Columbia Encyclopedia

Search results

500 results found

fortification

(Encyclopedia)fortification, system of defense structures for protection from enemy attacks. Fortification developed along two general lines: permanent sites built in peacetime, and emplacements and obstacles hasti...

artillery

(Encyclopedia)artillery, originally meant any large weaponry (including such ancient engines of war as catapults and battering rams) or war material, but later applied only to heavy firearms as opposed to small arm...

Coriolis effect

(Encyclopedia)Coriolis effect kôrˌē-ōˈlĭs [key] [for G.-G. de Coriolis, a French mathematician], tendency for any moving body on or above the earth's surface, e.g., an ocean current or an artillery round, to ...

Knox, Henry

(Encyclopedia)Knox, Henry, 1750–1806, American Revolutionary officer, b. Boston. He volunteered for service and went, in 1775, to Ticonderoga to retrieve the captured cannon and mortar there for use in the siege ...

siege

(Encyclopedia)siege, assault against a city or fortress with the purpose of capturing it. The history of siegecraft parallels the development of fortification and, later, artillery. In early times battering rams an...

Doppler effect

(Encyclopedia)Doppler effect, change in the wavelength (or frequency) of energy in the form of waves, e.g., sound or light, as a result of motion of either the source or the receiver of the waves; the effect is nam...

Compton effect

(Encyclopedia)Compton effect [for A. H. Compton], increase in the wavelengths of X rays and gamma rays when they collide with and are scattered from loosely bound electrons in matter. This effect provides strong ve...

Coanda effect

(Encyclopedia)Coanda effect or wall-attachment effect, the tendency of a moving fluid, either liquid or gas, to attach itself to a surface and flow along it. As a fluid moves across a surface a certain amount of fr...

Hall effect

(Encyclopedia)Hall effect, experiment that shows the sign of the charge carriers in a conductor. In 1879 E. H. Hall discovered that when he placed a metal strip carrying a current in a magnetic field, a voltage dif...

greenhouse effect

(Encyclopedia)greenhouse effect: see global warming. ...