to Electricity and Magnetism. 501 



amount of inductive force expended remains the same ; hence, 

 shice the same quantity of force is exerted in a less time, a 

 greater intensity of action will be produced (57.)? a'ld con- 

 sequently a current of more intensity, but of less duration, 

 will be generated in the secondary conductor. The intensity 

 of the induced currents will, therefore, evidently be expressed 

 by the ratio of the ordinate c B to the abscissa Ac. Or, in 

 more general and definite terms, the intensity of the induc- 

 tive action at any moment of time will be represented by the 

 ratio of the rate of increase of the ordinate to that of the 

 abscissa for that moment*. 



64'. It is evident from the last paragraph, that the greater 

 or less intensity of the inductive action will be immediately 

 presented to the eye, by the greater or less obliquity of the 

 several parts of the curve to the axis. Thus, if the battery be 

 suddenly plunged into the acid for a short distance, and then 

 gradually immersed through the remainder of the depth, the 

 varying action will be exhibited at once by the form of A B, 

 the first part of the curve, fig. 17. The steepness of the part 

 A^ will indicate an intense action for a short time A a, while 

 the part ^ B denotes a more feeble induction during the time 

 represented by a c. In the same way, by drawing u\) the 

 battery suddenly at first, and afterwards slowly, we may pro- 

 duce an inductive action such as would be represented by the 

 parts between C and D of the ending of the curve. 



65. Having thus obtained representations of the different 

 elements of action, we are now prepared to apply these to 

 the phajnomena. And, first, however varied may be the in- 

 tensity of the induction expressed by the different parts of 

 the two ends of the curve, we may immediately infer that a 

 galvanometer, placed in the circuit of the secondary conduc- 

 tor, will be equally affected at the beginning and ending of 

 the primary current ; for, since the deflection of this instru- 

 ment is due to the whole amount of a current, whatever may 

 be its intensity (57.), and since the ordinates c B and C d are 

 equal, which represent the (juantity of induction in the two 

 directions, and, consequently, the amount of the secondary 

 current, therefore the deflection at the beginning and ending 

 of the battery ciu'rent will, in all cases, be equal. This in- 

 ference is in strict accordance with the results of experiment; 



* Accoriling to the differential notntion, tlic intensity will be exj)resscd 



by--^. In some cases the effect may be proportional to the intensity nuil- 

 dx 



ti|)lied by the quantity, and this will be expressed by ~, x anil j/ rei)rc- 

 scnting, as usual, the viiriable abscissa and ordinate. 



