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longitude

(Encyclopedia)longitude lŏnˈjĭto͞odˌ [key], angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. A meridian of longitude is an imagin...

pi

(Encyclopedia)pi, in mathematics, the ratio of the circumference of a circle to its diameter. The symbol for pi is π. The ratio is the same for all circles and is approximately 3.1416. It is of great importance in...

Charles III, king of Spain, and of Naples and Sicily

(Encyclopedia)Charles III, 1716–88, king of Spain (1759–88) and of Naples and Sicily (1735–59), son of Philip V and Elizabeth Farnese. Recognized as duke of Parma and Piacenza in 1731, he relinquished the duc...

international date line

(Encyclopedia)international date line, imaginary line on the earth's surface, generally following the 180° meridian of longitude, where, by international agreement, travelers change dates. Traveling eastward acros...

tachyon

(Encyclopedia)tachyon tăkˈēŏnˌ [key], hypothetical elementary particle that travels only at speeds exceeding that of light. According to the theory of relativity, the speed of light is the limiting velocity fo...

Redgrave

(Encyclopedia)Redgrave, family of English actors. Sir Michael Redgrave, 1908–85, b. Bristol, Eng., was an actor, director, and writer. After his first professional performance in Counsellor-at-Law (1934), he appe...

Herrick, Robert, English poet

(Encyclopedia)Herrick, Robert, 1591–1674, English poet, generally considered the greatest of the Cavalier poets. Although he was born in London, he spent most of his childhood in Hampton. In 1607 he became appren...

stealth technology

(Encyclopedia)stealth technology, designs and materials engineered for the military purpose of avoiding detection by radar or any other electronic system. Stealth, or antidetection, technology is applied to vehicle...

equatorial coordinate system

(Encyclopedia)CE5 Equatorial coordinate system equatorial coordinate system, the most commonly used astronomical coordinate system for indicating the positions of stars or other celestial objects on the celesti...

dice, in games and gambling

(Encyclopedia)dice [plural of die], small cubes used in games. They are usually made of ivory, bone, wood, plastic, or similar materials. The six sides are numbered by dots from 1 to 6, so placed that the sum of th...