434 



GENERAL SCIENCE 



Shellac makes the mixture of equal consistency and the cotton 

 flock holds the material together much as hair does in plaster. 



An Edison record is made from cheap pulp covered with a veneer 

 of condensite made from carbolic acid and formaldehyde and many 



FIG. 327. A phonograph record. 



FIG. 328. Thomas A. Edison 



other chemicals. This material meets the chief requirements of 

 a record. It is soft when warm, readily taking the impression of 

 the die. It is very hard when cooled and expands or contracts 

 very little from heat or cold. 



FIG. 327a. The reproducer and record on the turn table. 



There are two types of recorders, one which cuts records up 

 and down, called the "Hill and Dale" method, and the other 

 the "Lateral Cut" which cuts the record in a side to side 

 motion. 



There are two types of reproducers. Some phonograph com- 

 panies use needles made of steel and wood, others use rounded 



