PHYSICAL MEASUREMENT OF X-RAYS. — BRONSON. 29 



proportional to the ionization produced in the air ininu-diately 

 surroundng them. 



2. A simple apparatus, making use of this principle, has 

 been devised for measuring the intensity and hardness of 

 th? rays. 



3. It has also been shown that this same apparatus 

 can be easilj' used to determine the length of time of exposure 

 needed to produce radiographs of suitable density. 



In conclusion, I desire to express my indebtedness to 

 Dr. Edward Weston for his kindness in fitting up and loaning 

 me a galvanometer suitable for this work; to Principal 

 Sexton and Professor Aj^ars of the Nova Scotia Technical 

 College for the use of their X-ray apparatus, and especially 

 to Dr. W. H. Eagar for his many helpful suggestions and for 

 the use of his office and equipment. 



Dalhcusie University, Halifax, N. S. 

 March 15, 1915. 



