ARTICLE IX. 



Contributions to Etedricity and Magnetism. Btj Joseph Henry ^ Pro- 

 fessor of Natural Philosophy in the College of New Jersey, Prince- 

 ton. 



No. III. — On Electro- Dynamic Induction. Read November 2, 1 838. 



INTRODUCTION. 



1. Since my investigations in reference to the influence of a spiral 

 conductor, in increasing the intensity of a galvanic current, were sub- 

 mitted to the Society, the valuable paper of Dr Faraday, on the same 

 subject, has been published, and also various modifications of the prin- 

 ciple have been made by Sturgeon, Masson, Page and others, to increase 

 the effects. The spiral conductor has likewise been applied by Cav. 

 Antinori to produce a spark by the action of a thermo-electrical pile ; 

 and Mr Watkins has succeeded in exhibiting all the phenomena of 

 hydro-electricity by the same means. Although the principle has 

 been much extended by the researches of Dr Faraday, yet I am happy 

 to state that the results obtained by this distinguished philosopher are 

 not at variance with those given in my paper. 



2. I now offer to the Society a new series of investigations in the 

 same line, which I hope may also be considered of sufficient impor- 

 tance to merit a place in the Transactions. 



3. The primary object of these investigations was to discover, if 



VI. — 4 A 



