THE CA TIIODE RA Y OSCILLOGRA PII 27 



of operation so that the handicaps under which the early apparatus 

 was used have been very largely eliminated. The introduction of the 

 low voltage, high sensitivity tube of moderate cost expanded the use 

 of cathode ray oscillographs rapidly, until now they are used in almost 

 every laboratory where high frequency measurements are made. In 

 the Bell System alone more than a hundred of these instruments are 

 in constant use for research and for the control and calibration of 

 manufactured products. Originally an intractable and little used de- 

 vice, the cathode ray oscillograph has become an almost universal 

 scientific and industrial tool. 



