xiv OBITUARY NOTICES OF MEMBERS DECEASED. 



they were to see him no more. The writer, since the early seven- 

 ties when Dr. Barker came to Philadelphia, had enjoyed his friend- 

 ship and kindly appreciation, and his loss has left a gap never to 

 be closed. 



Nevertheless, he survived many of his associates, if only for a 

 short time. In 1891 he headed a committee of five members of the 

 National Academy of Sciences, appointed to report on the Henry 

 Draper Medal, the others besides Dr. Barker being Wolcott Gibbs, 

 Simon Newcomb, and C. A. Young, and Professor A. W. Wright,, 

 who is the only one who now survives. It was when Dr. Barker 

 took the chair of physics in the University of Pennsylvania that 

 the writer first had the privilege of his acquaintance. He was then 

 among the faithful attendants upon the meetings of the American 

 Philosophical Society, of which he became a member in 1873 and 

 later, as is well known, served as an officer of the Society, acting as 

 Secretary from 1877 to 1897, and also as Vice-President, between 

 1899 and 1908. 



The record of the scientific work of Dr. Barker is distinguished 

 by remarkable versatility. Moreover, his temper of mind was such 

 that, while giving full worth to research in so-called pure science,, 

 he did not lose sight of the practical application of scientific prin- 

 ciples as a most important factor in human progress. As a chemist 

 he dealt ably with the purely theoretical side of chemical problems,, 

 yet was an eminent and trusted practical chemist. He "gave a large 

 fraction of his life's work to abstract physical science, but was ever 

 keenly interested in engineering. Nor did he fail in extending this 

 interest to other branches of science besides those which he had 

 made peculiarly his own. We find him observing transits and solar 

 eclipses, and making and recording observations in astronomy with 

 the same ability and enthusiasm which he manifested in chemistry 

 or physics. Even in his later years we find the same acute interest 

 in his studies and work in Roentgen rays and radio-activity. It 

 was also true that at all times he showed for the work of others 

 a generous appreciation and interest, and when such work com- 

 mended itself to him he was not slow in assisting towards its proper 

 recognition. 



As a friend and associate he was held in the highest personal 



