French mathematician who specialized in celestial mechanics (1811–1877) best known for his part in the discovery of Neptune. ALS in French, signed “Ub Le Verrier,” one page, 5.25 x 7.25, Observatoire Imperial letterhead, June 18, 1851. Untranslated letter to an unidentified gentleman. In very good condition, with scattered toning. RRAuction COA.