swelled, because that would indicate full strength and vigour of age,
which they have not yet attained. Nevertheless they must be more or
less expressed, as they are more or less employed. For those which are
in motion are always more swelled and thicker than those which remain
at rest. The intrinsic and central line of the members which are bent,
never retains its natural length.
/Chap. XLVI./--_The Extension and Contraction of the Muscles._
/The/ muscle at the back part of the thigh shows more variety in
its extension and contraction, than any other in the human body; the
second, in that respect, are those which compose the buttocks; the
third, those of the back; the fourth, those of the neck; the fifth,
those of the shoulders; and the sixth, those of the Abdomen, which,
taking their rise under the breast, terminate under the lower belly; as
I shall explain when I speak of each.
/Chap. XLVII./--_Of the Muscle between the Chest and the lower Belly._
/There/ is a muscle which begins under the breast at the Sternum, and
is inserted into, or terminates at the Os pubis, under the lower belly.
It is called the Rectus of the Abdomen; it is divided, lengthways,
into three principal portions, by transverse tendinous intersections
or ligaments, viz. the superior part, and a ligament; the second part,
with its ligaments; and the third part, with the third ligament;
which last unites by tendons to the Os pubis. These divisions and
intersections of the same muscle are intended by nature to facilitate
the motion when the body is bent or distended. If it were made of one
piece, it would produce too much variety when extended, or contracted,
and also would be considerably weaker. When this muscle has but little
variety in the motion of the body, it is more beautiful[14].
/Chap. XLVIII./--_Of a Man's complex Strength, but first of the Arm._
/The/ muscles which serve either to straighten or bend the arm, arise
from the different processes of the Scapula; some of them from the
protuberances of the Humerus, and others about the middle of the Os
humeri. The extensors of the arm arise from behind, and the flexors
from before.
That a man has more power in pulling than in pushing, has been proved
by the ninth proposition De Ponderibus[15], where it is said, that of
two equal weights, that will have the greatest power which is farthest
removed from the pole or centre of its balance. It follows then of
course, that the muscle N B, _Plate II._ and the muscle N C, being of
equal power, the inner muscle N C, will nevertheless be stronger than
the outward one N B, because it is inserted into the arm at C, a point
farther removed from the centre of the elbow A, than B, which is on
the other side of such centre, so that that question is determined.
But this is a simple power, and I thought it best to explain it before
I mentioned the complex power of the muscles, of which I must now
take notice. The complex power, or strength, is, for instance, this,
when the arm is going to act, a second power is added to it (such as
the weight of the body and the strength of the legs, in pulling or
pushing), consisting in the extension of the parts, as when two men
attempt to throw down a column; the one by pushing, and the other by
pulling[16].
/Chap. XLIX./--_In which of the two Actions, Pulling or Pushing, a Man
has the greatest Power_, Plate II.
/A man/ has the greatest power in pulling, for in that action he has
the united exertion of all the muscles of the arm, while some of them
must be inactive when he is pushing; because when the arm is extended
for that purpose, the muscles which move the elbow cannot act, any
more than if he pushed with his shoulders against the column he means
to throw down; in which case only the muscles that extend the back,
the legs under the thigh, and the calves of the legs, would be active.
From which we conclude, that in pulling there is added to the power
of extension the strength of the arms, of the legs, of the back, and
even of the chest, if the oblique motion of the body require it. But
in pushing, though all the parts were employed, yet the strength of
the muscles of the arms is wanting; for to push with an extended arm
without motion does not help more than if a piece of wood were placed
from the shoulder to the column meant to be pushed down.
[Illustration:
_Page 22_.
_Chap. 48, 49_.
_Plate 2_.
_London, Published by J. Taylor High Holborn._]
/Chap. L./--_Of the bending of Members, and of the Flesh round the
bending Joint._
/The/ flesh which covers the bones near and at the joints, swells or
diminishes in thickness according to their bending or extension; that
is, it increases at the inside of the angle formed by the bending, and
grows narrow and lengthened on the outward side of the exterior angle.
The middle between the convex and concave angle participates of this
increase or diminution, but in a greater or less degree as the parts
are nearer to, or farther from, the angles of the bending joints.
