Gauge glass

( Mach.) A strong gla tube, connected with the boiler of a locomotive-engine by two cocks attached to the gauge-cock pedestal. The water is admitted to this tube by the lower cock, the steam by the upper cock. It thus becomes an index to what is going on inside the boiler, exhibiting the height or agitation of the water in it. A small cock is placed below the gla for blowing out any sediment which may be deposited in it. by which the art can be practised by any one of moderate intelligence. The instrument usually employed is the G. rod, or diagonal rod, by which the contents of a cask are inferred from its diagonal length, measured from the bung-hole to the extremity of the opposite stave at the head. A scale of inches, for taking the measure of the diagonal, is described on one face of a square rule, usually about four feet long; and on the opposite face is a scale expre ing the corresponding contents of the cask in gallons. Although this method, obviously, can only give approximate results, yet, by using larger sliding-rules for calculation, and the aid of habit, derived from experience, it is po ible to attain considerable accuracy in measuring the contents of casks, which do not depart from a given standard of form. Gauging-rod, n. See GAUGING. Gaul, n. [Lat. Gallia .] This name, when used alone, was applied to that part of W. Europe bounded N. and W. by the sea, S. by the Pyrenees, and E. by the Alps and the Rhine, thus comprising modern France, Belgium, and a part of Switzerland, Germany, and Holland. Neverthele , in modern language, the name is generally applied exclusively to France. - See GALLIA. Gaul'ish, a . Pertaining to ancient Gaul, or to modern IMG:content-0336.png:[blocks in formation] Gault, ( gawlt .) ( Geol . ) A local name for a series of dark blue marls or calcareous clays found in the middle cretaceous system of England. It can be well examined at Cambridge and Folk est one. The word G. is a provincial term for the clay itself, which is much used for brickmaking. It contains marine shells, and decomposes into a very fertile soil.