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ratchet and pawl

(Encyclopedia)ratchet and pawl, mechanical device that permits motion in one direction only. The ratchet is usually a wheel with slanting teeth. The pawl is a lever tangential to the wheel with one end resting on t...

Kapteyn, Jacobus Cornelius

(Encyclopedia)Kapteyn, Jacobus Cornelius yäkōˈbəs kôrnāˈlēəs käptīnˈ [key], 1851–1922, Dutch astronomer. He was an authority on the Milky Way, of which he made notable statistical studies; he construc...

community chest

(Encyclopedia)community chest, cooperative organization of citizens and social welfare agencies in a city. Also known as a united fund, it has two purposes: to raise funds through an annual campaign for its member ...

Andromeda Galaxy

(Encyclopedia)Andromeda Galaxy, cataloged as M31 and NGC 224, the closest large galaxy to the Milky Way and the only one visible to the naked eye in the Northern Hemisphere. It is also known as the Great Nebula in ...

transportation

(Encyclopedia)transportation, conveyance of goods and people over land, across water, and through the air. See also commerce. The first practical attempts at air transportation began with the invention of the h...

Coalsack

(Encyclopedia)Coalsack: see Milky Way.

disk plow

(Encyclopedia)disk plow or disk, farm implement employing a row or rows of concave circular steel disks that cut and pitch the soil in a way somewhat similar to a moldboard plow. It can be used in many situations w...

icebreaker

(Encyclopedia)icebreaker, ship of special hull design and wide beam, with relatively flat bottom, designed to force its way through ice. When the icebreaker charges into the ice at full speed, its sharply inclined ...

galactic coordinate system

(Encyclopedia)galactic coordinate system, astronomical coordinate system in which the principal axis is the galactic equator (the intersection of the plane of the Milky Way with the celestial sphere) and the refere...

Athabasca, Lake

(Encyclopedia)Athabasca, Lake, fourth largest lake of Canada, c.3,120 sq mi (8,100 sq km), c.200 mi (320 km) long and from 5 to 35 mi (8–56 km) wide, NE Alta., and SW Sask., at the edge of the Canadian Shield. A ...