Pon-ton′.
1. (Military Engineering.) A bateau of wood or metal, or a light framework covered with water-proof material, used as a float for supporting a temporary bridge. Pontoon. In the United States Engineer Service they are made of wood. Corrugated metal and rubber have also been employed. The British service employs either Colonel Blanchard's or Colonel Pasley's pontons. The former are cylindrical and are made of tin-plate; they have hemispherical ends, and are divided into compartments by longitudinal and transverse partitions, which serve as braces. Pasley's consist of a light timber frame covered with copper; they are transversely divided into two halves, which are united by lashings for use and separated for transportation. Each half is also divided into compartments. The whole forms a decked canoe adapted for rowing. See Ponton-bridge.
2. (Nautical.) a. A barge or lighter of large capacity, used in careening ships, raising weights, [1764] drawing piles, etc., or capable, in pairs, of acting as camels. See camel. b. A barge or flat-bottomed vessel furnished with cranes, capstans, and hoisting tackle, used in wrecking, in connection with a diving-bell, or in raising submerged vessels.
3. (Hydraulic Engineering.) a. A water-tight structure or frame covered with water-resisting material placed beneath a submerged vessel and then filled with air to assist in refloating the vessel. b. A water-tight structure which is sunk by filling with water, and raised by pumping it out, used to close a sluiceway or entrance to a dock. It works in grooves in the dock walls, and acts as a lock-gate. See Plate XIX. page 884.
