330 



M I N E. 



Mines of the coals will be deeper than calculated ; in large ba- 

 Coai. sons this difference in the line of bearing will not be 

 much when at a moderate distance from the dip-bore-, 

 kut m a snla " bason the difference will be found con- 

 siderable, for this very evident cause, that if the bason 

 is not broken by dislocations of the strata, all the coals 

 crop or come to day, in the line of bearing. Having 

 these corrections in view, if the coals are found at a 

 depth corresponding to the calculations made from 

 practical data, it may be concluded that the coals are 

 Jying in that field, so far as proved, fair and regular ; 

 but if these bores require to be put down to a much 

 greater depth than was calculated upon before striking 

 the coals found in the bottom of No. 4. ; or if these 

 coals are found much sooner than was expected, it 

 may be then concluded that a slip or dislocation of the 

 strata exists betwixt the two bores, throwing down the 

 strata in the first instance, or throwing them up in the 

 second. Under such circumstances a few additional 

 bores will be required, to ascertain the coal field still 

 farther, and the line or direction of the slip, particu- 

 larly if the dislocation is of considerable magnitude. 

 The position of such bores can only be determined on 

 by weighing every circumstance which may occur 

 while the operation of boring is carrying forward. 



If in proceeding with a series of bores where the 

 line of dip is not known, nor conesquently the line of 

 bearing, it is an important and primary point to ascer- 

 tain this, not only as regarding the situation of the 

 coal-field, but how it ranges within an estate or parti- 

 cular property. The mode practised is by putting 

 down three bores in the following position. Suppose 

 a bore No. 1. (Fig. 3. Plate CCCXC.) put downjwhich 

 reaches a coal at the depth of 50 yards, at the dis- 

 tance of 300 yards a place is marked for No. 2. bore 

 at B, and a place for No. 3. bore at C, equidistant 

 from No. 1. and No. 2., so that the bores are placed 

 at the angles of an equilateral triangle ; then suppose 

 the bores No. 2. and 3. to be put down, and that the 

 coal is found in No. 2. at the depth of 30 yards, and in 

 No. 3. at the depth of 44 yards, from this it is evident 

 that neither of the lines AB, BC, or CA, are in the 

 line of level, which in short distances, as before men- 

 tioned, approximates to the line of bearing, particularly 

 in coals which have a very moderate dip. As No. 1. 

 is the deepest of the three bores, and No. 3. the next 

 in depth, this shews that the line AC is nearer the line 

 of level, than either the lines AB or BC. The question 

 therefore is, at \vhat distance upon the protracted line 

 BC, is the point at which, if a bore were put down, it 

 would reach the coal at the same depth as at No. 1 . 

 viz. at 50 yards. It is thus resolved : as 14 yards the 

 difference of depth betwixt the bores No. 2. and No. 3. 

 is to 300 yards the distance betwixt them, so is 20 the 

 difference of depth betwixt No. 1. and No. 2. to the 

 proportion resulting, which is 428 yards, 1 foot, 8 

 inches; this distance, measured from No 2. reaches 

 to the point D on the protracted line BC, at which 

 point D, the coal will be found at 50 yards deep, as at 

 A ; hence the line A D is the true level line of the 

 coal or strata. A line drawn at right angles to AD, 

 such as BF, is the true dip-line of the coal. In this 

 example, the dip, in the miner's language, is 1 in 14^, 

 that is, in each distance of 14| yards, measured along 

 the line from B to F, the coal is found one yard 

 deeper. Hence a calculation is easily made at what 

 depth the coal would be found at any point of dis- 

 tance from B, along the protracted line BG, viz. by 

 dividing the given length by the dip. If the distance 



Pi ATE 



CCCXC. 



fig. 3. 



from B to G in the line of dip is 455 yards, this, di- Mines of 

 vided by 14^ the dip, gives 30 yards, which, added to ^'al. 

 30 yards, the depth of No. 1. gives .60 yards for the ,T~" V ~~"' 

 depth at which the coal would be found at G. As any , ng 

 line drawn at right angles to the line of level AD, is"* 

 the line of dip, s-o any line drawn parallel to AD is a 

 level line. Hence, if from No. 3. bore, a line C E is drawn 

 parallel to AD, the coal at the point E will be found 

 upon a level with the coal at C, viz. at 44 yards. 

 The point E may, however, be found on a level with 

 No. 3. by a rule of proportion, similar to the former, 

 viz. as 20 yards the difference of depth betwixt No. 1. 

 and No. 2. so is 300 yards the distance betwixt them, 

 to 14 yards the difference of depth betwixt No. 2. and 

 No. 3, the proportion resulting is 2 10 yards; which 

 distance, measured from B, is found to be at E. Had 

 this proportion been first tried, then AD drawn parallel 

 to EC would have given the point D, upon the pro- 

 tracted line BC, where the coal would be found on a 

 level with the coal at the point A. In this example, 

 the surface is supposed to be level ; but as this is sel- 

 dom the case, the relative situation of the bores at the 

 surface with each other must be accurately ascertained. 

 If No. 1. is situated higher than either No. 2. or No. 

 3. the difference of altitude must be added to each 

 bore, so as they may be equal to No. 1, which cor- 

 rection brings them to the same horizontal plane, and 

 then the projection and calculations are made as be- 

 fore exemplified. It is by this theorem for finding the 

 line of dip and of level, that the most eligible spot in a 

 coal-field or coal property can be selected ; where, by 

 sinking a pit, the coal, under all circumstances, can be 

 wrought to the greatest advantage, particularly as. to 

 the drainage of the coal-field. 



The process of boring, as before described, is the \ cw mode 

 same which has been long practised, and which is in of boring 

 common use at present. A new mode was invented b J **' ity- 

 and brought forward under letters patent, some years "" 

 ago, by Mr. James Kyan, from Ireland. The princi- 

 ple is very ingenious, and it is this. The common 

 boring-rods are the same as before described ; but, in 

 place of chissels, a forked cutting-tool is used, in the 

 same way as formerly described in the process of bor- 

 ing ; but, in place of the strata passed through being 

 comminuted or ground to powder, a core or cylinder 

 of the strata is formed; and as soon as the boring-bit 

 has advanced as deep as the shoulder of the fork, the 

 rods are drawn up, and a pair of nippers substituted ; 

 these seize the core, break it off, and bring it up. In 

 this manner the boring proceeds through the strata to 

 the required depth, and each piece of core brought up, 

 is laid in a horizontal direction, each piece regularly 

 joining the preceding one at the line of I'racMire ; by 

 this means, a true section of the strata bored through, 

 with the coals found, is as distinctly seen as if a pit 

 had been Mink through them. Besides wiiich, the dip 

 or declivity of the strata is also ascertained. It is said 

 that the true line of clip can also be found during the 

 process of putting down a single bore, but it is appre- 

 hended that the accuracy of the result cannot be de- 

 pended on. 



Mr. Ryan made every proper exertion to bring his 

 ingenious mode of boring into practice ; a mode, the 

 result of which was so satisfactory, leaving no ambi- 

 guity as to the strati* passed through, and particularly 

 as to the thickness and quality of coals, in ascertaining 

 which so great mistakes have unfortunately taken 

 place, because by the new plan the strata and coals in 

 their natural compact state are laid upon the surface of 



