Secondary IL-rays and Electromagnetic Pulse Tlieory. 275 

 Table I. 



(1) 



(2) . 



(3) 

 Calculated appro- 

 ximately for the 



(4) 



(5) 

 Percentage dif- 

 ference between 





Calculated for 



actual conditions 





calculated and 



Angle a. 



narrow pencils 



T„ OS 



of experiment 



h 



Observed 



la 



observed values of 



la 





£5-=(l+ cos a a). 





X ' 



1 /..* 





Iff/3 



iff/2' 



ff/2 



X 7T/2 



20° 



T88 



1-90 



37 



4-95 



30 



1-75 



1-76 



2-1 



+19 



40 



1-59 



1-59 



1-58 



-0-6 



60 



1-41 



1-40 



1-43 



+2 



60 



1-25 



1-23 



1-27 



+ 3 



70 



1-12 



1-09 



102 



-6 



80 



103 



1-03 



107 



+4 



90 



[1-00J 



[1-00] 



[1-00] 



— 



100 



1-03 



1-03 



1-06 



4-3 



110 



112 



109 



111 



4- .2 



120 



1-25 



1-23 



1-27 



+3 



130 



1-41 



1-40 



1-41 



+ 1 



140 



1-59 



1-59 



1-51 



-5 



150 



1-75 



1-76 



1-69 



-4 



160 



1-88 



1-90 



1-84 



-3 



170 



1-97 



200 



1-99 



-0-5 



-50° 



1-41 



1-40 



1-48 



+6 



-120 



1-25 



1-23 



1-24 



+ 1 



-150 



1-75 



1-76 



1-70 



-3 



Column 3 gives the values of the ratio calculated for the 

 actual conditions of the experiments as nearly as possible, — 

 taking into account the slight polarization of the primary 

 beam used, and the obliquity of the rays for the position 



a=--. (In other positions of the axis of the ionization 



vessel, the errors due to obliquity of rays on each side of 

 this axis approximately cancelled, and were neglected except 

 for the positions ct = 80° and 100°, in which it was estimated 

 the outstanding error would be of the order of 3 per cent. 

 The others would be less. Accordingly the ratio calculated 

 for these positions was increased that amount.) The axis of 

 the cathode stream in the X-ray tube in these experiments 

 was horizontal, and the tube was in a condition which in 

 previous experiments had been found to give a partially 

 polarized radiation, the behaviour of which could be explained 

 by the presence of about 5 per cent, of piano polarized 

 radiation, the direction of electric force being horizontal. 

 Also the obliquity of secondary rays to the axis in the 



