NOTES ON ANIMAL LOCOMOTION
In the usual manner of locomotory progress in the four-footed beasts,
with but a few exceptions, the actions of the limbs with respect to
the reciprocal movement of the two pairs, is the same as that of man.
When, for instance, a fore limb moves, corresponding to the human
arm, the diagonally opposite hind limb, corresponding to the human
lower limb, moves also.
To explain this matter, again, we shall find it helpful to give a
somewhat humorous, but at the same time a very practical example. An
artist intends to draw the picture of a man crawling on his hands
and knees. Before beginning to work, the artist will visualize the
movement if he can, if not, try it by personal experiment. Then he
will see that when the right hand, we will say, is lifted to go
forward, immediately the left knee leaves the floor and the two
limbs—the right arm and the left leg—advance at the same time.
On the completion of this advancing action, the hand and the knee
touch the floor nearly at the same instant. (Exactly, though, the
hand is carried forward more rapidly and anticipates the knee
in reaching the floor.) After this action, which has just been
described, is concluded, it is the turn of the other arm and leg to
go through the same movements. This is the manner, in a general way,
that the four-footed animals walk, successively moving together the
diagonally opposite limbs.
An understanding of this locomotory principle—the reciprocal actions
of the two pairs of limbs—in the generality of quadrupeds, will help
an artist to animate the various types of animals that he will from
time to time wish to put into his cartoons. Naturally, they will be
in most cases combined with a comical screen story. Their depiction,
then, can be represented in a humorous way and the artist merely
needs to show in his drawings the essentials of animal locomotion.
Instantaneous photographs of moving animals, especially those
of Muybridge, are helpful in studying the movements of the dumb
creatures. The mindful examination of such photographs gives hints
as to the particular phases of movement adaptable to animation.
Besides photographs, an ingenious auxiliary, as a help in study,
would be a little cardboard jointed model of an animal. Say it is
one to represent a horse, it can be employed by moving the limbs
about in their order as they successively make the steps while the
artist selects from a series of photographs a cycle of positions for
a movement. In making a jointed cut-out model, however, and fastening
the limbs by pivoting pins, it is well to remember that the model
can be approximate only. Take the fore limbs, for instance. In your
model you will probably fasten them to the trunk at some fixed place.
That is not the way that they are joined in the bony framework. The
joining of the fore limbs is not by a hard articulation as in the
arms of man which are joined, through the intermediary collar-bone,
to the breast-bone. In the horse and in quadrupeds, generally, the
joining to the main bulk of the body is by soft tissues. That is, by
layers and bands of muscle.
[Illustration: TROTTING HORSE.
The horse in the first series moves from _A B_ to _C D_. The
drawings in the second series, on the next page, with plus marks
are the same in silhouette as the correspondingly numbered ones of
the first series.]
[Illustration: TROTTING HORSE (continued).
In the second series the horse moves from _C D_ to _E F_, where he
takes the same attitude as that of number 1 of the first series.]
In studying the actions of animals it will be observed, especially
in the antelope and deer kind, that in leaping they land on their
forefeet. Any hard articulations of the fore limbs with the rest of
the skeleton could not submit to the shock of these landings. When
they land, it is the soft yielding and elastic muscular parts of the
shoulders and adjacent regions that absorb the force of the jolts.
The characteristic of life activity, flexion and extension, is
exemplified clearly in the actions of an animal’s hind limbs as they
double up in the preparation for a leap; and then suddenly spread out
during the first part of the leap.
Taking it as a whole, in fleet-footed animals, the function of the
hind limbs is to furnish the forward propelling force while that of
the fore limbs is to land on the ground at an advanced position.
This observation, of course, applies to certain rapid methods of
progression, and it will do as a general statement only, as it has
been shown by photographs that the fore limbs have a share in giving
an impulse in locomotion. For example, photographs of the horse
in action show the quick springing action of the fetlock and the
pastern joints as they bend in the hoof’s impact, and its subsequent
extension when the foot leaves the ground.
In a rapid walk of a horse a phase of movement that is apprehended by
the eye is the lifting of a forefoot and then the immediate impact of
the hind limb of the same side as it nearly falls into the impression
left by the fore foot. There are speeds in which the footprints
coincide. In a more rapid pace than a walk, the imprint of the hind
foot is farther forward than that of the forefoot. As the speed
increases the stride lengthens and the footprints are much farther in
advance.
In a certain type of humorous animation—the panorama—to be explained
in a succeeding chapter, the artist is quite satisfied with his
animation of a quadruped if a lively bewildering effect of agitated
limbs is produced on the screen. This bewildering blur has after all
a resemblance to that which the eye sees in rapidly running animals;
namely, a confused disturbance of limbs. This effect on the screen
always causes laughter and the artist considers that as a proof of
the success of his work.
To produce this effect, the animator selects from his studies three
or five consecutive positions of a gallop, or trot, that will animate
well. This means, specifically, that any particular drawing should,
with the next in order, give an appearance of movement when they
are synthesized. The drawings are made in a cycle so that when used
continuously in their order they will give the illusion desired.
[Illustration: A PANORAMA EFFECT OBTAINED BY THE USE OF THE THREE
DRAWINGS ON THE OPPOSITE PAGE.]
In a panorama it is not necessary to trouble about a matter that
in other forms of screen representation of locomotion are highly
important. This is to have the feet register, by which is meant that
in any several succeeding drawings where a foot is represented as
touching, bearing down, and leaving the ground, it should do all this
on a footprint that coincides in all of the series. Tracing over the
illuminated glass, while making the drawings, is the only way to get
footprints accurately placed.
