Alexis Marie Rochon (1741–1817), astronomer, inventor, and optician, was born in Brest, France. Trained as a priest, Rochon instead chose scientific pursuits, although he was often referred to as Abbé Rochon. As official astronomer in charge of observing longitude, in 1767 he traveled to Morocco. During the voyage he tested his method for measuring the distance from the stars to the moon. Rochon embarked on an exploratory trip the following year to research the hydrography of the Indian Ocean, during which trip he studied the coasts of Madagascar, the Maldives, Sri Lanka, and the Malabar region. His investigation of rock-crystal specimens found in Madagascar led to his invention of the prismatic micrometer, an instrument attached to a telescope that uses the double refraction property of crystals to measure distances. In 1771 Rochon became a member of the Académie Royale des Sciences, and two years later he became curator of the royal physics cabinet at the Château de la Muette at Passy. Benjamin Franklin later lived nearby and introduced Rochon to the typographic arts, leading Rochon to develop an experimental printing process that TJ described in 1786. A year later Rochon was named astronomer-optician to the French navy, went to Great Britian to announce a French system of weights and measures, and became chief commissary of the French mint. After the French Revolution, Rochon continued to manufacture telescopes and lenses for the navy, pursued his research on optics and fluid-filled lenses, nautical science, and instrumentation, and published extensively on his studies and travels (Hoefer, Nouv. biog. générale description begins J. C. F. Hoefer, Nouvelle biographie générale depuis les temps les plus reculés jusqu’a nos jours, 1852–83, 46 vols. description ends , 42:466–8; Danielle Fauque, “Alexis-Marie Rochon [1741–1817], savant astronome et opticien,” Revue d’Histoire des Sciences 38 [1985]: 3–36; PTJ description begins Julian P. Boyd, Charles T. Cullen, John Catanzariti, Barbara B. Oberg, and others, eds., The Papers of Thomas Jefferson, 1950– , 34 vols. description ends , 7:517, 10:323–4, 325–6).

For Rochon’s work on his voyages, see TJ to William Short, 26 Apr. 1812, and note. His work on matters monetaire may have been Aperçu présenté au Comité des monnoies de l’Assemblée Nationale, Des avantages qui peuvent résulter de la conversion du métal de cloches en Monnoie moulée, pour faciliter l’échange des petit assignats (Paris, 1791; Sowerby, description begins E. Millicent Sowerby, comp., Catalogue of the Library of Thomas Jefferson, 1952–59, 5 vols. description ends no. 3582). Writing from 1732–58 as “Richard Saunders,” Benjamin Franklin published the almanac of Poor Richard (bonhomme richard), whose aphorisms included attacks on flattery.