trap valve

A clack-valve (q. v.). trăp (2), s . [ Sw.trappa =astair; trapp =trap-rock; Danish trappe =a stair; trap =trap; Dutch trap =a stair, a step; Ger, treppe a flight of stairs.] 1. Ord. Lang .: Akind of movable ladder or steps; a kind of ladder leading up to a loft. 2. Petrol .: A name originally given to certain igneous rocks, of great geological age, occurring in Sweden, which, partly from weathering and partly as the result of succe ive extrusions, presented a stair-like aspect. Subsequently this name was loosely applied to any ancient, fine-grained, igneous rock which had undergone a certain amount of alteration. Most of the so-called "traps" have since been identified as varieties of dolerite or basalt. Trap, in this general sense, is widely diffused, and where it occurs, it exerts much influence in determining the surface configuration of the region. When it decays it produces rich, agricultural soil, "Says, aw, 'Smash! thou is up to trap!" For he lets the folks byeth in and out." Robson: Bards of the Tyne, p. 275. trap-ball, s. The name as TRAP (1). 8. 8. trap-bat, subst. A bat used in the game of trap (q. v.).