113 



Several of the lists, especially Table VI, show the effect of the drift 

 of I lie needle. 



A number of efforts were made to overcome this difficulty, none of 

 which were entirely successful. 



One entire day was spent trying to get data for a curve which would 

 show the influence of this ever present but very variable factor. In the 

 first four readings of Table VII the drii'l was taken every five or six 

 minutes and the succeeding readings were with the radium, readings 

 every minute. 



8— A. or Science. 



