ON THE PHONOGRAPH. 771 



of the tinfoil phonograph made progress impossible for ten years (from 1878 to 1888), 

 during which time, however, Edison, Graham Bell and others were engaged in working 

 out the mechanical details of the wax-cylinder phonograph. The subject was then taken 

 up by Hermann # of Konigsberg, and he succeeded in obtaining photographs of the 

 vibrations produced by the vowel sounds, a beam of light reflected from a small mirror 

 attached to the vibrating disk of the phonograph being allowed to fall on a sensitive 

 plate while the phonograph was slowly travelling. The curves thus obtained were very 

 beautiful, and present a striking resemblance to some of Koenig's flame pictures. In 

 1891 BoEKEt of Alkmar, in a laborious microscopical research, measured the transverse 

 diameters of the depressions on the wax cylinder at different depths, and from these 

 measurements calculated the depths of the curves. He thus reconstructed the curves 

 on a large scale. The last attempt at recording sound vibrations by photography that 

 has come under my notice is by William Hallock J of Columbia College, who has 

 succeeded in photographing the flames of an apparatus somewhat similar to the analyser 

 constructed by Koenig. Manometric capsules were attached to eight resonators corre- 

 sponding to the eight tones of a harmonic series, and when the flames were lit, by a 

 device of swinging the camera in front of them, a photograph was obtained of the eight 

 bands of flame, as modified by singing the vowels in front of the resonators. 



12. I have endeavoured to study the marks on the wax cylinder in three different 

 ways : — (a) Taking a cast of the surface of the cylinder ; (6) taking a microphotograph 

 of a portion of the surface of the cylinder ; and (c) recording the curves on a slowly 

 moving surface, by a method to be afterwards described. 



A. Casts. 



13. As regards the first method, taking casts, which was also attempted by Hermann 

 and Boeke,§ the results were not satisfactory. The most efficient method followed by 

 me was to paint on the cylinder, with a camel-hair brush, a layer of celloidin dissolved 

 in ether. This soon hardened and the film could then be peeled off. The thin film 

 thus obtained was then inverted on the stage of a microscope, and the marks were seen 

 in relief, as in fig. 3 (Plate L). This method had the disadvantage of flattening the 

 curves. The depressions are well seen and their differences as regards length are 

 obvious. 



* Hermann, " Ueber das Verhalten der Vocale am neuen Edisonschen Phonographen," Pfilger's Archiv, 

 vol. 47, 1890, p. 42; also Phonophotographische Untersuchungen, ii. p. 44; also Phonophotographische Unter- 

 suehungen, iii. p. 347. See also curves of the phonautograph obtained by Pipping, Zeitschrift fur Biologie, 

 vol. xxvii. p. 1, 1890. 



f Boeke, " Mikroskopiscbe Phonogrammstudien," Pfliiger's Archiv, vol. 50, 1891, p. 297. 



\ Hallock, "Photographic record of Sound Analysis," Tlie American Annual of Photography for 1896, 

 p. 21. 



§ Herr Boeke informs me in a letter that he obtained casts of the surface of the wax cylinder by 

 covering the surface with very thin tinfoil such as is used for covering chocolate. 



