
 of motion almost like that of the hand. We have 
 seen the dancers, in their morning exercises, stand 
 for twenty minutes on the extremities of their 
 toes, after which the effort is to bend the inner 
 ankle down to" the floor, in preparation for the 
 Bolero step. By such unnatural postures and 
 exercises the foot is made unfit for walking, as 
 may be observed in any of the retired dancers 
 and old figurantes. By standing so much upon 
 the toes, the human foot is converted to some- 
 thing more resembling that of a quadruped, where 
 the heel never reaches the ground, and where the 
 paw is nothing more than the phalanges of the 
 toes. 
 
58 ANIMAL MECHANICS 
 
 This arch of the foot, from the heel to the toe, 
 has the astragalus (A) resembling the keystone 
 of an arch ; but, instead of being fixed, as in 
 masonry, it plays freely betwixt two bones, and 
 from these two bones, B and C, a strong elastic 
 *l ligament is ex- 
 
 tended, on which 
 the bone (A) rests, 
 sinking or rising as 
 the weight of the 
 body bears upon it, or is taken off, and this it is 
 enabled to do by the action of the ligament which 
 runs under it. 
 
 This is the same elastic ligament which runs 
 extensively along the back of the horse's hind 
 leg and foot, and gives the fine spring to it, but 
 which is sometimes ruptured by the exertion of 
 the animal in a leap, producing irrecoverable 
 lameness. 
 
 Having understood that the arch of the foot is 
 perfect from the heel to the toe, we have next to 
 observe, that there is an arch from side to side ; 
 for when a transverse section is made of the bones 
 of the foot, the exposed surface presents a perfect 
 arch of wedges, regularly formed like the stones 
 of an arch in masonry. If we look down upon 
 the bones of the foot, we shall see that they form 
 a complete circle horizontally, leaving a space in 
 their centre. These bones thus form three dif- 
 
BONES AND JOINTS OF THE EXTREMITIES 59 
 
 f erent arches — forward ; across ; and horizon- 
 tally : they are wedged together, and bound by 
 ligaments, and this is what we alluded to when 
 we said that the foundations of the Eddystone 
 were not laid on a better principle ; but our ad- 
 miration is more excited in observing, that the 
 bones of the foot are not only wedged together, 
 like the courses of stone for resistance, but that 
 solidity is combined with elasticity and lightness. 
 
 Notwithstanding the mobility of the foot in 
 some positions, yet when the weight of the body 
 bears directly over it, it becomes immovable, and 
 the bones of the leg must be fractured before the 
 foot yields. 
 
 We shall proceed to explain how the knee- 
 joint and hip- joint, independently of the exertion 
 of muscles, become firm in the standing position, 
 and when at rest : but, before we enter upon this, 
 let us understand the much-talked-of demonstra- 
 tion of Borelli, who explained the manner in 
 which a bird sits upon a branch when asleep : 
 the weight of the creature and the consequent 
 flexion of the limbs drawing the tendons of the 
 talons, so as to make them grasp the branch with- 
 out muscular effort. 
 
 The muscle A passes over the joint at B, and 
 then proceeds to the back of the leg, and be- 
 hind the joint at C, and so descends behind the 
 foot at D, and extends to the talons; and the 
 
60 
 
 ANIMAL MECHANICS 
 
 dm 
 
 Fig. 13. 
 
 weight of the bird, bending the joint B and C, 
 
 produces the effect 
 of muscular effort, 
 and makes the claws 
 cling. 
 
 But why should 
 the anatomist have 
 recourse to this piece 
 of comparative anat- 
 omy, when he has 
 
 dBB "^^^^^^^^' s0 fi ne an exam pi e 
 
 in the human body ? 
 And one which is 
 much more inter- 
 esting, as, in fact, 
 it is the foundation of reasoning upon the dis- 
 eases and accidents of the limb. If this beauti- 
 ful arrangement in the healthy and perfect struc- 
 ture of a man's limb be not attended to, it would 
 be easy to prove that many important circum- 
 stances, in regard to disease and accidents, must 
 remain obscure. 
 
 The posture of a soldier under arms, when his 
 heels are close together, and his knees straight, 
 is a condition of painful restraint. Observe, then, 
 the change in the body and limbs, when he is 
 ordered to stand at ease ; the firelock falls against 
 his relaxed arms, the right knee is thrown out, 
 and the tension of the ankle-joint of the same 
 
BONES AND JOINTS OF THE EXTREMITIES 61 
 
 leg is relieved, whilst he loses an inch and a half 
 of his height, and sinks down upon his left hip. 
 This command to " stand at 
 ease" has a higher authority 
 than the general orders. It 
 is a natural relaxation of all 
 the muscles; which are, con- 
 sequently, relieved from a pain- 
 ful state of exertion : and the 
 weight of the body bears so 
 upon the lower extremity, as 
 to support the joints independ- 
 ently of muscular effort. The 
 advantage of this will be un- 
 derstood, when we consider that 
 all muscular effort is made at 
 the expense of a living power, 
 which, if excessive, will ex- 
 haust and weary a man, whilst 
 the position of rest which we 
 are describing is without effort, 
 and therefore gives perfect 
 relief. And it is this which 
 makes boys and girls, 
 who are out of health 
 and languid, lounge too Fi(} u 
 
 much in the position of 
 
 relief, from whence comes permanent distortion. 
 Fig. 14 represents the bones of the leg. 
 
62 
 
 ANIMAL MECHANICS 
 
 The plumb-line shows the direction of the grav- 
 itation of the body falling behind the head of the 
 thighbone. Now, if it be understood that the 
 motions of the trunk are performed on the cen- 
 tre of the head of 
 the thighbone; it 
 must follow that 
 the weight of the 
 body in the direc- 
 tion of the plumb- 
 line must raise the 
 corner of the 
 haunchbone, at 
 
 A. From this cor- 
 ner of the bone, a 
 broad and strong 
 band runs down 
 to the knee-pan, 
 
 B, in the direction 
 of the dotted line. 
 The powerful mus- 
 cles which extend 
 the leg are at- 
 tached to the knee- 
 pan, and through 
 the ligament at C, 
 
 operate on the bones of the leg, stretching them, 
 and preventing the flexion of the joint; but, in the 
 absence of the activity of these muscles, the band 
 
BONES AND JOINTS OF THE EXTREMITIES 63 
 
 reaching from A to B, drawn, as we have said, 
 by the weight of the body, is equivalent to the 
 exertion of the muscles, braces the knee-joint, 
 and extends the leg; and we have before seen 
 that the extension of the leg fixes the ankle-joint. 
 Thus the limb is made a firm pillar under the 
 weight of the body, without muscular effort. 
 
 When the human figure is left to its natural 
 attitudes, we see a variety and contrast in the 
 position of the trunk and limbs. 
 
 This position of the body resting on the lower 
 extremities throws the trunk into an elegant line, 
 and places the limbs in beauti- 
 ful contrast, as we see in all 
 the best specimens of sculp- 
 ture. See Fig. 15. 
 
 Now that we have under- 
 stood that the lower extrem- 
 ity becomes in some positions 
 a firm pillar, it is the more 
 necessary to observe the par- 
 ticular form of the head of the 
 thighbone (Fig. 16). 
 
 It is here seen that the head 
 of the bone A stands off from 
 the shaft by the whole length 
 of the neck of the bone B ; the 
 effect of this is, that as the powerful muscles are 
 attached to the knobs of bone C D, they turn the 
 
 Fig. 16. 
 
64 ANIMAL MECHANICS 
 
 thighbone round in walking with much greater 
 power than if the head of the bone were on a line 
 with the shaft. They, in fact, acquire a lever 
 power, by the distance of D from A; as, during 
 the action of these muscles, the limb is stiff, the 
 rolling of the thigh directs the toe outwards in 
 walking. 
 
 When the weight of the body is perpendicu- 
 larly over the ball of the great toe, the whole 
 body is twisted round on that point as on a pivot. 
 This rolling of the body on the ball of the toe, 
 and consequent turning out of the toes in step- 
 ping forward, is necessary to the freedom and 
 elasticity of the motion. The form of all the 
 bones of the leg, and the direction of all the 
 muscles of the thigh and leg, combine to this 
 effect. So far is it from being true, as painters 
 affect to say, that the turning out of the toes is 
 the result of the lessons of the dancing-master. 
 
 A certain squareness in the position of the feet 
 is consistent with strength, as we see in the 
 statues of the Hercules, etc. ; but the lightness of 
 a Mercury is indicated by the direction of the 
 toes outwards. In women, there would be a de- 
 fect from the breadth of the pelvis, and a rolling 
 and an awkward gait would be the consequence ; 
 but in them the foot is more turned out, and a 
 light, elastic step balances the defect arising from 
 the form of the pelvis. Any one may be con- 
 
BONES AND JOINTS OP THE EXTREMITIES 65 
 
 vinced of this by observing people who walk awk- 
 wardly, especially if they walk unequally. Look 
 at their feet, and you will see that one foot goes 
 straight forward, whilst the other is turned out- 
 wards, and that when they come upon the straight 
 foot, they come down awkwardly, and have no 
 spring from it. 
 
 There is another curious circumstance in the 
 form of the thighbone, showing how it is calcu- 
 lated for strength as well as freedom of motion. 
 To understand it, we must first look to the dish- 
 ing of a wheel — the dishing is the oblique 
 position of the spokes from the nave to the 
 felly, giving the wheel 
 a slightly conical form. 
 When a cart is in the 
 middle of a road, the 
 load bears equally upon 
 both wheels, and both 
 wheels stand with their 
 spokes oblique to the 
 line of gravitation. 
 
 If the cart is moving 
 on the side of a barrel- 
 shaped road, or if one 
 wheel falls into a rut, 
 the whole weight comes 
 upon one wheel : but the 
 spokes of that wheel, which were oblique to the 
 
 Fig. 17. 
 
66 , ANIMAL MECHANICS 
 
 load when it supported only one half of the weight, 
 are now perpendicular under the pressure, and 
 are capable of sustaining the whole. If roads 
 were made perfectly level, and had no holes in 
 them, the wheels of carts might be made without 
 
 dishing; but if a 
 cart is calculated for 
 a country road, let 
 the wheelwright con- 
 sider what equiva- 
 lent he has to give for 
 that very pretty re- 
 sult proceeding from 
 the obliquity of the 
 spokes, or dishing of 
 the wheel. 
 
 When we return to consider the human thigh- 
 bone, we see that the same principle holds ; that 
 is to say, that whilst a man stands on both his 
 legs, the necks of the thighbones are oblique 
 to the line of gravitation of the body ; but when 
 one foot is raised, the whole body then being 
 balanced on one foot, a change takes place in the 
 position of the thighbone, and the obliquity of 
 that bone is diminished ; or, in other words, now 
 that it has the whole weight to sustain, it is per- 
 pendicular under it, and has therefore acquired 
 greater strength. See Fig. 18. 
 
 Fig. 18. 
 
CHAPTEE V 
 
 OF THE TENDONS COMPARED WITH CORDAGE 
 
 Where nature has provided a perfect system 
 of columns, and levers, and pulleys, we may an- 
 ticipate that the cords by which the force of the 
 muscles is concentrated on the movable bones 
 must be constructed with as curious a provision 
 for their offices. In this surmise we shall not be 
 disappointed. 
 
 To understand what is necessary to the strength 
 of a rope or cable, we must learn what has been 
 the object of the improvements and patents in 
 this manufacture. The first process in rope-mak- 
 ing is hatchelling the hemp ; that is, combing out 
 the short fibres, and placing the long ones paral- 
 lel to one another. The second is spinning the 
 hemp into yarns. And here the principle must 
 be attended to which goes through the whole 
 process in forming a cable; which is, that the 
 fibres of the hemp shall bear an equal strain : and 
 the difficulty may be easily conceived, since the 
 twisting must derange the parallel position of the 
 fibres. Each fibre, as it is twisted, ties the other 
 fibres together, so as to form a continued line, 
 
68 ANIMAL MECHANICS 
 
 and it bears at the same time a certain portion of 
 the strain, and so each fibre alternately. The 
 third step of the process is making the yarns. 
 Warping the yarns is stretching them to a certain 
 length ; and for the same reason, that so much 
 attention has been paid to the arrangement of the 
 fibres for the yarns, the same care is taken in the 
 management of the yarns for the strands. The 
 fourth step of the process is to form the strands 
 into ropes. The difficulty of the art has been to 
 make them bear alike, especially in great cables, 
 and this has been the object of patent machinery. 
 The hardening, by twisting, is also an essential 
 part of the process of rope-making ; for without 
 this, it would be little better than extended paral- 
 lel fibres of hemp. In this twisting, first of the 
 yarns, and then of the strands, those which are 
 on the outer surface must be more stretched than 
 those near the centre ; consequently, when there 
 is a strain upon the rope, the outer fibres will 
 break first, and the others in succession. It is to 
 avoid this, that each yarn and each strand, as it 
 is twisted or hardened, shall be itself revolving, 
 so that when drawn into the cable, the whole 
 component parts may, as nearly as possible, resist 
 the strain in an equal degree ; but the process is 
 not perfect, and this we must conclude from ob- 
 serving how different the construction of a tendon 
 is from that of a rope. A tendon consists of a 
 
TENDONS COMPARED WITH CORDAGE 69 
 
 strong cord, apparently fibrous; but which, by 
 the art of the anatomist, may be separated into 
 lesser cords, and these, by maceration, can be 
 shown to consist of cellular membrane, the com- 
 mon tissue that gives firmness to all the textures 
 of the animal body. The peculiarity here results 
 merely from its remarkable condensation. But 
 the cords of which the larger tendon consists do 
 not lie parallel to one another, nor are they sim- 
 ply twisted like the strands of a rope ; they are, 
 on the contrary, plaited or interwoven together. 
 
