C L I 



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O A 



support themselves by means of their 

 tendrils, or adhesive fibres. 



CLI'NKSTONE. (So named from its yield- 

 ing a metallic sound when struck.) 

 Called also phonolite, a felspathic rock of 

 the trap family. In basalt or wacke, 

 when the felspar greatly prevails, and the 

 texture becomes nearly compact, basalt 

 passes into clinkstone ; again, when clink- 

 stone has a more earthy texture, it passes 

 into claystone. Clinkstone often contains 

 imbedded crystals of felspar, and then 

 becomes a trap-porphyry, varying in 

 colour according to the prevailing ingre- 

 dients of its base. The colour of clink- 

 stone is grey, of various shades. 



CLINO'METER. (from K\iva> and /jgrpov, 

 Gr.) An instrument, invented by R. 

 Griffith, Esq., for measuring the dip of 

 mineral strata. 



CLO'VEN. In botany, leaves are called clo- 

 ven, when the margins of the segments 

 and fissures are straight. 



CLO'VATE. In corichology, thicker towards 

 the top, elongated towards the base. 



CLUNCH. A provincial term for a sort of 

 indurated clay which is found dividing the 

 coal seams. 



CLY'PEUS. (Lat.) A division of the first 

 class of echinites. The fossil echinites of 

 the second division of anocysti are distin- 

 guished as clypei, from their similitude in 

 form to the round bucklers of the ancient 

 foot-soldiers. 



COAL, (col, Sax. kol, Germ, kole, Dutch.) 

 Coal is composed of charcoal, bitumen, 

 and earthy matter ; the latter forms the 

 ashes which remain after combustion. 

 Common coal is a black, solid, and com- 

 pact substance, generally of a foliated, or 

 rather laminated, structure, which neces- 

 sarily directs its fracture. Its specific gra- 

 vity is T25 to 1'37. It cakes into cinders 

 during combustion in proportion to its 

 degree of purity, and the nature of the 

 earths which enter into its composition. 

 Coal has obtained various names from va- 

 rieties of appearance, hardness, situation 

 whence obtained, &c. &c. 



COAL FORMATION. The carboniferous group 

 succeeds the grauwacke in the ascending 

 series of Europe, and is so called because 

 the great mass of European coal is in- 

 cluded among the rocks of which it is 

 composed. Considered in its greatest 

 generality, and with reference to where 

 the masses appear in the greatest simpli- 

 city, the carboniferous system consists of 

 three formations, namely, the coal forma- 

 tion, a mass 1000 yards or more in thick- 

 ness, consisting of indefinite alternations 

 of shales and sandstones of different kinds, 

 with about fifty feet of coal in many beds, 

 some ironstone layers, and (very rarely) 

 thin layers of limestone ; mountain lime- 



stone, a mass of calcareous rocks, from 

 500 to 1500 feet in thickness ; and old 

 red sandstone, a mass of arenaceous and 

 argillaceous rocks, varying in thickness 

 from 100 to 10,000 feet. The total thick- 

 ness of coal existing in the English and 

 Scotch fields is generally about 50 or 60 

 feet, divided into 20 or more beds, of a 

 thickness of from six feet to a few inches, 

 alternating with from twenty to fifty or 

 one hundred times as great a thickness of 

 shales and sandstones. Every coal dis- 

 trict has its peculiar series of strata, un- 

 connected with any other. A district 

 with its peculiar series of strata is called 

 a coal-field. Coal-fields are of limited 

 extent, and the strata frequently dip to a 

 common centre, being often arranged in 

 basin-shaped concavities, which appear to 

 have been originally detached lakes, that 

 were gradually filled up by repeated depo- 

 sitions of carbonaceous and mineral mat- 

 ter. In some of the larger coal-fields, the 

 original form of the lake cannot be traced, 

 but in the smaller ones it is distinctly 

 preserved. The stratum lying over a bed 

 of coal is called its roof, and the stratum 

 under it, the floor. On the eastern side 

 of England, the coal strata generally dip 

 to the south-east point : on the western 

 side the strata are more frequently thrown 

 into different and opposite directions, by, 

 what are termed, faults and dykes. A 

 fault is a break or intersection of strata, 

 by which they are commonly either sud- 

 denly raised or depressed, so that in 

 working a coal-mine, the miners come 

 suddenly to its apparent termination. A 

 dyke is a wall of mineral matter which 

 from igneous or volcanic action has forced 

 upwards through the strata, cutting them 

 in a direction nearly vertical. In these 

 cases sometimes the coal is reduced to a 

 cinder for some distance on either side of 

 the wall or dyke. One of the green-stone 

 dykes of Ireland, passing through a bed of 

 coal, has reduced it to a cinder for the 

 space of nine feet on each side. Our an- 

 cient coal formation has not been found 

 in Italy, Spain, Sicily, or in any of the 

 more southern countries in Europe. Coal 

 is now universally admitted to be of ve- 

 getable origin, a question which was long 

 disputed. It is not uncommon to find 

 among the cinders beneath our grates, 

 traces of fossil plants, whose cavities 

 having been filled with silt, at the time of 

 their deposition in the vegetable mass, 

 that gave origin to the coal, have left the 

 impression of their forms upon clay and 

 sand enclosed within them, sharp as those 

 received by a cast from the interior of a 

 mould. Mr. Hutton has recently disco- 

 vered the most decisive and indisputable 

 proof of the vegetable origin even of the 



