18 CONTRIBUTIONS TO ELECTRICITY AND MAGNETISM. 



or from a battery current, and that produced by the movement up and down 

 of a battery in the acid, are of the nature of the first mentioned part, while the 

 currents of the third, fourth, and fifth orders partake almost exclusively of the 

 properties of the second part. 



53. The principal facts and conclusions of this section were announced to 

 the Society in October, 1839, and again presented in the form in which they 

 are here detailed in June last. Since then, however, I have had leisure to ex- 

 amine the subject more attentively, and after a careful comparison of these re- 

 sults with those before given, I have obtained the more definite views of the 

 phenomena which are given in the next section. 



Section III. 



Tfiecyretical Considerations relating to the Phenomena described in this and the 

 preceding Communications. Read November 20, 1840. 



54. The experiments given in the last No. of my contributions were merely 

 arranged under different heads, and only such inferences drawn from them as 

 could be immediately deduced without reference to a general explanation. The 

 addition, however, which I have since made to the number of facts, affords the 

 means of a wider generalization ; and after an attentive consideration of all the 

 results given in this and the preceding papers, I have come to the conclusion 

 that they can all be referred to the simple laws of the induction at the begin- 

 ning and the ending of a galvanic current. 



55. In the course of these investigations the limited hypotheses which I have 

 adopted have been continually modified by the development of new facts, and 

 therefore my present views, with the farther extension of the subject, may also 

 require important corrections. But I am induced to believe, from its exact ac- 

 cordance with all the facts, so far as they have been compared, that if the ex- 

 planation I now venture to give be not absolutely true, it is so, at least, in ap- 

 proximation, and will therefore be of some importance in the way of suggesting 



