THE 



AMERICAN 

 URNAL OF SCIENCE, &c. 



Art. I. — Co7itrihutions to Electricity and Magnetism. On 

 Electro- Dyiiamic Induction ; by Joseph Henry, Professor of 

 Natural Philosophy in the College of New Jersey, Princeton. 

 Read November 3, 1838.* 



INTRODUCTION. 



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

 spiral conductor, in increasing the intensity of a galvanic current, 

 were submitted to the Society, the valuable paper of Dr. Faraday, 

 on the same subject, has been published, and also various modifi- 

 cations of the principle have been made by Sturgeon, Masson, 

 Page and others, to increase the effects. The spiral conductor 

 has likewise been applied by Cav. Antonori to produce a spark by 

 the action of a thermo-electrical pile ; and Mr. Watkins has suc- 

 ceeded in exhibiting all the phenomena of hydro-electricity by 

 the same means. Although the principle has been much exten- 

 ded 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 

 importance to merit a place in the Transactions. 



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

 if possible, inductive actions in common electricity analogous to 



* From the Transactions of the American Philosophical Society, Vol. 6. N. S. 

 Vol. xxxvin, No. 2.— Jan.-March, 1840. 27 



