THE subject of this sketch, Professor J. P. Lesley, this year President of the American Association for the Advancement of Science, was born in Philadelphia, September 17, 1819. He is of Scotch extraction, his grandfather, Peter Lesley, having emigrated from Aberdeenshire in Scotland. From his sixth to his twelfth year he was under the instruction of William Tucker, and showed a marked predilection for mathematics and geography. His father, a cabinet-maker, was an accurate draughtsman and an intelligent lover of architecture, and that he was in advance of his age in the matter of education is shown by the fact that he placed the pencil in his children's hands before they could write, and daily exercised them during the dinner-hour in the precise use of language for describing places and things, while obliging them to test the accuracy of their descriptions by drawings and sketches, which he mercilessly criticised. A good foundation was thus laid for those logical, linguistic, and artistic pursuits which young Lesley followed up throughout his academical years, and at the University of Pennsylvania, from which he graduated in 1838. The acquisition of French and German, music, painting, and the construction of toy machinery of all kinds in his father's workshop, were his recreations out of school-hours, and led him afterward into the ardent study of the classical and Oriental languages, and finally to that of the Egyptian hieroglyphics, those fossils of comparative philology, while occupied with the mechanical problems of geology, to which subject his life has been mainly devoted. From 1839 to 1841 Mr. Lesley was engaged on the Geological Survey of the State of Pennsylvania, under Professor Henry D. Rogers. Early interested in religious subjects, in the autumn of 1841 he entered the theological seminary at Princeton, New Jersey, and in 1844 was licensed as a minister by the Presbytery of Philadelphia. He devoted himself for a year or two to religious teaching among the German population of Pennsylvania, and in 1847 became the regular pastor of a Congregational church in Milton, Massachusetts; but his theological views soon underwent such expansion that he left the pulpit and settled in Philadelphia, to devote himself to work in the field of science. He was married, in 1849, to Miss Susan Lyman, of Northampton, Massachusetts.
In the spring of 1844 he sailed for Europe, and walked with knap-sack and blouse through the western and southern provinces of France, through Savoy, Switzerland, and Germany to Halle, where he attended the lectures of Tholuck, Erdmann, Leo, and Ulrici, and returned home in the spring of 1845. In 1863 he was sent by the President of the Pennsylvania Railroad to examine the methods of hardening the surface of rails, and to report on the success of Bessemer's invention. In