windsail

Definitions

1. A wide tube or funnel of canvas, used to convey a stream of air for ventilation into the lower compartments of a vessel.
2. The sail or vane of a windmill.

Examples

“We were ventilated by a big canvas windsail, opening between the fore and main masts, and running down into the hold⟳.”

“The dome in turning carries with it the windsails, M N, and their axle, P Q ; and thus the latter may be made to coincide with the direction of the wind, or the plane in which the radii of the sials turn⟳ may be made perpendicular to that direction.”

CEFR level