148 BIOGRArHICAL MEMOIR OF JOSEPH HENRY. 



dred aud twenty times their own weight, of those which with less than 

 a pint of dihite acid acting on two hands' breadth of zinc would lift 

 seven hundred and fifty pounds, and this afterward carried up to a 

 magnet lifting thirty-three hundred pounds, was simply astonishing. 

 Yet it was not these extraordinary results, nor their mechanical appli- 

 cations, which engaged Professor Henry's attention so much as the 

 prospect they opened of a way by which to ascend to higher discovery 

 of the laws of nature, lii other hands, his discoveries furnished the 

 means by which diamagnetism, magnetic effects on polarized light, and 

 magneto-electricity — now playing so conspicuous a part — soon came to 

 bo knovn. In his own hands, the immediate discovery of the induction 

 of a current in a long wire on itself* led the way to his next fertile field 

 of inquirj', the following up of which caused unwise tardiness in the 

 announcement of what he had already done. For it is within our 

 knowledge that the publication of the paper which initiated his fame 

 had been urged for months by scientific friends, and at length was has- 

 tened by the announcement of some partly similar results reached in a 

 different way by Moll, of Utrecht. In a letter not long afterward writ- 

 ten to one of us, Professor Henry" had occasion to declare : " My whole 

 ambition is to establish for myself a7i(l to deserve the reputation of a man 

 of science." Yet throughout his life ardor for discovery and pure love 

 of knowledge were unattended by corres])onding eagerness for publica- 

 tion. At the close of that very year, 1832, however, he did announce 

 the drawing of a spark from a magnet, that first fact in magneto-elec- 

 tricity, and, as he supposed, a new one. But he had been anticipated. 

 In May, 1830, Professor Henry married his cousin, Harriet L. Alex- 

 ander, of Schenectady, who, with three daughters, survives. Two 

 earlier children died in infancy, and a son in early manhood. 



Pleasant in most respects as his situation at Albany was, it was not 

 an unwelcome invitation which, in the summer of 1832, it became the 

 duty and the privilege of the most venerable of our number, then vice- 

 president of the College of iSlew Jersey, to give to Professor Henry, 

 ofTering him the chair of Natural Philosophy at Princeton. By this early 

 call that college secured him for her own during the years most prolific 

 for science. It was on a later occasion that Sir David Brewster wrote : 

 '• The mantle of Franklin has fallen upon the shoulders of Henrys" 

 But the aureole was already visible to his fellow- workers in science; 



* Aunomxced iu American Journal ol" Scioucc and tlie Arts in 1832. 



