Physics 527 



portance, and time has served only to magnify the value of 

 Henry's discovery. Learning of Faraday's experiments, he 

 was led, through their verification, to discover induction by 

 induced currents, concerning which he made a most interest- 

 ing and valuable investigation. Of his many other important 

 discoveries in electricity there is one that must not be passed 

 without mention. It was, that the discharge of a Leyden jar 

 was oscillatory in character, in which he anticipated Helm- 

 holtz and Lord Kelvin in the recognition of a phenomenon 

 which has, within a very few years, come to have a deep im- 

 port. The present estimate of the value of Henry's work in 

 electricity is reflected in the following remarks, made not long 

 ago by one of England's leading electricians: "At the head 

 of this long line of illustrious investigators stand the names 

 of Faraday and Henry. On the foundation-stones of truth 

 laid down by them all subsequent builders have been content 

 to rest. ... In them [the scientific writings of Henry] we 

 have not only the lucid explanations of the discoverer, but 

 the suggestions and ideas of a most profound and inventive 

 mind, and which indicate that Henry had early touched levels 

 of discovery only just recently becoming fully worked." 



Most of Henry's electrical investigations were carried on at 

 Albany, and afterward at Princeton, whither he was called, in 

 1832, as professor of natural philosophy in the College of 

 New Jersey. From Princeton he removed to Washington in 

 1846, to become first Secretary of the Smithsonian Insti- 

 tution, then just established. During his more than thirty 

 years of service in this capacity, administrative duties pre- 

 vented, in a large measure, a continuation of the scientific 

 investigations for which he was now famous, but they did not 

 diminish his interest in research, nor prevent his doing a 

 good deal of it during the remainder of his life. It must be 

 admitted, however, that he was no longer master of his own 



