WEL 



WH E 



weight of a cubic decimetre of water at the 

 temperature of four degrees above that of 

 melting ice. The millier is 1000 kilo- 

 grammes, or the weight of a tun of 

 sea-water ; the quintal is 100 kilo- 

 grammes; the hectogramme is 1-lOth of 

 a kilogramme, the decagramme 1-1 00th, 

 the gramme 1-lOOOth, the decigramme 



1 -10,000th of a kilogramme. The unit used 

 in weighing is the kilogramme. It has been 

 fixed by, and is equal to, the specific 

 weight of the distilled water contained in 

 one cubic decimetre. It is equal to 



2 livres, 5 gros, 35 grains, ^ poids de 

 marc, and to 21bs. 8oz. 3dwt. 6.355 grains 

 troy weight, and 21bs 2oz. 4 drams, 

 16 grains avoirdupois weight. The kilo- 

 gramme is divided into two livres; the 

 livre is subdivided into 16 ounces, the 

 ounce into 8 gros, and the gros into 72 

 grains. This new livre exceeds the old 

 one (poids de marc) by ■^^, so that, to 

 reduce kilogrammes into old measure, 

 we must multiply by 2, and add ^. 



17. Terms employed in the l^th cen- 

 tury. The measures appear in most cases 

 to have reference to the human body. 

 The breadth (not the length) of four bar- 

 leycorns make a digit, or finger-breadth ; 

 four digits make a. palm (measured across 

 the middle joints of the fingers, and the 

 24th part of the height of a well-propor- 

 tioned man); four palms are difoot, or a 

 6th of the height of a man ; a foot and a 

 a half isa CMfet^, measured from the elbow 

 to the ends of the extended fingers, the 

 4th of the height of a man ; ten palms, or 

 two feet and a half are a step (gressus) ; 

 two steps, or five feet, are a. pace (passus) ; 

 ten feet are a perch; a hundred and 

 twenty-five paces are an Italic stadium ; 

 eight stadia, or a thousand paces, are an 

 Italic mile ; four Italic miles are a Ger- 

 man mile ; and five Italic miles are a 

 Swiss mile. 



WEISS-ERTZ. The name given by 

 Werner to some varieties of arsenical 

 pyrites or mispickel, which contain acci- 

 dentally admixed silver. 



WELDING. A property of certain 

 metals, as platinum, by which at a white 

 heat, an incipient fusion takes place, 

 which covers their surface with a kind 

 of varnish, so that, when brought into 

 contact in this state, different species may 

 be permanently united by forging. 



WELTER'S THBE. A safety-tube, 

 introduced into a Woolfe's bottle, to pre- 

 vent retrograde pressure. The tube is 

 twice curved and expanded at one part 

 into a bulb; water is poured into the 

 S76 



tube till the bulb is half full ; when ab- 

 sorption takes place, the water rises in 

 the bulb until none remains in the tube, 

 and then the air rushes in ; on the other 

 hand, no gas can escape, since it has to 

 overcome the pressure of a high column 

 of water in the perpendicular tube. 



WENLOCK LIMESTONE and 

 SHALE. A component part of the Upper 

 Silurian Rocks, 1800 feet in thickness; 

 it consists of a crystalline grey or blue 

 limestone, abounding in corals, encrinites, 

 marine mollusca, and crustaceous ani- 

 mals of the trilobite family; and a dark- 

 coloured shale, with nodules of earthy 

 limestone, and containing mollusca and 

 trilobites. 



WERNERIAN THEORY. Werner 

 supposed that all the geological strata 

 were originally in solution in an aqueous 

 fluid, from which they were deposited or 

 precipitated. The first deposits were in 

 crystals, and constituted his primitive 

 rocks ; these contain no fossils. The 

 deposits he termed ' formations,' and he 

 taught that ' the exterior of the earth 

 consists of a series of these formations 

 laid over each other in a certain deter- 

 minate order.' 



1. The next deposits he called trans- 

 ition formations, or secondary rocks; the 

 former term denoting that the earth was 

 passing into a fit state for animals and 

 vegetables. These rocks contain fossils, 

 or alternate with those which do so. 



2. A third series was then deposited, 

 formed in great measure from the de- 

 struction of the primitive and the transi- 

 tion formations, and containing numerous 

 fossils. From their greater approach to 

 the horizontal position, Werner termed 

 them floetz. 



WE'RNERITE. Under this name, 

 which was formerly restricted to some 

 varieties of common and compact scapo- 

 lite, are now united the meionite of Vesu- 

 vius, and the greater part of the scapolite 

 of Werner, the paranthine and also the 

 dipyre — substances which stand in need 

 of further investigation as to their che- 

 mical and crystallographical characters. 



WHEEL AND AXLE. One of the 

 mechanical powers, consisting of two 

 cylinders, having their axes coincident, 

 the two cylinders forming one rigid piece, 

 or being cut from the same piece : the 

 larger is called the wheel, the smaller tlie 

 axle. The cord by which the weight is 

 suspended is fastened to the axle and 

 coiled round it; the power acts some- 

 times by a cord coiled round the wheel ; 



