In my library of old conjuring books the thread method is ably described by Hofrath von Eckartshausen, mentioned earlier in this chapter. In fact in the pictorial appendix of this work he gives this trick prominence by minutely illustrating the same. He makes use of two hands, and to make the trick infallible he explains that the best way would be to use two glass disks, have them held together by a brass rim, and your threads will work with absolute certainty. The spectators imagine that they are seeing only one glass clock.
Johann Conrad Gutle, the well-known delver after secrets of natural magic, also explains several cabalistic clock tricks in his book published in 1802.
I am reproducing herewith a number of programmes describing the effect of the trick and proving that it was no novelty when Robert-Houdin “invented” it. In fact the trick was so common that only the supreme egotism of the man can explain his having introduced it into the pages of his book as an original trick. The mysterious clock worked by the counterweight, which has been described, is credited as having been the invention of Johann Nep. Hofzinser.
In an advertisement, published in the London Post of May 23d, 1778, included in my collection, this announcement, among others of much interest, will be found:
“Part II.—Breslaw will exhibit many of his newly invented deceptions with a grand apparatus and experiments and particularly the Magic Clock, Sympathetic Bell, and Pyramidical Glasses in a manner entirely new.”
In 1781, while showing at Greenwood’s Rooms, Haymarket, London, Breslaw heavily advertised, “Particularly an experiment on a newly invented mechanical clock will be displayed, under the direction of Sieur Castinia, just arrived from Naples, the like never attempted before in this metropolis.”