THE INCORPORATORS 161 



On his return to America in 1845, he spent two years in mis- 

 sionary work in Pennsylvania, after which he was invited to assist 

 Professor H. D. Rogers in Boston in preparing a map of 

 Pennsylvania, showing the work of the first geological survey of 

 the State. After a winter spent in Boston, Lesley was for three 

 years pastor of a church in Milton, Massachusetts, at the end of 

 which time, his religious views having undergone a change 

 which made it impossible for him to remain a clergyman, he 

 resigned his parish in May, 1852, and went to Philadelphia. 

 Afterwards he was engaged for a period of about ten years in 

 surveys of iron, coal and oil fields for the Pennsylvania Rail- 

 road and other companies, as well as on his own account. During 

 the summer of 1855, Lesley performed a notable piece of geolog- 

 ical work, consisting of a survey of the Broad Top Mountain 

 region of central Pennsylvania, which included a contour-line 

 map of the semi-bituminous coal-field, " with over eleven thou- 

 sand stations levelled." In 1856, he became Secretary of the 

 American Iron Association, which necessitated his visiting all 

 the iron works of the United States. He published at this time 

 a large volume of statistics of the iron industries, also the " Iron 

 Manufacturers' Guide," and his " Coal Manual." 



In 1858 he was elected librarian of the American Philosophi- 

 cal Society, which position he held for twenty-five years, giving 

 much time and attention to the duties of the office. In 1860 he 

 became interested in a process for the desulphurization of coal, 

 but it was not financially successful, and he confined his energies 

 thereafter to scientific and literary work. In 1862 and 1863 he 

 was engaged in surveying at Glace Bay, on the coast of Cape 

 Breton, and in the latter year made a trip to Europe to study the 

 Bessemer steel process. 



During the season of 1865-66, Lesley delivered a course of 

 lectures before the Lowell Institute in Boston, choosing for his 

 subject " Man's Origin and Destiny." 



Ill health again obliged him to desist from work, and he spent 

 a year in Europe and a winter on the Nile. After his return, 

 in 1869, he became editor of the United States Railroad and 



