caisson

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A watertight structure within which construction work is carried on under water.
2. n. See camel.
3. n. A large box open at the top and one side, designed to fit against the side of a ship and used to repair damaged hulls under water.
4. n. A floating structure used to close off the entrance to a dock or canal lock.
5. n. A horse-drawn vehicle, usually two-wheeled, used to carry artillery ammunition and coffins at military funerals.
6. n. A large box used to hold ammunition.

Century Dictionary and Cyclopedia

1. n. Milit.: A wooden chest into which several bombs are put, and sometimes gunpowder, to be exploded in the way of an enemy or under some work of which he has gained possession.
2. n. An ammunition-wagon; also, an ammunition-chest.
3. n. In architecture, a sunken panel in a coffered ceiling or in the soffit of Roman or Renaissance architecture, etc.; a coffer; a lacunar. See cut under coffer.
4. n. In civil engineering: A vessel in the form of boat, used as a flood-gate in docks.
5. n. An apparatus on which vessels may be raised and floated; especially, a kind of floating dock, which may be sunk and floated under a vessel's keel, used for docking vessels at their moorings, without removing stores or masts. (See floating dock, under dock.)
6. n. A water-tight box or casing used in founding and building structures in water too deep for a coffer-dam, such as piers of bridges, quays, etc. The caisson is built upon land, and then chained and anchored directly over the bed, which has been leveled or piled to receive it. The masonry is built upon the bottom of the caisson, which is of heavy timber. As the caisson sinks with the weight, its sides are built up, so that the upper edge is always above water. In some cases the masonry is at first built hollow, and is not filled in until after it has reached its bed, and its sides have been carried higher than the surface of the water. Sometimes the sides of the masonry itself form the sides of the caisson. In another form the caisson, made of heavy timbers, is shaped like an inverted shallow box, having sharp, iron-bound edges. The weight of the masonry forces the caisson into the sand and mud on the bottom. Air under pressure is then forced into the caisson, driving out the water and permitting the workmen to enter through suitable air-locks. A sealed well or a pipe and sand-pump are provided, through which the material excavated under the caisson may be removed. The latter gradually sinks under the weight of the superstructure and the removal of the loose soil below, until a firm foundation is reached, when the whole interior of it is filled with concrete. The caissons beneath the towers of the East River suspension-bridge, connecting New York and Brooklyn, are of this description. The pneumatic caisson is an inverted air-tight box, into which air is forced under a pressure sufficient to expel the water, thus leaving a space in which men can work to loosen the soil as the caisson descends. The principle of the pneumatic caisson is applied to the sinking of large iron cylinders to serve as piers or land-shafts. Sometimes written caissoon.

Wiktionary

1. n. engineering An enclosure, from which water can be expelled, in order to give access to underwater areas for engineering works etc.
2. n. The gate across the entrance to a dry dock.
3. n. nautical A floating tank that can be submerged, attached to an underwater object and then pumped out to lift the object by buoyancy; a camel.
4. n. military A two-wheeled, horse-drawn military vehicle used to carry ammunition (and a coffin at funerals).
5. n. military A large box to hold ammunition.
6. n. architecture A variant of coffer.

GNU Webster's 1913

1. n. A chest to hold ammunition.
2. n. A four-wheeled carriage for conveying ammunition, consisting of two parts, a body and a limber. In light field batteries there is one caisson to each piece, having two ammunition boxes on the body, and one on the limber.
3. n. A chest filled with explosive materials, to be laid in the way of an enemy and exploded on his approach.
4. n. A water-tight box, of timber or iron within which work is carried on in building foundations or structures below the water level.
5. n. A hollow floating box, usually of iron, which serves to close the entrances of docks and basins.
6. n. A structure, usually with an air chamber, placed beneath a vessel to lift or float it.
7. n. (Arch.) A sunk panel of ceilings or soffits.

WordNet 3.0

1. n. large watertight chamber used for construction under water
2. n. an ornamental sunken panel in a ceiling or dome
3. n. a chest to hold ammunition
4. n. a two-wheeled military vehicle carrying artillery ammunition