CHAPTER VI
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.
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.