 If the strong tendon of the heel, or Achilles 
 tendon, be taken as an example, on first inspec- 
 tion, it appears to consist of parallel fibres, but by 
 maceration, these fibres are found to be a web of 
 twisted cellular texture. If you take your hand- 
 kerchief, and, slightly twisting it, draw it out like 
 a rope, it will seem to consist of parallel cords ; 
 such is, in fact, so far the structure of a tendon. 
 But, as we have stated, there is something more 
 admirable than this, for the tendon consists of 
 subdivisions, which are like the strands of a rope ; 
 but instead of being twisted simply as by the 
 process of hardening, they are plaited or inter- 
 woven in a way that could not be imitated in 
 cordage by the turning of a wheel. Here, then, 
 is the difference, — by the twisting of a rope, the 
 strands cannot resist the strain equally, whilst we 
 see that this is provided for in the tendon by the 
 
70 
 
 ANIMAL MECHANICS 
 
 regular interweaving of the yarn, if we may so 
 express it, so that every fibre deviates from the 
 parallel line in the same degree, and, conse- 
 quently, receives the same strain when the tendon 
 is pulled. If we seek for examples illustrative of 
 this structure of the tendons, we must turn to the 
 subject of ship-rigging, and see there how the 
 seaman contrives, by undoing the strands and 
 yarns of a rope, and twisting them anew, to make 
 his splicing stronger than the original cordage. 
 A sailor opens the ends of two ropes thus : * and 
 
 places the strand of 
 one opposite and 
 between the strand 
 of another, and 
 so interlaces them. 
 And this explains 
 why a hawser-rope, 
 a sort of small ca- 
 ble, is spun of three 
 strands ; for as they 
 are necessary for 
 many operations in the rigging of a ship, they 
 must be formed in a way that admits of being 
 cut and spliced, for the separation of three 
 strands, at least, is necessary for knotting, spli- 
 
 1 A, Strands and yarns opened. 
 
 B, Ends opened and laid for splicing, in a manner exactly 
 like the interlacing of the tendon. 
 
 Fig. 19. 
 
TENDONS COMPAEED WITH CORDAGE 71 
 
 cing, whipping, mailing, etc., which are a few of 
 the many curious contrivances for joining the 
 ends of ropes, and for strengthening them by 
 filling up the interstices to preserve them from 
 being cut or frayed. As these methods of spli- 
 cing and plaiting in the subdivisions of the rope 
 make an intertexture stronger than the original 
 rope, it is an additional demonstration, if any 
 were wanted, to show the perfection of the cord- 
 age of an animal machine, since the tendons are 
 so interwoven ; and until the yarns of one strand 
 be separated and interwoven with the yarns of 
 another strand, and this done with regular ex- 
 change, the most approved patent ropes must be 
 inferior to the corresponding part of the animal 
 machinery. 
 
 A piece of cord of a new patent has been 
 shown to us, which is said to be many times 
 stronger than any other cord of the same diame- 
 ter. It is so far upon the principle here stated, 
 that the strands are plaited instead of being 
 twisted ; but the tendon has still its superiority, 
 for the lesser yarns of each strand in it are inter- 
 woven with those of other strands. It, however, 
 gratifies us to see, that the principle we draw from 
 the animal body is here confirmed. It may be 
 asked, do not the tendons of the human body 
 sometimes break? They do; but in circum- 
 stances which only add to the interest of the sub- 
 
72 ANIMAL MECHANICS 
 
 ject. By the exercise of the tendons (and their 
 exercise is the act of being pulled upon by the 
 muscles, or having a strain made on them), they 
 become firmer and stronger ; but in the failure of 
 muscular activity, they become less capable of 
 resisting the tug made upon them, and if, after 
 a long confinement, a man has some powerful 
 excitement to muscular exertion, then the tendon 
 breaks. An old gentleman, whose habits have 
 been long staid and sedentary, and who is very 
 guarded in his walk, is upon an annual festival 
 tempted to join the young people in a dance; 
 then he breaks his tendo Achillis. Or a sick 
 person, long confined to bed, is, on rising, subject 
 to a rupture or hernia, because the tendinous 
 expansions guarding against protrusion of the 
 internal parts have become weak from disuse. 
 
 Such circumstances remind us that we are 
 speaking of a living body, and that, in estimating 
 the properties of the machinery, we ought not to 
 forget the influence of life, and that the natural 
 exercise of the parts, whether they be active or 
 passive, is the stimulus to the circulation through 
 themj and to their growth and perfection. 
 
CHAPTEE VI 
 
 OP THE MUSCLES OF MUSCULARITY AND ELAS- 
 TICITY 
 
 There are two powers of contraction in the 
 animal frame — elasticity, which is common to 
 living and dead matter, and the muscular power, 
 which is a property of the living fibre. 
 
 The muscles are the only organs which properly 
 have the power of contraction, for elasticity is 
 never exerted but in consequence of some other 
 power bending or stretching the elastic body. In 
 the muscles, on the contrary, motion originates ; 
 there being no connection, on mechanical princi- 
 ples, betwixt the exciting cause and the power 
 brought into action. 
 
 The real power is in the muscles, while the safe- 
 guard against the excess of that power is in the 
 elasticity of the parts. This is obvious in the 
 limbs and general texture of the frame ; but it is 
 most perfectly exhibited in the organs of circula- 
 tion. If the action of the heart impelled the 
 blood against parts of solid texture, they would 
 quickly yield. When, by accident, this does take 
 place, even the solid bone is very soon destroyed. 
 
74 ANIMAL MECHANICS 
 
 But the coats of the artery which receive the rush 
 of blood from the heart, although thin, are limber 
 and elastic ; and by this elasticity or yielding they 
 take off or subdue the shock of the heart's action, 
 while no force is lost ; for as the elastic artery has 
 yielded to the sudden impulse of the heart, it con- 
 tracts by elasticity in the interval of the heart's 
 pulsation ; and the blood continues to be pro- 
 pelled onward in the course of the circulation, 
 without interval, though regularly accelerated by 
 the pulse of the heart. 
 
 If a steam-engine were used to force water 
 along the water-pipes, without the intervention of 
 some elastic body, the water would not flow con- 
 tinuously, but in jerks, and, therefore, a reservoir 
 is constructed containing air, into which the water 
 is forced, against the elasticity of the air. Thus, 
 each stroke of the piston is not perceptibly com- 
 municated to the conduit-pipe, because the inter- 
 vals are supplied by the push of the compressed 
 air. The office of the reservoir containing air 
 is performed in the animal body by the elasticity 
 of the coats of the arteries, by which means the 
 blood which flows interruptedly into the arteries 
 has a continuous and uninterrupted flow in the 
 veins beyond them. 
 
 A muscle is fibrous, that is, it consists of minute 
 threads bundled together, the extremities of which 
 are connected with the tendons which have been 
 
OF MUSCULARITY AND ELASTICITY 75 
 
 described. Innumerable fibres are tbus joined 
 together to form one muscle, and every muscle is 
 a distinct organ. Of these distinct muscles for 
 the motions of the body there are not less than 
 436 in the human frame, independent of those 
 which perform the internal vital motions. The 
 contractile power, which is in the living muscular 
 fibre, presents appearances which, though famil- 
 iar, are really the most surprising of all the pro- 
 perties of life. Many attempts have been made 
 to explain this property, sometimes by chemical 
 experiment, sometimes on mechanical principles, 
 but always in a manner repugnant to common 
 sense. We must be satisfied with saying, that it 
 is an endowment, the cause of which it would be 
 as vain to investigate as to resume the search into 
 the cause of gravitation. 
 
 The ignorance of the cause of muscular con- 
 traction does not prevent us from studying the 
 laws which regulate it, and under this head are 
 included subjects of the highest interest ; which, 
 however, we must leave, to pursue the mechanical 
 arrangement of the muscles. 
 
 Since we have seen that there are 436 distinct 
 muscles in the body, it is due to our readers to 
 explain how they are associated to effect that com- 
 bination which is necessary to the motion of the 
 limbs and to our perfect enjoyment. In the first 
 place, the million of fibres which constitute a 
 
76 ANIMAL MECHANICS 
 
 single muscle are connected by a tissue of nerves, 
 which produce a union or sympathy amongst them, 
 so that one impulse causes a simultaneous effort of 
 all the fibres attached to the same tendon. When 
 we have understood that the muscles are dis- 
 tinct organs of motion, we perceive that they 
 must be classed and associated in order that many 
 shall combine in one act ; and that others, their 
 opponents, shall be put in a state to relax, and 
 offer no opposition to those which are active. 
 These relations can be established only through 
 nerves, which are the organs of communication 
 with the brain, or sensorium. The nerves convey 
 the will to the muscles, and at the same time they 
 class and arrange them so as to make them con- 
 sent to the motions of the body and limbs. 
 
 On first looking to the manner in which the 
 muscles are fixed into the bones, and the course 
 of their tendons, we observe everywhere the ap- 
 pearance of a sacrifice of mechanical power, the 
 tendon being inserted into the bone in such a 
 manner as to lose the advantage of the lever. 
 This appears to be an imperfection, until we learn 
 that there is an accumulation of vital power in 
 the muscle in order to attain velocity of move- 
 ment in the member (Fig. 20). 
 
 The muscle D, which bends the forearm, is 
 inserted into the radius E, so near the fulcrum, 
 or centre of motion in the elbow-joint, and so 
 
OF MUSCULARITY AND ELASTICITY 
 
 77 
 
 oblique that it must raise the hand and forearm 
 with disadvantage. But, correctly speaking, the 
 power of the muscle is not sacrificed, since it 
 gains more than an equivalent in the rapid and 
 lively motions of the hand and fingers, and since 
 these rapid motions are necessary to us in a thou- 
 sand familiar actions ; and to attain this, the Cre- 
 ator has given sufficient vital power to the mus- 
 cles to admit of the sacrifice of the mechanical 
 or lever power, and so to provide for every degree 
 and variety of motion which may answer to the 
 capacities of the mind. 
 
 If we represent the bones and muscles of the 
 forearm by this diagram, we shall see that power 
 
 Fig. 20. 
 
 is lost by the inclination of the tendon to the 
 lever, into which it is inserted. It represents the 
 lever of the third kind, where the moving power 
 operates on a point nearer the fulcrum than the 
 weight to be moved. 
 
78 ANIMAL MECHANICS 
 
 Here A represents the muscle, B the lever, and 
 C the fulcrum. The power of the ntuscle is not 
 represented by the distance of its insertion a, 
 
 from the fulcrum 
 C. The line which 
 truly represents 
 the lever must pass 
 
 from the centre of 
 Pig. 21. . ,. 
 
 motion, perpendic- 
 ularly to the line of the tendon, viz., C b. Here, 
 again, by the direction of the tendon, as well as 
 by its actual attachment to the bone, power is lost 
 and velocity gained. 
 
 We may compare the muscular power to the 
 weight which impels a machine. In studying 
 machinery, it is manifest that weight and velocity 
 are equivalent. The handle of the winch in a crane 
 is a lever, and the space through which it moves, 
 in comparison with the slow motion of the weight, 
 is the measure of its power. If the weight, raised 
 by the crane, be permitted to go down, the wheels 
 revolve, and the handle moves with the velocity 
 of a cannon-ball, and will be as destructive if it 
 hit the workman. The weight here is the power, 
 but it operates with so much disadvantage, that 
 the hand upon the handle of the winch can stop 
 it: but give it way, let the accelerated motion 
 take place, and the hand would be shattered which 
 touched it. Just so the fly-wheel, moving at first 
 
OF MUSCULARITY AND ELASTICITY 79 
 
 slowly, and an impediment to the working of a 
 machine, at length acquires momentum, so as to 
 concentrate the power of the machine, and enable 
 it to cut bars of iron with a stroke. 
 
 The principle holds in the animal machinery. 
 The elbow is bent with a certain loss of mechan- 
 ical power; but by that very means, when the 
 loss is supplied by the living muscular power, the 
 hand descends through a greater space, moves 
 quicker, with a velocity which enables us to strike 
 or to cut. Without this acquired velocity, we 
 could not drive a nail : the mere muscular power 
 would be insufficient for many actions quite ne- 
 cessary to our existence. 
 
