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Davidson, Donald Herbert

(Encyclopedia)Davidson, Donald Herbert, 1917–2003, American philosopher, b. Springfield, Mass., grad. Harvard (B.A., 1939; Ph.D., 1949). A student of W. V. Quine, Davidson emerged as one of the major figures in p...

Hamilton, Sir William Rowan

(Encyclopedia)Hamilton, Sir William Rowan, 1805–65, Irish mathematician and astronomer, b. Dublin. A child prodigy, he had mastered 13 languages by the age of 13 and was still an undergraduate when he became prof...

Nicol prism

(Encyclopedia)Nicol prism nĭkˈəl [key], optical device invented (1828) by William Nicol of Edinburgh. It consists essentially of a crystal of calcite, or Iceland spar, that is cut at an angle into two equal piec...

Summerhill

(Encyclopedia)Summerhill, radical progressive school in Leiston, Suffolk, England, and the educational movement based on principles developed at the school. The school was founded (1924) by A. S. Neill, who headed ...

surface chemistry

(Encyclopedia)surface chemistry, study of chemical reactions in which the reactants are first adsorbed onto a surface medium (see adsorption) that then acts as a catalyst for the reaction; after the reaction the pr...

spectroscope

(Encyclopedia)spectroscope, optical instrument for producing spectral lines and measuring their wavelengths and intensities, used in spectral analysis (see spectrum). When a material is heated to incandescence it e...

threshing

(Encyclopedia)threshing or thrashing, separation of grain from the stalk on which it grows and from the chaff or pod that covers it. The first known method was by striking the reaped ears of grain with a flail. In ...

rectifier

(Encyclopedia)rectifier, component of an electric circuit used to change alternating current to direct current. Rectifiers are made in various forms, all operating on the principle that current passes through them ...

Proclus

(Encyclopedia)Proclus prōˈkləs [key], 410?–485, Neoplatonic philosopher, b. Constantinople. He studied at Alexandria and at Athens, where he was a pupil of the Platonist Syrianus, whom he succeeded as a teache...

Desmoulins, Camille

(Encyclopedia)Desmoulins, Camille kämēˈyə dāmo͞olăNˈ [key], 1760–94, French revolutionary and journalist. His oratory of July 12, 1789, contributed to the storming of the Bastille two days later. His pamp...