It will suffice for you, though, Tom, if Nelly will make the pirouette, simple or reversed, without substantially shifting the position of the two pivot feet. But you must remember that if you start with a half-and-half education, it is more difficult to perfect the training than if you start in a more systematic manner; and I do not pretend that these are the proper, but only easy methods.
It is by the union of the side steps of forehand and croup, the former always a trifle in advance, that a horse is taught to "traverse," that is, to move sideways at a walk, trot, or gallop. But the traverse is a School gait rarely needed on the road, and a horse may be trained to entire usefulness without being able to traverse, _as a gait_, if he can willingly make a few quick side steps in either direction. Moreover, to properly traverse, a horse should be taught the passage, which is a gait in which the feet are raised much higher, by the inducement of the spur and the indication of the rein, than the horse would naturally lift them. The passage is put to use in very many of the airs of the _manège_.
To revert now to the canter, for which the pirouettes are preparations. There are two or three ways of teaching a horse to lead with either foot, but the best way is to begin with the flexions which I have just described to you, and the more perfect these are, the easier and quicker the progress, and the more satisfactory the result.
If you have not patience to wade through all these, you may try the following plan, which is founded on the natural instincts and balance of the horse, but for the execution of which, with your load on his back, he has not been prepared.
A horse will lead with the off foot most readily if he is going round a circle to the right; with the near foot, if circling to the left. In other words, the foot which will quickest sustain his weight against the centrifugal motion is the one which is planted first, that is, the foot not leading. The way a horse is taught in a riding-school to lead with either foot is by associating the proper indication to do so with the lead he naturally takes as he canters around the right or left of the ring, or changes direction in what are called the voltes in teaching pupils. But I have seen many horses who would do this very readily inside school walls, who were very stupid or refractory on a straight bit of road. I think this is universally true, in fact, and that is why I recommend road teaching whenever practicable.