[This is the last of the contemporary documents bearing upon the performance of Reis’s instruments. From the prominent notice obtained at the time by the inventor, it is clear that his invention was even then accorded an honourable place amongst the acknowledged conquests of science. A critical examination of this body of evidence proves not only the substantial nature of Reis’s claim, but that the claim was openly recognised and allowed by the best authorities of the time. The thing was not done in a corner.] FOOTNOTES: [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. [19] [That is, at any single demagnetisation of the needle, it vibrates and emits the same tone as if it had been struck or mechanically caused to vibrate longitudinally.]--S. P. T. [20] [This range was simply due to the degree of tension of the tympanum; another tympanum differently stretched, or of different proportions, would have a different range according to circumstances.]--S. P. T.