[10] ‘Electrical Review,’ July 22, 1882, p. 49.
[11] Mr. E. Albert, of the firm of J. W. Albert and Sohn, of Frankfurt, to whom Reis entrusted the manufacture of Telephones for public sale, thus writes: “The most important part was the membrane, because the delicacy of the apparatus depended principally upon that part. As it was not possible to make every membrane equally good, so it came about that instruments of different degrees of superiority came into use, and various decisions were arrived at as to the ability of the instrument to perform the functions for which it was designed. Those who happened to have a poor instrument were able to hear but little; while those who possessed a good instrument were astonished at its performances. A good instrument reproduced the words sung into it in such a manner that not only the pitch but also the words of the song were perfectly understood, even when the listener was unacquainted with the song and the words.”
M. St. Edmé, of Paris, who contributed to ‘Cosmos,’ vol. xxiv. p. 349, 1864, an article on Reis’s Telephone, of which he had seen an example in König’s atelier, said that when the scale was sung it needed a trained ear to distinguish the notes amidst the noises of the receiver. He must have got hold of an uncommonly bad transmitter with a flabby tympanum to have failed so completely.
[12] Letter of Dr. Messel to Professor W. F. Barrett quoted, in Professor Barrett’s memoir, ‘On the Electric Telephone,’ read Nov. 19, 1877, to the Dublin Royal Society. Vide Proc. Roy. Soc. Dubl. 1877.
[13] See Barrett’s ‘Telephones Old and New’ (1878), p. 12.
[14] See Reis’s own remark at bottom of p. 57.
[15] [This was the number formerly accepted on the authority of Despretz as the minimum number of vibrations that could evoke the sensation of a tone in the human ear. The limit now more usually recognized is that of Helmholtz, who assigns from thirty to forty double vibrations per second as the minimum.]—S. P. T.
[16] [The three plates or tables with which Reis accompanied his Memoir, containing a variety of undulatory curves corresponding to various combinations of tones, both of musical concords and of dissonant sounds, are not reprinted in this book in their entirety. Table I. contained three sets, the first of which is reproduced by photo-lithography in reduced facsimile in [Fig. 47], p. 173. It was also reproduced by W. von Legat in his Report from which [Plate I.] at end of this book is copied, Fig. 1 of that plate being the same as Fig. 1 of Reis’s Table I. Fig. 2 of Plate 1, was in like manner copied by Legat from the first figure of Reis’s Table II., and Fig. 3 of Plate I., which represents the curves of a non-harmonious combination is the same as Reis’s Table III., the only difference being that in Reis’s Table III. the irregular undulations of the resultant curve were emphasised by being labelled ‘Dissonanz.’]—S. P. T.
[17] [This is true for speech-tones as well as for musical tones. Each kind of tone may be represented by its own characteristic curve.]—S. P. T.
[18] [This is the fundamental principle, not only of the telephone, but of the phonograph; and it is wonderful with what clearness Reis had grasped his principle in 1861.]—S. P. T.