38(3 Mr. A. A. Campbell Swinton. 



Fig. 6 shows the arrangement of the scale, from which the positions 

 of the reflector and the Faraday cylinder relatively to the axis of the 

 primary cathode stream can be seen for each observation in the follow- 

 ing tables. The observed galvanometer deflections are in degrees of 

 an arbitrary scale. 



The first experiments were made with the Faraday cylinder station- 

 ary, the anti-cathode reflector being rotated ; a specimen set of the 

 results obtained is given in Table I. 



Table I. 



Faraday cylinder fixed at Q0. 



Readings taken with reflector at different angles from 75 to 175. 



Pressure 0-000018 to 0-000023 atmosphere. 



Eeflector. 

 75 

 90 

 100 

 110 

 120 

 130 

 140 

 150 

 160 

 170 

 175 



It will be observed that as the reflector was rotated the galvano- 

 meter deflections gradually increased in value up to a certain point, 

 and then decreased again ; also that the maximum mean deflection was 

 obtained with the reflector at 140, i.e., very nearly at that position 

 which would give equal angles of incidence and reflection for the 

 cathode rays. 



Next, the reflector was kept stationary, and the cylinder moved so as 

 to explore the field of reflected rays. A specimen set of the results 

 thus obtained is given in Table II. 



In this instance, on the assumption of partial specular reflection, the 

 maximum galvanometer deflection should of course be obtained with 

 the cylinder as near to as it could be placed without interfering 

 with the primary cathode rays. It was not found practicable to place 

 it nearer than 45, but, as will be observed, the deflections rise steadily 

 up to this latter position. 



Several other series of observations were made with this tube, with 

 the cylinder stationary at 45 and at 130, with the reflector at varying 

 angles, and also with the reflector stationary at 70 and at 135, and 



