124 Prof. E. Rutherford on Uranium Radiation and 



rod R to a screw adjustment, S, so that the condenser AB 

 could be moved as a whole parallel to the base-plate. The 

 system AB was adjusted parallel to the uranium surface and 

 did not rotate with the screw. The rod R passed through 



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a short glass tube fixed in the ebonite plate C. A short 

 piece of indiarubber tubing T was passed over the glass 

 tube and a projecting flange in which the rod R was screwed. 

 This served the same purpose as the usual stuffing-box, and 

 allowed the distance of AB from the uranium to be adjusted 

 under low pressures. 



The plate A was connected to one pole of a battery of 

 60 volts, the other pole of which was to earth. The plate B 

 was connected through the screw to one pair of quadrants of 

 an electrometer, the other pair of which was to earth. In 

 order to avoid the collection of an electrostatic charge on the 

 glass surface due to the conduction between the uranium and 

 the glass near it, it was found very necessary to coat the 

 inside of the glass cylinder with tinfoil. The tinfoil and 

 base-plate P were connected to earth. 



Since the surface of the uranium layer may be supposed 

 to be giving out radiation uniformly from all parts, the 

 intensity of the radiation at points near the centre of the 

 uranium surface should be approximately uniform. If there 

 were no absorption of the radiation in the gas, we should 

 expect the intensity of the radiation to vary but slightly with 



