I recognize, in rendering the hand, three different actions.
The first occurs when the horse has his head flexed at the axoid articulation, and the muscles of the neck, being under restraint by the tension of the reins, begin to show fatigue, stiffness, and a failure of sensibility. But if, after a time, the rider eases this tension, either by advancing the hand or by letting the reins slip in his fingers, he allows the animal to rest his muscles, and renders his hand in the first sense.
The second way of rendering the hand depends on fingering. When the head is flexed, as in the first instance, the rider's control over the neck is by way of the lower jaw. But since the bars are of uncertain sensibility, if the mouth remains closed notwithstanding the pressure of the bit, the contraction at the tempero-maxillaris articulation will be communicated to the alto-axoid. The result is still greater fatigue, stiffness, and loss of sensibility. But when the neck is flexed and the bit in contact with the bars, pressure of the fingers on the reins opens the mouth, while cessation of this pressure allows it to close. This cessation of the pressure which has flexed the lower jaw is rendering the hand in the second sense. The repetition of this flexing and rendering constitutes fingering.
"Fingering" is the only possible translation of the French, doighter, used by musicians to mean the delicate sensibility by which they distinguish