304 SPEAKING AND HEARING 



sessed of neither wealth nor skill. That the music reproduced 

 by a phonograph is in general of a low order, vulgar operas, 

 coarse songs, etc., does not detract from the interest and won- 

 der of the instrument. It can reproduce what it is called 

 upon to reproduce, and if human nature demands vulgarity, 

 the instrument will be made to satisfy the demand. On the 

 other hand, speeches of famous men, national songs, magnifi- 

 cent opera selections, and other pleasing and instructive pro- 

 ductions can be reproduced fairly accurately. In this way 

 the phonograph, perhaps more than any other recent inven- 

 tion, can carry to the " shut-ins " a lively glimpse of the out- 

 side world and its doings. 



The phonograph consists of a cylinder or disk of wax upon 

 which the vibrations of a sensitive metallic disk are recorded 



by means of a fine 

 metal point. The 

 action of the pointer in 

 reporting the vibra- 

 tions of a disk is easily 

 understood by refer- 

 ence to a tuning fork. 

 Fasten a stiff bristle 



FIG. 195. A vibrating tuning fork traces a curved Q a tuning fork by 

 line on smoked glass. 



means of wax, allow- 

 ing the end of the point to rest lightly upon a piece of smoked 

 glass. If the glass is drawn under the bristle a straight line 

 will be scratched on the glass, but if the tuning fork is struck 

 so that the prongs vibrate back and forth, then the straight 

 line changes to a wavy line and the type of wavy line depends 

 upon the fork used. 



In the phonograph, a disk replaces the tuning fork and a 

 rotating cylinder coated with wax replaces the glass plate. 

 When the speaker talks or the singer sings, his voice strikes 



