The wonderful ease with which electricity adapts itself to the production
of mechanical, calorific, and luminious effects at a distance, long ago
gave rise to the idea of applying it to certain curious and amusing
effects that simple minds willingly style _supernatural_, because of
their powerlessness to find a satisfactory explanation of them.
[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.
Fig. 2 represents a device especially designed as a parlor ornament. When
the plant is touched, the insects resting upon it immediately begin to
flap their wings as if they desired to fly away. These insects are
actuated by a Leclanche pile hidden in the pot that contains the plant.
The insect itself is nothing else than a mechanism analogous to that of
an ordinary vibrating bell. The body forms the core of a straight
electro-magnet, _c_, which is bent at right angles at its upper part, and
in front of which is placed a small iron disk, _b_, forming the animal's
head. This head is fixed upon a spring, like the armature of ordinary
bells, and causes the wings to move to and fro when it is successively
attracted and freed by the electro-magnet. The current is interrupted by
means of a small vibrating device whose mode of operation may be easily
understood by glancing at the section in Fig. 2. The current enters the
electro-magnet through a fine copper wire hidden in the leaves and
connected with the positive pole of the pile. The negative pole is
connected with the bottom of the pot. The wire from the vibrator of each
insect reaches the bottom of the flower-pot, but does not touch it. A
drop of mercury occupies the bottom of the pot, where it is free to move
about. It results that if the pot be taken into the hand, the exceedingly
mobile mercury will roll over the bottom and close the circuit
successively on the different insects, and keep them in motion until the
pot has been put down and the drop of mercury has become immovable.
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