A martial musical instrument in the form of a cylinder, hollow within, and covered at the two ends with vellum, which is stretched or slackened at pleasure, by means of cords with sliding knots. The cylinders are usually made of wood, but sometimes of brass. Kettle-drums are large basons or hemispheres of copper or brass, covered on their flat sides with vellum, which is fastened to the peripheries by circular rims of metal, provided with tightening screws for tuning them; they are usually played upon in pairs, and are chiefly used in the musical bands of cavalry regiments, or in oratorios, operas, etc.
Drum is a term in machinery, applied to cylinders or barrels, around which endless straps, chains or cords, are passed, to communicate motion or power to other mechanism. When cylinders so employed are narrow in the direction of their axes, they are usually denominated pulleys or riggers.