MINE. 



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ICCLXXX 

 Kig. 7. 



ig. . 



Lime stone, which abounds with organic remains, 

 particularly if it is of some considerable thickness, is, 

 in many cases, an index to a coal-field ; as it is much 

 harder than the common strata of a coal-field, it crops 

 frequently cut to day, that is, it is distinctly seen at 

 the surface. We find also, that these thick beds of 

 limestone are commonly found in the lower series of 

 the strsta of the coal formation, for which reason, where- 

 ever a bed of this kind of limestone is found, the dip 

 should be first ascertained, and then the coals searched 

 for in the line of dip ; for although coals, and their ac- 

 companying strata, exist to a great depth under these 

 beds of limestones, it seldom happens that any coals 

 of good quality, or workable thickness, are found there. 

 If a district of country is to be surveyed, in which 

 are mountains, or elevated ground abounding with 

 rocks, these require in the first place to be surveyed. 

 In roost instances there is no great difficulty in deter- 

 mining to what class of rocks the mountain formation 

 belongs, as some part of them is laid open by the 

 streams of water with which they generally abound. 

 If it is found they are composed of primitive or secon- 

 dary rocks as before enumerated, it is certain that no 

 coals will be found under them ; therefore the next 

 point to be ascertained is, the dip of these rocks, be- 

 cause in searching for a coal-field, it will be necessary 

 ta follow the primitive rocks in the line of dip, as the 

 others follow in overlying succession. If the coal forma- 

 tion exists in that district, it v-ill be found by tracing 

 forward in that direction, and if found at the foot of pri- 

 mitive or secondary mountains, the strata of the coal- 

 field will be found lying in a conforming situation with 

 the face of the mountains, and forming a very great 

 angle with the horizon. If the coal formation exist* 

 at the foot of such mountains, it will bo in most case* 

 easily discovered in the ravines and hollows formed by 

 the mountain streams; and in many instances the coal 

 and accompanying strata are seen so clear and distinct, 

 that the operation of mining and working the coal may 

 be immediately commenced without farther investiga- 

 tion ; but as the edge coals are more difficult and ex- 

 pensive to work than the flat coals, it may be desirable 

 to trace the coal-field farther onward. It has been 

 found from experience, that when edge coals are thus 

 found resting upon primitive or secondary rocks, that 

 they form part of a great bason, and that after dipping 

 to considerable depth, they begin to deflect from their 

 vertical line and form a hollow, or, what is termed by 

 miners, a trough or bason, upon the opposite side of 

 which the edge coals are found forming flat coals, ris- 

 ing in an opposite direction, a* represented in Plate 

 '.XX XIX. Fig. 7. where I is the transition rock*, 

 and a, b the coals in the coal-field, A forming a trough 

 or ! MaV 



There are also instances of coal-fields where the edge 

 coals have been wrought to a considerable depth with- 

 out any symptom of their deflecting, and adjoining 

 them flat coals are found cropping or rising toward* 

 the edge coals, as represented Fig. 0. We are inclined 

 to think that, in this instance, the edge coals, a, b, c, 

 pass under the flat coals, d, e,f, at a great depth, and 

 defecting from the vertical line form the flat coals of 

 the bason, a, b, c, on the opposite side ; and that the 

 grent baton, formed by the edge coals thus deflecting, 

 is filled up by a distinct set of flat coals and their 

 accompanying strata, d, t, f. We are of opinion 

 the very interesting coal-field, south from Edin- 

 burgh, is of this kind of formation. All these varieties 

 now and formerly described, require to be kept in 



view, together with the various dislocations and Mines of 



troubles incident to coals. In prosecuting the search 



for coals beyond the edge coals, it generally happens S "~V" 



that a short distance from the mountain foot or rising 



ground, the alluvial cover prevents the rocks or strata 



being any more seen ; in this case, the whole district 



under survey must be minutely investigated, in parti- 



cular all broken ground, bed* of rivers, quarries, anil 



new.fonned ditches, where it is probable, if the alluvi.il 



cover is not very thick, some vestiges of the strata will 



be seen, but if no vestiges of the strata can be discov- 



ered, the next step is to proceed with pitting and bo- 



ring. 



The foregoing rules are such as are at present adopt- 

 ed in surveying a district of country in which no coal 

 is known to exist. 



The next cae is the searching for coal in a district Searching 

 of country where the coal formation is known to exist, Tor coal in 

 or where coals are working at no great distance from <linri 



where the 



If it is only .known that the coal formation exists in ^J 

 the district, without any particular account of the beds | lncwn ., 

 of coal, the dip, line of bearing, or form of the coal- exit. 

 field ; the survey and investigations must be proceeded 

 in according to the rules laid down, connected u ith 

 the particular circumstances of the surface of the coun- 

 try under turvey ; and if coal cannot be discovered by 

 minute investigation, the search must proceed by means 

 of pitting and boring. 



If coals have been wrought, or are working in the 

 district of country under survey, particular inquiry 

 muit, in the first place, be made, as to the quality and 

 thickness of the coals, their general dip, line of bear- 

 ing, and shape of the coal-field, also if any dikes or 

 slips are known to exist, and if they do, to learn their 

 line of bearing, and extent of the dislocations of the 

 strata produced. The form of the coal-field is impor- 

 tant, as without knowledge of this, much difficulty 

 and great mistakes may be the consequence. When nu- 

 merous collieries are opened in a district of country, 

 the subterranean geography of the strata is well 

 known, the series or cystem of beds of coal compos- 

 ing the coal- field are ascertained, with their accompa- 

 nying str.ita; and to an experienced miner they are as 

 well known as the leaves of a book, excepting in case* 

 where great derangement and dislocation of the strata 

 have taken place. It is also of importance to know if 

 the coals are liable to Mich troubles as alter their qua- 

 lity, render them thinner, or if they are separated oc- 

 casionally by bands of stone, which in some instances 

 separate the upper and lower parts of the bed of coal 

 to such an extent as to form two coal*. 



The same general survey and investigation of the 

 district must be followed according to the rules for- 

 merly laid down ; and if no distinct view of the coals 

 or strata can be seen, so as to draw accurate conclu- 

 sions, the farther investigation must proceed by bor- 

 ing, care being taken not to overstep the coal-field or 

 beds of coals which are known to exist. This mistake 

 will take place with the most cautious, if the form of 

 the coal-field is not known and attended to. 



The art of boring for coal is one of the chief point* Baring for 

 in mining, in order to ascertain the strata and beds of coal. 

 coal, before any great operation is commenced in win- 

 ning or establishing a colliery, in which a great capital 

 is frequently invested. 



The rods commonly used are made of the best Swe- 

 di-h iron, about an inch and a quarter square; each rod 

 is three feet in length, having a male screw at the one 



