I N E. 



321 



PLITE 

 CCCLIXXIX. 

 F. 1- 



FltT* 

 CCCLIXXTI11. 



Fig. ia 



in prosecuting the mine, as at C, a dike, D, U met with, 

 which forms with the pavement a right angle, viz. of 

 90", 't i concluded that the dike only has divided and 

 Dikes and separated the strata its own thickness, so that when a 

 lip*- mine is driven through it, the coal is found directly op- 



posite ; but, in the further prosecuting of the mine, if 

 a dike, F, is met with as at E, which forms an obtuse 

 angle with the jiavement, that is an angle greater than 

 9<)*, it :s concluded that the dike has not only divided 

 and separated the strata its own thickness, but has 

 thrown up the coal and accompanying strata, which, on 

 running a mine through the dike, is found to be the 

 case as at G. Lastly, if a dike H is met with at I, forming 

 an acute angle with the pavement, as in the figure, that 

 is, an angle less than 9p degrees, it is concluded that 

 the dike has not only divided and separated the strata 

 its own thickness, but has thrown down the coal and 

 accompanying strata, which, on running a mine though 

 the dike, is found to be the case as at K. 



The ame very useful and important law hold* as to 

 slips, with this difference, that, when the slip forms an in- 

 gle of <X> with the pavement, there is a great uncertain- 

 ty whether the strata on the other side are thrown up or 

 down ; and this can only be proved by mining and l>or- 

 ing ; only it must be remarked, that if, in perforating 

 the slip, the coal is found neither thrown up or down, 

 the occurrence is not a slip, but simply a fissure of the 

 ttrata. 



Dikes and slips are denominated upthrow or down- 

 throw, according to the position in which thry are 

 met in working the mine. Thus, in Fig 10. Plate 

 I.XXXV1M. if the miner is advancing to the rise, 

 the dike AR neither throw* up nor down. CD is a 

 down-throw dike to the rise of a certain number of fa- 

 thoms, and EF is an upthrow dike also to the rise. On 

 the contrary, if the dike* are met with in working from 

 the rue to the dip, the names of the dikes, as to being 

 upthrow and downthrow, are exactly reversed ; vii. 

 what was an upthrow in the first instance, is a down- 

 throw in the second , and, in meeting the dikes or slips 

 this reverse way, the same law of course holds as to the 

 angle formed by the pavement, and the intersecting 

 line of the dike or slip. 



In the Mir.e manner, dikes and slips, which run from 

 the dip to the rise direction, are denominated upthrows 

 or downthrows, to the east, to the west, to the south, or 

 to the north, according to the line of bearing of the 

 coal-field, and the direction in which the dikes or flip* 

 are met with in the mine ; so that a dike or slip which 

 is an upthrow tn the east, when pursuing the coal mine 

 eastward, is a downthrow dike or slip, when pursuing 

 the coal mine westward. 



Hitches are lij.* of the strata of a small size, and 

 are so denominated when the slip nr dislocation does 

 net exceed the height of the coal ; they are frequently 

 very small, even the least part of an inch, yet though 

 of the smallest sise, their effects are distinctly visible 

 fleeting the coal. Hitches are frequently denominat- 

 ed, very appropriately, itept by the miner. (Plate 

 \IX Fig. 2. shews the effect of hitches 

 upon the strata, where the hitches A, B. C, D, E, F, ( . . 1 1 . 

 l:-'<K-ate the coal and accompanying strata. At A 

 th- hitch is the height of the coal, at B it is half the 

 height up, at C and D the effect is less, at E it is near- 

 ly the height of the coal, at F the effect is scam 

 sible, at O it it down, and at H the coal is again 

 thrown up tn the extent of its height Hitches do not 

 extend generally very far, either in a longitudinal or in 



VOL. XIV. PA HI 1. 



Mines of 

 Cos). 



Ilncliei. 



PLAT* 



CCrtdxlX. 



Fig. I. 



a perpendicular direction ; for though they may be 

 found in one or two coals in a coal-field, they may not 

 lie seen in the upper or under coals, so that their ef- 

 fects in the coal-field are commonly very limited when 

 compared with the effects of dikes or of slips. 



Trouble*. These affect the stratum or bed of coal, 

 and are of various kinds, as before mentioned, viz. 



1st, Stone in irregular brdt.This trouble sometimes Troubles in 

 begins as a horizontal division in the coal scarcely visi- the **& of 

 ble, gradually increasing in thickness, and that fre- co *' i 

 quently to such a degree as to render the coal altoge- 

 ther unworkable ; in a thick bed of coal, a stone of this 

 kind sometimes increases from a line even to several 

 fathoms in thickness, in which case one or other of the 

 portions of the coal thus divided, is either abandoned 

 as unworkable, or each of the two divisions is wrought 

 as separate and distinct coal. It is to be remarked, 

 that the two portions of coal are together generally 

 equal in thickness to the bed of coal before the stone 

 nude its appearance ; if however bands of stone or of 

 argillaceous clay are found lying regularly through 

 coals in a coal-field, these are nut reckoned troubles. 



2d, Nipt. This is a very remarkable trouble in 

 coal, and is not very common ; it is produced by the 

 roof and pavement of the coal gradually approaching 

 each other, until not a vestige of coal is to be seen. 

 The extent of this trouble is from an area of a few feet 

 to that of many acres. The horizontal form of a nip is 

 very irregular, and when found, no idea can l>e funned 

 of its extent ; it is frequently the case, that if the coal 

 has an argillaceous roof and pavement, these disappear 

 with the coal, and the upper nnd under harder suata 

 of sandstone are in contact, divided only by a very Pun 

 thin sooty line. Plate CCCLXXXIX. Fig. 3. repre- CCCLMXIT. 

 ents the vertical, and Fig. 4. the horizontal section of K 'fc> * & 

 a nip. * 



3d, Shaken Coal. By this trouble the texture of the 

 coal is not only destroyed entirely, but the whole of 

 the coal from roof to pavement is of no use whatever; 

 the roof and pavement generally keep their common 

 parallelism, and no convulsion is to be observed in the 

 adjoining strata. The shaken coal has the appearance 

 of the rubbish of an old coal watte, being a heteroge- 

 neous mass of dusty coal, mixed with small cubical 

 pi acts of good coal. This shaken coal is so soft, that 

 frequently it can be dug with a spade. 



4. Foul Coal. This denomination of trouble is ap- 

 plied to no specific kind of coal, every coal which is 

 deteriorated in quality, or so mixed with heterogeneous 

 matter as to be useless, or the greater part so, is de- 

 nominated fuul coal. 



;">. I'yrilaceoHM Coal, or the Brain Coal of the miner*. 

 This trouble arises from the coal being so mixed nnd 

 entwined with p\ rites as to be of no use at coal. It 

 may be remarked, however, that the term pyritaceouR 

 coal is not applicable to those coals which have pyrites 

 in them of a lenticular form, and which can with ease 

 be separated from the coals, for these do not deteriorate 

 the quality of the coal, as they are picked out. 



^l*>rry CooL This trouble arises from the coal 

 having an increased number of fissures together, and 

 filled with a hard white sparry suhttance, the sulphate 

 of lime, so that the coal is rendered useless and very 

 difficult to work. 



7. Slonry Coal. This trouble arises from the coal 



becoming very much mixed with stone in an irregular 



manner. These stones do not lie in regular beds; and 



they are so intimately joined or connected witlt the 



2 s 



