Page:Popular Science Monthly Volume 6.djvu/148

136 The elevated and lengthened trot is represented in Fig. 8. The animal is depicted at the instant which in the notation is represented by a dot; that is to say, during the time of the suspension, at the moment when the left diagonal biped has just risen, and the right diagonal biped is about to descend.

Tracings afforded by the walking-pace are shown in Fig. 9. If we let fall a perpendicular from the points at which the curves commence, we shall have the positions of the successive impacts of the four legs. The order of succession of impacts is represented by the letters AD, PG, AG, PD, that is to say, right fore-foot, left hind-foot, left fore-foot, right hind-foot. The notation of the rhythm of the pressure of each foot, as derived from the registered curves, shows that the interval which separates the impacts is the same throughout, and consequently that the horse rests during the same time on the lateral as on the diagonal bipeds. This, however, is not always the case, some horses resting longer on the lateral biped than on the diagonal, and vice versa. The change of position of the centre of gravity may be seen by reference to Fig. 9. From 1 to 2 the horse will rest on the right lateral biped; from 2 to 3 on the right diagonal biped (that is to say, on that in which the right foot comes first); from 3 to 4 on the left lateral biped; from 4 to 5 on the left diagonal biped; again, from 5 to 6 the horse would find himself, as at the beginning, on the right lateral biped.

Observations on draught-horses have shown that, when the animal strives to react against a load, he may have three feet on the ground at once. This is held by some to be the rule in the normal walking-pace, but M. Marey has proved to the contrary. The vertical oscillations of the walk are chiefly at the withers, those of the croup being very slight. The actions of the hinder parts seem to consist chiefly