 Let us take some examples to show what ob- 
 jects are attained through the oblique direction 
 of the fibres of the muscle, and we shall see that 
 here, as well as by the mode of attachment of 
 the entire muscle, velocity is attained by the sac- 
 rifice of power. Suppose that these two pieces of 
 wood (Fig. 22) be drawn together by means of 
 a cord, but that the hand which pulls, although 
 possessing abundant strength, wants room to re- 
 cede more than what is equal to one third of the 
 space betwixt the pieces of wood ; it is quite clear, 
 that if the hand were to draw direct on the cord 
 A B, the point A would be brought towards B, 
 through one third only of the intervening space, 
 and the end would not be accomplished. But if 
 
80 
 
 ANIMAL MECHANICS 
 
 the cord were put over the ends of the upper 
 
 piece, C D E, and, 
 consequently, directed 
 obliquely to their at- 
 H D ' tachment at A, on 
 drawing the hand back 
 a very little, but with 
 more force, the lower 
 piece of wood would be 
 suddenly drawn up to 
 the higher piece, and the object attained. Or we 
 may put it in this form : — If a muscle be in the 
 direction of its tendon, the motion of the extrem- 
 ity of the tendon will be the same with that of the 
 muscle itself : , but if the attachment of the muscle 
 to the tendon be oblique, it will draw the tendon 
 through a greater space ; and if the direction 
 of the muscle deviate so far from the line of the 
 tendon as to be perpendicular to it, it will then 
 be in a condition to draw the 
 tendon through the greatest 
 space with the least contraction 
 of its own length. Thus, if A B 
 be a tendon, and C D a mus- ' 
 
 cle, by the contraction of C to D the extremi- 
 ties of the tendon A B will be brought together, 
 through a space double the contraction of the 
 muscle. It is the adjustment, on the same prin- 
 ciple, which gives the arrow so quick an impulse 
 
OF MUSCULAEITY AND ELASTICITY 81 
 
 from the spring of the bow, the extremities of the 
 bow drawing obliquely on the string. 
 
 To free breathing, it is necessary that the ribs 
 shall approach each other, and this is performed 
 by certain intercostal muscles (or muscles play- 
 ing between the ribs), and now we can answer 
 the question, why are the fibres of these muscles 
 oblique ? 
 
 Let us suppose this figure to represent two ribs 
 with thin inter- 
 vening muscles. 
 If the fibres of 
 the muscle were 
 
 in the direction 
 . , Fig. 24. 
 
 A, across, and 
 
 perpendicular to the ribs ; and if they were to 
 contract one third of their length, they would not 
 close the intervening space — they would not ac- 
 complish the purpose. But being oblique, as at 
 
 B, although they contract no more than one third 
 of their length, they will bring the ribs C, D 
 together. By this obliquity of the intercostal 
 muscles, they are enabled to expand the chest 
 in inspiration, in a manner which could not be 
 otherwise accomplished. 
 
 In the greater number of muscles the same 
 principle directs the arrangement of the fibres; 
 they exchange power for velocity of movement, 
 by their obliquity. They do not go direct from 
 
82 
 
 ANIMAL MECHANICS 
 
 origin to insertion, but obliquely, thus, from 
 tendon to tendon : — 
 
 Fig. 25. 
 
 Supposing the point A to be the fixed point, 
 these fibres draw the point B with less force, but 
 through a larger space, or more quickly than if 
 they took their course in direct lines ; and by this 
 arrangement of the fibres the freedom and extent 
 of motion in our limbs are secured. 
 
 But the muscles must be strengthened by addi- 
 tional courses of fibres, because they are oblique ; 
 since by their obliquity they lose something of 
 their force of action : and therefore it is, we must 
 presume, that we find them in a double row, mak- 
 ing what is termed the penniform muscle, thus, — 
 
 and sometimes the 
 texture of the mus- 
 cle is still further 
 compounded by the 
 intermixture of ten- 
 dons, which permit additional series of fibres ; and 
 all this for the obvious purpose of accumulating 
 power, which may be exchanged for velocity of 
 movement. 
 
 We may perceive the same effect to result from 
 the course of the tendons, and their confinement 
 
 Fig. 26. 
 
OF MUSCULARITY AND ELASTICITY 
 
 83 
 
 in sheaths, strengthened by cross-straps of liga- 
 ment. If the tendon, A (Fig. 27), took the short- 
 est course to its termination at B, it would draw 
 up the toe with greater force ; but then the toe 
 
 Fig. 27. 
 
 would lose its velocity of movement. By taking 
 the direction C, close to the joints, the velocity 
 of motion is secured, and by this arrangement 
 the toes possess their spring, and the fingers their 
 lively movements. We may take this opportu- 
 nity of noticing how the mechanical opposition 
 is diminished as the living muscular power is 
 exhausted. For example, in lifting a weight, the 
 length of the lever of resistance will be from 
 the centre of the elbow-joint, A (Fig. 28), to the 
 centre of the weight, B. As the muscles of the 
 arm contract, they lose something of their power; 
 but in a greater proportion is the mechanical 
 
84 ANIMAL MECHANICS 
 
 resistance diminished, for when the weight is 
 raised to C A D, it becomes the measure of the 
 lever of resistance. 
 
 A more admirable thing is witnessed by the 
 anatomist, — we mean the manner in which the 
 lever, rising or falling, is carried beyond the 
 sphere of action of one class of muscles, and 
 enters the sphere of activity of others. And this 
 adaptation of the organs of motion is finely ad- 
 justed to the mechanical resistance which may 
 arise from the form or motion of the bones. In 
 short, whether we contemplate the million of 
 fibres which constitute one muscle, or the many 
 muscles which combine to the movement of the 
 limb, nothing is more surprising and admirable 
 than the adjustment of their power so as to bal- 
 ance mechanical resistance, arising from the 
 change of position of the levers. 
 
 In the animal body, there is a perfect relation 
 preserved betwixt the parts of the same organ. 
 The muscular fibres forming what is termed the 
 belly of the muscle, and the tendon through 
 which the muscle pulls, are two parts of one 
 organ ; and the condition of the tendon indicates 
 the state of the muscle. Thus jockeys discover 
 the qualities of a horse by its sinews or tendons. 
 The most approved form in the leg of the hunter, 
 or hackney, is that in which three convexities can 
 be distinguished, — the bone ; the prominence of 
 
OF MUSCULARITY AND ELASTICITY 85 
 
 the elastic ligament behind the bone ; and behind 
 that the flexor tendons, large, round, and strong. 
 Strong tendons are provided for strong muscles, 
 and the size of these indicate the muscular 
 strength. Such muscles, being powerful flexors, 
 cause high and round action, and such horses are 
 
 Fig. 28. 
 
 safe to ride; their feet are generally preserved 
 good, owing to the pressure they sustain from 
 their high action. But this excellence in a horse 
 will not make him a favorite at Newmarket. 
 The circular motion cannot be the swiftest; a 
 blood-horse carries his foot near the ground. 
 The speed of a horse depends on the strength of 
 his loins and hind quarter ; and what is required 
 
86 ANIMAL MECHANICS 
 
 in the forelegs is strength of the extensor ten- 
 dons, so that the feet may be well thrown out 
 before, for if these tendons be not strong, the 
 joints will be unable to sustain the weight of his 
 body, when powerfully thrown forward, by the 
 exertion of his hind-quarters, and he will be apt 
 to come with his nose to the ground. 
 
 The whole apparatus of bones and joints being 
 thus originally constituted by nature in accurate 
 relation to the muscular powers, we have next to 
 observe, that this apparatus is preserved perfect 
 by exercise. The tendons, the sheaths in which 
 they run, the cross ligaments by which they are 
 restrained, and the bursce muscosce 1 which are 
 interposed to diminish friction, can be seen in 
 perfection only when the animal machinery has 
 been kept in full activity. In inflammation, and 
 pain, and necessary restraint, they become weak ; 
 and even confinement, and want of exercise, with- 
 out disease, will produce imperfections. Exercise 
 unfolds the muscular system, producing a full 
 bold outline of the limbs, at the same time that 
 the joints are knit, small, and clean. In the 
 loins, thighs, and legs of a dancer we see the 
 muscular system fully developed; and when we 
 
 1 These bursa mucosce (mucous purses) are sacs containing a 
 lubricating fluid. They are interposed wherever there is much 
 pressure or friction, and answer all the purposes of friction-wheels 
 in machinery. 
 
OF MUSCULARITY AND ELASTICITY 87 
 
 turn our attention to his puny and dispropor- 
 tioned arms, we acknowledge the cause — that, 
 in the one instance, exercise has produced per- 
 fection, and that, in the other, the want of it has 
 occasioned deformity. Look to the legs of a poor 
 Irishman travelling to the harvest with hare feet : 
 the thickness and roundness of the calf show that 
 the foot and toes are free to permit the exercise 
 of the muscles of the leg. Look, again, to the 
 leg of our English peasant, whose foot and ankle 
 are tightly laced in a shoe with a wooden sole, 
 and you will perceive, from the manner in which 
 he lifts his legs, that the play of the ankle, foot, 
 and toes are lost, as much as if he went on stilts, 
 and, therefore, are his legs small and shapeless. 
 
 And this brings us naturally to a subject of 
 some interest at present : we mean the new 
 fashion of exercising our youth in a manner 
 which is to supersede dancing, fencing, boxing, 
 rowing, and cricket, and the natural impulse of 
 youth to activity. 
 
 By this fashion of training to what are termed 
 gymnastics, children at school are to be urged to 
 feats of strength and activity, not restrained by 
 parental authority, nor left to their own sense of 
 pleasurable exertion. They are made to climb, to 
 throw their limbs over a bar, to press their foot 
 close to their hip, their knees close to their stom- 
 ach j to hang by the arms and raise the body, — 
 
88 ANIMAL MECHANICS 
 
 to hang by the feet and knees, — to struggle 
 against each other, by placing the soles of their 
 feet in opposition, and to pull with their hands. 
 No doubt, if such exercises be persevered in, the 
 muscular powers will be strongly developed. But 
 the first question to be considered is the safety of 
 this practice. We have seen a professor of gym- 
 nastics, by such training, acquire great strength 
 and prominence of muscles ; but by this unnat- 
 ural increase of muscular power, through the 
 exercises he recommended, he became ruptured 
 on both sides. The same accident has happened 
 to boys too suddenly put on these efforts. 
 
 It is proper to observe, that when the muscular 
 power is thus, we may say, preternaturally in- 
 creased, whether in the instance of a race-horse, 
 an opera dancer, or a pupil of the Calisthenic 
 school, it is not merely necessary to put them on 
 their exercises gradually in each successive lesson, 
 but each day's exertion must be preceded by a 
 wearisome preparation. In the great schools, like 
 that at Stockholm, the master makes the boys 
 walk- in a circle ; then run, at first gently ; and 
 so he gradually brings them into heat, and the 
 textures of their frame are composed to thai state 
 of elasticity and equal resistance, as well as to 
 vital energy, which is necessary for the safe dis- 
 play of the greater feats of strength and activity. 
 This caution in the public exercises is the very 
 
OF^MUSCULAEITY AND ELASTICITY 89 
 
 demonstration of the clangers of the system. The 
 boys will not be always under this severe control, 
 and yet it is important to their safety. 
 
 We may learn how necessary it is to bring the 
 animal system gradually into action from the 
 effects of very moderate exercise on a horse just 
 out of the dealer's hands. The purchaser thinks 
 he may safely drive him ten miles, not aware 
 that the horse has not moved a mile in a week, 
 and the consequence is, inflammation and conges- 
 tion in his lungs. The regulation in the army 
 has been made on a knowledge of these facts. 
 When young horses are brought from the dealer 
 they are ordered to be walked an hour a day the 
 first week, two hours a day the second week, 
 three hours a day in the third week. They are 
 to be fatigued by walking, but they must not be 
 sweated in their exercise. Horses for the turf, 
 under three years old, in training for the Derby, 
 are brought very slowly to their exercise, begin- 
 ning with the lounge ; then a very light weight 
 is put upon them, and that gradually increased. 
 Indeed, nothing can better show the effects of ex- 
 ercise in perfecting the muscular action than the 
 consequence of the loss of one day's training. It 
 will bring the favorite to the bottom of the list, 
 and that without any suspicion of lameness, but 
 from a knowledge of the fact, that even such a 
 
90 ANIMAL MECHANICS 
 
 slight irregularity in his training will have a sen- 
 sible effect on his speed. Shall the possibility of 
 pecuniary loss excite the jockey to more care for 
 his horse than we, in our rational and humane 
 attention to the education of our youth, pay to 
 their health and safety ? 
 
 In reflecting on these many proofs of design in 
 the animal body, it must excite our surprise that 
 anatomy is so little cultivated by men of science. 
 We crowd to see a piece of machinery or a new 
 engine, but neglect to raise the covering which 
 would display in the body the most striking 
 proofs of design, surpassing all art in simplicity 
 and effectiveness, and without anything useless 
 or superfluous. 
 
