the quality of pressure which they exert upon their instruments to make them produce the exact quality of sound which renders the musical phrase. Their instruments, however, are machines which do not tire; whereas the horse is a creature with bones, muscles, nerves, and will, capable of fatigue, and needing relaxation, lest the will move nerves and muscles to resist. It is, therefore, to prevent the state of revolt occasioned by fatigue that we must, though always retaining the contact, render the fingers, so that the horse vibrates under the rider's control, without excessive fatigue.
The third sort of rendering the hand consists in allowing the horse to place its head and neck in a position other than that which they have been holding under the rider's control. The horse has completed a series of movements, head in position and fixed point at the atlas region. The contraction starting from this point tends to create weariness, so that the horse needs to rest this region. The rider, therefore, by lengthening his reins, lets the horse extend his neck. The fixed point shifts from the atlas region to the shoulders, and the horse rests. This action of rendering has to be learned by the horse, first standing; then progressively at walk, trot, and gallop. (Figure 20.)
