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photometry

(Encyclopedia)photometry fōtŏmˈətrē, branch of physics dealing with the measurement of the intensity of a source of light, such as an electric lamp, and with the intensity of light such a source may cast on a ...

musical instruments

(Encyclopedia)musical instruments are classified in various ways, but the system devised in 1914 by Kurt Sachs and E. M. von Hornbostel has been accorded recognition by both anthropologists and musicologists becaus...

Pickering, Edward Charles

(Encyclopedia)Pickering, Edward Charles, 1846–1919, American astronomer and physicist, b. Boston, grad. Harvard (B.S., 1865); brother of W. H. Pickering. He was professor of physics (1868–77) at the Massachuset...

illuminance

(Encyclopedia)illuminance: see photometry.

candlepower

(Encyclopedia)candlepower: see photometry.

lumen

(Encyclopedia)lumen: see photometry.

foot-candle

(Encyclopedia)foot-candle: see photometry.

illumination, in physics

(Encyclopedia)illumination, in physics: see lighting; photometry. ...

Gregory, James

(Encyclopedia)Gregory, James, 1638–75, Scottish mathematician. He invented a reflecting telescope (1661), which he described in his Optica promota (1663). In 1668 he became professor of mathematics at the Univ. o...

Bouguer, Pierre

(Encyclopedia)Bouguer, Pierre pyĕr bo͞ogĕrˈ [key], 1698–1758, French mathematician and hydrographer. He made some of the first photometric measurements, calculating the intensity of the light of the sun as co...