London : Longman, Rees, Orme, Brown, Green, and Longman · leaf 417
180. In,;%. 178., whichshows the ground plan, a isa lever of wood or metal; andb b blocks attached to theunderside of the floor, forlevers to work in. In Jig.179., the same letters applyto the same parts ; and c is a metal spring, also affixed to theunder side of flooring board. The principle of… … a Double Door for a Room. 401 shown here as closed,consequently the bolt{g) is withdrawn fromthe bottom of door(/0.The reverse is thecase in the front sec-tion,^^. 179., wherethe door (J.) is sup-posed to be open, andthe spring (c), pres-sing on the end ofthe lever at «, forcesthe crank [d)…
Architecture
Internet Archive · Public Domain Mark 1.0. Free to use for anything.
![An illustration from A Dictionary of science, literature, and art [electronic resource]: comprising the history, description, and scientific principles of every branch of human knowledge; with the derivation and definition of all the terms in general use (1844)](https://img.insideoutlibrary.com/img/200/ia-62523189.5956.emory.edu-1032-297.webp)