Hatches, as at present arranged, are extremely dangerous, they are almost invariably placed at the entrance of the stairways of buildings, and the upper doors are, in consequence, adjacent to the upper stairways, so that if the doors are left open, which is generally the case, through carelessness, inattention, or other causes, accidents often of a serious nature are likely to occur. Such casualties are rendered entirely impossible by an improvement, the invention of Daniel Tallcot, of New York City, who has taken measures to secure a patent. The improvement consists in attaching to the axis or pivojbs of e ach door of the hatch a half pulley, to which a lever is connected by a chain or rope, the lever being constructed in such a manner that the carriage, in its descent, will operate upon the lever and open the doors, thus allowing the carriage to pass through, the doors afterwards closing by their own weight, the effect of which is graduated by springs. In like manner the carriage is elevated by means of a pulley hung on a cross-piece at the top of the uprights between which it travels, and which are grooved for this purpose, serving as guides, and as it ascends, of course raises the doors. There are other springs secured to the inner side of one of the uprights, which are intended to throw the doors out of their vertical position when the carriage has passed through, and thus facilitate their closing.
This article was originally published with the title "Self-Adjusting Hatch" in Scientific American 8, 31, 244 (April 1853)