His inability to grasp the principles on which other performers built their tricks is shown most clearly when he attempts to describe and explain the performances of the Arabian mountebanks whom he saw during his stay in Algiers. These tricks have been handed down from one generation to another, and now that Arabian conjurers and acrobats are imported for hippodrome and vaudeville performances in all civilized countries, the tricks described by Robert-Houdin are familiar to the general public. They are also copied by performers of other nationalities, and can be seen in circus side-shows and at fairs, as well as in the better grade of houses. Having worked on the same bill with genuine Arabian performers, I know just how the tricks are accomplished. Robert-Houdin undertakes to explain these tricks in chapter XXII. of the American edition of his "Memoirs." So long as he quotes reliable authorities like the _Journal des Sciences_, the explanations are correct. Directly he attempts an independent exposure, he strikes far from the correct explanation. On page 424 he states: "In the following experiment, two Arabs held a sabre, one by the hilt, the other by the point; a third then came forward, and after raising his clothes so as to leave the abdomen quite bare, laid himself flat on the edge of the blade, while a fourth mounted on his back, and seemed to press the whole weight of his body on him. "This trick may be easily explained. "Nothing proves to the audience that the sabre is really sharpened, or that the edge is more cutting than the back, although the Arab who holds it by the point is careful to wrap it up in a handkerchief--in this, imitating the jugglers who pretend they have cut their fingers with one of the daggers they use in their tricks. "Besides, in performing this trick, the invulnerable turned his back on the audience. He knew the advantage to be derived from this circumstance; hence, at the moment when about to lay himself on the sabre, he very adroitly pulled back over his stomach that portion of his clothing he had raised. Lastly, when the fourth actor mounted on his back, he rested his hands on the shoulders of the Arabs who held the sabre. The latter apparently maintained his balance, but, in reality, they supported the whole weight of his body. Hence, the only requirement for this trick is to have the stomach more or less pressed in, and I will explain presently that this can be effected without any danger or injury." [Illustration: A Rannin lithograph, showing him doing the sword-walking act which Robert-Houdin claimed to have been a fraud. Rannin is still working in Germany, imitated by many, equalled by none. From a photograph in the Harry Houdini Collection.]