EAR 



E AS 



trees, commonly called heartwood, as dis- 

 tinguished from the exterior portion, 

 alburnum, or sapwood. 



DUTCH GOLD. An alloy of copper 

 and zinc, in which the zinc is in greater 

 proportion than it exists in brass. It is 

 allied to tombac and pinchbeck. 



DUTCH MINERAL. Metallic copper 

 beaten out into very thin leaves. 



DUTCH PINK. Chalk or whiting, 

 dyed yellow, with a decoction of birch 

 leaves, French berries, and alum. 



DYES. Colouring matters derived from 

 vegetable substances. See Lakes. 



DYKE or DIKE (a provincial name 

 for wall). A term applied to a mass of 

 the unstratified or igneous rocks, as 

 granite, trap, and lava, when it appears 

 as if injected into a rent in the stratified 

 rocks, cutting across the strata. A mass 

 of this kind is sometimes seen running 

 along the ground, and projecting, like a 

 wall, owing to the softer strata on both 

 sides of it having wasted away. A dyke 

 differs from a vein in being generally of 

 larger dimensions, and having its sides 

 parallel for a considerable distance ; while 

 a vein has generally many ramifications, 

 and these often become gradually reduced 

 to slender threads. 



Dyke is also the name given to a mound 



of earth, stones, &c., employed as a bar- 

 rier against inundation by the sea, as the 

 dykes of Holland. 



DYNA'MICS (auva/itf, force). That 

 branch of mechanics which relates to 

 the action of forces which are not in 

 equilibrio. It, therefore, treats of bodies 

 in motion. See Statics. 



DYNAMIC THEORY. A theory for 

 explaining the nature of matter, or the 

 mode of its formation, invented by Kant. 

 He supposed that all matter existed or 

 was originated by two antagonist and 

 mutually counteracting principles, which 

 he called attraction and repulsion, all 

 the predicates of which he referred to 

 motion. See Atomic Theory. 



DYNAMO'METER {buvanii, force, 

 juerpof, a measure). A measurer of 

 power; an instrument for measuring, 

 with accuracy, the magnifying powers of 

 microscopes and telescopes, the force of 

 machinery, the strength of animals, &c. 



DYNA'STlDiE {bwdarn^, a master). 

 A family of beetles, comprehending the 

 giants of the Coleopterous order, remark- 

 ably powerful in excavation. 



DYSO'DILE (5i/crti3nf, fetid). A mi- 

 neral found near Syracuse, emitting, on 

 combustion, an insupportably fetid odour. 



E 



EAGLE STONE. Aetites lapis, A 

 globular clay iron stone, supposed to 

 have been found in the nest of the eagle. 



EARTH. Terra. A planet of the 

 solar system, the orbit of which lies be- 

 tween Venus and Mars. It revolves 

 round the sun in 365 days, 5 hours, and 

 48 minutes, at the distance of 95 millions 

 of miles. Its diameter is 7912 miles. 

 Its rotation upon its axis furnishes a 

 uniform measure of time, called the 

 sidereal day. 



EARTH (in Chemistry). A solid, 

 opaque, friable substance, without lustre, 

 and incombustible; it is thus distin- 

 guished from metals on the one hand, 

 and from carbon and other combustible 

 substances on the other. In chemical 

 language, the earths are termed metallic 

 oxides, and formerly, earths of the metals. 

 Four of these, viz. baryta, strontia, 

 lime, and magnesia, are termed, from 

 their properties, alkaline earths. 

 114 



EARTH OF ALUM. A preparation 

 used for paints, and procured by preci- 

 pitating the earth from alum dissolved 

 in water, by adding ammonia or potass. 



EARTH OF BONE. A phosphate 

 of lime, sometimes called bone phos- 

 phate, existing in bones after calcina- 

 tion. 



EARTH-FALL. A natural pheno- 

 menon which occurs when portions of the 

 earth's surface are elevated, then cleft 

 asunder and depressed, the space once 

 occupied by soHd earth becoming covered 

 with water. 



EARTHQUAKE. A sudden motion 

 of the solid surface of the globe, probably 

 occasioned by the same causes as those 

 which produce volcanic eruptions. 



EAST. That point of the compass 

 which is in a direction at right angles to 

 that of the north and south, and towards 

 the right hand of the spectator when 

 facing the north. It is that point of the 



