COAL. 



701 



Coach- 



waking, 



Coal. 



PLATE 

 CXCIX. 

 Fif. 4. 



A and D, act as a itrir.g to a bow, preserving die fitch- 

 ell stays DCC in their curve against the pressure of the 

 carriage ; H, the fore, and G the hind socket for the 

 pole; K, the splintree bar and roller bolt ; E, the top of 

 the perch bolt. The splintree stays are left out here for 

 the same reason as before. 



Fig. 4. is a representation of the front of the fore or un- 

 der carriage : MM the axletree ; AB the locking wheel 

 and transome plate ; KL, the splintree bar ; DC, DC 

 the fitchell stays ; MN, MN, the splintree stays ; AM, 

 B M two strong stays which connect the locking wheel 

 and axletree at the shoulders ; H the fore, and G the 

 hind socket for the pole ; EF the perch bolt. 



In Figures 2, 3, and 4, the several letters apply to the 

 corresponding parts. 



We have been thus particular in our description of 

 these improvements, from the originality and simplicity 

 of the principles upon which they are constructed, and 

 from the ingenuity of their execution. To have supposed 

 it possible to have made a carriage without a mortice 

 or tenon, or wooden joint of any kind, would, only a short 

 time ago, have been considered as absurd, but in the pre- 

 ceding construction this has been completely accomplish- 

 ed ; and we cannot help thinking, that this of itself must 

 be of great importance to all carriages, but more particu- 

 larly to those for public use, where durability is the prin- 

 cipal requisite. But this improvement appears equally 

 applicable to carriages generally, as from the nature of 

 the materiel made use of, it is not additional strength 

 alone that is procured, but variety of shape, elegance, 

 and lightness ; for we are assured that these carriage* 

 are at an average one seventh lighter than those built 

 on the ordinary construction.* (v) 



COAL is an inflammable substance, of a very black 

 colour, somewhat shining, opaque, soft, dry, and light in 

 comparison with any ofthe strata in which it is found. 

 It occurs in bcda varying in thickness from an inch to 

 many fathoms. 



It is used for fuel, and is found widely scattered over 

 the globe. The most valuable and extensive beds of 

 coal which have been found and wrought, are in Great 

 Britain. 



This mineral is nerer found in the primitive nor tran- 

 sition rocks, but in a third class of rocks very regularly 

 stratified, the most common of which are, 1st, sandstone, 

 2d, slate clay ; 3d, indurated or fire clay ; 4th, argillaceous 

 iron stone ; 5th, limestone ; and 6th, greenstone. Of the 

 two first there are very many varieties, both in respect of 

 colour and hardness. In the coal, and in all its accom- 

 panying strata, distinct organic remains are found be- 

 longing to the animal and vegetable kingdom : the jrreen- 

 stone, nowevcr, is an exception, as it is questioned whe- 

 ther any organic remains have ever been found in that 

 rock. In the sand stones, the forms of large trees, and 

 jointed reed?, (arundo,) are found abundant, but impres- 

 sions of shells re very rare. In the slate clay, the forms 

 of large trees are seldom teen, but innumerable impres- 

 sions of leaves, ferns, and moss plants, (cryptqgamia,) are 

 found in the area of a few feet ; and it it remarkable that 

 where the forms of shell fish are found in this kir.d of 

 strata, they are never of the same substance as the ma- 

 trix, but are always of argillaceous iron stone embedded 

 in the slate clay. In the fire clay, a branched tree of 

 singular appearance is most frequently found. The iron 

 stone abounds with forms and impressions of plants, but 

 more frequently with the forms of shell lisa of the class 



Mytelus. The upper part of the coals have frequently the Cuai. 

 distinct impressions of large trees, and the lime stone is in 

 many instances a congeries of marine animals. In the 

 sand stone, where forms of trees are found, the bark or 

 exterior part is of coal only, which is very thin, of a bright 

 shining black colour, and cubical. 



From the very regular stratification of this iield of the 

 mineral kingdom, the vast beds oi inflammable matter it 

 contains, the great abundance of organic remains found 

 in it, and as none of the primitive or secondary rocks 

 are connected with the strata, it has therefore very pro- 

 perly been denominated by the celebrated and great mi- 

 neralogist Werner, the independent coal formation. 



Coals, with their various accompanying and parallel 

 strata, are found lying in every inclination to the hori- 

 zon. Some of them are vertical, others nearly horizon- 

 tal, but never absolutely so to any considerable extent. 

 The most common dip or declination is from 1 in ,">, 

 to 1 in 20. A bed of coal, as to its form or shape, con- 

 sidered in the abstract, is generally somewhat semicir- 

 cular or semi-elliptical ; and is the segment of a flat ba- 

 son. There are some instances where the bason shape L 

 complete, the slips and dislocations of the strata which 

 occur, derange the general form ; still, however, each 

 segment evidently partakes ofthe bason form. In some 

 few instances the form is quite the reverse, as if the coal 

 bed was formed by being revolved round a cone. The 

 vertical coals do not partake of this bason shape, whicb- 

 might be easily inferred from their peculiar situation. 



We are inclined to conclude from practical observa- 

 tion, that the forms of coal fields depend upon the shape 

 of the primitive or secondary rocks, upon which they 

 certainly rest. Coals, we believe, and as far as our in- 

 vestigation goes, are never found in veins in the moun- 

 tain rocks, similar to those in which metals occur. 



The coal formation is found chiefly in the northern 

 hemisphere, and abounds in the countries lying nearly in 

 the same latitudes with Great Britain. Coal ia found, 

 in Siberia, Canada, Newfoundland, and Cape Breton ; 

 also in France, Germany, and Sweden. It is likewise said 

 to be found in the northern parts of China . In the south- 

 ern hemisphere, it i stated to be very abundant in New 

 Holland, but we have no distinct accounts of coal in the 

 continent of Africa. 



As to the surface of the ground under which coal i* 

 found, it is much doubted if any peculiar character ex- 

 ists, (as has been advanced by some mineralogists) in Great 

 Britain. It is found under every variety of surface, ex- 

 cepting the wild and rocky mountains. It is, how- 

 ever, to be remarked, that a great part of the valuable 

 and extensive coal field of South Wales, is found in a 

 mountain district, and the strata of the coal field form 

 these mountains even to their summits, which are ele- 

 vated not only very much above the level of the sea, but 

 also above the adjoining country. These hills are smooth 

 ud covered with verdure, aud present no rocky cliffs 

 on account of their comparatively soft strata. Hence 

 the existence of coal in .any district of 'Country, not moun- 

 tainous, cannot be deduced from the appearance of the 

 surface, but rather from the relative situation of the par- 

 ticular district with respect to the rocks of the primitive 

 or secondary class. 



Of coals there -are various f.peciea, viz. 



1. Cubical Coal Is black-shining, compact, and TOO- Cubical 

 tkrately hard; when wrought, it turns out in quadran- coaU 

 gukr masses, and when broken small, the fragments we 



" We are bappy to bave it in our power to lay before our rekr n acoount -of the great improvements which have been recently 

 made ii|x>n carriages, by II. R. BUOWM, <q. Edinburgh. .The uncommon cKgance of the carriages which he lias constructed, and tho 

 great ingenuity which is displayed in the formation of hi ptium aaJetrce and wheels, will do more to recommend tlwin to notice, 

 than any praise oCcurs ; and We tiav? no doubt but that the inventor and patentee Yi'iin>e rewarded by the patronage of the public, tfii* 



