180 Mr Campbell, The study of discontinuous phenomena. 



mean fluctuations by means of an approximate value of the 

 electronic charge. (It may be noted that it might be possible 

 to use some other form of high resistance, but probably all 

 conductivity is ultimately discontinuous and we know far more 

 about the conductivity of a gas than about that of a solid or 

 liquid.) 



Secondly, there is a source of error in the fluctuations of other 

 parts of the apparatus during the period of observation: the cells 

 used for maintaining the potential are the most likely source of 

 trouble on this account. Perhaps such errors might be estimated 

 and eliminated by means of carefully devised 'blank' experiments. 



Meyer and Regener seem to suggest that an error may be 

 introduced by the finitude of the time required for a charge 

 received by the electrode system to attain a steady distribution 

 on that system. But it can be shown readily by a little arithmetic 

 that error from this source is negligible. The error could only 

 enter by fluctuations of the electrometer due to the vibration of 

 the charge about its final position. Now, if R is the resistance 

 of the vibrating circuit (in ohms), L its self-inductance (in henries), 

 G its capacity (in farads), the period of vibration of the charge is 



47ri 





R' 



Now taking the values of R, L, G, v/hich will give the greatest 

 possible value for the period, we may put R = l, G— 10~^ L = 10~" 

 (rememberiog that the self-inductance in henries of a solenoid 

 of 100 turns and 1 cm,^ area is lO"*^). Then the period is about 

 10~^ seconds. Now in the experiments of Geiger and Meyer and 

 Regener the number of a particles coming off per second was 

 never greater than 10": hence the period of oscillation of the 

 charge is small not only compared with that of the instrument, 

 but also with the average interval between two charges. 



I 12. It may be desirable to comment upon the work of 

 Meyer and Regener in the light of the considerations which 

 have been advanced. 



Meyer and Regener did not make use of the actual theory 

 which has been elaborated, but they made use of its principle. 

 They assumed that A^ was proportional to IjN and that the 

 factor of proportionality depended on the instrumental constants 

 only: this assumption, as we have seen, is justified. Accordingly 

 they were justified in their expectation that, if the same instru- 

 mental arrangements are used throughout, A^ should be pro- 

 portional to IjN for diiferent values of N. Since they only took 

 some 100 observations of A^ they could only hope for an agreement 



