"A covering of black cloth impermeable to light is, attached to the sides of the moveable plate, enveloping the whole inclined plane, rolling freely over two rollers, R, R, placed the one at the upper and the other at the lower part of the inclined plane. This cloth prevents the light striking the sensitive surface before and after the passage of the moveable plate.英文原著 · 《The History and Practice of the Art of Photography》