Columbia Encyclopedia

Search results

500 results found

logic

(Encyclopedia)logic, the systematic study of valid inference. A distinction is drawn between logical validity and truth. Validity merely refers to formal properties of the process of inference. Thus, a conclusion w...

Arago, Dominique François

(Encyclopedia)Arago, Dominique François dômēnēkˈ fräNswäˈ ärägōˈ [key], 1786–1853, French physicist and astronomer. He is noted for his discoveries in magnetism and optics as well as for his astronomi...

electric shock

(Encyclopedia)electric shock, effect of the passage of a current of electricity through the body. Fatality may result from shocks of from 1 to 2 amperes and 500 to 1,000 volts. However, the effect of electric shock...

Braid, James

(Encyclopedia)Braid, James, 1795?–1860, English surgeon and writer on hypnotism and magic. The first to use the term hypnotism instead of mesmerism or animal magnetism, he also demonstrated that it was achieved b...

electric fish

(Encyclopedia)electric fish, name for various fish that produce electricity by means of organs usually developed from modified muscle tissue. The electric eels of South America are freshwater knifefish unrelated to...

selective service

(Encyclopedia)selective service, in U.S. history, term for conscription. Conscription was established (1863) in the U.S. Civil War, but proved unpopular (see draft riots). The law authorized release from service to...

Schwabe, Samuel Heinrich

(Encyclopedia)Schwabe, Samuel Heinrich zäˈmo͞oĕl hīnˈrĭkh shväbˈə [key], 1789–1875, German apothecary and amateur astronomer. In the hope of discovering a new planet between Mercury and the sun, he made...

magnet

(Encyclopedia)magnet: see electromagnet; magnetism. ...

Ritz, Walter

(Encyclopedia)Ritz, Walter, 1878–1909, Swiss physicist. He taught at the universities of Zürich and Göttingen. Ritz's combination principle, confirmed by later research, stated that the frequencies of spectral ...

physics

(Encyclopedia)physics, branch of science traditionally defined as the study of matter, energy, and the relation between them; it was called natural philosophy until the late 19th cent. and is still known by this na...