/Chap. LI./--_Of the naked Body._
/The/ members of naked men who work hard in different attitudes, will
shew the muscles more strongly on that side where they act forcibly to
bring the part into action; and the other muscles will be more or less
marked, in proportion as they co-operate in the same motion.
/Chap. LII./--_Of a Ligament without Muscles._
/Where/ the arm joins with the hand, there is a ligament, the largest
in the human body, which is without muscles, and is called the strong
ligament of the Carpus; it has a square shape, and serves to bind
and keep close together the bones of the arm, and the tendons of the
fingers, and prevent their dilating, or starting out.
/Chap. LIII./--_Of Creases._
/In/ bending the joints the flesh will always form a crease on the
opposite side to that where it is tight.
/Chap. LIV./--_How near behind the Back one Arm can be brought to the
other_, Plate III. and IV.
/When/ the arms are carried behind the back, the elbows can never be
brought nearer than the length from the elbow to the end of the longest
finger; so that the fingers will not be seen beyond the elbows, and
in that situation, the arms with the shoulders form a perfect square.
The greatest extension of the arm across the chest is, when the elbow
comes over the pit of the stomach; the elbow and the shoulder in this
position, will form an equilateral triangle.
/Chap. LV./--_Of the Muscles._
/A naked/ figure being strongly marked, so as to give a distinct view
of all the muscles, will not express any motion; because it cannot
move, if some of its muscles do not relax while the others are pulling.
Those which relax cease to appear in proportion as the others pull
strongly and become apparent.
[Illustration:
_Page 24_.
_Chap. 54_.
_Plate 3_.
_London, Published by J. Taylor High Holborn._]
[Illustration:
_Page 24_.
_Chap. 53_.
_Plate 4_.
_London, Published by J. Taylor High Holborn._]
/Chap. LVI./--_Of the Muscles._
/The/ muscles of the human body are to be more or less marked according
to their degree of action. Those only which act are to be shewn, and
the more forcibly they act, the stronger they should be pronounced.
Those that do not act at all must remain soft and flat.
/Chap. LVII./--_Of the Bending of the Body._
/The/ bodies of men diminish as much on the side which bends, as they
increase on the opposite side. That diminution may at last become
double, in proportion to the extension on the other side. But of this I
shall make a separate treatise[17].
/Chap. LVIII./--_The same Subject._
/The/ body which bends, lengthens as much on one side as it shortens
on the other; but the central line between them will never lessen or
increase.
/Chap. LIX./--_The Necessity of anatomical Knowledge._
/The/ painter who has obtained a perfect knowledge of the nature of the
tendons and muscles, and of those parts which contain the most of them,
will know to a certainty, in giving a particular motion to any part of
the body, which, and how many of the muscles give rise and contribute
to it; which of them, by swelling, occasion their shortening, and which
of the cartilages they surround.
He will not imitate those who, in all the different attitudes they
adopt, or invent, make use of the same muscles, in the arms, back, or
chest, or any other parts.
MOTION AND EQUIPOISE OF FIGURES.
/Chap. LX./--_Of the Equipoise of a Figure standing still._
/The/ non-existence of motion in any animal resting on its feet, is
owing to the equality of weight distributed on each side of the line of
gravity.
/Chap. LXI./--_Motion produced by the Loss of Equilibrium._
/Motion/ is created by the loss of due equipoise, that is, by
inequality of weight; for nothing can move of itself, without losing
its centre of gravity, and the farther that is removed, the quicker and
stronger will be the motion.
[Illustration:
_Page 27_.
_Chap. 62_.
_Plate 5_.
_London, Published by J. Taylor High Holborn._]
/Chap. LXII./--_Of the Equipoise of Bodies_, Plate V.
/The/ balance or equipoise of parts in the human body is of two sorts,
viz. simple, and complex. Simple, when a man stands upon his feet
without motion: in that situation, if he extends his arms at different
distances from the middle, or stoop, the centre of his weight will
always be in a perpendicular line upon the centre of that foot which
supports the body; and if he rests equally upon both feet, then the
middle of the chest will be perpendicular to the middle of the line
which measures the space between the centres of his feet.
The complex balance is, when a man carries a weight not his own, which
he bears by different motions; as in the figure of Hercules stifling
Anteus, by pressing him against his breast with his arms, after he has
lifted him from the ground. He must have as much of his own weight
thrown behind the central line of his feet, as the weight of Anteus
adds before.
