, or caissoon
An adopted term for a sort of float sunk to a required depth by letting water into it, when it is hauled under the ship's bottom, receives her steadily, and on pumping out the water floats her. These were long used in Holland, afterwards at Venice, and in Russia, where they were known as camels (which see). Caisson is also a vessel fitted with valves, to act instead of gates for a dry dock. Used also in pontoons (which see).