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thunder

(Encyclopedia)thunder, sound produced along a path of a lightning flash, caused by the rapid heating and expansion of the adjacent air; lightning can heat air to temperatures as much as five times hotter than those...

Guericke, Otto von

(Encyclopedia)Guericke, Otto von ôˈtō fən gāˈrĭkə [key], 1602–86, German physicist, noted for his study of pneumatics. He carried out his most important researches while burgomaster (1646–81) of Magdebu...

Lewis, Wyndham

(Encyclopedia)Lewis, Wyndham (Percy Wyndham Lewis) wĭnˈdəm [key], 1886–1957, English author and painter, born on a ship on the Bay of Fundy. With Ezra Pound, he was cofounder and editor of Blast (1914–15), a...

torsion balance

(Encyclopedia)torsion balance, instrument used to measure small forces. It is based on the principle that a wire or thread resists twisting with a force that is proportional to the stress. The torsion balance consi...

grease

(Encyclopedia)grease, mixture of lubricant and thickener. It is used to reduce friction between surfaces from which oils would leak away or cause damage by dripping, or where lubrication must be assured for extende...

buoyancy

(Encyclopedia)buoyancy boiˈənsē, bo͞oˈyən– [key], upward force exerted by a fluid on any body immersed in it. Buoyant force can be explained in terms of Archimedes' principle. ...

cyclone

(Encyclopedia)cyclone, atmospheric pressure distribution in which there is a low central pressure relative to the surrounding pressure. The resulting pressure gradient, combined with the Coriolis effect, causes air...

smoke

(Encyclopedia)smoke, visible gaseous product of incomplete combustion. Smoke varies with its source, but it usually comprises hot gas and suspended particles of carbon and tarry substances, or soot. To reduce the a...

pound

(Encyclopedia)pound, abbr. lb, unit of either mass or force in the customary system of English units of measurement. Two different pounds of mass are defined, one in the avoirdupois system of units and one in the T...

shuffleboard

(Encyclopedia)shuffleboard, sport in which players use cue sticks to push disks onto a scoring diagram at either end of a concrete or terrazzo court. The court is 52 ft (15.85 m) long and 6 ft (1.83 m) wide. The ba...