I was speaking with my Father about his Army days. Old Army. How old - Horses.

He described horses pulling the caisson, a wagon with ammunition for the artillery pieces. (The caissons go rolling along...)

Why is this also the term for an open bottomed apparatus used for underwater excavation?

Thanx

Well, caisson is from Old French, meaning large box, so I suppose that is why the term came to mean both a structure used underwater and a horse-drawn vehicle used to draw cannon and ammunition. Caisson is also defined as a large box open on one side and the top, designed to fit against the side of a ship and used for underwater repair, as a floating structure used to close off a dock or canal, and as a device used to raise sucken objects. It seems that they are all just big boxes. More on the etymology: the Old French is an alteration of casson, from Italian cassone, augmentative of cassa, box, from Latin capsal.

caisson
n.
5Fr < It cassone < cassa, a chest < L capsa, a box, CASE26
1 a chest for holding ammunition
2 a two-wheeled wagon for transporting ammunition
3 a watertight enclosure inside which underwater construction work can be done
4 a watertight box for raising sunken ships: after the box is sunk and attached, the water is forced out of it so that it floats
5 a hollow, boat-shaped box, used as a floodgate at a dock or basin

For State funerals the coffin is often carried on a caisson usually pulled by horses.

Sparteye: whoa, you go, girl! [impressed]

"and as a device used to raise sucken objects."

Ahhhh. Vampire caissons.

Tim didn't pass on my IM message?

Actually, I don't need any caisson to raise sucken objects.

Caisson disease used to be a serious complication in workers before it was learned that
they had to be slowly decompressed, or bubbles could form in blood and block small
capillaries causing serious nerve damage.

Commonly known as "the bends" because of the sufferer's contortions due to muscle cramps.

the first italian meaning I thought of
the cassa del tesoro = the wooden cointeiner for gold and jewelry (stolen by pirates)
tesoro is treasure

the caissons' used under water,look like barges, that have been turn over. a flat bottomed water tight wooden structure.
it would have a opening, with a stair or ladder shaft.

the top would be weighted with rocks, to sink the caisson, and it would come to rest at the bottom of a river or under water place and workers could climb down the shaft into the caisson.

there was some sort of an air lock -- think about it,if you take a glass, turn it up side down, you can sink it bottom end down, and the air will stay in the glass, but if put in a straw, An opening to the surface, the water will rush in,

caisson did have leaks like this too, and workers risked being drowned as well as the bends.