WELL, an apartment formed in the middle of a ship's hold to enclose the pumps, from the bottom to the lower deck. It is used as a barrier to preserve those machines from being damaged by the friction or compression of the marlins contained in the hold, and particularly to prevent the entrance of ballast, &c., by which the tubes would presently be choked, and the pumps rendered incapable of service. By means of this enclosure, the artificers may likewise more readily descend into the hold in order to examine the state of the pumps, and repair them as occasion requires.