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Perkins, Frances

(Encyclopedia)Perkins, Frances, 1882–1965, U.S. Secretary of Labor (1933–45), b. Boston. She worked at Hull House, was executive secretary of the New York Consumers' League (1910–12) and of the New York Commi...

Trumbull, John , American painter

(Encyclopedia)Trumbull, John, 1756–1843, American painter, b. Lebanon, Conn.; son of Gov. Jonathan Trumbull. He served in the Continental Army early in the Revolution as an aide to Washington. He resigned his com...

dimension, in physics

(Encyclopedia)dimension, in physics, an expression of the character of a derived quantity in relation to fundamental quantities, without regard for its numerical value. In any system of measurement, such as the met...

spring, in mechanics

(Encyclopedia)spring, in mechanics, any of several elastic devices used variously to store and to furnish energy, to absorb shock, to sustain the pressure between contacting surfaces, and to resist tensional or com...

Richland

(Encyclopedia)Richland, city (1990 pop. 32,315), Benton co., S Wash., at the confluence of the Columbia and Yakima rivers, in an irrigated farm and vineyard region; inc. 1958. It is the headquarters of the U.S. Dep...

fuel cell

(Encyclopedia)fuel cell, electric cell in which the chemical energy from the oxidation of a gas fuel is converted directly to electrical energy in a continuous process (see oxidation and reduction). The efficiency ...

photochemistry

(Encyclopedia)photochemistry, study of chemical processes that are accompanied by or catalyzed by the emission or absorption of visible light or ultraviolet radiation. A molecule in its ground (unexcited) state can...

superfluidity

(Encyclopedia)superfluidity, tendency of liquid helium below a temperature of 2.19K to flow freely, even upward, with little apparent friction. Helium becomes a liquid when it is cooled to 4.2K. Special methods...

machine

(Encyclopedia)machine, arrangement of moving and stationary mechanical parts used to perform some useful work or to provide transportation. From a historical perspective, many of the first machines were the result ...

civil service

(Encyclopedia)civil service, entire body of those employed in the civil administration as distinct from the military and excluding elected officials. The term was used in designating the British administration of I...