 A more important deduction from the view of 
 the animal structure is, that our conceptions of 
 the perfection and beauty in the design of nature 
 are exactly in proportion to the extent of our 
 capacity. We are familiar with the mechanical 
 powers, and we recognize the principles in the 
 structure of the animal machine ; and in propor- 
 tion as we understand the principles of hydro- 
 statics and hydraulics, are able to discern the 
 most beautiful adaptation of them in the vessels 
 of an animal body. But when, to our further 
 progress in anatomy, it is necessary that we should 
 study a matter so difficult as the theory of life, 
 
OF MUSCULARITY AND ELASTICITY 91 
 
 imperfect principles or wrong conceptions distort 
 and obscure the appearances : false and presump- 
 tuous theories are formed, or we are thrown back 
 in disappointment into scepticism, as if chance 
 only could produce that of which we do not com- 
 prehend the perfect arrangement. But studies 
 better directed, and prosecuted in a better spirit, 
 prove that the human body, though deprived of 
 what gave it sense and motion, is still a plan 
 drawn in perfect wisdom. 
 
 A man possessed of that humility which is akin 
 to true knowledge may be depressed by too ex- 
 tensive a survey of the frame of nature. The 
 stupendous changes which the geologist surveys 
 — the incomprehensible magnitude of the hea- 
 venly bodies moving in infinite space, bring down 
 his thoughts to a painful sense of his own little- 
 ness : — "To him the earth with men upon it, 
 will not seem much other than an ant-hill, where 
 some ants carry corn, and some carry their young, 
 and some go empty, and all to and fro a little 
 heap of dust." x 
 
 He is afraid to think himself an object of 
 Divine care ; but when he regards the structure 
 of his own body, he learns to consider space and 
 magnitude as nothing to a Creator. He finds 
 that the living being, which he was about to con- 
 temn, in comparison with the great system of the 
 
 1 Bacon. 
 
92 ANIMAL MECHANICS 
 
 universe, exists by the continuance of a power, no 
 less admirable than that which rules the heavenly 
 bodies ; he sees that there is a revolution, a circle 
 of motions no less wonderful in his own frame, 
 in the microcosm of man's body, than in the 
 planetary system ; that there is not a globule of 
 blood which circulates, but possesses attraction as 
 incomprehensible and wonderful as that which 
 retains the planets in their orbits. 
 
 The economy of the animal body, as the eco- 
 nomy of the universe, is sufficiently known to us 
 to compel us to acknowledge an Almighty Power 
 in the creation. What would be the consequence 
 of a further insight — whether it would conduce 
 to our peace or happiness — whether it would 
 assist us in our duties, or divert us from the per- 
 formance of them, is very uncertain. 
 
CHAPTER VII 
 
 BOOKS 
 
 Ray, " On the Wisdom of God manifested in 
 the Works of the Creation," has several chapters 
 on the animal economy. 
 
 Archdeacon Paley has composed a work of 
 high interest, by taking the common anatomical 
 demonstrations, and presenting them in an ele- 
 gant and popular form. His work is entitled, 
 Natural Theology ; or, Evidences of the Existence 
 and Attributes of the Deity, collected from the 
 Appearances of Nature. 
 
 The celebrated Fenelon has, with the same 
 pious object, composed a small duodecimo, in 
 which he draws his arguments from the structure 
 of animal bodies. 
 
 Wollaston, in the " Religion of Nature Deline- 
 ated," has the same train of reflection to prove 
 that there can be no such thing as chance oper- 
 ating in and about what we see or feel ; and he 
 says, with great propriety, "How may a man 
 qualify himself so as to be able to judge of the 
 religions professed in the world; to settle his 
 own opinions in disputable matters ; and then to 
 enjoy tranquillity of mind, neither disturbing oth- 
 ers, nor being disturbed at what passes among 
 them?" 
 
94 ANIMAL MECHANICS 
 
 Derham, in sixteen sermons, preached in 1711, 
 at the lecture founded by Mr. Boyle, treats at 
 length of the structure of our organs. These are 
 also published, separately, under the title of 
 Physico-Theology ; and they naturally suggest 
 to learned divines the expediency of sometimes 
 expounding to their hearers the evidences of de- 
 sign apparent in the universe, as a sure means of 
 enlightening their understandings, elevating their 
 views, and awakening their piety. 1 
 
 This cultivation of the mind, by exercising it 
 upon the study of proper objects, is a man's first 
 duty to himself. Without it, he can have no 
 steady opinion, on points of the nearest concern. 
 He is wrought upon by circumstances which 
 ought not to sway the mind of a sensible man; 
 at one time depressed to the depths of despond- 
 ency, and, at another, exalted into unreasonable 
 enthusiasm. Without such cultivation, were a 
 man to live a hundred years, he is at last like one 
 cut off in infancy. 
 
 1 Henry Lord Brougham, man of letters, man of science, advo- 
 cate, orator, statesman, and Lord Chancellor of England, wrote as 
 follows to Sir Charles Bell, after the publication of this treatise : — 
 
 " I cannot refrain from telling you the prodigious success your 
 admirable treatise [Animal Mechanics] has among us on this cir- 
 cuit — judges, lawyers, wranglers, metaphysicians, and theologians, 
 men who are devoid of science, saint, savage, and sage, all unite 
 in its praise and in gratitude to you. But should not the subject 
 have a second handling? H. Brougham, August, 1827." — Let- 
 ters of Sir C. Bell, 1870, p. 295. 
 
Aa rvwj' 
 
 IV>N^. 
 
ANIMAL MECHANICS 
 
 ON THE CANCELLATED STRUCTURE OP SOME OF 
 THE BONES OF THE HUMAN BODY 
 
 OR 
 
 OF THOSE BONES WHICH HAVE A DEFINITE 
 
 RELATION TO THE ERECT POSITION 
 
 WHICH IS NATURALLY ASSUMED 
 
 BY MAN ALONE 
 
 BY 
 
 JEFFRIES WYMAN, A. M., M. D. H. C. 
 
 COMMUNICATED TO THE BOSTON SOCIETY OF NATURAL HISTORY 
 November 7, 1849 
 
JEFFRIES WYMAN 
 
 Deed 4th Sept., 1874 
 
 The wisest man could ask no more of Fate 
 Than to be simple, modest, manly, true, 
 Safe from the Many, honored by the Few ; 
 Nothing to court in World, or Church, or State, 
 But inwardly in secret to be great ; 
 To feel mysterious Nature ever new, 
 To touch, if not to grasp, her endless clew, 
 And learn by each discovery how to wait ; 
 To widen knowledge and escape the praise ; 
 Wisely to teach, because more wise to learn ; 
 To toil for Science, not to draw men's gaze, 
 But for her lore of self-denial stern ; 
 That such a man could spring from our decays 
 Fans the soul's nobler faith until it burn. 
 
 James Russell Lowell. 
 
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 055 g o» 
 
 £ a* T 
 
 
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 £.$, Si?'" 
 13 ja cli © 
 
ON THE CANCELLATED STRUCTURE OF 
 SOME OF THE BONES OF THE HU- 
 MAN BODY 
 
 With the exception of the great work of Bour- 
 gery and Jacob, Traite Complete de l'Anatomie 
 de l'Homme, and the excellent and instructive 
 Outlines of Human Osteology, by F. 0. Ward, 
 nearly all systematic treatises are deficient in de- 
 scriptions of the mechanical arrangement of the 
 cancellated structure of bones. The student will 
 look in vain through the works of Cruveilhier, 
 Meckel, Bichat, Von Behr, Weber, Soemmering, 
 and Wilson, for any allusion to the manner in 
 which the cancelli are arranged, with reference to 
 the weight which they sustain, and the distribu- 
 tion of that weight to the parts on which they 
 rest. The whole subject is passed by without 
 any other notice than that which would be nat- 
 urally suggested in describing the " spongy," 
 " reticulated," or " cancellated structure," in con- 
 trast with the more dense " compact substance," 
 forming the external walls and crust of the differ- 
 ent bones. This is the more remarkable, when 
 it is remembered that the bones have been so 
 perseveringly studied, not only as regards their 
 
100 THE CANCELLI OF BONES 
 
 external characters, but as to their microscopic 
 structure and chemical composition. 
 
 Sir Charles Bell, in his Treatise on Animal 
 Mechanics, 1 alludes to the direction of the can- 
 celli in the neck of the thighbone, but his de- 
 scription will be found, on comparison, to be 
 inaccurate. Mr. Quain, in the last edition of his 
 Anatomy, 2 in referring to the cancellated struc- 
 ture of bones, states correctly the general princi- 
 ple according to which these fibres are arranged. 
 " It may be usually observed," he says, " that the 
 strongest laminae run through the structure in 
 those directions in which the bone has naturally 
 to sustain the greatest pressure." (Vol. I. p. 75.) 
 But he does not adduce a single instance in illus- 
 tration of his general proposition. 
 
 Bourgery and Jacob, to whom the merit be- 
 longs of first calling attention to the subject, have 
 recognized its interest, and have shown that there 
 exists in several of the bones a definite relation 
 between the direction of the cancelli and the 
 weight that the bones, of which they form a part, 
 are destined to sustain, Their description of the 
 neck of the thighbone, it is believed, will be found 
 
 1 Animal Mechanics, or Proofs of Design in the Animal Frame. 
 Published by the Society for the Diffusion of Useful Knowledge. 
 
 2 Human Anatomy, by Jones Quain, M. D. Edited by Richard 
 Quain, P. R. S., and William Sharpey, M. D., F. R. S. First 
 American Edition. Edited by Joseph Leidy, M. D. Philadel- 
 phia : 1849. 
 
THE CANCELLI OF BONES 101 
 
 on comparison to be incorrect. In the lower ex- 
 tremity of the femur, and in both extremities of 
 the tibia, in the astragalus and os calcis, the can- 
 celli are accurately described and figured. Mr. 
 F. 0. Ward, in his Outlines, 1 as regards the struc- 
 ture of the bones of the tarsus, simply follows the 
 descriptions of Bourgery and Jacob. He has at- 
 tempted a description of the mechanical structure 
 of the neck of the thighbone, but as will be 
 shown further on, there is sufficient reason for 
 regarding his description, as well as that of the 
 last mentioned authors, incorrect in its details. 
 These constitute the only references which I have 
 been able to find, bearing upon the subject of 
 this communication. 
 
 Before proceeding to the detailed description 
 of individual parts, it may be proper to state, in 
 general terms, the inferences which are deducible 
 from the structures of the various bones, and, 
 more especially, from those which assist in main- 
 taining the body in its erect position ; there are 
 two : — 
 
 1. The cancelli of such bones as assist in sup- 
 porting the weight of the body are arranged 
 either in the direction of that weight, or in such 
 a manner as to support and brace those cancelli 
 which are in that direction. In a mechanical 
 
 1 Outlines of Human Osteology, by F. O. Ward. Loudon : 
 1838. 
 
102 THE CANCELLI OP BONES 
 
 point of view they may be regarded in nearly all 
 these bones as a series of "studs" and "braces." 
 
 2. The direction of these fibres in some of the 
 bones of the human skeleton is characteristic, 
 and, it is believed, has a definite relation to the 
 erect position which is naturally assumed by man 
 alone. 
 
 These structures are the most conspicuous in 
 the lumbar portion of the vertebral column, in 
 the thighbone, both in its neck and lower ex- 
 tremity, in the tibia, in the astragalus, and the os 
 calcis. It should be remarked, however, in ad- 
 vance, that they are not equally distinct in the 
 bones of all individuals, nor at all periods of life. 
 The cancelli of the bones of young subjects gen- 
 erally have between them rounded areolae, and do 
 not appear to assume one direction more than 
 another. In very old subjects they seem to be 
 less clearly defined than in adult and middle-aged 
 skeletons. In these last, while considerable va- 
 riety exists, I have rarely failed to recognize the 
 general plan of the arrangement of the cancelli. 
 In bones filled with fat the structure is obscured, 
 but it is readily exposed by washing them in a 
 solution of potash or other alkali. 
 
 I. VERTEBRA 
 
 The functions of the vertebra? are threefold : 
 — they serve as columns for the support of 
 
THE CANCELLI OF BONES 103 
 
 weight ; they form, by their union, a canal for 
 the lodgment and protection of the spinal mar- 
 row; and constitute a series of levers for the 
 application of muscular force. The first of these 
 functions is performed by the "body," whose 
 special use in a given region is to support the 
 weight of the head, arms, and of all that portion 
 of the trunk which is above it ; which weight ac- 
 quires its maximum in the lumbar region, where 
 the vertebrae acquire their greatest size. The 
 pressure on all the vertebrae is vertical. 
 
 If a section be made through a lumbar ver- 
 tebra, the areolae between the cancelli will be 
 found to have generally a quadrangular form, 
 and the direction of the cancelli either vertical 
 or transverse {Fig. 29 J ). The vertical ones ex- 
 tending from the upper to the lower face of the 
 vertebra receive the weight which they sustain 
 on their ends ; and this they will sustain in virtue 
 of their rigidity. If they have a tendency to 
 yield, it is either by being crushed, or by bending 
 in a lateral direction. This last is prevented by 
 the transverse cancelli which are placed at right 
 angles to the vertical ones, and serve the purpose 
 
 1 This and the following diagrams are intended merely as 
 plans of the cancelli, the different lines representing their general 
 directions. For accurate figures of the bones described, except 
 the neck of the thigh, the vertebra, and astragalus, see the plates 
 of Bourgery and Jacob. 
 
