1814.) Northumberland, Durham, &c. 411 



other beds of coal, one of which, called Coal Bcnsham, is four 

 feet thick ; and another, called Coal Yard Coal, is three feet thick. 

 Seven beds of coal have been observed under tlie Low Main, some 

 of which are of considerable thickness. The superior excellence of 

 the coal found in this formation over every other is sufficiently 

 known. The quantity of coal raised annually in this district, and 

 sent to London, and the whole east and south coast of Great 

 Britain, is quite enormous. Shields and Sunderland are the two 

 places from which they are exported, and a curious distribution of 

 the trade has taken place, depending upon the size of the two 

 rivers. The Tyne vessels are larger, and therefore chiefly destined 

 for the London market. The Wear vessels, on the contrary, are so 

 small that they can make their wav into the small rivers and har- 

 bours all over the kingdom, and therefore they supply the whole 

 east and south coast as far west as Plymouth. 



To form an idea of the quantity of coal contained in this forma- 

 tion, let us suppose it to extend in length from north to south 23 

 miles, and that its average breadth is eight miles. This makes a 

 surface amounting to rather more than I.sO square miles, or 

 557,568,000 square yards. The utmost thickness of all the beds of 

 coal put together does not exceed 44 feet ; but there are eleven 

 beds not workable, the thickness of each amounting onlv to a few 

 inches. If they be deducted, the amount of the rest will be 36 

 feet, or 12 yards. Perhaps five of the other beds likewise should 

 be struck off, as they amount altogether only to six feer, and there- 

 fore at present are not considered as worth working. The remainder 

 will he ten yards; so that the whole coal in this formation amounts 

 to 5,575,680,000 cubic yards. How much of this is already re- 

 moved by mining I do not know ; but the Newcastle collieries have 

 been wrought for so many years to an enormous extent that the 

 quantity already mined must be considerable. I conceive the 

 quantity of coals exported yearly from this formation exceeds two 

 millions of chaldrons; for the county of Durham alone exports 1» 

 million. A chaldron weighs 1*4 ton; so that 2*8 millions of tons 

 of coal are annually raised in these counties out of this formation. 

 Now a ton of coal is very nearly one cubic yard ; .so that the yearly 

 loss from mining amounts to 2 - S millions, or (adding a third for 



e) to .i'7 millions of yards. According to this statement, the 

 Newcastle coals may be mined to the present extent for 1500 years 



re they be exhausted. But from this number we must deduct 

 the amount of the years durii :h they have been already 



wrought. We need not be afraid, then, of any sudden injury to 

 iritain from the exhaustion of the coal-mines, it is necessary 

 to keep in mind likewi 1 that 1 have taken ihe greatest thickness of 

 the co I beds. Now as this thickness is far from uniform, a consi- 

 derable deduction (I should conceive one-third ol the whole) must 

 be made in ord :r to obtain the medium thickness; bo thai we may 

 in round numl ination, at the present rate of 



tc, will upply coal for 1000 years j but its price will be con- 



