808 Prof. H. A. Rowland on the Ratio of the Electrostatic 



of this quantity in an ordinary building *, and also because a 

 damping magnet, reducing the earth's field to about one third 

 its normal value, was used. For this purpose the ballistic 

 galvanometer was set up inside the large circle of 80 centim. 

 diameter with one turn of wire, and simultaneous readings of 

 the electrodynamometer and needle of ballistic galvanometer 

 were made. 



Theory of Experiment. 

 We have for the potential 



•00021 



Y = ed\/w\l + 



d J 



For the magnetic intensity acting on the needle, 



tj_ 2irnr 2 c x/K Vsin ct 

 *(r 2 + 6 2 )Uan<£ ' 



For the condenser charge, 





Whence 



eGCV m s/wd 



v— 



sin^ L * J 



2nc \/K(r 2 + b 2 y T VST^ 2,. 

 buf 



and 



2smi0 = | D [l-J( s )]nearly. 



So that, finally, 



eGCV m^x/w <* A „ „ „ 



2nc VK(r + 67 1 v sin « o L J 



A = ; -0011 ; '0030 ;;0056; -0090 for 1, 2, 3, 4, 5 dis- 

 charges as investigated below. 





* This experiment was completed before the new physical laboratory 

 was finished. 



