Portscullis

A cannon fired at sunset is the signal for hauling up the various portscullis, and shutting off communication with the rest of the world.

Source: wiktionary

There are no trap machicoulis in the floors, so far as these are preserved, and there were no portscullis.

Source: wiktionary

There is surely a closer and more obvious connection between Battens and triangular candlesticks than between Battens and portscullis. (This plural is my own and will not be found in Larousse). If the term “portcullis” had to be brought into the French theatre, it would—I should have thought—have been more likely to be applied to flown scenery, tabs, sky borders and suchlike. Surely a cut cloth would give a much better representation of a portcullis than would a row of smelly little lamps? And he admits the use of “coulisse” in connection with sliding scenery.

Source: wiktionary