* * * * *

THE ADER FLOURISH OF TRUMPETS.

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 calculated for the effect to be produced.  Opposite the vacant space left by the two cores, there is a small piece, t, of rectangular form, and also of soft iron, fixed to a vibrating strip of firwood, L, of about 4 inches section.  The periodical breaking of the circuit produced by the transmitter causes a variation in the magnetization of the iron cores of the five receivers and makes the firwood strips vibrate energetically.  These vibrations are received and poured forth as it were in front of the telephone pavilion, by large brass trumpets arranged in front of each receiver, as shown in Fig. 3.