366 PIONEERS OF SCIENCE IN AMERICA. 



with which he tested the radiation of the atmosphere and the 

 clouds. He also made other researches in radiation ; he in- 

 vestigated the expansion of a bar of iron at the moment of 

 magnetization by a galvanic current, and many minor ques- 

 tions. In 1868 he was elected President of the National 

 Academy of Sciences to succeed his friend Prof. Bache, who 

 had died in the preceding year. 



"After an almost uninterrupted period of excellent health 

 for fifty years," to quote his own words, Prof. Henry was 

 attacked early in December, 1^77, with what seemed to be 

 paralysis, but in a few days proved to be nephritis. The dis- 

 ease was already far advanced and steadily progressed, with 

 occasional alternations of more favourable symptoms, to the 

 inevitable result. On May 13, 1878^ calmly and with unim- 

 paired intellect, Joseph Henry passed away. 



Prof. Henry was above the middle height, finely propor- 

 tioned, and of dignified bearing. In his character earnestness 

 was his most conspicuous trait. This was evinced in his pur- 

 suit of knowledge, which was so earnest that he never thought 

 about securing personal glory in connection with it, and had 

 no time for arguing when his hypothesis was assailed. His 

 friends early learned that the way to get him to take any de- 

 sired action was not to point out the honour or other benefit 

 that it would secure for him, but to show that it would promote 

 the interests of science. The same trait explains his intense 

 antipathy to scientific or other hoaxes, and the fact that in 

 working for any desired end he never concealed his purpose. 

 Thus, when he took charge of the Smithsonian he made no 

 secret of his wish to secure important changes in the act of 

 Congress which prescribed its scope, and he worked for this 

 end with the inflexibility of purpose, which was another of his 

 characteristics, until the soundness of his views was acknowl- 

 edged. He was also remarkably considerate of the feelings of 

 others, as was shown conspicuously in his dealings with those 

 who differed from him, and with the visionaries that afflict 

 every one in a conspicuous scientific station. 



Prof. Henry married in May, 1830, Miss Alexander, of 

 Schenectady, the sister of Prof. Alexander, of Princeton, and 

 from the ardent devotion of his wife, and the fraternal sympathy 

 of her brother in his pursuits, he received assistance and support 

 beyond that which usually fall to the lot of men. The most 



