Tome, a N. E. department of France, formed from parts of Burgundy, Champagne, and Orléanais, bordering on the departments of Seineet-Marne, Aube, Côte-d'Or, Niévre, and Loiret; area, 2,868 sq. m.; pop. in 1872, 363,608. It takes its name from the river Yonne (anc. Icauna), which rises in the E. part of Nievre, flows N. through the middle of Yonne, and joins the Seine at Montereau in the S. part of Seine-et-Marne, after a course of about 170 m. It is navigable as high as Auxerre. Its affluents in the department include the Cure, Armancon, and Vannes. The Burgundian canal runs through the E. part. The surface is undulating and the soil excellent. The department is rich in cattle, horses, sheep, grain, and hemp. The chief exports are red and white wines, timber, and coal. Iron, lithographic stones, and ochre are the principal mineral products, and woollen and cotton goods, beet sugar, and glass are manufactured. Yonne is divided into the arrondissements of Auxerre, Avallon, Joigny, Sens, and Tonnerre. Capital, Auxerre.