/Chap. LXIII./--_Of Positions._
/The/ pit of the neck, between the two Clavicles, falls perpendicularly
with the foot which bears the weight of the body. If one of the arms be
thrown forwards, this pit will quit that perpendicular; and if one of
the legs goes back, that pit is brought forwards, and so changes its
situation at every change of posture.
/Chap. LXIV./--_Of balancing the Weight round the Centre of Gravity in
Bodies._
/A figure/ standing upon its feet without motion, will form an
equipoise of all its members round the centre of its support.
If this figure without motion, and resting upon its feet, happens to
move one of its arms forwards, it must necessarily throw as much of its
weight on the opposite side, as is equal to that of the extended arm
and the accidental weight. And the same I say of every part, which is
brought out beyond its usual balance.
/Chap. LXV./--_Of Figures that have to lift up, or carry any Weight._
/A weight/ can never be lifted up or carried by any man, if he do not
throw more than an equal weight of his own on the opposite side.
/Chap. LXVI./--_The Equilibrium of a Man standing upon his Feet_, Plate
VI.
/The/ weight of a man resting upon one leg will always be equally
divided on each side of the central or perpendicular line of gravity,
which supports him.
/Chap. LXVII./--_Of Walking_, Plate VII.
/A man/ walking will always have the centre of gravity over the centre
of the leg which rests upon the ground.
[Illustration:
_Page 28_.
_Chap. 66_.
_Plate 6_.
_London, Published by J. Taylor High Holborn._]
[Illustration:
_Page 28_.
_Chap. 67_.
_Plate 7_.
_London, Published by J. Taylor High Holborn._]
/Chap. LXVIII./--_Of the Centre of Gravity in Men and Animals._
/The/ legs, or centre of support, in men and animals, will approach
nearer to the centre of gravity, in proportion to the slowness of their
motion; and, on the contrary, when the motion is quicker, they will be
farther removed from that perpendicular line.
/Chap. LXIX./--_Of the corresponding Thickness of Parts on each Side of
the Body._
/The/ thickness or breadth of the parts in the human body will never be
equal on each side, if the corresponding members do not move equally
and alike.
/Chap. LXX./--_Of the Motions of Animals._
/All/ bipeds in their motions lower the part immediately over the foot
that is raised, more than over that resting on the ground, and the
highest parts do just the contrary. This is observable in the hips and
shoulders of a man when he walks; and also in birds in the head and
rump.
/Chap. LXXI./--_Of Quadrupeds and their Motions._
/The/ highest parts of quadrupeds are susceptible of more variation
when they walk, than when they are still, in a greater or less degree,
in proportion to their size. This proceeds from the oblique position of
their legs when they touch the ground, which raise the animal when they
become straight and perpendicular upon the ground.
/Chap. LXXII./--_Of the Quickness or Slowness of Motion._
/The/ motion performed by a man, or any other animal whatever, in
walking, will have more or less velocity as the centre of their weight
is more or less removed from the centre of that foot upon which they
are supported.
/Chap. LXXIII./--_Of the Motion of Animals._
/That/ figure will appear the swiftest in its course which leans the
most forwards.
Any body, moving of itself, will do it with more or less velocity
in proportion as the centre of its gravity is more or less removed
from the centre of its support. This is mentioned chiefly in regard
to the motion of birds, which, without any clapping of their wings,
or assistance of wind, move themselves. This happens when the centre
of their gravity is out of the centre of their support, viz. out of
its usual residence, the middle between the two wings. Because, if
the middle of the wings be more backward than the centre of the whole
weight, the bird will move forwards and downwards, in a greater or
less degree as the centre of its weight is more or less removed from
the middle of its wings. From which it follows, that if the centre of
gravity be far removed from the other centre, the descent of the bird
will be very oblique; but if that centre be near the middle of the
wings, the descent will have very little obliquity.
[Illustration:
_Page 31_.
_Chap. 74_.
_Plate 8_.
_London, Published by J. Taylor High Holborn._]
/Chap. LXXIV./--_Of a Figure moving against the Wind_, Plate VIII.
/A man/ moving against the wind in any direction does not keep his
centre of gravity duly disposed upon the centre of support[18].
