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Rh forest counties of Pennsylvania, and for three years had charge of a church in Milton, near Boston. There he was married and there he returned to live in his old age. But he was not sufficiently orthodox for the ministry and was fortunately driven back to geology.

In Philadelphia he became a geological and mining expert. He made maps of coal fields for the Pennsylvania Railway and compiled an iron manufacturer's guide. He was for many years secretary and librarian of the American Philosophical Society and in 1872 became professor of geology in the University of Pennsylvania. In 1874 the second geological survey of Pennsylvania was inaugurated and Lesley accepting the directorship carried out the great work of his life, though begun at the age of fifty-five years. The hundred and twenty volumes of the reports of the survey are due to the men he selected for the work, to his constant oversight, and to his careful editing. The work gives him high rank among those who have done most to advance geology in this country.

Lesley's interests were wide, being by no means confined to geology. He himself says in a letter to Professor O. N. Rood "I have done nothing worthy of record in science." He then tells what he believes his services to have been—improvements in certain instruments—the odometer, the measuring divider and the aneroid barometer; the introduction of contour curves in geological field work; and two theories—the determination of the present system of surface drainage by the dimpled form of the plicated original surface and the production of modern topography chiefly by the underground solution of limestone strata.

In 1893 Lesley's health failed and he lived quietly until his death in 1903 at the age of eighty-four years. The photograph which his friends regard as the best is here given, and a reproduction of a portrait painted in the old age of her parents by Mrs. Bush-Brown.

record with regret the deaths of Dr. Friederich Kohlrausch, the eminent