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Langdon, John

(Encyclopedia)Langdon, John, 1741–1819, American political leader, b. Portsmouth, N.H. A prosperous merchant, Langdon was active in pre-Revolutionary activities. In 1775 he became a delegate to the Continental Co...

Rittenhouse, David

(Encyclopedia)Rittenhouse, David, 1732–96, American astronomer and instrument maker, b. near Germantown, Pa., self-educated. A clockmaker by trade, he developed great skill in the making of mathematical instrumen...

weather vane

(Encyclopedia)weather vane or wind vane, instrument used to indicate wind direction. It consists of an asymmetrically shaped object, e.g., an arrow or a rooster, mounted at its center of gravity so it can move free...

actinometer

(Encyclopedia)actinometer ăkˌtənŏmˈətər [key], instrument used to measure the heating power of radiation. Actinometers are used chiefly in meteorology to measure solar radiation as transmitted directly by th...

stamp tax

(Encyclopedia)stamp tax, method of collecting duties on certain transactions by means of a validating stamp attached to the taxable instrument, which may be a judicial act, a commercial document, a transfer of prop...

tourniquet

(Encyclopedia)tourniquet to͝orˈnĭkĕt, –kā, tûrˈ– [key], compression device used to cut off the flow of blood to a part of the body, most often an arm or leg. It may be a special surgical instrument, a ru...

barbed wire

(Encyclopedia)barbed wire, wire composed of two zinc-coated steel strands twisted together and having barbs spaced regularly along them. The need for barbed wire arose in the 19th cent. as the American frontier mov...

periscope

(Encyclopedia)periscope pĕrˈĭskōp [key] [Gr.,=view around], instrument to enable a person to see objects not in his direct line of vision or concealed by some intervening body. Its essential parts are a tube, p...

Woolf, Virginia

(Encyclopedia)Woolf, Virginia, 1882–1941, English novelist and essayist, b. Adeline Virgina Stephen; daughter of Sir Leslie Stephen. A successful innovator in the form of the novel, she is considered a significan...

tower

(Encyclopedia)tower, structure, the greatest dimension of which is its height. Towers have belonged to two general types. The first embodies practical uses such as defense (characteristic of the Middle Ages), to ca...