THE GALLOP BACKWARD
For the gallop backward, the horse must be of perfect conformation, especially in its hind quarters, and must be educated to the point where it can interpret almost imperceptible effects of the rider. Its equilibrium and assemblage must be perfect—the sine qua non of this air, since the gait is very precise and the beats equal and uniform—and its strength must be sufficient to sustain without apparent exertion the gallop terre-à-terre. (Figure 41.)
In the gallop terre-à-terre, as in the piaffer, the horse is like a ball resting on one pole and movable by the slightest force. If, then, the rider's effects, by their lack of equality, timing, fineness, or uniformity, disturb this perfect equilibrium, the gallop terre-à-terre becomes impossible. But if the rider's effects are precisely correct, the horse will continue to gallop on the same spot, like the ball resting on a pole. Under these conditions, if the rider's weight shifts on the seat to throw the center of gravity backward of the perpendicular around which the whole mechanism has centered, the horse will be forced to move backward in order to prevent falling.
Meanwhile, of course, the rider, by his effects, must continue to maintain the equilibrium and the gait of the gallop. If either is disturbed ("evaporated" is the expression I use with my pupils), the horse loses either its equilibrium and then its gallop, or else its gallop and then its equilibrium. In either
