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ILLINOIS STATE ACADEMY OF SCIENCE 







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tensity was determined by the method of comparisons 

 with a variable standard, recommended by Van der Bijl 

 on page 337 of his book, ''The Thermionic Tube". The 

 circuit and equipment actually used is sho^^^l in Diagram 

 B. D is the tube under test, Ds is the standard tube 

 with which the signal strength from oscillator is ad- 



