Cleaning the Bottoms of Iron ships.
--The expense and inconvenience which attend the taking out of ships on every occasion when the bottom becomes foul, gives value to any contrivance by which the process of cleaning can be performed while the vessel is afloat, in harbor or at sea. The apparatus which has lately been brought forward to meet the want so long felt, consists of eight rectangular pieces of cork wood, eighteen inches long, ten inches wide, and seven inches deep. Each of these corks is covered with a board, fastened with iron bands, on the top of which are fixed nine knives, which move, six parallel and three at right angles, while the machine is in motion. The boxes are hauled under the ship's keel, and are worked by five or six men. By this means a vessel whose keel is one hundred and eighteen feet can be thoroughly cleaned of barnacles in half a day. The apparatus has been practically tasted in Amsterdam, and found to work well. By the use of mechanical power, it could, no doubt, be rendered more effective.
