IN the November Monthly we gave a brief account of Prof. Marey's method of representing the step of animals by means of graphic illustrations, with its application to human locomotion; we will now consider it as applied to the more complex paces of the horse. Hitherto, the locomotion of the horse has been mainly studied by means of the eye and ear. In the horse, even at a walk, the motions of the limbs are so confusing as to make it difficult for the untrained eye to follow them, and, when the pace is more rapid, the movements seem hopelessly intricate. Indeed, observation by the eye alone long since gave place to the use of the ear, which, taking account of the rhythm of the steps by the sounds they produce, afforded much more accurate results.
An expedient which greatly aided the observer, and which we shall find of service in explaining the results obtained by the graphic method, was to concentrate the attention on a single pair of limbs, instead of attempting to keep all four under observation at once. Any two limbs thus selected are called a biped, and this is designated according to the relative position of the limbs chosen. The horse may thus be parceled out into six different bipeds. The forward limbs constitute the anterior biped; the hind-limbs, the posterior biped; the two right limbs, the right lateral biped; the two left limbs, the left lateral biped; the right fore-leg and the left hind-leg, the "right diagonal biped"; the left fore-leg and the right hind-leg, the left diagonal biped. The horsey reader may dwell a moment upon this bit of equine technics, as it will materially assist him in understanding the explanation of the various paces.
The quadruped, when walking, has been compared to two men, placed one before the other, the hindmost following close upon the forward step of his companion. According as these persons (who ought both to take the same number of steps) move their limbs simultaneously, or alternately, according as the man in front executes his
- Abstract of Chapters IV., V., and VI., of "Animal Mechanism," by Prof. Marey. (Vol. XI. of "The International Scientific Series.")