Vanishing a horse is one of Presto's signature effects -- often copied but never truly duplicated. Because Presto specializes in mastery of the mind, the horse vanish is always performed as a feat of mentalism.
Presto, dressed in an old-fashioned military parade uniform, rides a horse onto the stage. He dismounts and tells the audience that although they see a horse before them, in reality there is no such animal. Presto is using the power of his mind to create a believable illusion.
To prove that this is the case, Presto asks assistants to come onto stage carrying a large curtain held between them on poles. Presto says that the curtain will act as an eraser, erasing the image of the horse.
The assistants walk past the horse, and the moment the horse is obscured by the curtain Presto gives a great show of concentration. The assistants stop and immediately drop the curtain. The horse is gone, and all that remains is its saddle.
This effect requires perfect timing, careful planning, and a very strong, well trained horse.
When Presto dismounts the horse on stage, he subtly reaches under it and unbuckles the saddle. Unknown to the audience, the horse actually has a second strap around its body, hidden by the saddle. Attached to this strap, on the far side of the horse, is an enormous piece of elastic, painted to match the stage background and attached to a sturdy wall off stage in the wings. As Presto rode the horse onto the stage, the elastic was stretched very tight.
At the exact second the horse is obscured by the curtain, a trainer located out of sight of the audience but visible to the horse gives a signal. At that signal, the horse lifts all four hoofs. With the horse no longer touching the ground, the elastic contracts violently, yanking the horse off stage too fast to be seen. Its saddle remains behind, much as the plates stay on a table when a tablecloth is rapidly pulled away.