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mirror

(Encyclopedia)mirror, in optics, a reflecting surface that forms an image of an object when light rays coming from that object fall upon it (see reflection). Usually mirrors are made of plate glass, one side of whi...

family, in sociology

(Encyclopedia)family, a basic unit of social structure, the exact definition of which can vary greatly from time to time and from culture to culture. How a society defines family as a primary group, and the functio...

Irish Republican Army

(Encyclopedia)Irish Republican Army (IRA), nationalist organization devoted to the integration of Ireland as a complete and independent unit. Organized by Michael Collins from remnants of rebel units dispersed afte...

Hegel, Georg Wilhelm Friedrich

(Encyclopedia)Hegel, Georg Wilhelm Friedrich gāˈôrkh vĭlˈhĕlm frēˈdrĭkh hāˈgəl [key], 1770–1831, German philosopher, b. Stuttgart; son of a government clerk. Hegel has influenced many subsequent p...

Garibaldi, Giuseppe

(Encyclopedia)Garibaldi, Giuseppe gărĭbôlˈdē, Ital. jo͞ozĕpˈpā gärēbälˈdē [key], 1807–82, Italian patriot and soldier, a leading figure in the Risorgimento. He remains perhaps the most popular of al...

Gascony

(Encyclopedia)Gascony găsˈkənē [key], Fr. Gascogne, region of SW France. It is now coextensive with the departments of Landes, Gers, and Hautes-Pyrénées and parts of Pyrénées-Atlantiques, Lot-et-Garonne, Ta...

Macedon

(Encyclopedia)Macedon măsˈədŏn [key], ancient country, roughly equivalent to the modern region of Macedonia. In the history of Greek culture Macedon had its single significance in producing the conquerors and a...

weights and measures

(Encyclopedia)CE5 weights and measures, units and standards for expressing the amount of some quantity, such as length, capacity, or weight; the science of measurement standards and methods is known as metrology...

balance

(Encyclopedia)balance, instrument used in laboratories and pharmacies to measure the mass or weight of a body. A balance functions by measuring the force of gravity that the earth exerts on an object, i.e., its wei...

clock

(Encyclopedia)CE5 A pendulum clock: Weight-driven clock mechanism clock, instrument for measuring and indicating time. Predecessors of the clock were the sundial, the hourglass, and the clepsydra. See also watc...