384 



Mr. A. A. Campbell S win ton. 

 FIG. 5. 



the spherically concave cathode C is 1-25 inch diameter and 0'75 inch 

 radius of curvature. A is the anti-cathode reflector, consisting of a 

 plain disc of polished platinum 0*5 inch diameter, mounted on a 

 vertical axis held in guides, and provided with a small bob weight, so 

 that by tapping the tube, the reflector can be set in the position necessary 

 to give any desired angle between its surface and the incident cathode 

 rays. The electrode B is provided for use as anode. The Faraday 

 cylinder is constructed with an inner and outer cylinder of brass, F 

 and G, similar to those described in connection with fig. 2. The 

 apertures into both cylinders are about 0*08 inch diameter. The 

 cylinder is carried by a curved arm of glass tube, fixed to the glass 

 stopper S, which is very carefully ground into the neck of the tube ; a 

 copper wire passing through the tubular arm serves to connect the 

 inner Faraday cylinder with the terminal F', while a thick coating of 

 copper electrolytically deposited over the entire outside surface of the 

 glass arm, and connected at one end to the outside Faraday cylinder G, 

 and at the other end to the terminal G', can be earthed and serves to 



