192 



SCIENCE. 



[Vol. IV., No. 83. 



The next ten years were the most active of 

 his life, most of the time being spent in the 

 field. In 1856 he published a "Manual of 

 coal and its topography, illustrated b}' original 

 drawings, chiefly of facts in the geology of 

 the Appalachian region of the United States," 

 and was appointed secretary of the American 

 iron association. In 1859 appeared his " Iron 

 manufacturer's guide to furnaces, forges, and 

 rolling-mills of the United States, with discus- 

 sions of iron as a chemical element, an Amer- 

 ican ore, and a manufactured article, in 

 commerce and in histoiy." Jan. 15, 1858, 

 while examining the iron-works of southern 

 Ohio, Mr. Lesley was elected librarian, and 

 Jan. 7, 1859, one of the four secretaries of the 

 American philosophical societ} T , and continues 

 to hold these offices, which, for the first year or 

 two, withdrew him almost entirely from field- 

 work. From 1860 to 1866 Mr. Lesley was 

 busily employed by capitalists to pronounce 

 upon projected mining-plants, and b} T mine- 

 owners to examine their properties, the call for 

 iron and coal being great on account of the 

 civil war. In 1864 and 1865 serious illnesses, 

 produced by overwork, prepared the wa} r for a 

 complete breakdown of his nervous system in 

 the early summer of 1866, from which he did 

 not recover until the early winter of 1869, this 

 interval of three } r ears and a half being spent 

 mostly in Europe. 



Mr. Lesle}^ went from Italy to the Paris 

 exposition of 1867 as one of the ten commis- 



sioners appointed bjr the United States senate ; 

 but his illness steadily increased, and he was 

 compelled to abandon his duties. Not until 

 1872 could he again do six hours of hard work 

 a day ; and a new career of usefulness was 

 opened to him by his appointment, in that } T ear, 

 to the professorship of geology in the new de- 

 partment of science of the University of Penn- 

 S3'lvania, and in 1873 to the directorship of the 

 Second geological survey of the state, still in 

 progress. For four years (1873-78) he per- 

 formed the duties of both offices, finding his 

 only relaxation in a short voyage to Europe 

 everj^ two years ; but a threatening recurrence 

 of his former malad} 7 induced him to offer his 

 resignation to the trustees of the university, 

 who, however, preferred to grant him an in- 

 definite furlough, until the close of the geologi- 

 cal surve}^. 



With what untiring zeal he has devoted him- 

 self to the work of that survey is only known 

 to those who have been associated with him in 

 the work. How successfully he has conducted 

 it, is shown to the world through the seventy 

 volumes recording its progress. If his hun- 

 dreds of papers, scientific and literary, read 

 before the American philosophical society, had 

 never been published, this great work alone 

 would place him in the front rank of American 

 geologists. Of the personal character of a 

 man whose modesty is his most prominent 

 trait, it is difficult to speak as one would wish 

 during his life. 



AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



PENDING PROBLEMS OF ASTRONOMY. 1 



Thirty-six years ago this very month, in this city, 

 and near the place where we are now assembled, the 

 American association for the advancement of science 

 was organized, and held its first meeting. Now, for 

 the first time, it revisits its honored birthplace. 



Few of those present this evening were, I suppose, 

 in attendance upon that first meeting. Here and 



1 Address to the American association for the advancement 

 of science at Philadelphia, Sept. 5, 1884, by Prof. C. A. Young, 

 professor of astronomy at Princeton, retiring president of the 

 association. 



there, among the members of the association, I see, 

 indeed, the venerable faces of one and another, who, 

 at that time in the flush and vigor of early manhood, 

 participated in its proceedings and discussions; and 

 there are others, who, as boys or youths, looked on 

 in silence, and listening to the words of Agassiz and 

 Peirce, of Bache and Henry, and the Rogers brothers 

 and their associates, drank in that inspiring love of 

 truth and science which ever since has guided and 

 impelled their lives. Probably enough, too, there 

 may be among our hosts in the audience a few who- 

 remember that occasion, and were present as spec- 

 tators. 



