486 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



to give a throw of 13.7 cms. per micro-coulomb of charge. The "free 

 charge " capacities of the condensers are approximately as follows : 



Air 



" Par. A " 

 " Par. B " 

 " Par. C " 



"Mica Bo" 



0.0428 mf. 

 0.041 " 

 0.040 " 

 0.047 " 

 0.043 " 



TABLE X. 



