iia 



Several uf the lists, especially Table \'I. show llie effect of the drift 

 of the needle. 



A uumbei- of efforts were made to overcome this dirticulty, none of 

 which were entirely successful. 



One entire day was spent trying to get data for a curve which ^A'ould 

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

 first four readings of Table VII the drift was taken every tivo or six 

 minutes and the succeeding readings were with the I-adium, readings 

 every minute. 



8— A. OF SOIENCK. 



