[425] As a naturalist, he was fascinated by the Natural Bridge geological formation, and in 1774 successfully acquired the Bridge by a grant from George III.[426]

American Philosophical Society
Jefferson was a member of the American Philosophical Society for 35 years, beginning in 1780. Through the society he advanced the sciences and Enlightenment ideals, emphasizing that knowledge of science reinforced and extended freedom.[427] His Notes on the State of Virginia was written in part as a contribution to the society.[428] He became the society's third president on March 3, 1797, a few months after he was elected Vice President of the United States.[428][429] In accepting, Jefferson stated: "I feel no qualification for this distinguished post but a sincere zeal for all the objects of our institution and an ardent desire to see knowledge so disseminated through the mass of mankind that it may at length reach even the extremes of society, beggars and kings."[427]
Jefferson served as APS president for the next eighteen years, including through both terms of his presidency.[428] He introduced Meriwether Lewis to the society, where various scientists tutored him in preparation for the Lewis and Clark Expedition.