Julius Timoleon Ducatel (1796–1849), scientist and educator, was born in Baltimore and studied at Saint Mary’s College (later Saint Mary’s Seminary and University) in that city before continuing his education in Paris, 1818–22. On his return to the United States he taught successively at the Mechanics’ Institute of Baltimore, the University of Maryland, and Saint John’s College in Annapolis. He provided instruction in chemistry, pharmacy, and geology. In 1832 the Maryland legislature appointed Ducatel to complete geological surveys for a new map of the state. He continued this work until funding ceased in 1841. Ducatel undertook a geological expedition to the upper Mississippi in 1843 and another to the Lake Superior region three years later. Elected to the American Philosophical Society in 1832, his most notable published work was a Manual of Practical Toxicology (1833). Ducatel died in Baltimore (Eugene Fauntleroy Cordell, The Medical Annals of Maryland, 1799–1899 [1903], 383; Memorial Volume of the Centenary of St. Mary’s Seminary of St. Sulpice [1891], 81, 84; APS description begins American Philosophical Society description ends , Minutes, 20 Jan. 1832 [MS in PPAmP]; American Journal of Science and Arts, 2d ser., 8 [1849]: 146–9).