WIC 



may be heard in the other. The obser- 

 vatory at Paris contains an apartment of 

 this kind. 



WHITE COPPER. Chinese Copper. 

 A white metallic compound brought from 

 China; its composition is not generally 

 known, but some of it is said to consist 

 of copper and arsenic. 



WHITE LEAD. Ceruse. Carbonate 

 of lead, occurring in nature well crystal- 

 lized, in the form of carbonate of barytes. 

 It is employed by painters, as a white 

 pigment, to give body to their co- 

 lours. 



WHITE PRECIPITATE. A com- 

 pound formed when ammonia is added 

 to a solution of chloride of mercury. It 

 is free from oxygen, and contains nothing 

 but the elements of a double chloride and 

 .amide of mercury. 



WHTTESTONE. Eurite. A variety 

 of granite, in which felspar is the chief 

 ingredient, the quartz, and especially the 

 mica, being very rare ; or in which all 

 the ingredients are blended into a finely 

 granular mass of a white appearance. 

 Crystals of quartz are sometimes dis- 

 persed through the mass, rendering it 

 porphyritic. 



WHORL. In Malacology, this word 

 denotes each complete turn of the spire 

 of a spiral shell ; the last, which termi- 

 nates the aperture, is the body or basal 

 whorl; the rest are the spiral whorls. 

 For the use of this term in botany, see 

 Verticillus. 



WHY ? As an interrogative, this word 

 is employed in three senses: viz. "By 

 what proof?" (or reason.) *' From what 

 cause?" "For what purpose?" This 

 last is commonly called the "final 

 cause." E. g. " Why is this prisoner 

 guilty of the crime?" "Why does a 

 stone fall to the earth ? " " Why did you 

 go to London?" Much confusion has 

 arisen from not distinguishing these 

 different inquiries. Whately. 



WICKLESS LAMP. This ingeniously 

 contrived lamp is, as it is commonly 

 called, a self-generating gas apparatus. 

 It iserves to manufacture oil-gas without 

 the inconvenience of a retort and fur- 

 nace. In its common form this lamp con- 

 sists of « light and buoyant dish, which 

 is intended to support the small tube 

 through which the oil is intended to be 

 raised ; this is effected, partly by capil- 

 lary attraction, and partly by hydrostatic 

 pressure. On applying a taper to the 

 tube, the oil is decomposed at the ex- 

 tremity, and gas is generated. 

 378 



WIN 



WI'LLEMITE. A variety of silicate 

 of zinc, from Aix-la-Chapelie. 



WINCH AND AXLE. A well-known 

 apparatus, constituting a small windlass, 

 and employed in its simplest form to 

 raise water from a well, or solid mate- 

 rials from the shaft of a mine ; in a more 

 complex form, it is connected with a 

 crane for the purpose of raising heavy 

 packages from the ground to the upper 

 part of a building. Its mechanical power 

 is precisely that of the wheel and axle. 



WIND. A current in the atmosphere, 

 occasioned by inequality of temperature 

 of the atmosphere at different points of 

 the earth's surface, or in different regions 

 of the atmosphere of equal eievanon. 

 Permanent winds are those which blow 

 constantly between, and a few degrees 

 beyond, the tropics (See Trade Winds). 

 Those which blow at certain periods, as 

 the monsoons, the land and sea-breezes, 

 &c., are called periodical winds. 



1. Etesian Winds. A term formerly 

 applied to those winds which blow every 

 summer during six weeks over the coun- 

 tries bordering the Mediterranean, but 

 now applied to other periodical winds, as 

 those which blow on the coast of Holland. 



2. Helm Wind. A violent wind which 

 occasionally prevails between Brampton 

 in Cumberland and Brough in West- 

 moreland, a distance of 40 miles. Its 

 presence is indicated by a belt of clouds, 

 denominated the helm bar, which re- 

 mains immoveable during twenty-four 

 or even thirty six hours, collecting or 

 attracting to itself all the light clouds 

 which approach it. So long as this bar 

 continues unbroken, the wind blows with 

 unceasing fury, not in gusts, like other 

 storms, but with continued pressure. 



WIND-GAGE. An instrument for 

 measuring the force or velocity of the 

 wind. Various contrivances for this 

 purpose have been employed. One of 

 these is described under the term Ane- 

 mometer. 



WIND-GUN. This is a more formid- 

 able instrument than the air-gun. It 

 contains a magazine of bullets as well as 

 another of air, and when it is properly 

 charged, the bullets may be projected 

 one after another as fast as the gun can 

 be cocked and the pan opened. The 

 syringe is fixed to the butt of the gun, by 

 means of which it is easily charged, and 

 may be kept in that state for a long time. 



WINDLASS. A modification of the 

 wheel and axle, consisting of a barrel 

 which turns upon two points of support 



