222 



Mr Townsend, Secondary Rontgen Rays. 



consisting of : — the insulated quadrants, the wire connecting the 

 quadrants to A, and the plate A. 



X = l, = 136-0, 



X = 2, = 114-5, 



X = 5, (7=98-5, 



X = 10, (7 = 93-5, 



X = 15, (7 = 93. 



Table II. 



Multiplying the deflections S by the corresponding capacities 

 we obtain from Table II. a second series of numbers N, Table III. 

 proportional to the number of ions produced between the plates A 

 and B in the various cases. 



Table III. 



Let us suppose for the moment that the aluminium plate B 

 gives out no secondary radiation, and let us consider the numbers 

 obtained with a brass plate at A. The experiments show that 



