“Prof. Poggendorff produces tones in a metal cylinder, the slit up edges of which touch one another firmly, and which is placed loosely round an induction-bobbin through which there goes an interrupted current.”
[This occasion was the crowning point of Philipp Reis’s career, and might have proved of even greater importance but for two causes: the inventor’s precarious health, and the indifference with which the commercial world of Germany viewed this great invention. Where the keen insight of Reis contemplated the vast possibilities opened out by the invention of a new mode of inter-communication, others saw only an ingenious philosophical toy, or at best a pleasing illustration of certain known principles of acoustic and electric science. And in spite of the momentary enthusiasm which the exhibition of the Telephone had evoked, the interest in it dwindled away. A few of the public journals of that date, noticed the invention in eulogistic terms and spoke of the prospect it afforded of communication between distant friends and of simultaneous concerts being given in different towns, all transmitted telephonically from one orchestra. But the invention came too early. The public mind was not yet prepared to take it up, and the enthusiasm died away. Still in a few of the more important books on Physics, Acoustics, and Electricity, the matter continued to receive attention. In the well-known Müller-Pouillet’s ‘Textbook of Physics’ (Lehrbuch der Physik) edited by Professor J. Müller; in the ‘Technical Physics’ of Hessler, of Vienna, edited by Professor Pisko; in Pisko’s ‘Recent Apparatus of Acoustics,’ and particularly in Kuhn’s admirable ‘Handbook of Applied Electricity,’ the Telephone was accepted as a definite conquest of science, and was described and figured. From the works named we transcribe the extracts which follow, and which sufficiently explain themselves.]
[14.] Extract from Müller-Pouillet’s ‘Textbook of Physics and Meteorology’ (Lehrbuch der Physik und Meteorologie).
[Published at Brunswick, Sixth ed., 1863, vol. ii. page 352, fig. 325; and Seventh ed., 1868, vol. ii. pages 386-388, figs. 348-350. The following translation is from the latter edition.]
“This tone ... has Reis used for the construction of his Telephone.
“Figure 348[33] exhibits Reis’s interrupting apparatus. In the lid of a hollow cube of wood A, a circular opening is made, which is closed by an elastic membrane (pig’s lesser intestine) strained over it. Upon the centre of this membrane is glued a little plate of platinum, which stands in conductive communication with the clamping-screw a by means of a quite thin little strip of metal f (distinctly visible in Fig. 349) [Fig. 31].
“Upon the middle of the little platinum plate, rests a short little platinum pencil, which is fastened at g to the under-side of the strip of tin-plate h g i, one end of which, h, rests upon the little metal pillar l, while a little platinum spike fastened upon its under-side at i, dips into the hollow of the little metal pillar k, containing some quicksilver. The clamping-screw b, is put into conductive communication with the little metal pillar k.
“From one pole of the battery there goes a conducting-wire to the clamping-screw a of the interrupting apparatus Fig. 348 [[Fig. 30]], from the other pole of the same there goes a wire to the clamping-screw d of the reproducing apparatus, Fig. 350 [[Fig. 32]], which is to be presently described. The clamping-screw c, of this apparatus, is connected by a wire with b, Fig. 348 [[Fig. 30]]. The clamping-screws c and d are connected with the ends of the wire of the small magnetising spiral M, Fig. 350 [[Fig. 32]]; with the connexion described above, the current of the current-generator (battery) goes, therefore, through the spiral M.
“As soon now as the sound-waves of an adequately powerful tone enter through the mouth-piece S into the hollow cube A, the elastic membrane which closes this at the top is set into vibrations. Each wave of condensation on entering lifts the little platinum plate together with the little spike which sits upon it; but if the membrane swings downwards, the tin-piece h g i, with the little spike at i, cannot follow it quick enough; there therefore occurs here, at each vibration of the membrane, an interruption of the current which lets itself be recognised by a little spark appearing at the place of interruption.