This general meaning is also preserved in British use, particularly for small windows into unoccupied attic or spire spaces.
[2] In industrial architecture a lucarne or lucam[citation needed] is a feature of warehouses, mills, factories or the like in which a window, opening or housing high up on an exterior wall supports a hoist above doors on the floors below.
[3] The simplest lucarne is no more than the extension of a roof beyond a gable wall, with a ridge timber strong enough to support a hoist.
A gin wheel on this beam can provide a simple rope hoist, sufficient to lift a sack of grain.
These doors sometimes have an iron fold-down flap outside them, as a short loading step, giving clearance for the hoist away from the wall.