The death of William Maclure[1] on the 23d of March, 1840, inflicted on the society the greatest loss it had yet sustained. In addition to his large pecuniary contributions, he had given in 1835 a selection from his library in New Harmony. The transfer of the collection, amounting to 2,259 volumes and an extensive series of maps and charts, had been safely accomplished by Charles Pickering, the distinguished author of the Chronological History of Plants, who was Librarian of the Academy from 1829 to 1833. He had also conducted the transfer and arrangement of a great number of plants bequeathed by the Rev. Lewis David von Schweinitz, who died in 1834.
Mr. Maclure was succeeded in the Presidency by William Hembel[2] who had been elected a member in 1825. He held the office from December, 1840, until December, 1849. His administration was uneventful. In the hope of being able to remedy impaired hearing resulting from an attack of scarlet fever he had studied medicine in the University of Pennsylvania but did not graduate.
Dr. Morton announced to the meeting held June 16, 1840, that a bill for the perpetual exemption of the property of the Academy from taxation had passed both houses of the Legislature.
The first annual election in the new building at Broad and Sansom Streets resulted as follows: President, William Hembel; Vice-Presidents, John Price Wetherill, Samuel Geo. Morton, M.D.; Corresponding Secretary, Eobert Bridges, M.D.; Recording Secretary, A. Denman Chaloner, M.D.; Librarian, A. L. Elwyn, M.D.; Curators, William S. Vaux, John S. Phillips, Eobert Pearsall, George C. Leib, M.D.
In March, 1841, the publication of the Proceedings was commenced. The sessions of the Academy were then and until May, 1903, held every Tuesday evening throughout the year. A most important event in the history of the society was the election to membership on July 29, 1845, of Dr. Joseph Leidy. He published the first of a brilliant series of contributions to natural history in the Proceedings a couple of months later and for the succeeding forty-six years he exerted a most active influence on the well-being of the institution in every department of its administration until, to the community at large, the names of Leidy and the Academy were inseparably associated.
