MINERAL BAS0V IN WALES. 3fig 



•'8* Notwithstanding the principal strata of coal in Gla- Strata worked 

 morganshirc lie from 5 fathoms to 6 or 700 fathoms deep, f&£fa£^ 

 still it has not been necessary to pursue these strata deeper 

 than about 80 fathoms. 



9. The veins of coal and iron ore, in the vicinity of Method of 

 most of the iron works in Monmouthshire and Glamorgan- wor n *' 

 shire, are drained and worked by levels or horizontal drifts, 



for which opportunity is given by the deep valleys which ge- 

 nerally run in a north and south direction, intersecting the 

 range of coal and iron ore, which run in an east and west 

 direction, under the high mountains, and thereby serving 

 as main drains, so that the collier or miner here gets at the 

 treasures of the earth, without going to the expense and 

 labour of sinking deep pits, and erecting powerful fire- 

 engines. However, in process of time, in situations where 

 the coal and iron ore that are above the level of these na- 

 tural drains become exhausted, it will be found necessary 

 to sink shallow pits, and erect fire-engines for the draining 

 and working of the coal and 'iron ore, and at a future 

 period, pits of greater depths must be sunk for the same 

 purposes. 



10. There are 12 veins or strata of coal in this mineral Number and 

 depository, from '3 to 9 feet thick each ; which together ^Jjj* 1 ** of 

 make 70f feet: and there are 11 more, from 18 inches to 



3 feet, which make 24| feet, making in all 95 feet ; beside 

 a number of smaller veins from 12 to 18 inches, and from 

 6 to 12 inches in thickness, not calculated upon. 



11. By taking the average length and breadth of the Produce in the 

 foregoing different strata of coal, the amount is about 1000 ™™i™° nwayof 

 square miles, containing 95 feet of coal in 23 distinct 



strata, which will produce in the common way of work- 

 ing 100,000 tons per acre, 64,000,000 tons per square 

 mile. 



12. If the whole extent of this mineral country was an Edges of the 

 even plain, the border or outbreak of each stratum would straU disturbed * 

 appear regular and true ; but owing to the interposition of 



hills and valleys, the edges of the strata, if nicely measured 

 and planned, would seem indented and uneven, yet in many 

 instances the due range is totally thrown out of course, 

 in consequence of knots, dikes, or faults. 



13. These 



