Although telephonic novelties are not numerous at the Universal
Exposition, telephony--that quite young branch of electric science--is
daily the object of curious and interesting experiments which we must
make known to our readers, a large number of whom were not yet born to
scientific life when the experiments were made for the first time at
Paris in 1881; and it is proper to congratulate the Societe Generale
des Telephones on having repeated them in 1889 to the great
satisfaction of the rising generation.

We allude to the Ader system of telephonic transmissions of sounds in
such a way that they can be heard by an audience.

The essential parts of this mode of transmission consist of two
distinct systems--transmitters and receivers.

[Illustration: FIG. 1.--THE ADER FLOURISH OF TRUMPETS]

The transmitters are four in number, and are actuated by the same
number of musicians, each humming into them his part of the quartet
(Fig. 1). This transmitter, represented apart in elevation and section
in Fig. 2, is identical with the one used in the curious experiment
with the singing condenser. At A is a mouthpiece before which the
musician hums his part as upon a reed pipe. He causes the plate, B, to
vibrate in unison with the sound that he emits, and this produces
periodical interruptions of varying rapidity between the disk, B, and
the point, C. The button, D, serves to regulate the distance in such a
way that the breakings of the circuit shall be very complete and
produce sounds in the receivers as pure as allowed by this special
mode of transmission, in which all the harmonics are systematically
suppressed in order to re-enforce the fundamental.

[Illustration: FIG. 2.--DETAILS OF THE TRANSMITTER.]

This transmitter interrupter is interposed in the circuit of a battery
of accumulators, with the five receivers that it actuates, in such a
way that the four transmitters and five receivers form in reality four
groups of distinct autonomous transmission, the accordance of which is
absolutely dependent upon that of the artists who make them vibrate.

The five receivers are arranged over the front door of the telephone
pavilion, near the Eiffel tower (Fig. 3). Each consists of a horseshoe
magnet provided, between its branches, with two small iron cores
having a space of a few millimeters between them (Fig. 4). Each of
these soft iron cores carries a copper wire bobbin, N, the number of
spirals of which is properly calc