cais·son (ka’son), n. 1. a box for ammunition. 2. a wagon to carry ammunition, especially artillery shells. 3. a watertight box or chamber in which men can work under water, as in laying foundations. It has an open bottom, the water being kept out by the high air pressure maintained within it. 4. a watertight float used in raising sunken ships: Huge steel tubes, or caissons, drop to the ocean floor and the powerful air jacks raise the hull above the water surface (Wall Street Journal). 5. a vessel in the form of a boat used as a floodgate in dikes. 6. Architecture. a coffer. [<French caisson or casson < Italian cassone < cassa < Latin capsa]
~ The World Book Dictionary
1. A box for ammunition. 2. A wagon to carry ammunition, especially artillery shells.
The word caisson comes to English from the French, in which it meant a large wooden chest, in the 18th century. It first applied to a chest holding ammunition and bombs, and was extended to apply to the wagon that carried the cases. The Oxford English Dictionary (OED) cites the word’s appearance in English as of 1704.
In the U.S. Army, the “Caisson Platoon” is the nickname for the 3rd U.S. Infantry Regiment, the oldest active regiment in the Army. Today, most people know them as The Old Guard. They are the unit assigned to defend the capital region in a case of emergency, though they also serve overseas. The Old Guard still pulls caissons, but today’s horse-drawn caissons do not pull ammunition cases, instead they bring flag-draped coffins to their final resting place in Arlington National Cemetery. (The Old Guard site has more information and additional information on their caisson horse adoption program.)
3. a watertight box or chamber in which men can work under water, as in laying foundations. It has an open bottom, the water being kept out by the high air pressure maintained within it.
The architectural caisson is in use in English as early as 1753 to build piers and bridges, such as the Blackfriars bridge in the London river, the Thames (OED). The chamber is watertight–as an ammunition box must also have been–and an air pocket is created in it while it is lowered to the river floor so that a foundation can be dug and laid.
The most famous use of architectural caissons in the United States is in the making of the Brooklyn Bridge, which crosses the East River in New York City. The famous German-American engineer, John Augustus Roebling, the inventor of the wire-ropes used in his suspension bridges, designed the Brooklyn Bridge. It would be his last project as he would die from tetanus contracted during the building from a freak accident that crushed his foot. His son, Washington A. Roebling, would complete project, but it would steal his health. It was in the building of the Brooklyn Bridge, that “caisson disease“, also known as “the bends” was first seen. Today, we know more about decompression sickness, which was caused by the caissons rising too rapidly. Suffering from this illness, Roebling would see the project finished from his bed and his wife would take an active role in its completion acting as an intermediary with the foremen at the site. (Primary references are the Library of Congress, http://memory.loc.gov/ammem/today/jun12.html; and PBS–this film being my first introduction to the Brooklyn Bridge and the concepts of caissons in construction–http://www.pbs.org/kenburns/brooklynbridge/.)
4. a watertight float used in raising sunken ships: Huge steel tubes, or caissons, drop to the ocean floor and the powerful air jacks raise the hull above the water surface (Wall Street Journal).
Raising ships with a caisson is an evolving technology. According to the U.S. Navy’s website of the Nomenclature of Naval Vessels, a caisson is the following:
CAISSON — A watertight structure used for raising sunken vessels by means of compressed air. Also the floating gate to close the entrance to a drydock.
During the attack on Pearl Harbor on December 7, 1941, the USS West Virginia was sunk by seven torpedoes and two bombs. Through the efforts of the crew, it avoided the fate of the USS Oklahoma which capsized, and sunk to the ocean’s floor on its hull. On May 17, 1942, the USS West Virginia was pumped with air, raised and taken to the Puget Sound in Washington and repaired so it could be returned to duty. 70 bodies were found by repairmen, including a calendar kept by men who were trapped below decks in the sinking; the last day scratched off was December 23. (The ship’s history has been collected and digitized at http://www.usswestvirginia.org/uss_west_virginia_history.htm.)
Another, more famous instance of the U.S. Navy raising a ship was the USS Maine. Believed to be sunk by Spanish mines near Cuba, and thus igniting the Spanish-American War, the U.S. Navy raised it from the shallow waters of Havana Harbor and sunk in deeper waters. The New York Times reported on July 6, 1911, that on the previous day the great caisson was in place around the USS Maine and the delays experienced previously were due to the debris and the need to pump mud out. (It was also found that the explosion that sunk the Maine was caused by an internal incident–not a Spanish mine.)
5. a vessel in the form of a boat used as a floodgate in dikes.
We again see an example of these in WWII, when Churchill commissions the building of pontoon bridges that were used later in the war and eventually employed to plug in dykes in the Netherlands:
Winston Churchill in 1942 orders the design of an artificial stand-in harbor on a stormy deep sea coast, able to receive ships and discharge material of the allies on an Atlantic coast…
In total 212 of these Phoenix caissons are being constructed for the purpose of the Mulberry harbours in Normandy. Of those 212 a number stayed behind in England because they were no longer required in France in 1944. These have been used in a later stage after the war in order to close openings in the dykes amongst others in Walcheren near Rithem where two of them still can be distinguished as they raise out of the sand (beetles), as floats of a pontoon bridge…
A great word for some fun historical exploration! Use it this week in a sentence!