WEI 



WEI 



admixed sulphate of lime. This mineral 

 must not he confounded with another 

 substance also called aluminile or alum- 

 stone (alunite of some mineralogists) from 

 Tolfa, &c., which is a basic sulphate of 

 alumina and potassa. 



WEPGE. One of the mechanical 

 powers, consisting of a triangular prism, 

 or a pair of inclined planes having a com- 

 mon base, made of some hard substance, 

 and employed to remove two objects from 

 one another laterally, or to cleave asunder 

 the parts of a body. When the edge is 

 introduced, the wedge is driven forward 

 by a violent blow, as from a hammer, 

 which generates an enormous force, of 

 momentary duration. Nails, awls, needles, 

 and many cutting instruments act on this 

 principle ; the stones of an arch are trun- 

 cated wedges. 



WEEK, DAYS OF. The English 

 names of the days of the week are de- 

 rived from the Saxons ; and these partly 

 adopted the names from the more civil- 

 ized nations of antiquity. Tuesday, 

 Wednesday, Thursday, and Friday are 

 derived respectively, from the names of 

 Tiw, Woden, Thor, and Friga, deities of 

 the ancient Saxons ; Thor being the god 

 of thunder, as well as the ancient Jove ; 

 and Friga, the wife of Woden. Saturday, 

 Sunday, and Monday, are derived re- 

 spectively, from the Saxon Seterne's, 

 Sun's, and Moon's day. 



WEIGHT. The comparative measure 

 of the gravity of bodies at the earth's 

 surface. In mechanics, weight is the 

 resistance, or the thing to be moved by 

 the force of the power : the stone is the 

 ■weight to be moved by the force of the 

 lever or bar. 



WEIGHT OF THE ATMOSPHERE. 

 The mean weight of the atmosphere at 

 the surface of the sea is generally esti- 

 mated as equal to the weight of a column 

 of mercury of 30 inches in height, which 

 is about 1 5 pounds on the square inch 

 of surface, and is equivalent to a column 

 of water of nearly 34 feet in height. 

 Hence the surface of the globe sustains a 

 weight of 11,449,000,000 hundreds of 

 millions of pounds. 



WEIGHTS AND MEASURES. The 

 following standards have been sanctioned 

 by Parliament for the purpose of ascer- 

 taining and establishing uniformity of 

 weights and measures : — 



ENGLISH MEASURES AND WEIGHTS. 



1. Lineal, Superficial, and Solid mea- 

 sures. The length of the pendulum, 

 874 



vibrating seconds of mean time in the 

 latitude of London at 62° Fahr., and in 

 a vacuum at the level of the sea, is equal 

 to 39.1393 inches of the Brass " Standard 

 Yard of 1760," or "Imperial Standard 

 Yard." Hence the length of the yard to 

 that of the pendulum is in the proportion 

 of 36 inches to 39.1393 inches, or of the 

 number 360,000 to the number 391.393 : 

 so that, if the length of the pendulum 

 be divided into 391.393 equal parts, then 

 will 10,000 of these parts be the length 

 of an inch, according to the imperial 

 standard. 



2. The English land-chain = 22 yards 

 or 66 feet, and contains 100 links ; 1 link 

 = 7.92 inches. The square chain = 484 

 square yards, and 10 square chains = 

 1 acre. 



3. Troy and Avoirdupois weights. The 

 old Troy pound is the standard unit of 

 weight, and contains 5760 grains ; while 

 the avoirdupois pound, now in use, con- 

 tains 7000 grains. Hence, the standard 

 pound is to the common pound as 5760 

 grains to 7000 grains ; or as the number 

 144 to the number 175. According to the 

 standard, one cubic inch of distilled 

 water at 62° Fahr., the barometer being 

 at 30 inches, weighs 252.458 troy grains, 

 one pound = 5760 grains. (A cubic inch 

 of distilled water, at the maximum den- 

 sity, weighs 253 troy grains). Then 175 

 troy pounds = 144 avoirdupois pounds; 

 and 175 troy ounces = 192 avoidupois 

 ounces. A cubic foot of distilled water 

 at 62° Fahr. weights almost exactly 

 997.\iQ9&9 ounces avoirdupois, and at 

 the maximum density, 999.2717 ounces 

 avoirdupois. 



4. Imperial Gallon Measure. This is 

 the measure for all sorts of liquids, corn, 

 and other dry goods. Ten pounds avoir- 

 dupois, or 277.274 cubic inches of dis- 

 tilled water at 62° Fahr., the barometer 

 being at 30 inches, are the contents of 

 the New Imperial Gallon. As 252.458 

 grains ', 1 cubic inch ; .' lOlbs. or 70,000 

 grains I 277.274 cubic inches, which is, 

 consequently, the content of the impe- 

 rial gallon. The proportion of the impe- 

 rial gallon to the wine gallon is as 6 to 5 

 nearly, to the ale gallon as 59 to 60 nearly, 

 and to the corn gallon as 33 to 32 nearly ; 

 its proportion to the sterling pint is as 

 59 to 22 nearly. 



5. Heaped Measure. Eighty pounds 

 avoirdupois, or 2218.192 cubic inches of 

 distilled water at 62° Fahr., the barometer 

 being at 30 inches, are the contents of 

 the New Bushel, which is to he made 



