niche d'éclairage

CONT: ... the powder magazine. Up to 65 barrels of powder for the guns were stored here. The alcove where the lamp is located is called a light closet. This closet would have had 5 or 6 plates of glass or mica, so that if one should break, the powder would not be exposed to an open flame.
OBS: By the use of double doors the interior of the magazine was never in direct contact with the rest of the building. To give light an aperture about two feet square went through the magazine's brick wall about five feet from the floor to a closet off the corridor. This aperture was fitted with a movable pane of glass, flush with the inner wall of the magazine, with a large sill behind it entirely cut off from the magazine. A burning lantern placed on the sill shone through the glass into the magazine without any risk of danger ....
OBS: The context and the first observation of this record apply respectively to the Murney Tower gunpowder and the Market Shoal Tower.