THE 
AMERICAN GEOLOGIST. 
Vol. XXXII. SEPTEMBER, 1903. No. 3. 
J. PETER LESLEY. 
By Peksifor Frazer. 
PORTRAIT— PLATE XIX. * 
By the death of J. Peter Lesley, the old time type of scien- 
tific man is left almost without a representative. He was born 
in Philadelphia, on Sept. 17th, 1819. After completing his 
studies in the University of Pennsylvania, in 1838, he was ap- 
pointed an assistant of professor Henry D. Rogers, on the 
First Geological Survey of Pennsylvania. Though his serv- 
ices were used in various regions, he was assigned to field 
work, chiefly in the bituminous coal measures, but also in the 
anthracite region. 
On the temporary pause in the prosecution of this Survey 
in 1 84 1, he studied Theology, in the Princeton Seminary, from 
1841 to 1844, interspersing his religious with much secular 
work for the Geological Survey. 
Nature combined in him, an artist and topographer, 
in a degree rarely witnessed, and it was manifest that 
he never could forsake, for an indefinite time, the field in which 
he stood without a rival. By a legitimate use of the imagin- 
ation he transformed many apparently incongruous field notes 
into orderly structure, often revealing new laws of plication, 
which afterwards proved of inestimable value in calculating 
the available mineral treasure in a given area. 
It was no wonder that Henry D. Rogers could not dispense 
with Lesley's services, either while a student at Princeton, or 
later, when the Pennsylvania legislature renewed the appro- 
priation for a final report. In the meantime he had concluded 
his studies and received his license to preach in 1844, upon 
* Sincere thanks are rendered to the Editor of "Mines and Minerals" for 
permission to use this plate which is considered by Prof. Lesley and family 
the best likeness of him. 