104 THE CANCELLI OF BONES 
 
 of "braces." The cancelli of the lumbar ver- 
 tebrae are, therefore, arranged in conformity with 
 the demand for resistance. The arrangement in 
 question is rarely obvious above the last dorsal 
 vertebra ; it is, however, present in precisely that 
 
 Fig. 29. 
 
 part of the column where the pressure, and, con- 
 sequently, the demand for resistance is greatest. 
 
 II. NECK OF THE THIGHBONE 
 
 The whole weight of the head, trunk, arms, 
 and pelvis rests on the heads of the two thigh- 
 bones, or more or less on one of them, according 
 to the attitude of the body when in a state of 
 rest. When the body is in motion they will sus- 
 tain, in addition to this, the momentum of the 
 trunk as it descends upon them in walking, run- 
 ning, jumping, etc. The heads of the bones are 
 
THE CANCELLI OF BONES 105 
 
 themselves immediately supported by the neck, 
 the axis of which forms an angle of about 120° 
 with that of the shaft of the bone, if the lower 
 angle be measured, or of 60° if the upper. 1 The 
 weight of the body will, therefore, have an angu- 
 lar bearing upon the axis of the neck, and its 
 tendency will be to bend or break the neck in a 
 downward direction. The means which nature 
 has adopted to counteract this tendency con- 
 sist : — 
 
 1. In making the vertical diameter of the neck 
 
 1 This measurement was made from the specimen which has 
 served for the present description. Great confusion exists in 
 systematic treatises, with regard to the size of the angle which 
 the neck makes with the shaft of the femur. Some writers de- 
 scribe it only in general terms, as Meckel, who refers to it as 
 " un angle presque droit ; '' Soemering, " un angle aigu ; " Cru- 
 veilhier and Quain, as " an obtuse angle,'' etc. Where more pre- 
 cise statements are made, great difference will be found, not only 
 as regards the number of degrees which the angle is estimated 
 to make, but, also, with regard to the angle which is measured ; 
 some measuring the angle which the axis of the neck makes with 
 that of the shaft below their union, and others with the continu- 
 ation of that axis above it. In order, therefore, to compare the 
 different statements, it will be necessary to give, in each case, the 
 complementary angles, and then we can designate the corre- 
 sponding angles. The angle which the neck makes with the 
 shaft, is, according to 
 
 Ward, 125° comp. angle 55°. 
 
 B. Cooper, 45° " " 135°. 
 
 Morton, 35°-40° " " 145°-140°. 
 
 Comparing the corresponding angles, we have 125°, 135°, 140°, 
 and 145°, giving a variation of 20°. 
 
106 THE CANCELLI OF BONES 
 
 the largest, a section at right angles to its axis 
 being oval, and the long diameter perpendicular. 
 
 2. In increasing the thickness of the wall of 
 bone on the under side of the neck and adjoining 
 portion of the shaft, on to which a large portion 
 of the weight of the body is directly transmitted. 
 
 3. In having the cancelli of each femur so 
 arranged as to form a segment of a framed arch 
 or truss, which cooperates with the external shell 
 in sustaining the weight of the body ; the necks 
 of the two femora forming together opposite seg- 
 ments of an arch. 
 
 The first and second of these conditions has 
 been frequently adverted to by anatomical writ- 
 ers, but the third has almost invariably escaped 
 observation. 
 
 Sir Charles Bell, whose views of the animal 
 mechanism are generally so beautiful and true, 
 has not manifested his usual accuracy in his de- 
 scription of the structure of the neck of the thigh, 
 as given in his tract on Animal Mechanics. One 
 who examines this bone, he says, " will find that 
 the head of the thigh stands obliquely off from 
 the shaft, and that the whole weight bears upon 
 what is termed the inner trochanter ; and to that 
 point, as to a buttress, all those delicate fibres 
 converge, or point from the neck and head of the 
 bone." 1 A careful examination of a section of 
 
 1 Op. cit, p. 14. 
 
THE CANCELLI OF BONES 107 
 
 the part in question will show that this descrip- 
 tion of the cancelli is imperfect as well as incor- 
 rect ; that the cancelli do not centre on the lesser 
 trochanter, as this process is situated not on the 
 under side of the neck, but on the posterior and 
 inner face of the upper portion of the shaft, and 
 does not, therefore, come within their range. The 
 cancelli converge and bear upon the under thick- 
 ened and arched shell of bone, but their common 
 centre is at least an inch exterior to and below it. 
 Bourgery and Jacob, in speaking of the inter- 
 nal structure of the head and neck, describe the 
 first as provided with cancelli forming circular 
 areolae ; the second as made up of two portions 
 — an inferior one consisting of " small parallel 
 columns, which evidently transmit the weight of 
 the superior segment of the head on to the in- 
 ferior border of the neck. Those parts which 
 are out of the line of pressure (hors de la ligne 
 de pression), having nothing to support, will 
 be formed of a more delicate tissue." They also 
 recognize a mass of fibres which enclose the vas- 
 cular canals, and which " seems to have for its 
 object the union of the head and trochanter with 
 each other and with the shaft of the bone." " It 
 communicates with the head and neck by a fasci- 
 culus of radiating fibres, and with the trochanter 
 by a strong lamina, which bifurcates, intercepting 
 two reticular spaces, and externally joins the com- 
 
108 THE CANCELLI OP BONES 
 
 pact substance. Inferiorly this lamina is again 
 made to bear on the compact substance by a bun- 
 dle of vertical columns ; the central mass descends 
 vertically for the space of an inch and a half 
 in the direction of the axis of the bone, and 
 then expands into a cone which joins the circum- 
 ference. This cone divides into two masses ; an 
 external stronger one, descending obliquely to the 
 right and left, joins the compact substance of the 
 opposite planes of the bone; the internal line 
 follows the course indicated by the base of the 
 neck, and limits the triangular space comprised 
 between it and the great fasciculus of support." 1 
 
 This description is too much confused to be 
 understood without the aid of their figure ; and 
 this, it is believed, will be found on comparison 
 with a section of the bone itself to be an inaccu- 
 rate representation of its structure. The descrip- 
 tion is correct, as far as it relates to the fibres 
 which transmit the weight from the head to the 
 under side of the neck, though they are not par- 
 allel ; the " central mass " I have not been able 
 to make out, and as for that portion which is 
 " out of the line of pressure," it has not a struc- 
 ture different from the adjoining parts, and, like 
 them, it performs an important office in sustain- 
 ing the weight of the body. 
 
 Mr. Ward, in his description of the neck, ap- 
 
 1 Bourgery and Jacob, op. cit., Tome I. p. 118. 
 
THE CANCELLI OF BONES 109 
 
 proacnes nearer the truth, though he seems to 
 have misconceived the plan of its structure. He 
 recognizes three series of fibres, one of which 
 extends from the head to the under surface of 
 the neck (Fig. 31, a) ; another forming a series of 
 pointed arches which abut on the outer and inner 
 walls of the base of the neck (b b) ; and a third 
 extending from the summit of this arch to the first 
 series (c) ; the whole of which he compares to a 
 bracket (d) ; series (a) resisting by its rigidity, (c) 
 by its tenacity, and (6) forming the " archwork," 
 which gives the last its points of resistance. The 
 cancelli of the triangular interval between these 
 three, he says, present no determinate arrange- 
 ment. In the sequel it will appear that neither 
 the interval which he describes nor the archwork 
 exists. 
 
 According to the view which I wish to advance, 
 and which seems to approach much nearer the 
 truth than either of those above referred to, two 
 series of cancelli exist ; one of these (Fig. 30, a a) 
 rests or abuts on the convex surface of the thick 
 shell which forms the under wall of the neck, and 
 from this they diverge towards the upper portion 
 of the head, neck, trochanter major, and that 
 portion of the shaft just below this last; those 
 which extend into the head are much the longest. 
 The fibres of the second series (b b) are arranged 
 in parallel curves, the extremes of which are at- 
 
110 THE CANCELLI OF BONES 
 
 tached on the one hand to the wall of bone at 
 the base of the great trochanter, and on the other 
 
 Fig. 30. 
 
 Fig. 31. 
 
 to that portion of the preceding class of fibres 
 which supports the upper surface of the head, as 
 well as to the shell of bone between it and the 
 
THE CANCELLI OF BONES 111 
 
 trochanter at (d). Both of these series are braced 
 by other fibres, which are arranged at right angles 
 to their direction. The cancelh of the great tro- 
 chanter at (c) have no determinate form. 
 
 If this description be correct, the " archwork " 
 described by Mr. Ward does not exist, nor the 
 more complex arrangement described by Bour- 
 gery and Jacob. In fact, an arch which should 
 be made to resist force in this direction would 
 not be used in accordance with recognized archi- 
 tectural rules. An arch is usually made to resist 
 or sustain pressure in lines perpendicular to its 
 surface ; but is not adapted for opposing lateral 
 traction. 
 
 The upper series of fibres will get their points 
 of resistance on the wall of bone below the tro- 
 chanter, and not on the supposed archwork. The 
 curved fibres (b b) will resist in virtue of their 
 tenacity, and the straight or radiating series (a a) 
 in virtue of their rigidity. One resists and is 
 adapted to resist pressure, and the other resists 
 and is equally adapted to resist traction. 
 
 We can appreciate the effect which force ap- 
 plied to the head of the femur would have upon 
 its shell and cancelli, by calling to mind what 
 takes place in a cylinder or tube when an attempt 
 is made to bend it. If it be but slightly elastic, 
 it will become more or less flattened or collapsed 
 on the side toward which it is bent ; if sufficient 
 
112 THE CANCELLI OP BONES 
 
 force be applied, when it yields it will bend into 
 an angle on the concave side, but the convex 
 side still retaining its curve. The tenacity of the 
 material being greater than its rigidity, it yields 
 to pressure rather than tension, the concave side 
 of the tube being compressed, while the convex 
 stretches. The same effect will be still better 
 seen in bending the branch of a tree, when the 
 bark, if it yield on the convex side, will be torn 
 asunder, whereas on the concave side it is thrown 
 into folds. The shell of the neck of the thigh 
 may be regarded as a bent tube, and is adapted 
 to resist pressure by its oval form, the longest 
 axis being vertical ; and secondly, by the greater 
 thickness of the concave side of the neck, to 
 which the weight is more directly transmitted, 
 and which in consequence of its curved form is 
 more likely to yield to compression than the con- 
 vex surface on the opposite side to traction. 
 
 The walls of the bone are still further sup- 
 ported by the disposition of the cancelli, which 
 act as so many braces within. In addition to 
 this, however, these last form a segment of an 
 arch, and themselves support directly a portion of 
 the weight of the body, and transmit it to the 
 walls of the neck. If, on the application of weight 
 to the head of the bone, the neck yield at all, the 
 effect will be tension of the fibres (b b) ; and in 
 consequence of their resting beneath upon the 
 fibres (a a), compression of these last. 
 
THE CANCELLI OF BONES 113 
 
 It is worthy of notice in connection with these 
 directions of force, that the radiating series (a a), 
 which support pressure by their rigidity, are the 
 strongest, and the series at right angles and 
 between them, which serve as braces, are more 
 slender ; while the curved series (b b), which 
 resist by their tenacity, are the strongest, and the 
 braces, which may be regarded as a continuation 
 of the radiating series, are the weakest ; precisely 
 as would be the case in the frame of a building : 
 the braces of the circular series become stronger 
 as you approach the centre of the bone where the 
 pressure becomes the greatest. 
 
 The shell of the neck is of itself sufficient to 
 support great weight, in virtue of its form and 
 structure ; but its power of resistance is still far- 
 ther increased by the cancelli, which form within 
 a light truss or framed arch ; the long fibres at 
 (a) transfer weight directly to the under side of 
 the neck. They, as well as the shell of the neck 
 at (d), are supported by the curved fibres (6 b), 
 and these in turn by the radiating fibres (a). 
 The whole may be regarded as equivalent to an 
 increased thickness of those portions of the shell! 
 of bone above and below, which are the seats of: 
 the greatest strain and pressure. 
 
 The weight of the body is transmitted through 
 the shaft of the femur to the condyles below, the 
 space between these sustaining but little pressure. 
 
114 THE CANCELLI OP BONES 
 
 III. THIGH 
 
 The lower portion of the thigh has only a thin 
 shell, but here its diameter is largest and filled 
 with the cancellated structure, which especially in 
 the lateral portions has a very definite arrange- 
 ment ; the cancelli forming a series of pillars, 
 which ascend very nearly vertically from the sur- 
 faces of the condyle to the walls of the bone 
 above them, which are bent inwards as the bone 
 diminishes its diameter towards the middle of the 
 shaft. A corresponding arrangement exists in 
 the two extremities of the tibia, where the surface 
 which is the seat of pressure is sustained by col- 
 umns of bony fibres extending to the walls above 
 or below it, according as the upper or lower por- 
 tion of the bone is examined. This structure has 
 been distinctly figured and described by Bour- 
 gery and Jacob. 1 The cancelli are, as in the parts 
 before described, prevented from lateral flexion 
 by braces which are interposed at right angles to 
 their direction. 
 
