a Plate exposed to a Beam of X-rays. 209 



cone whose generatrices form the angle Q with the incident 

 radiation wiil then be 



(*+«r) ; 



|Lr(l + cos 2 0)sin0e co " 



xe V cos ^ dxdO. . (1) 



In the first place, I effect the integration in regard to x 

 and obtain 



-JT 



\ 8 * + ' ! L_ 



cos 6 



e -^i 



p cost) 



\ cos B / 



f 1-s l c05 * ; W . (2) 



The next thing is to find an expression for this integral 

 adapted to numerical calculation. For this purpose I put 



( K + a)l=k, 



1 



1=07, 



1=-, 



cos 6 



1 



cos 6i 

 and obtain 



For the sake of brevity, I write 



K C z l-e~ kx /_l -1 \^ 



J 07 V(l + ^) 2 (H-*) 4 / v y 



I now pass to an examination of the integral K. First of 

 all we may write 



1_ _ 1 1_ 1 



x(l + x) m ~~x l + # (l + x) m ' 



By using this relation we obtain, after some reductions]: 



rz e -kx rz e -kx rz e -iix 



+2 J xr^? dx+ l w^? dx+ l e+sj** 



+ <T^.-0 + K(r^- i ) + K(i^?- 1 )- ^ 