[Illustration: GALLOPING HORSE.
Three phases of the action for panorama effects.]
The droll-looking giraffe, with his awkwardly set limbs, has a
different sort of movement, in some of his paces, from that remarked
as natural to quadrupeds. In the giraffe, the two limbs of the same
side move at the same time and in the same direction. The camel is
also noted as going this way, and the elephant has a pace that seems
to be a combination of the amble and the typical four-footed way of
walking.
[Illustration: THE ELEPHANT IN MOTION.]
Now and then the animator has as one of his characters a walking
bird; an ungainly ostrich is a good example, or a droll duck,
perhaps. Here he will have plenty of scope in applying his skill as
a humorous draftsman. A nodding of the head and a bobbing of the
body from side to side in the duck, and in the case of the ostrich a
wiggling of the neck, are appropriate adjuncts to such animation.
[Illustration: THE ELEPHANT IN MOTION (continued).]
In the walking movement of a bird the method of getting the different
phases will be the same as that of planning a walk for the human
figure. Particularly, too, must the artist observe in the bird’s
walk, the middle phases in which one leg crosses the vertical of the
body to go forward for the implanting of its foot upon the ground.
With respect to the study of wing movement in flying birds, it
is interesting to note that the Japanese artist apprehended the
various positions that wings took in flying before the fact was
demonstrated by photography. The Occidental artist, before the
days of the instantaneous snap-shot camera, had but one or two
stereotyped positions for picturing flying birds. Generally one of
these positions had the wings pointing upward, and another with
them outspread, more or less, horizontally. But the Japanese artist
anticipated the snap-shot picture; he often had his flying birds
with the wings drawn below the level of the bird’s body and pointing
downward.
[Illustration: PIGEON IN FLIGHT.
Note the positions with the wings pointing downward. These are phases
of wing movement anticipated by the Japanese artist before their
existence was clearly shown by instantaneous photography.
Part of a plate in Muybridge’s “Animals in Motion.” Copyright, 1899,
by Eadweard Muybridge. London, Chapman & Hall, Ltd. New York, Charles
Scribner’s Sons. A valuable work for the artist in studying movement
in animals.]
[Illustration: COMIC WALK OF A DUCK.
Series of drawings required to move the bird from _A_ to _C_.]
One good way, if an animator wishes to represent a bird flying across
the sky, is to have several—five or seven—positions for the action
drawn on cardboard and then cut out. These little bird models are
placed, one at a time, over the general scene during the photography
and manipulated in the same way as described for other cut-out
models. The slight wavering from the direct line of the bird’s flight
that may occur by this cut-out method would not matter very much. The
bird describes a wavering line anyway as he flies—its body dropping
slightly when the wings go up and a correlative rise occurring when
the wing flap takes place.
[Illustration: CYCLE OF PHASES OF A WALKING DOG ARRANGED FOR THE
PHENAKISTOSCOPE.]
[Illustration: PHENAKISTOSCOPE WITH A CYCLE OF DRAWINGS TO SHOW A DOG
IN MOVEMENT.]
If an artist wishes scrupulously to be exact in drawing a bird flying
across the sky, he should observe certain rules of perspective
applying to the case. The problem is the same as that of the
airplane, previously noted, which flew across the field of the
picture. Regarding this matter, to specify: When the bird appears on
one side it is represented in a side view, which changes as it gets
near the centre to a profile. After it has been viewed in profile,
the perspective changes again and when it reaches the other side it
is again in a perspective side view, slightly from the back.
In the mode of progression that was given as the usual one in
quadrupeds, in which a diagonally opposite fore and hind limb moved
simultaneously, there is a sinuous lateral twisting of the back-bone.
It is not so perceptible to us in the larger beasts. It is an effect,
though, that takes place in other creatures and in some of them can
be clearly seen. In the walk of the lizard, as an instance, when
viewed from above, a successive undulation of the back-bone takes
place. As one fore limb—the right, to particularize—moves forward,
that side of his body—the right shoulder, moves forward, too; while
approximately at the same time the left hind limb moves forward and
carries with it that side or the left pelvic regions. This causes an
alternating obliquity of the transverse axes of the shoulder and the
hind regions of the body of the reptile as he walks on the ground.
And this alternate changing of these axes gives rise to a continuing
sinuosity in the spine.
[Illustration: RUNNING COW.
Positions selected and adapted from Muybridge’s photographs.]
[Illustration: PHASES OF MOVEMENT OF A WALKING LION.]
[Illustration: DOG WALKING.]
The mode of progression in legless creatures is distinguished, too,
by a lateral bending in and out. Snakes and eels, for example,
as they proceed agitate their bodies in wave-like motions. The
waves pass from the head to the tail, the fluctuations taking the
form of rather large loop-like wrigglings of the elongated body. A
spring-like coiling up and then an expanding—flexion and extension
again—is the principle of the locomotory manœuvre in the snake.
[Illustration: VARIOUS KINDS OF WAVE MOTION.
A characteristic of many forms of movement which the animator gets in
certain of his delineations.]
The undulatory motive impulse of a creeping animal is somewhat like
the sudden lashing of a whip, or the wave-like disturbance given to a
rope when it is sharply and strongly shaken in a certain way.
INANIMATE THINGS IN MOVEMENT