TRANSACTIONS 



OF 



THE AMERICAN PHILOSOPHICAL SOCIETY. 



ARTICLE I. 



Contributions to Electricity and Magnetism. By Joseph Henry, LL. D. Pro- 

 fessor of Natural Philosophy in the College of Nero Jersey, Princeton. Read 

 June 19, 1840. 



No. IV. — On Electro-Dynamic Induction. {Continued.) 



INTRODUCTION. 



1. In the course of my last paper, it was stated that the investigations which 

 it detailed were not as complete in some parts as I could wish, and that I hoped 

 to develope them more fully in another communication. After considerable 

 delay, occasioned by alterations in the rooms of the physical department of 

 the college, I was enabled to resume my researches, and since then I have been 

 so fortunate as to discover a series of new facts belonging to different parts of 

 the general subject of my contributions. These I have announced to the 

 Society at different times, as they were discovered, and I now purpose to 

 select from the whole such portions as relate particularly to the principal 



VIII. — A 