 IV. ASTRAGALUS 
 
 The tibia alone bearing vertically on the astrag- 
 alus, this last bone will necessarily sustain in 
 each foot one half the weight of the body, or the 
 whole of it when it is supported on one foot. 
 
 1 Op. cit., Tome I. pp. 119 and 121, also PI. 43, Figs. 3, 4, and 7. 
 
THE CANCELLI OF BONES 115 
 
 When the small size of the surface on which the 
 tibia rests is borne in mind, it will be readily anti- 
 cipated that in its internal structure it will give 
 us another illustration of mechanical adaptation. 
 The astragalus, though it receive so many shocks 
 in the violent movements of the body and is 
 called upon to resist so much vertical force, is 
 nevertheless a light bone and presents areolae in 
 its interior of large size. The astragalus rests 
 below on the os calcis, by means of two artic- 
 ulating surfaces of different sizes, and in front 
 on the scaphoid bone, so that whatever pres- 
 sure is transmitted to it is in turn transferred to 
 the surfaces of the bones just named, with which 
 it is in contact. The pressure is therefore trans- 
 mitted in two directions, but as the astragalus, by 
 means of its greater articulating surfaces, rests 
 mainly on the os calcis, the larger amount is trans- 
 ferred in the direction of this bone. 
 
 On making a longitudinal section of this bone 
 {Fig. 32), two series of cancelli are distinguishable 
 at sight — one, a nearly vertical series (a), one 
 end of which sustains the arched portion of the 
 astragalus on which the tibia bears, and the other 
 rests on the surface beneath, which articulates 
 with the os calcis ; the second (&), a horizontal 
 series nearly at right angles to the preceding, one 
 end of which rests on the vertical series and the 
 other on the surface articulating with the sea- 
 
116 THE CANCELLI OF BONES 
 
 phoid bone. In the angle formed by these two 
 series is a third (c), much less regular, the direc- 
 tion o£ which is not well defined, but has a gen- 
 eral tendency downwards and forwards towards 
 
 Fig. 32. 
 
 the anterior and inferior articulating surfaces of 
 the bone. This portion sustains no direct pres- 
 sure. 
 
 v. OS CALCIS 
 
 It is through this bone that the weight is at 
 last transmitted to the ground, and this takes 
 place in two different directions : one directly 
 through the tuberosity of the heel, and the other 
 indirectly through that surface which articulates 
 with the cuboid bone, and this in turn with the 
 4th and 5th toes. The os calcis, however, does 
 not simply form a basis of support ; it is at the 
 same time one of the arms of a lever by which 
 the body is raised from the ground under the 
 influence of great muscular action. The whole 
 
THE CANCELLI OF BONES 117 
 
 foot forms an arch, one end of which springs 
 from the ground in the os calcis, and the other 
 from " the ball of the foot " or the ends of the 
 metatarsal bones. The arch is formed by the 
 metatarsal and tarsal bones, the centre of which 
 corresponds with a line passing transversely 
 through the scaphoid and cuboid bones. By re- 
 ference to the skeleton, it will be seen that the 
 surface of the astragalus, on which the tibia rests, 
 and the surfaces of the os calcis, which support 
 the astragalus, are behind this centre of the 
 arch ; consequently, the weight of the body will 
 be thrown more upon the os calcis than upon 
 
 Fig. 33. 
 
 the metatarsal bones. A section through this 
 bone {Fig. 33) gives two series of cancelli, one 
 radiating from the upper surface towards the two 
 surfaces on which the bone rests, and more spar- 
 
118 THE CANCELLI OF BONES 
 
 ingly to the intervening portions ; a second series 
 at right angles to the last and which, as the 
 former radiate from a common centre, will ne- 
 cessarily assume a curved direction. By far the 
 largest portion of the first are directed towards 
 the tuberosity of the heel, which serves the dou- 
 ble purpose of a base and lever. That portion 
 which is just beneath the articulating surface, 
 and which does not come within the range of 
 either of the surfaces of support, may be regarded 
 as forming an inverted arch. 
 
 The os calcis of man contrasts with that of 
 other animals, not only in its size and relation to 
 the rest of the foot, but in its minute and inter- 
 nal arrangement, so that the assertion made by 
 Mr. Lawrence many years ago, independently of 
 its structure within, that " ex calce hominem " 
 would be a safer rule than " ex pede fferculem" 
 gains additional force. 1 
 
 In the above descriptions the minute structure 
 of several bones has been described as well as the 
 nature of the force which they are intended to 
 resist. It is not always safe to attempt to assign 
 the final cause of animal structures, to indicate 
 the intention of nature in certain conditions of 
 things — though there can be no risk in describ- 
 ing in connection such conditions of organization 
 
 1 Lectures on Physiology, Zoology, and the Nat. Hist, of Man, 
 p. 124. London, 1822. 
 
THE CANCELLI OF BONES 119 
 
 as co-exist. 1 As to the individual bones, it has 
 been shown in what direction force or weight is 
 applied to them, and in what direction the cancelli 
 are arranged within them. On the lumbar verte- 
 brae there is vertical pressure ; within, the principal 
 fibres are also vertical. On the neck of the thigh- 
 bone the weight of the body is applied obliquely 
 to the end of an arm ; within it there is a com- 
 bination of fibres, giving strength with lightness, 
 which forms a frame mechanically adapted for 
 resisting the weight which rests upon it. On the 
 astragalus the pressure again is vertical, but this 
 bone rests on two others, one below it, the os 
 calcis, and the other in front, the scaphoides; 
 within there exists two series of cancelli direct- 
 ing the pressure on the surfaces of support, and 
 very nearly the same description applies to the os 
 calcis. A certain direction of fibres in all these 
 instances co-exists with a certain direction, or cer- 
 tain directions, of the transmission of pressure. 
 From this constant association of structure and 
 function, the inference seems unavoidable, that 
 they are means and ends. 
 
 The next subject for consideration is, as to the 
 existence of some more general condition to which 
 
 1 " Whatever may become of hypothesis, the man who has 
 made a permanent addition to the knowledge of facts has ren- 
 dered an imperishable service to science." — Georges Cuvxeb, 
 Anatomie Comparee. 
 
120 THE CANCELLI OF BONES 
 
 these individual instances are subservient — and 
 this involves the necessity of inquiring, to what 
 extent similar structures exist in other members 
 of the Mammif erous series ? After having made 
 numerous sections of the corresponding bones of 
 other animals, scarcely any indications of these 
 peculiar arrangements of the cancelli have been 
 demonstrated. The columnar arrangement of the 
 bony fibres of the vertebrae seems the most com- 
 mon. As a general rule, the strength of the bone 
 seems to be obtained in other mammals at the 
 expense of its lightness, by giving greater thick- 
 ness and density to the outer shell, as well as by 
 stouter cancelli with smaller areolae. The peculiar 
 structure of the neck of the thigh, and of the 
 astragalus, seems to exist in man alone. The only 
 animals in which I have detected any approach to 
 the structure of the neck of the thigh in man are 
 in the two species of anthropoid African apes, the 
 Chimpanzee {Troglodytes niger), and the Enge- 
 ena ( T. gorilla), the two species which stand at 
 the head of the brute creation, and which of all 
 brutes make the nearest approximation to the 
 erect attitude. In these, slight traces of the truss- 
 work described in man exist, but in them as in 
 other animals the shell of the neck is much stouter 
 and thicker. 
 
 The structures which have been described in 
 this communication are found mainly, if not 
 
THE CANCELLI OF BONES 121 
 
 solely, in the bones connected directly with loco- 
 motion. And as they exist in man alone, or cer- 
 tainly present in him the highest degree of per- 
 fection, we cannot escape the conviction that they 
 relate to the kind of locomotion which he alone 
 of the whole animal series can be said to possess, 
 namely, that of walking erect, and which requires 
 in the passive and resisting organs subservient to it, 
 in order that it may be effected with ease and grace, 
 a nice combination of lightness with strength in 
 the materials. His attitude more than any other, 
 in consequence of the pillars of support being 
 arranged in vertical planes, requires the most 
 effectual means for counteracting shocks ; for in 
 all other mammals the points of support are usu- 
 ally four, and at the same time the bones of the 
 legs make angles more or less acute with each 
 other, and therefore are in a condition to yield 
 readily by flexion to any increased force; and 
 this is true of all birds and reptiles. In the ele- 
 phant, the thighbones are vertical, but they are 
 nearly at right angles with the vertebral column, 
 and the pillars of support are four instead of two. 
 From the considerations which have now been 
 offered, it is believed that the two propositions 
 which were stated at the commencement of the 
 article have been sustained, and that if any addi- 
 tional facts were necessary to show that the human 
 skeleton deviates widely in the details of its struc- 
 
122 
 
 THE CANCELLI OF BONES 
 
 ture from that of all brutes, even the most anthro- 
 poid, we should have a characteristic sign in the 
 arrangement of the cancelli of such of his bones 
 as play the most important part in sustaining and 
 moving his body. 
 
 SKJOEKKENMOEDDINGf 
 
 JefErieB "Wyman, Del. 
 
 Searching Indian Shell Heaps, in Maine. 
 
LIST OF SCIENTIFIC PAPEES AND WORKS 
 BY JEFFRIES WYMAN 
 
 1. On the indistinctness of images formed by oblique 
 vision. Boston Medical and Surgical Journal, Sept. 1837. 
 
 2. On fossil bones from Georgia and Burmah and a 
 recent elephant's tooth from Singapore. Amer. Journ. Sci., 
 xxxvi. 1839, pp. 385-386. 
 
 3. Note on a collection of fossil bones from Athens. 
 Amer. Journ. Sci., July, 1839 ; Proc. Bost. Soc. Nat. Hist., 
 1839. 
 
 4. Remarks on the worms in measly pork. Amer. Journ. 
 Sci., July, 1839 ; Proc. Bost. Soc. Nat. Hist., 1839. 
 
 5. Remarks on a bat, Molossus ater, etc., from Surinam. 
 Amer. Journ. Sci., July, 1839. Proc. Bost. Soc. Nat. Hist., 
 1839. 
 
 6. Notice of the tooth of a mastodon. Amer. Jour. Sci., 
 xxxix. 1840, pp. 53-54. 
 
 7. On the anatomy of Tebennophorus carolinensis. Bos- 
 ton, Proc. Nat. Hist. Soc, i. 1841-44, pp. 154-155 ; Boston 
 Journ. Nat. Hist., iv. 1843^4, pp. 410-415. 
 
 8. On the anatomy of Otion cuvieri, Leach. Proc. Bost. 
 Soc. Nat. Hist. [1840.] Amer. Journ. Sci., xxxix. p. 182. 
 June, 1840. 
 
 9. On a species of Filaria in the lungs of a sheep. Proc. 
 Bost. Soc. Nat. Hist. [1840.] Amer. Journ. Sci., xxxix. 
 p. 183. Oct. 1840. 
 
 10. Report on Nautilus umbilicatus. Proc. Bost. Soc. 
 Nat. Hist. [Feb. 19, 1840.] Amer. Jour. Sci., xxxix. 
 p. 185. Oct. 1840. 
 
124 LIST OF SCIENTIFIC PAPERS AND WORKS 
 
 11. On buried wood, Unio, etc., in river sand at Lowell. 
 Proc. Bost. Soc. Nat. Hist. [July 15, 1840.] Amer. Journ; 
 Sci., xl. p. 388. March, 1841. 
 
 12. Note on the cranium of a seal (Stenorhynchus lep- 
 tonyx) from the South Pacific. Proc. Bost. Soc. Nat. Hist. 
 [Jan. 20, 1841.] Amer. Journ. Sci., xl. p. 390. March, 
 1841. 
 
 13. Notice of the howling monkey {Simla seniculus). 
 Amer. Journ. Sci., xl. 1841, pp. 387-388. 
 
 14. On the anal pouches of the skunk (Mephitis Ameri- 
 cana). Boston, Proc. Nat. Hist. Soc, i. 1841^44, p. 110. 
 
 15. On the sternum of a male trumpeter swan (Cygnus 
 buccinator). Boston, Proc. Nat. Hist. Soc, i. 1841-44, 
 p. 119. 
 
 16. On the microscopic structure of the teeth of the Lepi- 
 dosteus and their analogies with those of the labyrinthodonts 
 (with a plate). Boston, Proc. Nat. Hist. Soc, i. 1841-44, 
 pp. 131-132 ; Amer. Journ. Sci., xlv. 1843, pp. 359-363 ; 
 London Physiol. Journ., 1843^4 (?). 
 
