188 



Transactions. — Miscellaneous. 



The current has here only risen to nine-tenths of its maxi- 

 mum vahie. It was not convenient to have the levers separated 

 by more than twenty turns, so that the whole curve is not com- 

 pletely determined. It has been shown that the throw of the 



fZN 

 galvanometer at any instant is proportional to , : i.e., to 



dc 

 L 3rin the case of a coil of constant inductance L. 

 dt 



A curve can therefore be constructed whose abscissae repre- 

 sent time and ordinates current. The theoretical curve of 



dc 

 rise, calculated from the equation CR = E — L t: , is plotted 



alongside the experimental curve. 



40 





n to tS 30 V 



r/M£ 



The close agreement between the two curves shows that 

 the time-apparatus may be relied on to give very accurate 



