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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...

diamond

(Encyclopedia)diamond, mineral, one of two crystalline forms of the element carbon (see allotropy), the hardest natural substance known, used as a gem and in industry. The discoveries of 1870–71 in South Africa...

forest

(Encyclopedia)forest, a dense growth of trees, together with other plants, covering a large area of land. The science concerned with the study, preservation, and management of forests is forestry. A forest is an ec...

navigation

(Encyclopedia)navigation, science and technology of finding the position and directing the course of vessels and aircraft. The next great revolution in navigation occurred in the 20th cent., when radio signals ...

periodic table

(Encyclopedia)CE5 periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arrange...

Milton, John

(Encyclopedia)Milton, John, 1608–74, English poet, b. London, one of the greatest poets of the English language. Milton's theology, although in the Protestant tradition, is extremely unorthodox and individu...

trigonometry

(Encyclopedia)trigonometry [Gr.,=measurement of triangles], a specialized area of geometry concerned with the properties of and relations among the parts of a triangle. Spherical trigonometry is concerned with the ...

free trade

(Encyclopedia)free trade, in modern usage, trade or commerce carried on without such restrictions as import duties, export bounties, domestic production subsidies, trade quotas, or import licenses. The basic argume...

sulfuric acid

(Encyclopedia)sulfuric acid, chemical compound, H2SO4, colorless, odorless, extremely corrosive, oily liquid. It is sometimes called oil of vitriol. Although sulfuric acid is now one of the most widely used c...

inscription

(Encyclopedia)inscription, writing on durable material. The art is called epigraphy. Modern inscriptions are made for permanent, monumental record, as on gravestones, cornerstones, and building fronts; they are oft...