DIE 



[ 136] 



D I K 



DI'ELECTIC. (from Sta, through, and 

 ijfXe/cT/x?!/, Gr.) Any body through 

 which the electric fluid may be 

 transmitted. 



DIGA'STRIC. (from $l<* and 

 Gr.) Having two bellies. 



DI'GITAGRADA. In Cuvier's arrange- 

 ment, the second tribe of carnivora. 

 The name digitagrada has been 

 applied to them from the circum- 

 stance of the animals which com- 

 pose this tribe walking on the ends 

 of their toes. The lion, wolf, and 

 hyaena are examples. 



DI'GITATE. j (digitatus, Lat.) A 



DI'GITATED. j sort of compound 

 leaf, composed of two or more 

 leaflets. Botanists include under 

 the name digitate, binate and ternate 

 leaves, as well as those having more 

 than five leaflets, as the horse- 

 chesnut, which has seven leaflets. 



DIGY'NIA. (from Sis and <ywrj, Gr.) 

 The second order in Linnaeus' s 

 artificial system, comprehending 

 such plants as have two styles, or 

 pistils. 



DIGY'NIAN. } Having two styles, or 



DIGY'NIOTJS. ) pistils ; belonging to 

 the order Digynia. 



Sax. die, Germ. deic\ D. dyJc. 



1 . A ditch ; a channel to receive 

 water. 



2. A mound ; defence; wall; for- 

 tification. 



3. Geologists use the word dike to 

 express a wall of mineral matter, 

 cutting through strata in nearly a 

 vertical direction. Trap dykes are 

 to be found in all parts of the 

 world, the composition of the rock 

 varying materially, even in the 

 dyke itself. Dykes are often of 

 great extent; one of the longest 

 with which we are acquainted has 

 been described by Prof. Sedgwick, 

 reaching from High Teesdale to 

 the confines of the eastern coast, a 

 distance exceeding sixty miles. 

 The trap dykes of Ireland have 

 been traced upwards of sixty 



miles, and they are found cutting 

 through all the stratified rocks, 

 from the gneiss to the carboni- 

 ferous limestone inclusive. They 

 are known as greenstone, porphyry, 

 basaltic or other dykes, according 

 to the kinds of rock of which they 

 are composed. Lyell observes, 

 " That it is not easy to draw the 

 line between dikes and veins ; the 

 former are generally of larger 

 dimensions, and have their sides 

 parallel for considerable distances ; 

 while veins have generally many 

 ramifications, and these often thin 

 away into slender threads." 



In the coal districts, the dykes 

 are an endless source of difficulty 

 and expence to the coal-owner, 

 throwing the seams out of their 

 levels, and filling the mines with 

 water and fire-damp. At the same 

 time they are not without their 

 use ; when veins are filled, as is 

 often the case, with stiff clay, 

 numerous springs are dammed up 

 and brought to the surface ; and by 

 means of downcast dikes valuable 

 beds of coal are preserved, which 

 would otherwise have cropped out 

 and been lost altogether. "What- 

 ever be the throw or difference of 

 level occasioned in the coal mea- 

 sures by these dikes, it never 

 happens, as might be expected, 

 that a precipitous face of rock is 

 left on the elevated side; or that 

 the lower side is covered by an 

 alluvial deposit, which connects 

 the inequality of the beds that are 

 in situ ; but the surface of the 

 ground covering the vein is rendered 

 level by the absolute removal of 

 the rocky strata on the elevated 

 side. The coal in contact with 

 the dykes is sometimes charred, 

 and resembles exactly the coke 

 obtained by baking coal in close 

 iron cylinders, in the process of 

 distilling coal-tar. In some parts 

 the coal is deteriorated to the 

 distance of twenty yards from the 



