1 62 NATIONAL ACADEMY OF SCIENCES 



Mining Register, and from that time until 1872 was engaged 

 chiefly in surveys in the South. In the latter year he was 

 appointed Professor of Geology in the School of Mines of the 

 University of Pennsylvania. In the organization of the Towne 

 Scientific School Professor Lesley took great delight and gave 

 much time and thought to his teaching, which was always a 

 favorite work, and aroused enthusiasm in his pupils. 



The crowning event of his life was, however, his appointment 

 to the office of State Geologist of Pennsylvania, which occurred 

 in 1874. The second Geological Survey of Pennsylvania was an 

 undertaking of great magnitude and extended over a period of 

 20 years. Lesley organized it with much care, and had as his 

 assistants Frazer, Stevenson, Prince, Chance, D'Invilliers, Genth, 

 and many other geologists and chemists. To the publication of 

 results he gave the closest personal attention. His system was 

 to publish numerous " reports of progress," each containing all 

 the data relating to a single district or county. More than a 

 hundred such volumes were issued, and at the end a final report 

 summarizing the whole. He had nearly finished this latter work 

 when in 1893 ms health gave way completely, and he was obliged 

 to desist. Sir Archibald Geikie said of the survey in a letter 

 written at this time " It is in my opinion a monument of patient 

 skill, thoughtfully organized, sympathetically carried on, and 

 admirably co-ordinated, through all its branches and all its prog- 

 ress. I think it will be of the utmost value industrially to the 

 State of Pennsylvania." 



Lesley remained some years in Philadelphia, and afterwards 

 returned once more to Milton, Massachusetts, where he died in 

 June, 1903. 



(From MARY LESLEY AMES, " Life and Letters of Peter and Susan Lesley," 

 1909.) 



MIERS FISHER LONGSTRETH 

 Born, March 15, 1819; died, December 27, 1891 



Longstreth was born in Philadelphia in 1819. He was edu- 

 cated in the schools of the Society of Friends, and his early life 

 was spent as a merchant. He devoted his leisure hours, however, 



