770 PROFESSOR JOHN G. M'KENDRICK 



marker leaves the surface altogether for a fraction of a second, there will be a rebound 

 from the glass disk (owing to the removal of pressure coming from the marker) which 

 is not exactly the same as the diminution of pressure due to the rarefaction of the aerial 

 wave in the immediately preceding vibration. These changes must affect quality of 

 tone. 



VI. The Nature of the Marks on the Cylinder 



11. Many attempts have been made to obtain tracings of the vibrations of mem- 

 branes and of glass or metallic disks. In 1856 Leon Scott* invented the well-known 

 phonautograph, which may be regarded as the precursor of the phonograph, and by 

 which vibrations were recorded. DoNDERS,t in 1870, applied the instrument to the 

 investigation of vowel sounds. Next came the logograph of Barlow,J by which curves 

 were obtained by the vibrations of a thin membrane of gold-beater's skin. These curves 

 represented the varying pressures of the expelled air taken as a whole, but did not 

 indicate pitch. About 1873 Koenig introduced the method of manometric flames, and 

 flame pictures of vibrations were thus obtained. In 1876 Clarence J. Blake § employed 

 the human membrana tympani as a logograph. In the same year Stein [| carried out a 

 method by which he photographed the vibrations of tuning-forks, strings, &c. , by attach- 

 ing to them plates of blackened mica perforated with small holes. A beam of light 

 passing through a hole was allowed to play on a sensitive photographic plate moving with 

 uniform velocity. There was thus recorded a curve representing the combined motions. 

 All of these instruments made it possible to record vibrations, but the sound could not 

 be reproduced from the tracings thus obtained. This was accomplished in 1877 by 

 Edison, by the invention of the phonograph. In 1878 Fleeming Jenkin and EwingII 

 succeeded in obtaining tracings of the record of vowel sounds on the tinfoil phonograph, 

 and the curves were submitted to harmonic analysis. Shortly afterwards, and in the 

 same year, E. W. Blake ## succeeded in photographing the minute vibrations of a circular 

 ferrotype plate screwed to a telephone mouthpiece by attaching a small mirror to the 

 back of the plate and directing a reflected beam of sunlight on a moving photographic 

 plate. Since that time, the marks on the tinfoil of the first phonograph have been 

 scrutinised by Grutzner, Mayer, Graham Bell, Preece, and LAHR.tt The imperfections 



* E. L. Scott, Comptes rendus, t. 53, p. 108. 



■(• Donders, De Physiologic der Spraachlclariken in het bijzonder van die der nederlandische taal. 

 Utrecht, 1870. 



% Barlow, Trans, of Royal Society, 1874. 



§ Blake, C. J., Archiv. of Ophthalmology and Otology, vol. v. 1, 1876. 



|| Stein, S. Th., "Die Photographie der Tone," Poggendorff's Annalen, 1876, p. 142. 



H Fleeming Jenkin and Ewing, " On the Harmonic Analysis of certain Vowel Sounds," Trans. Roy. 

 Soc. FAin., vol. xxviii. p. 145. 



** Blake, E. W., "A Method of recording Articulate Vibrations by means of Photography," Amer. Jl. 

 of Science and Arts, 3rd ser., vol. xvi. p. 54. 



ft Referred to in The Telephone, the Microphone, and the Phonograph, by Count du Monce, London, 

 1884. Sec also The Speaking Telephone and Talking Phonograph, by G. B. Prescott, New York, 1878. 



