The doubler is a straight line which we take, either across or down the centre of the school, after having started from some spot in the wall. Having arrived at the opposite wall, we turn, and continually go on to the same hand. (Fig. 25).

Fig. 25. — Doubler.

The volte is a circle which we describe on some point. But, at the beginning, it is best to do the volte by leaving the end of one of the long sides of the school. As a horse has always a tendency to enlarge the circle, he will keep in bounds by the angle formed by the two walls which face him. (Fig. 26).