1840] WRITINGS OF JOSEPH HENRY. 171 



of current electricity, and each of these additions produces 

 an inductive action on the adjoining secondary conductor. 

 The amount therefore of induced current produced during 

 any moment of time will be just in proportion to the cor- 

 responding increase in the current of the battery during the 

 same moment. Also, the amount of induction during any 

 moment while the current of the battery is diminishing in 

 quantity will be in proportion to the decrease during the 

 same moment. 



60. The several conditions of this experiment may be 

 represented by the different parts of the curve, A, B, C, D, 

 Fig. 17, in which the distances A a, A b, A c, represent 

 the times during which the battery is descending to different 

 depths into the acid; and the corresponding ordinates, a g, 

 b h, c B, represent the amount of current electricity in the 

 battery conductor corresponding to these times. The differ- 

 ences of the ordinates, namely, a g, m h, n B, express the 

 increase in the quantity of the battery current during the 

 corresponding moments of time represented hy Aa,ab,bc\ 

 and since the inductive action (59) is just in proportion to 

 the increase, the same differences will also represent the 

 amount of induced action exerted on the secondary conductor 

 during the same moments of time. 



rb^ 



Fig. 17. 



61. When the battery is fully immersed in the acid, or 

 when the current in the conductor has reached its state of 

 maximum quantity, and during the time of its remaining 

 constant, no induction is exerted; and this condition is 

 expressed by the constant ordinates of the part of the curve 

 B C, parallel to the axis. Also, the inductive action pro- 

 duced by each diminution of the battery current, while the 

 apparatus is in the progress of being drawn from the acid, 

 will be repi"esented by the differences of the ordinates at the 

 other end, C, D, of the curve. 



