MINES 271 



and tin ores together ; a mixture which occurs often near the points of intersection 

 of the two metallic veing. Certain mines furnish alternately both copper and tin ; 

 but the most part produce only one of these metals, especially Dolcoath and the sur- 

 rounding mines. 



Among the more important mines of the above metals in the western districts may 

 be noticed : Huel Basset, North and West Basset, South Francis, United Mines, Hud 

 Buller, Alfred Consols, Cam Brea, Levant, and Botallack ; for tin more especially, 

 Huel Vor, Dolcoath, and Polberro. 



In the environs of St. Austell the more remarkable mines were those of Fowey Consols, 

 which was once the deepest-worked mine in Britain, Par Consols, Crinnis, the tin 

 mine of Polgooth, abandoned, and the singular open-cast of Carclaze, worked on 

 numerous small strings of tin, coursing through a granite so decomposed as to be in 

 great part available for china-clay. 



North of Liskeard, the Phoenix and Caradon mines have attained, since 1838, a 

 great degree of prosperity; whilst still further cast the neighbourhood of Callington 

 is marked by several productive copper mines on a smaller scale, and the large ancient 

 tin mine of Drake Walls. The Tavistock district has been rendered famous by the 

 long-continued successful working of Huel Friendship, and the enormous wealth ex- 

 tracted since 1845 from the series of mines on one great lode, entitled the Devon 

 Great Consols. 



There exists also in Cornwall veins running more or less N. and S. ; these are lead lodes 

 generally. The ' cross-courses,' which intersect and often dislocate these lodes, some- 

 times containing only clay (flucari) or quartz (spar), at other times particular metallic 

 minerals. Thus, near Helston several such veins have been worked for silver-lead 

 ore ; at Restormel near Lostwithiel, and in tho St. Austell granite, for red and brown 

 oxides of iron : east of Liskeard, at Herodsfoot, Huel Mary Anne, Eedmoor, and the 

 Tamar mines, for lead ores containing from 30 to 80 ounces of silver to the ton. 



In some few instances, and chiefly in connection with these cross veins, ores of 

 silver, cobalt, and nickel, have been raised ; whilst very rich silver ores were ob- 

 tained some years ago from E. and W. veins, at Huel Vincent, Huel Brothers, &c., 

 near Callington. 



Antimony has been raised from mines near Endellion, and at Huel Boys ; and 

 manganese is now worked from shallow irregular deposits in the slates at many points 

 in the east of Cornwall, and in Devonshire. 



The tin and copper ores of Cornwall are accompanied with arsenical pyrites, which 

 is turned to some account by the production of white arsenic (arsenious acid). 



The tin ores are treated at several works situated in Cornwall. All the copper ores 

 are sent to Swansea in South Wales to be smelted ; and a part of the lead ores only 

 is reduced at smelting-works near Truro, at Par, and on the Tamar. 



In consequence of the great influx of subterranean waters, the mines of Cornwall 

 and Devonshire are worked upon principles somewhat differing from those of many 

 other mining districts, expedition being regarded as one great source of economy. 

 Especially in the application of steam-power to pumping-purposes have the inventive 

 powers of the engineers, in modifying the engines and boilers, and the skill of tho 

 miners, in placing the pit-work and pumps, attained a high degree of perfection. 

 For this purpose engines having a cylinder of 80, 90, and even 100 inches in diameter 

 have been erected, employing high-pressure steam expansively. 



Many of tho mines are explored to a depth of between 1,200 and 2,000 feet; and 

 some are celebrated for the boldness of their workings. Thus several mines, espe- 

 cially Botallack and Levant, in the parish of St. Just, near Cape Cornwall, have their 

 shafts placed close to the edge of the cliffs, and extend several hundred fathoms 

 under the sea, and to depths of from 120 to 240 fathoms beneath its level. At Huel 

 Cock so small a thickness of rock has been left to support the weight of the waters 

 that the rolling of pebbles on the bottom is distinctly heard by miners during a storm. 

 The mine of Huel Worry, near Penzance, was worked by means of a single shaft 

 opened on a reef of rock in a space left dry by the sea only for a few hours at every 

 ebb. A small wooden tower was built over the mouth of the shaft, which, being 

 carefully caulked, kept out the waters of the ocean when the tide rose, and served to 

 support the machines for raising the ore and water. A vessel driven by a storm over- 

 turned it during the night, and put an end to this hazardous mode of mining, which 

 has not been resumed. 



An important group of veins of lead, often argentiferous, is opened in the slaty 

 rocks of Cardiganshire and Montgomeryshire, all of which have an E. and W. direction, 

 although so far from parallel that they often meet, and frequently form at such 

 points of intersection ' courses ' of ore. The galena is accompanied generally by 

 quartz and blende, more rarely by iron pyrites and calcspar. Some of these mines 

 were very profitably worked in the 17th century, and during the last forty years 



