594 Dr. N. Bohr on the Decrease of 



we see that it is unaltered. If the electrons were free there 

 would thus be no correction to introduce in the calculation 

 due to the effect of the velocity of the ft particle being 

 of the same order as c. If, however, we take the effect 

 of the interatomic forces into account, the problem is a 

 little more complicated. In this case it is necessary to 

 introduce a correction in the expression for p v . In addition 

 the effect of the interatomic forces will involve a certain 

 transfer of energy due to the component of the force parallel 

 to the path of the ft particle ; this is due to a sort of re- 

 sonance effect which comes into play when the "time of 

 collision " is of the same order of magnitude as the time of 

 vibration of the electrons. 



In the former paper it was shown that the contribution to 

 AT due to the component parallel to the path is given by* 



From (17) it therefore follows that the contribution to AT], 

 due to the component perpendicular to the path of the 

 ft particle, is given by 



Y=A]T-Z= mV2 2(log( w )-!)• 



If we now in the expression for Y replace V and E by 7V 

 and 7E, and in the expression for Z replace Y by 7Y but 

 leave E unaltered, we get, by adding the two expressions 

 together and substituting for 7, the following corrected 

 formula for A,T : 



aiT . |lf ™ f i [ , og( ™A i) _ log(l _V. ) _,. ] 



* L p. 17. The expression deduced in this paper was 

 where 



JO X V / JO (l+g*Vt 



L formed part ot a complicated expression, used in determining p v and 

 evaluated by numerical calculation. The value of L, however, can be 

 simply obtained by noticing that 



f'(x)-\f(x)-f(x) = 0. 

 This gives 



L= £>(*)(/''(*)-/<*))<&= 1 [ (f(x))' -(/(*))']. 

 Now/(0) = 1 and/'(0)=/(oo)=./'(oo) = 0; consequently L = ±. 



