A mechanical curtain, upwardly movable into open position and downwardly movable into closed position, the curtain comprising: a) a plurality of similarly constructed trains of elongated members, the members of each train arranged to form a single pantograph forming longitudinally aligned rows of diamonds, the trains spaced laterally to form a curtain plane and oriented so that the diamonds of the pantographs operate in a plane at a 90° angle to that curtain plane, b) a plurality of bars secured in parallel spaced fashion to corresponding members in adjacent trains, perpendicular thereto, and, c) one or more cables to raise and lower the trains at a similar rate the pantographs being contracted when the curtain is in open position and the pantographs being elongated when the curtain is in closed position.