WINDSAIL

This machine is usually extended by large hoops situated in different parts of its heighth. It is set down perpendicularly through the hatches, being expanded at the lower end like the base of a cone; and having its upper part open on the side which is placed to windward, so as to receive the full current of the wind; which, entering the cavity, fills the tube, and rushes downwards into the lower regions of the ship. There are generally three or four of these in our capital ships of war, which, together with the ventilators, contribute greatly to preserve the health of the crew.

Reference Works