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Mason-Dixon Line

(Encyclopedia)Mason-Dixon Line, boundary between Pennsylvania and Maryland (running between lat. 39°43′26.3″N and lat. 39°43′17.6″N), surveyed by the English team of Charles Mason, a mathematician and ast...

Rittenhouse, David

(Encyclopedia)Rittenhouse, David, 1732–96, American astronomer and instrument maker, b. near Germantown, Pa., self-educated. A clockmaker by trade, he developed great skill in the making of mathematical instrumen...

fall line

(Encyclopedia)fall line, boundary between an upland region and a coastal plain across which rivers from the upland region drop to the plain as falls or rapids. A fall line is formed in an area where the rivers have...

Maginot Line

(Encyclopedia)Maginot Line măzhˈĭnō, Fr. mäzhēnōˈ [key], system of fortifications along the eastern frontier of France, extending from the Swiss border to the Belgian. It was named for André Maginot, who w...

assembly line

(Encyclopedia)assembly line, manufacturing technique in which a product is carried by some form of mechanized conveyor among stations at which the various operations necessary to its assembly are performed. It is u...

Line Islands

(Encyclopedia)Line Islands or Equatorial Islands, coral group, 43 sq mi (111 sq km), central and S Pacific. Once valuable for their guano deposits, the islands now have coconut groves, airfields, and meteorological...

line spectrum

(Encyclopedia)line spectrum: see spectrum.

Wallace's line

(Encyclopedia)Wallace's line, imaginary line postulated by A. R. Wallace as the dividing line between Asian and Australian fauna in the Malay Archipelago. It passes between Bali and Lombok islands and between Borne...

snow line

(Encyclopedia)snow line, altitude above which or latitude beyond which snow does not melt in summer (usually called the permanent snow line), or, in winter, the line to which snow extends at a given point in time. ...

base line

(Encyclopedia)base line: see geodesy.