CYLINDER

(Gr. kvXivSoj, I roll ) In Geometry, a solid which may be conceived to be formed by the revolution ofa rectangular parallelogram about one of its sides. The surface of a cylinder, not including the two ends, is equal to the rectangle formed by multiplying the circumference of its base into its altitude; and the >olid content is equal to its altitude multiplied into the area of its base. The cone, the sphere, and the cylinder have a remarkable relation lo each other, first discovered by Arch i me des: namely, that the cone is one-third of the cylinder, having the same base and altitude; and the inscribed sphere two thirds of the cylinder; or the cone, the sphere, and the cylinder are to each other as the numbers 1, 2, and 3. CYLINDROH). (Gr. KvXivSpov, cylinder, and liiof, form.) A solid which differs from a cylinder in having ellipses instead of circles for its ends or bases. CYMa, or [s. 327]