EEPOET 



RECENT PEOGRESS IN PHYSICS. 



BY Dr. JOEl. MULLER, 



PROFESSOR 0? PHYSICS AND TECHflOLOGY i;« TUE DNIVERSITY OF FEEIBCRQ. 



[Translated from the German for the Smithsonian Institution.! 



In revising this translation, originally made by different persons, 

 it lias been the constant aim to give as nearly and as literally as pos- 

 sible the exact language of the author. But one exception has been 

 made to this rule. In the case of the citation of English philosophers 

 reference has been made to the original memoirs, and their own lan- 

 guage adopted, instead of that of the report, wherever it was evident 

 that the intention had been to give the equivalent German to their 

 English. It is due to the author, however, to state that this change 

 has been at most but a verbal one, not material to the sense. The 

 notice is, however, deemed necessary, because this is the only departure, 

 save in one or two unimportant cases, from the strict rendering of the 

 language of the text. 



GEORGE C. SCHAEFFER. 



SECTION THIRD. 

 THE LEYDEN JAR AND EFFECTS OP THE DISCHARGE. 

 [Continued from page 456, of the Report of 1856.] 

 . THE SECONDARY CURRENT. 



§ 56. Nature of the secondary current. — When a battery is dis- 

 jcharged by a long metallic wire the current in the conducting circuit 

 ■ wire induces a current in an adjoining closed wire conductor. 



The wire which forms the conducting circuit of the battery is known 

 as the main ivire. 



The wire in which a cifrrent is induced by the action of the current 

 in the main wire is termed the secondary loire. 



[The existence of the secondary current was demonstrated in a series 

 of experiments by Professor Joseph Henry in 1838, published in the 

 jTransactioQs of the American Philosophical i?ociety," vol. 6, p. 40, 

 in 1839, a publication apparently unknown to our author. 



