76 Extracts relating to Coal, 8fc. 



therefore, in this and all similar situations, the first hole that 

 is bored for a trial for Coal should be on the west side of the 

 ground, or to the full rise of the strata as at A, where boring 

 down through the strata 1, 2, 3, suppose 10 fathoms, and not 

 finding Coal, it will be better to bore a new hole than to pro- 

 ceed to a greater depth in that; therefore, proceeding so far 

 to the eastward as B, where the stratum 1, of the first hole is 

 computed to be 10 or 12. fathoms deep, a second hole may be 

 bored, where boring down the strata 4, 5, G, 7, 8, the stratum 

 1 is met with, but no Coal ; it would he of no use to bore 

 farther in this hole, as the same strata would be found which 

 in the hole A : therefore, proceeding again so far to the 

 nard, as it may be computed the stratum 4 of the second 

 hole will be met at ihe depth of 10 or 12 fathoms, a new hole 

 may be bored C, where, boring through the strata 9, 10, 1 1, 12, 

 the Coal is met with at 13, before the hole proceed so deep as 

 the stratum 4 of the former. It is evident, that, by this method 

 of procedure, neither the Coal nor any other of the strata 

 can be passed over, as the last hole is always bored down to 

 that stratum which was nearest th-j surface in the former hole. 



Rocky or mineral strata met ivitli in what is usually understood 

 by the Coal formation. 

 1. Whin-stone, — The strata of what is denominated whin- 

 stone are the hardest of all others ; the angular pieces of it will 

 cut glass; it is of a very coarse texture, and when broken 

 across the grain, exhibits the appearance of large grains of 

 sand half vitrified ; it can scarcely be wrought, or broken in 

 pieces, by common tools, without the assistance of gunpow- 

 der ; each stratum is commonly homogeneous in substance 

 and colour, and cracked in the rock to a great depth. The 

 most common colours of these strata are black or dark blue, 

 yet there are others of it ash coloured and light brown. 

 Their thickness in all the Coal countries is but. inconsiderable, 

 from six or five feet down to a few inches , and it is only in a 

 few places they are met with of these thicknesses. In the air it 

 decays a little, having a brown powder; and in the fire it 

 cracks, and turns reddish brown. Limestone, and what is 

 called bastard limestone, is sometimes, though rarely, met 

 with in coaleries. It is a well known stone; but from its re- 

 semblance in hardness and colour is often mistaken for a kind 

 of whin. Sometimes, particularly in hilly countries, the solid 

 ext the surface is found to be a kind of soft or rotten 

 whin ; — but it may be noted, that this is only a mass of hete- 

 matter disposed upon the regular strata; and that 

 ih this, all the strata are generally found in as regular 



matter does not occur. 



