ON ELECTRO-DYNAMIC INDUCTION. 19 



new forms of experiment, or as a first step towards a more perfect generali- 

 zation. 



56. To render the laws of induction at the beginning and the ending of a 

 galvanic current more readily applicable to the explanation of the phenomena, 

 they may be stated as follows: — 1. During the time a galvanic current is in- 

 creasing 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 produced 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, rohatever he the in- 

 tensity of the electricity. By intensity is here understood the numerical 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 evident inference from dynamic prin- 

 ciples. 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 phenomena which we are about to investigate, I have adopted the 

 method often employed in physical inquiries, of representing the varying ele- 

 ments 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 present my views in an intelligible manner 

 to the Society, 



59. After making these preliminary statements, we will now proceed to con- 

 sider the several phenomena; and, first, let us take the case in which the in- 

 duction is most obviously produced in accordance with the laws as above 

 stated, (56,) namely, by immersing a battery into the acid, and also by with- 

 drawing it from the same. During the time of the descent of 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 indue- 