/Chap. LXXV./--_Of the Balance of a Figure resting upon its Feet._
/The/ man who rests upon his feet, either bears the weight of his body
upon them equally, or unequally. If equally, it will be with some
accidental weight, or simply with his own; if it be with an additional
weight, the opposite extremities of his members will not be equally
distant from the perpendicular of his feet. But if he simply carries
his own weight, the opposite extremities will be equally distant from
the perpendicular of his feet: and on this subject of gravity I shall
write a separate book[19].
/Chap. LXXVI./--_A Precept._
/The/ navel is always in the central or middle line of the body, which
passes through the pit of the stomach to that of the neck, and must
have as much weight, either accidental or natural, on one side of the
human figure as on the other. This is demonstrated by extending the
arm, the wrist of which performs the office of a weight at the end of
a steelyard; and will require some weight to be thrown on the other
side of the navel, to counterbalance that of the wrist. It is on that
account that the heel is often raised.
/Chap. LXXVII./--_Of a Man standing, but resting more upon one Foot
than the other._
/After/ a man, by standing long, has tired the leg upon which he
rests, he sends part of his weight upon the other leg. But this kind
of posture is to be employed only for old age, infancy, or extreme
lassitude, because it expresses weariness, or very little power in the
limbs. For that reason, a young man, strong and healthy, will always
rest upon one of his legs, and if he removes a little of his weight
upon the other, it is only a necessary preparative to motion, without
which it is impossible to move; as we have proved before, that motion
proceeds from inequality[20].
/Chap. LXXVIII./--_Of the Balance of Figures_, Plate IX.
/If/ the figure rests upon one foot, the shoulder on that side will
always be lower than the other; and the pit of the neck will fall
perpendicularly over the middle of that leg which supports the body.
The same will happen in whatever other view we see that figure, when it
has not the arm much extended, nor any weight on its back, in its hand,
or on its shoulder, and when it does not, either behind or before,
throw out that leg which does not support the body.
[Illustration:
_Page 32_.
_Chap. 78_.
_Plate 9_.
_London, Published by J. Taylor High Holborn._]
[Illustration:
_Page 33_.
_Chap. 80_.
_Plate 10_.
_London, Published by J. Taylor High Holborn._]
/Chap. LXXIX./--_In what Manner extending one Arm alters the Balance._
/The/ extending of the arm, which was bent, removes the weight of the
figure upon the foot which bears the weight of the whole body: as is
observable in rope-dancers, who dance upon the rope with their arms
open, without any pole.
/Chap. LXXX./--_Of a Man bearing a Weight on his Shoulders_, Plate X.
/The/ shoulder which bears the weight is always higher than the other.
This is seen in the figure opposite, in which the centre line passes
through the whole, with an equal weight on each side, to the leg on
which it rests. If the weight were not equally divided on each side
of this central line of gravity, the whole would fall to the ground.
But Nature has provided, that as much of the natural weight of the man
should be thrown on one side, as of accidental weight on the other,
to form a counterpoise. This is effected by the man's bending, and
leaning on the side not loaded, so as to form an equilibrium to the
accidental weight he carries; and this cannot be done, unless the
loaded shoulder be raised, and the other lowered. This is the resource
with which Nature has furnished a man on such occasions.
/Chap. LXXXI./--_Of Equilibrium._
/Any/ figure bearing an additional weight out of the central line, must
throw as much natural or accidental weight on the opposite side as is
sufficient to form a counterpoise round that line, which passes from
the pit of the neck, through the whole mass of weight, to that part
of the foot which rests upon the ground. We observe, that when a man
lifts a weight with one arm, he naturally throws out the opposite arm;
and if that be not enough to form an equipoise, he will add as much of
his own weight, by bending his body, as will enable him to resist such
accidental load. We see also, that a man ready to fall sideways and
backwards at the same time, always throws out the arm on the opposite
side.
/Chap. LXXXII./--_Of Motion._
/Whether/ a man moves with velocity or slowness, the parts above the
leg which sustains the weight, will always be lower than the others on
the opposite side.
/Chap. LXXXIII./--_The Level of the Shoulders._
/The/ shoulders or sides of a man, or any other animal, will preserve
less of their level, in proportion to the slowness of their motion;
and, _vice versâ_, those parts will lose less of their level when the
motion is quicker. This is proved by the ninth proposition, treating of
local motions, where it is said, any weight will press in the direction
of the line of its motion; therefore the whole moving towards any one
point, the parts belonging to it will follow the shortest line of the
motion of its whole, without giving any of its weight to the collateral
parts of the whole.
