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fifth force

(Encyclopedia)fifth force, postulated fifth basic force of nature (the four known forces of nature are gravity, electromagnetism, and the strong and weak interactions). Proposed in 1986 to account for gravitational...

Palmdale

(Encyclopedia)Palmdale, city (1990 pop. 68,842), Los Angeles co., S Calif., in the irrigated Antelope Valley; a growing residential suburb of Los Angeles near Little Rock Creek where it forms Lake Palmdale Reservoi...

base line

(Encyclopedia)base line: see geodesy.

electromotive force

(Encyclopedia)electromotive force, abbr. emf, difference in electric potential, or voltage, between the terminals of a source of electricity, e.g., a battery from which no current is being drawn. When current is dr...

Walker, Mary Edwards

(Encyclopedia)Walker, Mary Edwards, 1832–1919, American surgeon and feminist, b. Oswego, N.Y., grad. Syracuse Medical College, 1855. At the beginning of the Civil War she offered her services to the Union army. F...

Force, Peter

(Encyclopedia)Force, Peter, 1790–1868, American journalist and historian, b. near Paterson, N.J. He served in the War of 1812 and afterward established himself in Washington, D.C., as a printer. Entering local po...

air pollution

(Encyclopedia)air pollution, contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. The major sources of air pollution are t...

force bill

(Encyclopedia)force bill, popular name for several laws in U.S. history, notably the act of Mar. 2, 1833, and the Reconstruction acts of May 31, 1870; Feb. 28, 1871; and Apr. 20, 1871. The first force bill, passed ...

air mass

(Encyclopedia)air mass, large body of air within the earth's atmosphere in which temperature and humidity, although varying at different heights, remain similar throughout the body at any one height. Air masses for...

air conditioning

(Encyclopedia)CE5 Cross section of air conditioning unit. air conditioning, mechanical process for controlling the humidity, temperature, cleanliness, and circulation of air in buildings and rooms. Indoor air i...