682 THE TALKING PHONOGRAPH. 



clear that the point on the metal diaphragm must, therefore, describe a 

 spiral trace over the surface of the cylinder. On the latter is cut a spiral 

 groove of like pitch to that on the shaft, and around the cylinder is attached 

 a strip of tinfoil. When sounds are uttered in the mouthpiece, A, the dia- 

 phragm is caused to vibrate and the point thereon is caused to make con- 

 tacts with the tintoil at the portion where the latter crosses the spiral 

 groove. Hence, the foil, not being there backed by the solid metal of the 

 cylinder, becomes indented, and these indentations are necessarily an 

 exact record of the sound which produced them. 



It might be said at this point the machine has already become a complete 

 phonograph or sound writer, but it yet remains to translate the remarks 

 made. It should be remembered'that the Marey and Rosapelly, the Scott, 

 or the Barlow apparatus, which were cently described, proceeded no further 

 than this. Each has its own system of caligraphy, and after it has inscribed 

 its peculiar sinuous lines it is still necessary to decipher them. Perhaps 

 the best device of this kind ever conceived was the preparation of the 

 human ear made by Dr. Clarence A. Blake,' of Boston, for Professor Bell, 

 the inventor of the telephone. This was simply the ear from an actual sub- 

 ject, suitably mounted and having attached to its drum a straw, which 

 made traces on a blackened rotating cylinder. The bifference in the traces- 

 of the sounds uttered in the ear was very clearly shown. Now there is no- 

 doubt that by practice, and the aid of a magnifier, it would bo pos- 

 sible to read phonetically Mr. Edson's record of dots and dashes, but he 

 saves us that trouble by literally making it read itself. The distinction is 

 the same as if, instead of perusing a book ourselves, we drop it into a ma- 

 chine, set the latter in motion, and behold ! the voice of the author is heard 

 repeating his own composition. 



The reading machine is nothing but another diaphragm held in the tube,, 

 D, on the opposite side of the machine, a point of metal which is heldJ 

 against the tinfoil on the cylinder by a delicate spring. It makes no differ- 

 ence as to the vibrations produced, whether a nail moves over a file or a 

 file moves over a nail, and in the present instance it is the file or indented 

 foil strip which moves, and the metal point is caused to vibrate as it is affect- 

 ed by the passage of the indentations. The vibrations however, at this point, 

 must be precisely the same as those of the other point which made the in- 

 dentations, and these vibrations, transmitted to a second membrane, must 

 cause the latter to vibrate similar to the first membrane, and the result is a 

 synthesis of the sounds which, in the beginning, we saw, as it were, an- 

 alysed. 



It is a little singular that the [machine pronounces its own name with 

 especial clearness. The crank handle shown in our perspective illustra- 

 tion of the device does not rightly belong to it, and was attached by Mr. 

 Edison in order to facilitate its exhibition to us. 



In order that the machine maybe able exactly to reproduce given sounds, 

 it is necessary, first, that these sounds should be analyzed into vibrations^ 



