51. (a.) Allied to the Membrane Phonautograph is the “Telephon” of Reis[34] ([Fig. 33]). Upon the little membrane, m m, in the middle, is fastened with adhesive wax the round end s of a light strip of platinum, n s, so that the platinum strip can join in with all the vibrations of the membrane. Very near to the central end, s, of the little platinum strip, n s, a platinum spike stands, in such a way that it is brought into contact, by the vibrations of the membrane, with the platinum strip that vibrates with the latter. Suppose now that the outer end, n, of the platinum strip and the platinum spike are connected with the poles of a galvanic battery, then, by the vibration of the membrane the galvanic current will, according to the phase of the vibration, be alternately established and interrupted. Inserted in this circuit, an electro-magnetic bell, or an electro-magnetic telegraph, will give signals to great distances that somebody is speaking;[35] though, obviously, it cannot inform what is being spoken.
Fig. 33.
(b.) As is known, an iron wire around which flow rapidly-interrupted powerful galvanic currents, is thereby thrown into tones which, according to circumstances, may be longitudinal or transverse or both together. Such an iron wire, lying in a multiplying wire-coil, G, Reis inserted at the second [receiving] station, C. The wire emitted sounds when the membrane was set into vibrations by singing or speaking (at S, [Fig. 33]) into the hollow cubical piece A. In the investigations made by me with the telephone, the rod (of iron) never altered the pitch of its tone with the most different kinds of tones and clangs, and always gave only the rhythm of the words sung or spoken into the piece A (the transmitter) at S. Usually the air of the song that was sung could be recognised by its rhythm.[36] The special researches on these points follow in paragraph 53. However, it is so far clear that there is still plenty of time yet before we have the simultaneous concerts, and the transmission of singing to different towns, as the daily newspapers have sanguinely expected. The apparatus of Reis is certainly a “Telephone” but not a “Phonic Telegraph.” The single means of transmission for song and speech—and that only for moderate distances—remains the old familiar speaking-tube. Nevertheless, the experiment of Reis must ever be reckoned amongst the most beautiful and interesting of school-experiments. And since the means for this are so simple, the apparatus of Reis will certainly find a speedy entrance into educational establishments that are only moderately endowed. It is easily proved that the tones of the wire in the telephone do not arise from acoustic conduction, for by cutting out the coil from the circuit the tones immediately cease.
1. The Telephone of Reis originally consisted of a cube of wood with a conical boring. The smaller opening was strained over with a membrane. A knitting-needle which served for a sounding wire projected about 2 inches on each side of the multiplying coil, and lay upon the two bridges of a sounding-box. The surrounding helix consisted of six layers of thin wire. [Fig. 33] shows the Telephone as it is constructed at the present time by the mechanician, Albert, in Frankfort, and by the mechanician, Hauck, in Vienna, according to the directions of the inventor.
[52.] Details about the Telephone.
(a.) The same ([Fig. 33]) consists in its essentials: