174 Mr Richardson, On an attempt to detect radiation, etc. 

 The following are typical of the observations taken : 



Conditions of 

 Experiment 



Initial 

 Eeading of 

 Electroscope 



6D 



a 'G 



1 g 



CO g 

 p '5) 



o I 



s * 





Stream of air 1 kq.q 

 very quick 



57-0 



1-0 



30 mins. 



Current not pass- 

 ing through wire 

 (Test Experiment) 



Stream of air 

 very quick 



57-0 



56-2 



0-8 30 „ 



Current passing 

 through wire 



Using small 

 Ley den jars 



56-0 



55-0 



1-0 



30 „ 



>j 



Using large 

 Ley den jars 



58-0 



56-8 



1-2 



30 „ 



>> 



Pressure inside 



apparatus = 4 



em's, of mercury 



54-7 



54-0 



0-7 



30 „ 



>> 



It is thus seen that within the limit of the experimental error 

 there is no extra leak produced by the current through the 



wire. 



But it seemed possible that, even if ionisation took place near 

 the wire, all the ions might have time to recombine before they 

 reached the leaking plates. A new apparatus was therefore con- 

 structed in which the conductivity of the air in the immediate 

 neighbourhood of the wire could be examined. The leaking part 

 now took the form of a wire spiral forming a cylinder round the 

 wire to be tested (Fig. 2 b). This was supported on a con- 

 tinuation (a) of the same stiff wire round which a sulphur cylinder 

 was cast. 



The wire was held in the end of the tube by sealing-wax i, 

 which was carefully treated on the outside to form a good insulat- 

 ing surface. The exterior insulation was therefore of sealing-wax, 

 the interior of sulphur. The end of the wire g could be put in 

 contact with the electroscope used before. The wire through 

 which the discharge passed was fastened (soldered when possible) 

 to the stout copper wires ff x . These were fixed air-tight into 

 small tubes at opposite sides of the bulb I by means of sealing 

 wax. To prevent a leak from the comparatively high potentials 



