to Electricity and Magnetism. 499 



the explanation of the phaenomena, they may be stated as fol- 

 lows : — ]. During the time a galvanic current is increasing in 

 quantity in a conductor, it induces, or tends to induce, a current 

 in an adjoining parallel conductor in an opposite direction to 

 itself. 2. During the continuance of the primary current in 

 full quantity, no inductive action is exerted. 3. But when 

 the same current begins to decline in quantity, and during 

 the whole time of its diminishing, an induced current is pro- 

 duced in an opposite direction to the induced current at the 

 beginning of the primary current. 



57. In addition to these laws, I must frequently refer to the 

 fact, that "when the same quantity of electricity in a current of 

 short duration is passed through a galvanometer, the deflecting 



force on the needle is the same, whatever be the intensity of the 

 electricity. By intensity is here understood the ratio of a 

 given quantity of force to the time in which it is expended*; 

 and according to this view, the proposition stated is an evi- 

 dent inference from dynamic principles. But it does not rest 

 alone on considerations of this kind, since it has been proved 

 experimentally by Dr. Faraday, in the third series of his re- 

 searches. 



58. In order to form a definite conception of the several 

 conditions of the complex phaenomena which we are about to 

 investigate, I have adopted the method often employed in 

 physical inquiries, of representing the varying elements of 

 action by the different parts of a curve. This artifice has 

 been of much assistance to me in studying the subject, and 

 without the use of it at present, I could scarcely hope to pre- 

 sent my views in an intelligible manner to the Society. 



59. After making these preliminary statements, we will now 

 proceed to consider the several phEenomena ; and, first, let 

 us take the case in which the induction is most obviously 

 produced in accordance with the laws as above stated (56.), 

 namely, by immersing a battery into the acid, and also by 

 withdrawing it from the same. During the time of the de- 

 scent ol the battery into the liquid, the conductor connected 

 with it is constantly receiving additional quantities 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 l)e just in proportion to the corresponding increase 

 in the current of the battery during the same moment. Also, 

 the amount of induction during any moment while the cur- 



• Or more correctly speaking, tlie ratio of two quantities of the same 

 species representing the force and time. 

 2K 2 



