Northumberland and Durham. 81 



at Thockrington, and at Welphington in the same neighbourhood, 

 20 miles west of the sea at Camboes. Strings of ore have also been 

 discovered on the coast of Northumberland at Ellwick nearly opposite 

 to Holy Island, and on the eastern side of the island itself: but all 

 undertakings begun in a flat country must be insignificant when 

 compared with those in a mountainous district, where the mines 

 are won by levels or drifts, which not only free the works from 

 water, but are the means of discovering numerous rich veins by 

 passing through them in their course. 



The veins bearing lead-ore on the hills near Shieldon and Blanch- 

 land, are reported to have attracted the notice of miners at a remote 

 period, and that part of their wealth, which lay near the surface, has 

 beeji long since removed. Within these few years an attempt has 

 been made on a great scale to win the ore supposed to lie below 

 the level of the Derwent, by drawing the water from a considerable 

 depth by powerful steam engines ; but it is said that as yet the 

 metal obtained repays but a small part of the annual cost of the 

 undertaking. 



In this dale the veins appear wide and open upwards, allowing 

 water to percolate through them from the surface. In Allenheads 

 mine, though the shaft is about 100 fathoms deep, the quantity of 

 water is so inconsiderable, that a set of water wheels, three in number, 

 are sufficient to raise it from the greatest depth of the workings, 

 and to discharge it at a drift.* 



* At Coal-cleugh an hydraulic machine more curious than powerful, but which fully 

 answers the purpose for which it was constructed, is employed to pump up the water. It 

 is situated at the further end of an adit, which serves for a water level drift, as well as for 

 conveying the ore from the- mine. A certain quantity of water from a brook on the 

 elevated ground above the mine is made to raise nearly an equal weight from below by 

 making a column of 20 fathoms act as a counterpoise to one of 19 fathoms. This engine 



Vol. iv. i* 



