Barthélemy Faujas de Saint-Fond (1741-1819) practiced law until 1778, when he left the legal profession to become an assistant naturalist under Louis Jean Marie Daubenton at the Muséum d’Histoire Naturelle. Beginning in 1793, Faujas was professor of geology at the museum. He served on a commission of scholars in the mid-1790s that seized the holdings of museums in countries that had fallen under French control, including the significant natural history collections of the former stadtholder of the Netherlands. Faujas became interested in the study of fossils and in theories of evolution and extinction. From the specimens sequestered in the Low Countries, he composed a monograph on fossils that had been found in chalk mines at Maastricht. He studied casts of prehistoric bison bones sent to Paris by Charles Willson Peale. TJ and Faujas never met while TJ was in France, but a few weeks after he received the letter printed above, TJ wrote a long reply in which he confided that “altho’ my engagements leave me time to read scarcely any thing, yet I could not resist” the volume Faujas had sent. TJ praised Faujas to Peale, Caspar Wistar, James Monroe, and Thomas Mann Randolph, and in a letter to Peale he gave Faujas “first rate eminence in geological things.” TJ purchased a copy of the geologist’s published account of a trip he had made through England, Scotland, and the Hebrides Islands. Faujas’s interpretations of fossil and geological evidence were often at odds with conclusions reached by Georges Cuvier, who had far more skill as an anatomist and scorned Faujas. Recognizing that Faujas’s and Cuvier’s classifications of large prehistoric quadrupeds such as the megalonyx conflicted, TJ refused to take sides, declaring that all systems of zoological classification were artificial (DSB description begins Charles C. Gillispie, ed., Dictionary of Scientific Biography, New York, 1970-80, 16 vols. description ends ; Martin J. S. Rudwick, Bursting the Limits of Time: The Reconstruction of Geohistory in the Age of Revolution [Chicago, 2005], 69-70, 325, 360-1, 371-3, 383-4, 402-3, 445, 499, 502, 558, 563; Richard W. Burkhardt, Jr., The Spirit of System: Lamarck and Evolutionary Biology [Cambridge, Mass., 1977], 33, 117, 129-30, 136-7, 202, 209-10; Robert E. Schofield, “The Science Education of an Enlightened Entrepreneur,” American Studies, 30 [1989], 32-3; Richard W. Burkhardt, Jr., “The Leopard in the Garden: Life in Close Quarters in the Muséum d’Histoire Naturelle,” Isis, 98 [2007], 684; TJ to Monroe, 8 Jan. 1804; to Faujas, 31 Jan. 1804; to Wistar, 27 Mch. 1804, 4 Jan. 1805; to Philippe Reibelt, 24 Dec. 1804; to John Vaughan, 15 Aug. 1805; to Peale, 13 Mch. 1808).

le premier volume de cet ouvrage: for the book he titled Essai de géologie, Faujas drew on his 1802 course of lectures at the Muséum d’Histoire Naturelle. He devoted most of the first volume, which was published in Paris in 1803, to descriptions of fossil remains of animals, some of which he compared to living species. He called the mastodon, which did not yet have that name, an elephant with “dents molaires protubérantes,” referring to the animal’s molar teeth, which had peaks on the chewing surfaces and were different from the teeth of a mammoth or modern elephant. Faujas knew that Peale had assembled a mastodon skeleton in Philadelphia, but the French scientist associated the animal almost exclusively with Big Bone Lick near the Ohio River and cited TJ’s Notes on the State of Virginia as a source of information. Faujas devoted a chapter of his book to the megatherium of South America and the megalonyx discovered in Virginia, which he considered to be the same animal. He called it “le Mégalonix,” using TJ’s name for the Virginia specimen, and rejected Cuvier’s classification, based on the almost complete South American example, of the megatherium as an animal related to sloths, anteaters, and armadillos. Thinking, as TJ had in assessing the megalonyx fossils in 1797, that the animal’s large size and strong claws could mean that it was a fierce beast (“ce fort et terrible animal”), Faujas insisted that it could not yet be affiliated with any living species. Without more information, he thought, it must be treated as its own category—“un grand quadrupède sui generis, … un type original.” The first volume of Faujas’s Essai de géologie was reprinted six years later when the second volume appeared (Barthélemy Faujas de Saint-Fond, Essai de géologie, ou Mémoires pour servir a l’histoire naturelle du globe, 2 vols. in 3 [Paris, 1803, 1809], 1:1, 188-93, 257-66, 273-8, 315-28; Sowerby, description begins E. Millicent Sowerby, comp., Catalogue of the Library of Thomas Jefferson, Washington, D.C., 1952-59, 5 vols. description ends No. 640; Notes, ed. Peden description begins Thomas Jefferson, Notes on the State of Virginia, ed. William Peden, Chapel Hill, 1955 description ends , 43-4; Vol. 29:292-9, 301n; Vol. 38:97n).

Later, Faujas informed TJ that he was delaying the completion of the second volume of the Essai de géologie to incorporate information brought back by the Lewis and Clark expedition. The French scientist apparently thought that the expedition’s discoveries might yield new information about geological topics of interest to him. When it appeared in 1809, the second volume of the Essai dealt exclusively with minerals, volcanoes, and volcanic rock (Faujas de Saint-Fond, Essai de géologie, v. 2, pts. 1-2; TJ to Faujas, 31 Jan. 1804; Faujas to TJ, 15 Oct. 1806, 16 Feb. 1807).