[Illustration:
_Page 35_.
_Chap. 84_.
_Plate 11_.
_London, Published by J. Taylor High Holborn._]
[Illustration:
_Page 35_.
_Chap. 84_.
_Plate 12_.
_London, Published by J. Taylor High Holborn._]
[Illustration:
_Page 35_.
_Chap. 85_.
_Plate 13_.
_London, Published by J. Taylor High Holborn._]
/Chap. LXXXIV./--_Objection to the above answered_, Plate XI. and XII.
/It/ has been objected, in regard to the first part of the above
proposition, that it does not follow that a man standing still, or
moving slowly, has his members always in perfect balance upon the
centre of gravity; because we do not find that Nature always follows
that rule, but, on the contrary, the figure will sometimes bend
sideways, standing upon one foot; sometimes it will rest part of its
weight upon that leg which is bent at the knee, as is seen in the
figures B C. But I shall reply thus, that what is not performed by the
shoulders in the figure C, is done by the hip, as is demonstrated in
another place.
/Chap. LXXXV./--_Of the Position of Figures_, Plate XIII.
/In/ the same proportion as that part of the naked figure marked D A,
lessens in height from the shoulder to the hip, on account of its
position the opposite side increases. And this is the reason: the
figure resting upon one (suppose the left) foot, that foot becomes the
centre of all the weight above; and the pit of the neck, formed by the
junction of the two Clavicles, quits also its natural situation at the
upper extremity of the perpendicular line (which passes through the
middle surface of the body), to bend over the same foot; and as this
line bends with it, it forces the transverse lines, which are always at
right angles, to lower their extremities on that side where the foot
rests, as appears in A B C. The navel and middle parts always preserve
their natural height.
/Chap. LXXXVI./--_Of the Joints._
/In/ the bending of the joints it is particularly useful to observe the
difference and variety of shape they assume; how the muscles swell on
one side, while they flatten on the other; and this is more apparent in
the neck, because the motion of it is of three sorts, two of which are
simple motions, and the other complex, participating also of the other
two.
The simple motions are, first, when the neck bends towards the
shoulder, either to the right or left, and when it raises or lowers
the head. The second is, when it twists to the right or left, without
rising or bending, but straight, with the head turned towards one of
the shoulders. The third motion, which is called complex, is, when to
the bending of it is added the twisting, as when the ear leans towards
one of the shoulders, the head turning the same way, and the face
turned upwards.
/Chap. LXXXVII./--_Of the Shoulders._
/Of/ those which the shoulders can perform, simple motions are the
principal, such as moving the arm upwards and downwards, backwards and
forwards. Though one might almost call those motions infinite, for if
the arm can trace a circle upon a wall, it will have performed all the
motions belonging to the shoulders. Every continued quantity being
divisible _ad infinitum_, and this circle being a continued quantity,
produced by the motion of the arm going through every part of the
circumference, it follows, that the motions of the shoulders may also be
said to be infinite.
[Illustration:
_Page 37_.
_Chap. 89_.
_Plate 14_.
_London, Published by J. Taylor High Holborn._]
/Chap. LXXXVIII./--_Of the Motions of a Man._
/When/ you mean to represent a man removing a weight, consider that the
motions are various, viz. either a simple motion, by bending himself
to raise the weight from the ground upwards, or when he drags the
weight after him, or pushes it before him, or pulls it down with a rope
passing through a pulley. It is to be observed, that the weight of the
man's body pulls the more in proportion as the centre of his gravity
is removed from the centre of his support. To this must be added the
strength of the effort that the legs and back make when they are bent,
to return to their natural straight situation.
A man never ascends or descends, nor walks at all in any direction,
without raising the heel of the back foot.
/Chap. LXXXIX./--_Of the Disposition of Members preparing to act with
great Force_, Plate XIV.
/When/ a man prepares himself to strike a violent blow, he bends and
twists his body as far as he can to the side contrary to that which
he means to strike, and collecting all his strength, he, by a complex
motion, returns and falls upon the point he has in view[21].
/Chap. XC./--_Of throwing any Thing with Violence_, Plate XV.