A mysterious bell was used in this connection, but he admits that it mattered not whether the bell struck or was silent, his son could name the object under consideration or answer the question. While Robert-Houdin asserts that he did not employ electricity for working his silent code, investigations make it almost certain that this was the method used. It is known throughout the world of conjuring that in 1850-51 Robert Heller (William Henry Palmer) reproduced Robert-Houdin's entire répertoire of tricks, with the exception of the suspension, and all worked precisely by Robert-Houdin's methods. In the second-sight trick, which he first presented with a young man as the medium, then later with Miss Haidee Heller, the medium was seated on a sofa fully equipped with wires and electric batteries. Heller's second sight was worked with both the speaking and silent codes. His confederate was concealed behind the scenes watching Heller through a peep-hole, or possibly he used another, seated in the audience, and had the wires strung under his chair, arranging the signal button so that it could be easily reached on the arm or front part of the seat. The receiving instrument was attached to the sofa on which the medium was seated. The latter would be silently informed as to what was being shown and would answer all questions. As proof that these statements are not mere hearsay, the Heller sofa can now be seen in the possession of Mr. Francis J. Martinka, of New York; and Dr. W. Golden Mortimer, who once presented "Mortimer's Mysteries," a show on the style of Heller's performance, furnishes the information that when Heller died in Philadelphia, November 28th, 1878, he engaged the dead magician's chief assistant, an expert electrician named E. J. Dale, who had acted as secret confederate, assisting the medium. [Illustration: Poster used by Robert Heller during his Boston engagement in 1853. From the Harry Houdini Collection.] After travelling with Mortimer some time, Dale eventually returned to England, and retired from the profession. He opened a large shop in London under the firm name of H. & E. J. Dale, Manufacturing Electricians, 4 Little Britain, E. C., in October, 1882. It was the easiest thing imaginable for Robert-Houdin to have his theatre arranged with secret confederates and wires back of the scenes, where a man with powerful opera-glasses could stand. The place being small, he could look all over the room and see the minutest article. When not making use of the talking code, the simplest method employed by second-sight artists is to have a confederate in the audience, with either an electrical push button or a pneumatic bulb, who gives the medium the signal. This is received by a miniature piston, which requires only a small hole in the stage, while the medium has a matching hole in the sole of his shoe. This allows the piston to touch the sole of the foot whenever the confederate presses the bulb or pushes the button.