482 Professor W. Stirling [May 10, 



1. Absolute synchronism between the Phonograph and the Cine- 

 matograph both in recording and reproducing the result. 



2. Registration of sound by the Phonograph at a sufficient dis- 

 tance at the same time as the registration of the pictures on the 

 moving film, without the Phonograph being in the field of the Cine- 

 matograph. 



8. The amplification of the sound so that a large audience can 

 hear the sound and observe the exact correlation between the move- 

 ments of the speakers, or actors, or singers, and the audible sounds as 

 regards pitch, loudness, and quality of the vocal or other sounds. 



It has been calculated that in a record on an ordinary 12-inch 

 disc of a gramophone the length of its sinusoidal sound line or spiral 

 groove — counting 100 grooves to the inch from the centre to the 

 circumference of the disc — is about 240 yards or 720 feet. If, how- 

 ever, the ripples made by the vibrating stylus as the disc revolves 

 under it at the rate of o2 inches per second be added, it brings up 

 the total length of the sound line — in the reproduction of a sound 

 record lasting from three to four minutes - to, it may be, 500 yards 

 or 1500 feet. The disc makes about 76 revolutions per minute or 

 an average rate of each revolution in " 8 second. 



It is also to be noted that in reproducing sound from a phono- 

 graph or gramophone record the stylus, in passing from the circum- 

 ference to the centre, travels over a regularly diminishing spiral, and 

 therefore covers a steadily diminishing distance, but it accomplislies 

 this in the same time, so that there is practically no alteration in ])itcli. 

 The marks of the vibrations are consequently much farther apart at 

 the circumference than at the centre of the disc. 



First Synchronisation of the two Instruments. 



It is not enough to have a perfect synchronism between the 

 Phonograph and the Cinematograph — between the talking-machine 

 and the camera. The vocal sounds of one or more speakers must be 

 registered at a distance of several yards from the phonograph. To 

 do this without altering the purity and intensity of the sounds 

 emitted is no easy problem. 



Obviously the Phonograpli and Cinematograph must be placed in 

 the same electrical circuit. Experience has shown that the Phono- 

 graph must control the action of both instruments. In July 1901, 

 the Gaumont Co. obtained the first patent for such an arrangement. 



The Chronophone. 



Considerable progress in the technique has been made since then. 

 The experiments which I have the honour to place before you 

 to-night have been prepared under the superintendence of Mons. 

 Gaumont himself, and I think you will agree with me that the 



