902 



On Secondary Homogeneous X Radiation. 



the electroscope A, and had the disturbance in the atom con- 

 tinued for a long enough period ionization should have been 



produced in the electroscope with consequent deflexion of 

 the gold leaf. Varying speeds were used but no leak effect 

 was observed. 



The number of revolutions per second made by the cylinder 

 was measured by an estimation of the note obtained by a 

 prong fixed to the cylinder striking a card once in each revo- 

 lution. The highest number of revolutions of the cylinder 

 which, by gearing, the motor was capable of giving, was 

 approximately 270 per second, and since the angle subtended 

 by S 2 and S 3 was 30°, the time which elapses between a 

 certain fixed part of the cylinder leaving the X rays and 

 coming into a position in which it was able, if still giving 

 off this secondary radiation, to affect the electroscope, works 

 out at approximately 1/3000 second. With the cylinder 

 rotating at this speed no appreciable leak was observed in 

 the electroscope over a period of five minutes, though a de- 

 flexion of 0*2 of a division could have been easily read. 

 On the other hand, had the homogeneous secondary X radia- 

 tion excited in the cylinder not decayed appreciably in the 



