THE EDISON PHONOGRAPH 



This quality of sound is reproduced by the form of the 

 indentations in the wax, regardless of their frequency or 

 depth. When it is considered that all the complicated 

 vibrations determining pitch, loudness, and quality 

 of sounds, are recorded by minute, almost microscopic, 

 indentations in little grooves scarcely perceptible to 

 the naked eye, it is little wonder that the Edison pho- 

 nograph remains a constant source of marvel. 



In the issue of the North American Review for May- 

 June, 1878, Edison described his then recent invention, 

 and recorded some of the prophecies as to the possibili- 

 ties of its use in the future. He said in part : 



"The apparatus now being perfected in mechanical 

 details will be the standard phonograph, and may be 

 used for all purposes except such as require special form 

 of matrix, such as toys, clocks, etc., for an indefinite 

 repetition of the same thing. The main utility of the 

 phonograph being, however, for the purposes of letter- 

 writing and other forms of dictation, the design is 

 made with a view of its utility for that purpose. 



"The general principles of construction are a flat 

 plate or disk, with a spiral groove on the face, worked by 

 clockwork underneath the plate; the grooves are cut 

 very closely together, so as to give a great total length to 

 each length of surface a close calculation gives as 

 the capacity of each sheet of foil nearly 40,000 words. 

 The sheets being but ten inches square, the cost is so 

 trifling that but a hundred words might be put on a 

 single sheet economically. 



"The practical application of this form of phono- 

 graph is very simple. A sheet of foil is placed in the 

 VOL. vm. 7 [ 97 ] 



