[Illustration:  FIG. 1.—­RAPPING AND TALKING TABLE. ]

Who has not seen, of old, Robert Houdin’s heavy chest and Robert Houdin’s magic drum?  These two curious experiments are, as well known, founded upon the properties of electro-magnets.

At present we shall make known two other arrangements, which are based upon the same action, and which, presenting old experiments under a new form, rejuvenate them by giving them another interest.

The first apparatus (Fig. 1), which presents the appearance of an ordinary round center table, permits of reproducing at will the “spirit rappings” and sepulchral voice experiments.  The table support contains a Leclanche pile, of compact form, carefully hidden in the part that connects the three legs.  The top of the table is in two parts, the lower of which is hollow, and the upper forms a cover three or four millimeters in thickness.  In the center of the hollow part is placed a vertical electro-magnet, one of the wires of which communicates with one of the poles of the pile, and the other with a flat metallic circle glued to the cover of the table.  Beneath this circle, and at a slight distance from it, there is a toothed circle, F, connected with the other pole of the pile.  When the table is pressed lightly upon, the cover bends and the flat circle touches the toothed one, closes the circuit of the pile upon the electro-magnet, which latter attracts its armature and produces a sharp blow.  On raising the hand, the cover takes its initial position, breaks the circuit anew, and produces another sharp blow.  Upon running the hand lightly over the table, the cover is caused to bend successively over a certain portion of its circumference, contacts and breakages of the circuit are produced upon a certain number of the teeth, and the sharp blow is replaced by a quick succession of sounds, or a tremulous one, according to the skill of the medium whose business it is to interrogate the spirits.  As the table contains within it all the mechanism that actuates it, it may be moved about without allowing the artifice to be suspected.

[Illustration:  FIG. 2.—­ELECTRIC INSECTS.]

The table may also be operated at a distance by employing conductors passing through the legs and under the carpet and communicating with a pile whose circuit is closed at an opportune moment by a confederate located in a neighboring apartment.

Finally, on substituting a small telephone receiver for the electro-magnet, and a microtelephone system for the ordinary pile, we shall convert the rapping spirits into talking ones.  With a little exercise it will be easy for the confederate to transmit the conversation of the “spirits” in employing sepulchral tones to complete the illusion.