 17. Review of Vogt's Embryologie des Salmones. Amer. 
 Journ. Sci., xlv. pp. 211-214. June, 1843. 
 
 18. Notice of the Zoology of New York. By J. E. 
 DeKay. Amer. Journ. Sci., xlv. pp. 397-399. Sept. 1843. 
 
 19. Notice of Agassiz's Monographies and Echinodermes 
 vivans et fossiles. Amer. Journ. Sci., xlv. pp. 399^400. 
 Sept. 1843. 
 
 20. On the anatomical structure of Glandina truncata, 
 Say. Boston, Proc. Nat. Hist. Soc, i. 1841-44, pp. 154- 
 155 ; Boston Journ. Nat. Hist., iv. 1843-44, pp. 416-421. 
 
 21. Description of a blind fish from a cave in Kentucky. 
 Amer. Jour. Sci., xlv. 1843, pp. 94-96. 
 
 22. (With Thomas S. Savage.) Observations on the ex- 
 ternal characters, habits, and organization of the Troglodytes 
 niger, Geof. Boston Journ. Nat. Hist., iv. 1843-44, pp. 
 362-376, 377-386. 
 
LIST OF SCIENTIFIC PAPERS AND WORKS 125 
 
 23. On Echinorhynchus nodosus. Proc. Bost. Soc. Nat. 
 Hist. Jan. 4, 1843. 
 
 24. On a Rotifer and Tardigrades. Proc. Bost. Soc. Nat. 
 Hist. Feb. 1, 1843. 
 
 25. Linguatula from a boa. Proc. Bost. Soc. Nat. Hist. 
 March 1, 1843. 
 
 26. Ascarides from Cyclopterus. March 1, 1843. 
 
 27. Description of a new species of torpedo. Proc. 
 Amer. Acad. Arts and Sci. April 25, 1843. 
 
 28. Annual address as president of the Boston Society of 
 Natural History. May 17, 1843. 
 
 29. On Spongia fluviatilis. Proc. Bost. Soc. Nat. Hist. 
 Sept. 4, 1844. 
 
 30. (With Thomas S. Savage.) Notice of the external 
 characters, habits, and osteology of Troglodytes gorilla, a 
 new species of ourang from the Gaboon River. Boston 
 Journ. Nat. Hist., v. 1845-47, pp. 417^22 ; Ann. Sci. Nat., 
 xvi. (Zool.), 1851, pp. 176-182 ; Boston, Proc. Nat. Hist. 
 Soc, ii. 1845-48, pp. 245-248 ; Amer. Journ. Sci., viii. 
 1849, pp. 141-142. 
 
 31. On the spiculse of actinia. Boston, Proc. Nat. Hist. 
 Soc, ii. 1845^8, pp. 51-52. 
 
 32. Linguatula armillata and L. clavata. Boston, Proc. 
 Nat. Hist. Soc, ii. 1845^48, p. 59; Boston, Journ. Nat. 
 Hist., v. 1845, pp. 255-296. 
 
 33. On the fossil skeleton recently exhibited in New 
 York as that of a sea-serpent under the name of Hydrarchos 
 Sillimani. Boston, Proc. Nat. Hist. Soc, ii. 1845-48, pp. 
 65-68. 
 
 34. On the fossil cranium and lower jaw of an extinct 
 rodent. Boston, Proc. Nat. Hist. Soc, ii. 1845-48, pp. 
 138-139. 
 
 35. A new species of Troglodytes. Silliman, Journ., v. 
 1848, pp. 106-107. 
 
 36. On two malformed cods' skulls. Boston, Proc. Nat. 
 Hist. Soc, iii. 1848-51, pp. 178-179. 
 
126 LIST OF SCIENTIFIC PAPERS AND WORKS 
 
 37. (With James Hall.) Notice of the geological posi- 
 tion of the cranium of the Castoroides ohiocensisj also an 
 anatomical description of the same. Boston Journ. Nat. 
 Hist., v. 1845-47, pp. 385-401 ; Bibl. Univ. Archives, ix. 
 1848, pp. 165-167. 
 
 38. (Dr. Morrill Wyman.) On valerianate of morphia. 
 Amer. Assoc. Proc, 1849, pp. 92-93. 
 
 39. Twelve lectures on Comparative Anatomy. Delivered 
 at the Lowell Institute, Boston, January and February, 
 1840. 
 
 40. A description of two additional crania of the enge"-ena 
 (Troglodytes gorilla, Savage and Wyman) from Gaboon, 
 Africa. [1849.] Boston, Proc. Nat. Hist. Soc, iii. 1848- 
 51, p. 179 ; Amer. Journ. Sci., ix. 1850, pp. 34-45 ; Edinb. 
 New Phil. Journ., xlviii. 1850, pp. 273-286. 
 
 41. On the foot of a species of musk (Moschus). Boston, 
 Proc. Nat. Hist. Soc, iii. 1848-51, p. 203. 
 
 42. On the jet from the blow-holes of whales. Boston, 
 Proc. Nat. Hist. Soc, iii. 1848-51, p. 228. 
 
 43. On some fossils from the Mississippi alluvium at 
 Memphis. Boston, Proc. Nat. Hist. Soc, iii. 1848-51, pp. 
 280-281 ; Amer. Journ. Sci., x. 1850, pp. 56-64. 
 
 44. On the embryo of Balcena mysticetus. Boston, Proc 
 Nat. Hist. Soc, iii. 1848-51, p. 355. 
 
 45. Notice of the cranium of the ne-hoo-le, a new species 
 of manatee (Manatus nasutus), from West Africa. [1849.] 
 Amer. Journ. Sci., ix. 1850, pp. 45-47 ; Proc. Amer. Acad. 
 Arts and Sci. 
 
 46. Notice of remains of vertebrated animals found at 
 Richmond, Virginia. Amer. Journ. Sci., x. 1850, pp. 228- 
 235. 
 
 47. Effect of the absence of light on the development of 
 tadpoles. Proc. Bost. Soc. Nat. Hist. April, 1853. 
 
 48. On the shell and sternum of the Trionyx ferox. 
 Boston, Proc. Nat. Hist. Soc, iv. 1851-54, p. 10. 
 
LIST OF SCIENTIFIC PAPERS AND WORKS 127 
 
 49. On the spinal cord of bats. Boston, Proc. Nat. Hist. 
 Soc, iv. 1851-54, p. 35. 
 
 50. On the development of Distomata. Boston, Proc. 
 Nat. Hist. Soc, iv. 1851-54, pp. 65-66. 
 
 51. On the brain and spinal cord of the lump-fish. 
 Boston, Proc. Soc. Nat. Hist., iv. 1851-54, pp. 82-83. 
 
 52. On the crania of Indians. Boston, Proc. Nat. Hist. 
 Soc, iv. 1851-54, pp. 83-84. 
 
 53. On the sudden bursting and scattering of seeds of the 
 capsule of the common garden balsam. Boston, Proc. Nat. 
 Hist. Soc, iv. 1851-54, pp. 106-107. 
 
 54. Results of microscopic examination of the structure of 
 the brain and spinal cord in frogs. Boston, Proc. Nat. Hist. 
 Soc, iv. 1851-54, p. 107. 
 
 55. On the anatomy of Carcharias obscurus. Boston, 
 Proc Nat. Hist. Soc, iii. 1851-54, pp. 123-124. 
 
 56. On the brain of Lophius Americanus, Cuvier. Bos- 
 ton, Proc. Nat. Hist. Soc, iv> 1851-54, pp. 149-151. 
 
 57. On the eye and the organ of hearing in the blind fishes 
 (Amblyopsis spelceus, Dekay) of the Mammoth Cave. Bos- 
 ton, Proc Nat. Hist. Soc, iv. 1851-1854, pp. 395-396; 
 Amer. Journ. Sci., xvii. 1854, pp. 258-261 ; Boston, Proc. 
 Nat. Hist. Soc, v. 1854-56, pp. 18-19 ; Midler's Archiv, 
 1853, pp. 574-576. 
 
 58. Description of the post-mortem appearances in the 
 case of Daniel Webster. American Journ. Med. Sci., Jan. 
 1853. 
 
 59. Notes on the remains of Dendrerpeton acadianum 
 from the coal-measures of Nova Scotia. Geol. Soc. Journ., 
 ix. 1853, pp. 64-66. 
 
 60. Anatomy of the nervous system of Bana pipiens. 
 [1852.] Smithsonian Contrib., v. 1853. 
 
 61. Description of the interior of the cranium and of the 
 form of the brain of Mastodon giganteus. Silliman Journ., 
 xv. 1853, pp. 48-55. 
 
128 LIST OF SCIENTIFIC PAPERS AND WORKS 
 
 62. Observations on the development of the Surinam 
 toad (Pipa Americana). Amer. Journ. Sci., xvii. 1854, pp. 
 369-374; Boston, Proc. Nat. Hist. Soc, v. 1854-56, pp. 
 13-14. 
 
 63. On the electrical organs of Torpedo occidentalis. 
 Boston, Proc. Nat. Hist. Soc, v. 1854-56, pp. 21-22. 
 
 64. Researches upon the structure of the heart and the 
 physiology of the respiration in the Menobranchus and ba- 
 trachians. Boston, Proc. Nat. Hist. Soc, v. 1854-56, pp. 
 51-52. 
 
 65. On the development of Anableps gronovii. Boston, 
 Proc. Nat. Hist. Soc, v. 1854-56, pp. 80-81 ; Boston Journ. 
 Nat. Hist., vi. 1857, pp. 432-443. 
 
 66. Parasitic plant on the common house-fly. Boston, 
 Proc. Nat. Hist. Soc, v. 1854-56, p. 90. 
 
 67. On the vagus of tadpoles. Boston, Proc. Nat. Hist. 
 Soc, v. 1854-56, pp. 119-120. 
 
 68. Observations on hibernating insects. Boston, Proc. 
 Nat. Hist. Soc, v. 1854-56, p. 157. 
 
 69. Remarks on the festal zygsena. Boston, Proc. Nat. 
 Hist. Soc, v. 1854-56, p. 157. 
 
 70. On the wing of the pin-tailed ducks (Anas acuta). 
 Boston, Proc. Nat. Hist. Soc, v. 1854-56, p. 169. 
 
 71. On formation of rain impressions in clay. Boston, 
 Proc Nat. Hist. Soc, v. 1854-56, pp. 253-254; Amer. 
 Journ. Sci., xxi. 1856, p. 175. 
 
 72. On footprints discovered by Prof. H. D. Rogers. 
 Boston, Proc. Nat. Hist. Soc, v. 1854-56, pp. 258-259. 
 
 73. Dissection of a black Chimpanzee (Troglodytes ni- 
 ger). Boston, Proc. Nat. Hist. Soc, v. 1854-56, pp. 274- 
 275. 
 
 74. Observations on Scaphiopus. Boston, Proc. Nat. 
 Hist. Soc, v. 1854-56, pp. 382-383. 
 
 75. On the development of the dorsal cord in the alewife. 
 Boston, Proc. Nat. Hist. Soc, v. 1854-56, pp. 394-395. 
 
LIST OF SCIENTIFIC PAPERS AND WORKS 129 
 
 76. Notice of fossil bones from the red sandstone of the 
 Connecticut River valley. Amer. Journ. Sci., xx. 1855, pp. 
 394-397. 
 
 77. Description of some instances of nerves passing across 
 the middle line of the body. 
 
 78. Note on the teeth of an elephant discovered near 
 Zanesville, Ohio. Amer. Assoc. Adv. Sci. Proc, 1856 (pt. 
 2), pp. 169-172. 
 
 79. On a batrachian reptile from the coal formation. 
 Amer. Assoc. Adv. Sci. Proc, 1856 (pt. 2), pp. 172-173. 
 
 80. On raindrop marks. Silliman Journ., xxi. 1856, 
 p. 145. 
 
 81. Memoir of Dr. John C. Warren. Proc. Bost. Soc. 
 Nat. Hist. Dec. 17, 1856. 
 
 82. Examination of the Bagre. Proc. Bost. Soc. Nat. 
 Hist. Dec. 16, 1857. 
 
 83. Account of some fossil bones collected in Texas. 
 Boston, Proc. Nat. Hist. Soc, vi. 1856-59, pp. 51-54. 
 
 84. Description of a cyclopean pig. Boston, Proc. Nat. 
 Hist. Soc, vi. 1856-59, pp. 380-382 ; also March 18, 1863. 
 
 85. Species of fishes from the Surinam River. Proc. 
 Bost. Soc. Nat. Hist. Sept. 16, 1857. 
 
 86. On the cancellated structure of some of the bones of 
 the human body. [1849.] Boston, Journ. Soc. Nat. Hist., 
 vi. 1857, pp. 125-140. 
 
 87. On some remains of batrachian reptiles discovered in 
 the coal formation of Ohio. Silliman Journ., xxv. 1858, pp. 
 158-164. 
 
