We proceed to study first the pace of ambling, because it is the most simple; we shall then consider the trot, and, finally, we shall examine that which is the most complicated, viz., the step. [Illustration: FIG. 124.--THE AMBLE: RIGHT LATERAL PRESSURE.[72]] [72] The figures which, in the present study, reproduce the different paces, have been made from our articulated horse (see the note on p. 282). =The Amble.=--To give an exact idea of the general character of the amble, let us fancy the two men whom we discussed above marching one behind the other and walking in step--that is, moving the legs of the same side simultaneously. They will thus represent the amble, which, indeed, results from the alternate displacements of the lateral bipeds; the limbs of the same side (right or left) execute the same movements in the same time. This is what the notation indicates (Fig. 123). We there see that the pressures of the right fore-foot, marked by the white bands in the upper range, are exactly superposed on those of the right hind one, which are marked by a similar band on the lower line; this means that the pressures took place in the same time. We there see also a similar arrangement of the gray bands, which has a similar significance for the left fore and hind feet. And if we recollect the three phases of pressure (see p. 289, and Figs. 121, 122), we shall comprehend, in looking at the diagrams, that, at the initial stage (A), the limbs are commencing their pressure, and are oblique downwards and forwards; that afterwards (B) the two limbs are vertical, since they are at the middle of the pressure stage; and that finally (C) they are oblique downwards and backwards, for it is then the termination of their pressure (Fig. 124). [Illustration: FIG. 125.--NOTATION OF THE GAIT OF THE TROT IN THE HORSE (AFTER PROFESSOR MAREY).] During the time that the right limbs are pressing (notation, white bands) the left limbs are raised; afterwards these latter take up the pressure (gray bands), and then the right limbs are raised in their turn. During the pace of ambling the weight of the body, which is wholly sustained by the limbs of one side only, is not in equilibrium, so that the limbs which are raised return by a brisk movement to the position of support in order to re-establish it. =The Trot.=--We have just seen that, in order to represent the amble, the two marchers moved their right limbs simultaneously, and then their left ones. Let us suppose now that the hinder man anticipated by half a pace the movement of the front one, then will be found realized the association and the nature of the displacements of the limbs during the pace of the trot.