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welding

(Encyclopedia)welding, process for joining separate pieces of metal in a continuous metallic bond. Cold-pressure welding is accomplished by the application of high pressure at room temperature; forge welding (forgi...

spear

(Encyclopedia)spear, primitive weapon consisting of a wooden shaft tipped with a sharp point, usually 8 to 9 ft (2.4–2.7 m) in length. The point may be carved from the shaft and hardened in a fire, or made from a...

Tours

(Encyclopedia)Tours to͞or [key], city (1990 pop. 133,403), capital of Indre-et-Loire dept., W central France, in Touraine, on the Loire River. It is a wine market and a tourist center, with metallurgical, chemical...

Yuma, city, United States

(Encyclopedia)Yuma yo͞oˈ mə [key], city (1990 pop. 54,923), seat of Yuma co., extreme SW Ariz., on the eastern bank of the Colorado River near the confluence of the Gila River; founded 1854, inc. as a city 1914....

Piltdown man

(Encyclopedia)Piltdown man, name given to human remains found during excavations (1908–15) at Piltdown, Sussex, England, by Charles Dawson. The find led to much speculation and argument. Since they were found wit...

Perth, town, Scotland

(Encyclopedia)Perth, town (1991 pop. 41,916), Perth and Kinross, central Scotland, on the Tay River. It was called St. Johnstoun until the 17th cent. Perth is famous for its dye works and cattle markets. Other indu...

geometry

(Encyclopedia)geometry [Gr.,=earth measuring], branch of mathematics concerned with the properties of and relationships between points, lines, planes, and figures and with generalizations of these concepts. Eucli...

crystal

(Encyclopedia)CE5 Types of crystal crystal, a solid body bounded by natural plane faces that are the external expression of a regular internal arrangement of constituent atoms, molecules, or ions. The formation...

interstellar matter

(Encyclopedia)interstellar matter, matter in a galaxy between the stars, known also as the interstellar medium. The interstellar gas, which constitutes about 99% of the interstellar matter, consists mostly of hyd...

dimension, in mathematics

(Encyclopedia)dimension, in mathematics, number of parameters or coordinates required locally to describe points in a mathematical object (usually geometric in character). For example, the space we inhabit is three...