 88. Account of the dissection of a human foetus. Proc. 
 Bost. Soc. Nat. Hist. Feb. 3, 1858. 
 
 89. Results of some examinations of a large number of 
 foetal pigs. Proc Bost. Soc Nat. Hist. April 7, 1858. 
 
 90. On several parasites found in the American deer. 
 
 91. Remarks on the death of Dr. Francis W. Cragin. 
 Proc. Bost. Soc. Nat. Hist. Sept. 15, 1858. 
 
130 LIST OF SCIENTIFIC PAPERS AND WORKS 
 
 92. Observations on the shedding of the antlers of the 
 American red deer. Proc. Bost. Soc. Nat. Hist. Oct. 19, 
 1859. 
 
 93. Observations on the habits of a species of hornet 
 (Vespa) which builds its nest in the ground. Boston, Proc. 
 Nat. Hist. Soc, vii. 1859-61, pp. 411-418. 
 
 94. Account of the collection of gorillas made by Mr. Du 
 ChaiUu. Proc. Bost. Soc. Nat. Hist. Jan. 4, 1860. 
 
 95. On some unusual modes of gestation in batrachians 
 and fishes. Amer. Journ. Sci., xxvii. 1859, pp. 5-13 ; Cana- 
 dian Naturalist, v. 1860, pp. 42-49 ; Newman's Zoologist, 
 xviii. 1860, 7173-7179. 
 
 96. On two parasites. Proc. Bost. Soc. Nat. Hist. April 
 18, 1860. 
 
 97. On the poison apparatus of the rattlesnake. Proc. 
 Bost. Soc. Nat. Hist. May 16, 1860. 
 
 98. On a fossil from the southwest frontier of the United 
 States. Proc. Bost. Soc. Nat. Hist. Sept. 19, 1860. 
 
 99. On a partially double pig. Proc. Bost. Soc. Nat. 
 Hist. Feb. 20, 1861. 
 
 100. On the mode of formation of the rattle of the rattle- 
 snake. Proc. Bost. Soc. Nat. Hist. March 6, 1861. 
 
 101. On the presentation to the society by Dr. William 
 J. Walker of the estate recently occupied by him. Proc. 
 Bost. Soc. Nat. Hist. Aug. 1861. 
 
 102. On bones of a gorilla recently obtained in Western 
 Equatorial Africa. Proc. Bost. Soc. Nat. Hist. Oct. 2, 1861. 
 
 103. On the bones of a supernumerary leg from a goose. 
 Proc. Bost. Soc. Nat. Hist. Nov. 20, 1861. 
 
 104. Dissection of a Hottentot. Proc. Bost. Soc. Nat. 
 Hist. April 2, 1862. 
 
 105. On larvae of Dactylethra capensis. Proc. Bost. 
 Soc. Nat. Hist. Sept. 17, 1862. 
 
 106. On reproduction of lost parts in planaria. Proc. 
 Bost. Soc. Nat. Hist. Sept. 17, 1862. 
 
LIST OF SCIENTIFIC PAPERS AND WORKS 131 
 
 107. On eggs of salamanders. Proc. Bost. Soc. Nat. 
 Hist. Oct. 15, 1862. 
 
 108. On a remarkable case of poisoning. Proc. Bost. 
 Soc. Nat. Hist. Oct. 15, 1862. 
 
 109. On the development of the human embryo. Proc. 
 Bost. Soc. Nat. Hist. Dec. 3, 1862. 
 
 110. Experiments on the formation of infusoria in boiled 
 solutions of organic matter, enclosed in hermetically sealed 
 vessels and supplied with pure air. Amer. Journ. Sci., 
 xxxiv. 1862, pp. 79-87 ; Chemical News, vi. 1862, pp. 109- 
 112; Journ. Microsc. Soc, iii. 1863, pp. 109-120; Proc. 
 Bost. Soc. Nat. Hist. May 22, 1862. 
 
 111. On two cases of monstrosity in serpents. Proc. 
 Bost. Soc. Nat. Hist. Jan. 21, 1863. 
 
 112. On localization of species. Proc. Bost. Soc. Nat. 
 Hist. May 20, 1863. 
 
 113. On the sea-serpent. Proc. Bost. Soc. Nat. Hist. 
 June 3, 1863. 
 
 114. On the mode of impregnation of the ova in Pomotis. 
 Proc. Bost. Soc. Nat. Hist. June 17, 1863. 
 
 115. On amphioxus. Proc. Bost. Soc. Nat. Hist. Dec. 
 2, 1863. 
 
 116. Description of a " white fish " or " white whale " 
 (Beluga borealis), Lesson. Boston Journ. Nat. Hist., vii. 
 1863, pp. 603-612. 
 
 117. Observations on Pentastoma (Linguatula Rudolphi) 
 armillata, Wyman, which infests the lungs of the Python 
 sebce of Africa. Boston, Proc. Nat. Hist. Soc, ix. 1863, pp. 
 179-181. 
 
 118. Observations on the cranium of a young gorilla. 
 Boston, Proc. Nat. Hist. Soc, iv. 1863, pp. 203-206. 
 
 119. On the mechanism of the tibio-tarsal joint of the 
 ostrich. Boston, Proc. Nat. Hist. Soc, ix. 1863, pp. 220- 
 221. 
 
 120. Observations recently made on an Amoeba. [1863.] 
 
132 LIST OF SCIENTIFIC PAPERS AND WORKS 
 
 Proc. Bost. Soc. Nat. Hist., ix. 1865, pp. 281-283 ; Ann. 
 Mag. Nat. Hist., xiv. 1864, pp. 394-395. 
 
 121. On the development of skates and especially of 
 Raia batis. [1863.] Proc. Bost. Soc. Nat. Hist., ix. 1863, 
 pp. 334-335 ; Ann. Mag. Nat. Hist., xiv. 1864, 399-400 ; 
 Amer. Acad. Mem. ix. (pt. 1), 1867, pp. 31-34. 
 
 122. On the skeleton of a Hottentot. [1863.] Proc. 
 Bost. Soc. Nat. Hist., ix. 1865, pp. 352-357 ; Anthropol. 
 Review, iii. 1865, pp. 330-335. 
 
 123. On reptilian bones from the new red sandstone at 
 Middlebury, Conn. Proc. Bost. Soc. Nat. Hist. June 1, 
 1864. 
 
 124. On malformations. Proc. Bost. Soc. Nat. Hist. 
 Oct. 19, 1864. 
 
 125. On Indian mounds of the Atlantic coast. Proc. 
 Bost. Soc. Nat. Hist. Nov. 2, 1864. 
 
 126. On accommodation of the eye. Proc. Bost. Soc. 
 Nat. Hist. Feb. 1, 1865. 
 
 127. On the power of vibrio, etc., to resist the action of 
 boiling water. Proc. Bost. Soc. Nat. Hist. Feb. 1, 1865. 
 
 128. On the formation of ripple marks. Proc. Bost. Soc. 
 Nat. Hist. Sept. 20, 1865. 
 
 129. On the human arterial system. Proc. Bost. Soc. 
 Nat. Hist. Nov. 15, 1865. 
 
 130. On the reproduction of lost parts in animals. Proc. 
 Bost. Soc. Nat. Hist. Jan. 17, 1866. 
 
 131. Dissection of a young pigeon. Proc. Bost. Soc. 
 Nat. Hist. June 20, 1866. 
 
 132. On the distorted skull of a child from the Hawaiian 
 Islands. Proc. Bost. Soc. Nat. Hist. Oct. 17, 1866. 
 
 133. Development of moulds in the interior of eggs. 
 [1865.] Proc. Bost. Soc. Nat. Hist, x. 1866, pp. 41, 97-98. 
 
 134. On the fossil bones recently collected near Rio 
 Bamba, South America. By Dr. C. F. Winslow. [1865.] 
 Proc. Bost. Soc. Nat. Hist., x. 1866, pp. 105-107. 
 
LIST OF SCIENTIFIC PAPERS AND WORKS 133 
 
 135. Description of a double foetus. Boston Med. Surg. 
 Journ., pp. 169-176. March 29, 1866. 
 
 136. Description of an anencephalous foetus with unusual 
 malformation. Boston Med. Surg. Journ. June, 1866. 
 
 137. Notice of observations on respiration, in the Chelo- 
 nia. By S. Weir Mitchell, M. D., and George N. More- 
 house, M. D. 
 
 138. Notice of Richard Owen's monograph of the Aye- 
 aye, with remarks on the origin of species. 
 
 139. Account of some irregularities noticeable in the cells 
 of the hive-bee. [1865.] Proc. Bost. Soc. Nat. Hist., 
 1866, pp. 234-235. 
 
 140. Observations and experiments on living organisms 
 in heated water. Amer. Journ. Sci., xliv. 1867, pp. 152-169. 
 
 141. Measurements of some human crania. Proc. Bost. 
 Soc. Nat. Hist. Nov. 20, 1867. 
 
 142. Examination of the animals of the New England 
 shell heaps. Proc. Bost. Soc. Nat. Hist. Dec. 4, 1867. 
 
 143. Account of the shell mounds of Florida. Proc. 
 Bost. Soc. Nat. Hist. April 17, 1867. 
 
 144. Account of the life and scientific career of Dr. A. A. 
 Gould. Proc. Bost. Soc. Nat. Hist. May 1, 1867. 
 
 145. Description of the shell heaps at Salisbury, Mass. 
 Proc. Bost. Soc. Nat. Hist. May 15, 1867. 
 
 146. Destruction of a male spider by the female. Proc. 
 Bost. Soc. Nat. Hist. Sept. 18, 1867. 
 
 147. Account of a visit to an Indian shell heap near 
 Mount Desert, Me. Proc. Bost. Soc. Nat. Hist. Sept. 18, 
 1867. 
 
 148. On flint implements from Northern Europe. Proc. 
 Bost. Soc. Nat. Hist. Oct. 2, 1867. 
 
 149. Shell heaps on Goose Island, Casco Bay, Me. Proc. 
 Bost. Soc. Nat. Hist. Oct. 2, 16, 1867. 
 
 150. On the occurrence of eels in the abdominal cavity of 
 the cod. Proc. Bost. Soc. Nat. Hist. Jan. 15, 1868. 
 
134 LIST OF SCIENTIFIC PAPERS AND WORKS 
 
 151. On the inscription of the Dighton rock. Proc. 
 Bost. Soc. Nat. Hist. Dec. 2, 1868. 
 
 152. On Nautilus pornpilius. Proc. Bost. Soc. Nat. 
 Hist. Dec. 16, 1868. 
 
 153. Notes on the cells of the bee. [1866.] Proc. Bost. 
 Soc. Nat. Hist. Jan. 17, 1866. Proc. Amer. Acad. Arts 
 and Sci., Boston, vii. 1868, pp. 68-83. 
 
 154. An account of some kjcekkenmceddings, or shell 
 heaps in Maine and Massachusetts. American Naturalist, 
 i. 1868, pp. 561-584. 
 
 155. On the morphology of the leaves of the pitcher- 
 plant, and especially of Sarracenia. [1866.] Proc. Bost. 
 Soc. Nat. Hist., xi. 1868, pp. 246-278. 
 
 156. On symmetry and homology in limbs. [1867.] 
 Proc. Bost. Soc. Nat. Hist., xi. 1868, pp. 246-278. 
 
 157. Observations on crania. Proc. Bost. Soc. Nat. 
 Hist., xi. 1868, pp. 440-462. 
 
 158. On the fresh-water shell heaps of the St. John's 
 river, East Florida. American Naturalist, ii. 1869, pp. 
 393-403, 449-463. 
 
 159. On a thread worm (Filaria anhingce) infesting the 
 brain of the snake bird (Plotus anhinga). [1868.] Proc. 
 Bost. Soc. Nat. Hist., xii. 1869, pp. 100-104. Month. 
 Microsc. Journ., ii. 1869, pp. 215-216. 
 
 160. On the head of a crocodile, G. acutus, obtained in 
 the Miami River. Proc. Bost. Soc. Nat. Hist. May 19, 
 1869. 
 
 161. On the existence of a crocodile in Florida. Amer. 
 Journ. Sci., xlix. 1870, pp. 105-106. 
 
 162. Experiments with vibrating cilia. American Natu- 
 ralist, v. 1871, pp. 611-616 ; Month. Microsc. Journ., vii. 
 1872, pp. 80-81. 
 
 163. On the brain of Didelphys virginiana. Mem. Bost. 
 Soc. Nat. Hist., ii. 1872, pp. 151-154. 
 
 164. Change of habit [in cows, etc., grazing under water 
 
LIST OF SCIENTIFIC PAPERS AND WORKS 135 
 
 in Florida]. American Naturalist, viii. p. 237. April, 
 1874. 
 
 165. Human remains in the shell heaps of the St. John's 
 river, East Florida. Cannibalism. American Naturalist, 
 viii. pp. 403-414. July 1, 1874. 
 
 166-173. First Seven Annual Reports of the Trustees of 
 the Peabody Museum of American Archaeology and Eth- 
 nology. Cambridge, 1868-74. 8vo. 
 
 174. Remarks on Cannibalism among the American Abo- 
 rigines. Proe. Bost. Soc. Nat. Hist. May 20, 1874. 
 
 175. Fresh-water shell mounds of the St. John's River, 
 Florida. Fourth memoir. Peabody Academy of Science. 
 Salem, Mass., 1875. Roy. 8vo, pp. 94, pi. i.-ix. 
 
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