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ANIMAL MECHANICS
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, .Animal mechanics,
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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.
° fc fc
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055 g o»
£ a* T
t- o
£.$, 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.
Electrotyped and printed by H. O. Houghton & Co.
Cambridge, Mass., U.S. A.
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