PHONOGRAPH. 



639 



cylinder. The distance of this stylus P from 

 the cylinder is regulated by a set-screw, S, 

 against which abuts the lever H G. Over tho 

 iron disk A is a vulcanite disk, B , with a hole 

 in its centre. The under side of this nearly 

 touches the iron disk ; its upper surface is cut 

 into a shallow funnel-shaped cavity, leading to 

 the opening in its centre. To operate the ma- 

 chine the cylinder is first neatly coated with a 

 sheet of tin-foil made to ad- 

 here by gumming the corners ; 

 the stylus P is then brought to 

 bear against the foil so that on 

 turning the cylinder it makes a 

 furrow. The mouth is now 

 placed close to the opening in 

 the vulcanite disk, and the 

 metal disk is talked to, the 

 cylinder at the same time be- 

 ing revolved with uniform mo- 

 tion. The voice causes the iron 

 disk to vibrate and the stylus 

 indents the foil, making there 

 a record of the vibrations. If 

 the vibrations given by the 

 voice are those causing simple 

 sounds, and are uniform and 

 regular, the depressions in the 

 foil will also be regular and un- 

 dulating. But if the vibrations 

 are those causing complex and 

 irregular sounds (like those of 

 the voice in speaking), the im- 

 pressions will be in like man- 

 ner complex and irregular. 

 These different effects are seen 

 in Fig. 3, where A shows the 

 appearance to the eye of the 

 impressions on the foil pro- 

 duced by singing the sound 

 of a in " bat " against the iron 

 disk ; the irregular curved line 

 B exhibits in profile (mag- 

 nified) the undulations produced by the vibra 

 tions 

 have 



their traces on the foil. The consequence is 

 that the iron disk gives out the vibrations 

 which previously fell upon it, and it talks back 

 what was said to it. Tho inventor has substi- 

 tuted clockwork in place of the crank turned 

 by hand, thus insuring uniformity of motion, 

 which is essential both for receiving and re- 

 producing correctly the vibrations made in 

 singing or even in speech. It is observed that 



FIO. 2. CB088-8KCT10N OT KDIBON'B PHONOGRAPH. 



even slight irregularities in the velocity of the 

 cylinder destroy the accuracy of the musical 

 intervals, and cause the machine to sing fal- 

 setto. So too in speaking, if you make tho 



the cylinder 



by revolving the lever 

 G H on the pivot 7. 

 Then by reversing the 

 motion of the crank the 

 cylinder is caused to go 

 back to its original posi- 

 tion. The stylus is 











n0 . 3.-I*PBES8IOK8 HADB BT TH 8TTLU8 OK TH FOIL-COVIRED 



raised and bv varying the 

 ^OT b 



depressions made by the stylus now 

 it, and in so doing cause 



und-vibrati,, 



?e"nforc5ng the iund a., it i^ues from the rl- 

 Sing disk. Thus, it ha, been propel to 



