196 



PROCEEDINGS OP THE AMERICAN ACADEMY 



Several tables follow, containing results which seem to warrant the 

 statements with which the paper commences. 



In these tables, column A gives the number of the experiment ia 

 the series, i? contains the observed galvanometer deflections when 

 the magnet was inactive ; C, deflections when the magnet was excited. 

 Z> and U contain averages of the groups given in B and C. At the 

 foot of the table is given the general average, and the deduced per- 

 centage variation. 



Table I. Magnetic force perpendicular to the plates of the con- 

 denser. Two condensers used, each consisting of 11 disks of copper 

 8 cm. in diameter, with plates of mica between them. In this series the 

 condenser which had the greatest normal capacity was placed between 

 the poles of the magnet. An increase in the differential deflection of the 

 needle when the magnet was excited indicates an increase of capacity 

 in this condenser. 



TABLE I. 



TABLE IL 



Table II. Exchanged the places of the condensers used in Table I., 

 the smaller of the two being now placed between the poles of the 

 magnet. Direction of the magnetic force as in Table I. In this series 

 a diminished differential deflection of the needle with the excitement 

 of the magnet shows an increase of capacity in the condenser between 

 the poles. 



