PHYSICAL MEASUREMENT OF X-RAYS. BRONSON. 



19 



The writer also makes use of the ionizing action of X-rays, 

 but employs quite a different method for measuring it. He is 

 able in a few seconds to determine with considerable accuracy 

 the intensity and hardness of the rays, as well as the time 

 of exposure necessary to obtain radiographs of proper density, 

 even under verv unfavorable conditions. 



ALSqA 



Lea J Sheet. 



AL£aA 



|o lesfino ]/es5el 



18 cm. 



C Ah Sh^^h 



D 5efl/;n^ Wax- 



Dunamo ordaikru. 



Lead Cable, 



Hioth Resistance. 



Fi^. I- 



Apparatus. 



Figure 1 shows a section of the testing vessel drawn 

 approximately to scale and gives a diagram of connexions. 

 The galvanometer was a Weston Model 89, having a tripod 

 base, and was very easily adjusted by means of an attached 

 spirit level. It was mounted on a window-stool, shelf or 

 mantel according to circumstances, and its deflection was 

 read by means of a lamp and scale. With the scale at a 

 distance of one meter, it gave a deflection of 1mm. for a 

 current of 3 x 10~^° amperes. The high resistance R. of about 

 10^ ohms, was made by a pencil line on ground glass and was 

 used merely to protect the galvanometer. The resistance of 



