What is "smoke sail"

Smoke \Smoke\ (sm[=o]k), n. [AS. smoca, fr. sme['o]can to smoke; akin to LG. & D. smook smoke, Dan. sm["o]g, G. schmauch, and perh. to Gr. ??? to burn in a smoldering fire; cf. Lith. smaugti to choke.]

1. The visible exhalation, vapor, or substance that escapes, or expelled, from a burning body, especially from burning vegetable matter, as wood, coal, peat, or the like.

   Note: The gases of hydrocarbons, raised to a red heat or thereabouts, without a mixture of air enough to produce combustion, disengage their carbon in a fine powder, forming smoke. The disengaged carbon when deposited on solid bodies is soot.

2. That which resembles smoke; a vapor; a mist.

3. Anything unsubstantial, as idle talk.
   --Shak.

4. The act of smoking, esp. of smoking tobacco; as, to have a smoke. [Colloq.]

   Note: Smoke is sometimes joined with other word. forming self-explaining compounds; as, smoke-consuming, smoke-dried, smoke-stained, etc.

   Smoke arch, the smoke box of a locomotive.

   Smoke ball (Mil.), a ball or case containing a composition which, when it burns, sends forth thick smoke.

   Smoke black, lampblack. [Obs.]

   Smoke board, a board suspended before a fireplace to prevent the smoke from coming out into the room.

   Smoke box, a chamber in a boiler, where the smoke, etc., from the furnace is collected before going out at the chimney.

   Smoke sail (Naut.), a small sail in the lee of the galley stovepipe, to prevent the smoke from annoying people on deck.

   Smoke tree (Bot.), a shrub ( Rhus Cotinus) in which the flowers are mostly abortive and the panicles transformed into tangles of plumose pedicels looking like wreaths of smoke.

   To end in smoke, to burned; hence, to be destroyed or ruined; figuratively, to come to nothing.

   Syn: Fume; reek; vapor.