304 



Prof. Richardson and Lieut. Bazzoni on the 



with the field reversed then become of the same order of 

 magnitude as the direct readings. These facts are well 



Fiir. 8. — Radiation in Mercury. 



Mm. in 



30 sec. 



SO 



5 







SO 



5 







30 



20 



60 







30 



20 



10 











V 



200 



mA 



•5 



t 



















/ 



K 







p=A 









/ 



p\ 



s^ 



ten 

























/ 



\ 







3=B> 



A 





( ^ssm 



4 



V 



S 



^ 



















/ 



> 



I 



[ 



>=D> 



C 





,,«—- 



/ 

















































/ 



\ 





f 



>=C> 



B 





p5&as»( 



/ 



1 





V 















1 



N 



sJ 



>.. 





'2 -4r -6 *8 



1*0 1-2 1-4 1-6 



*- Amperes 



Scale for X and v as for tig. (5. 



shown by the curves of fig. 9. Curves A, B, and C were 

 taken in a mixture of hydrogen and mercury vapour which 

 had a pressure of roughly -1 mm. The mean free path 

 under these conditions is about 10 mm., while the distance 

 around from target to cup is about 15 mm. Curves of the 

 type of D were obtained with pressures above *5 mm. The 

 reverse readings are generally about equal to the direct ones 

 under these conditions, so that the curves have no signi- 

 ficance. 



