[104] See Dr. Forbes's paper on the temperature of mines, in the Transactions of the Royal Geological Society of Cornwall, vol. 2, p. 208; also on the temperature of mines, by R. W. Fox, Esq. ibid. p. 14, and a paper on the same subject by M. P. Moyle, Esq. p. 404. [105] Crennis Copper Mine returned a clear profit to the adventurers of £84,000 in one year; and Huel Alfred, during the last period of its working, yielded very nearly £130,000, after having defrayed every necessary expense. The adventurers in Huel Vor have lately gained £10,000 in three months. But, on the contrary, how numerous are the losses, not perhaps corresponding in magnitude, in any individual mine, to the gains which have been above stated. In North Downs as much as £90,000 were lost, but this is a rare instance. [106] The consumption of such articles in a great mine far exceeds any estimate which a person unacquainted with mining operations could possibly imagine. In _Huel Vor_, no less than Three thousand pounds of candles are consumed in a month, and about Three thousand five hundred pounds of Gunpowder. [107] Before the invention of the _Stamping Mill_, the Tin was pulverised in a kind of mortar, called a _Crazing Mill_; one of which ancient machines is still in the possession of Mr. Williams of Scorrier House. [108] This process might be more generally employed in Cornwall with much advantage. The green coloured water which so frequently issues from the adits, might be made to yield a considerable portion of Copper, if it were properly received in pits, and submitted to the action of Iron. [109] Stream Tin, on account of its purity, is alone capable of furnishing the _grain tin_, employed principally by dyers. [110] The principal Stream works are in the parishes of Lanlivery, Luxilian, St. Blazy, St. Austel, St. Mewan, St. Stephens, and St. Columb. The greatest Stream work in the county is at Carnon, about half-way between Truro and Penrhyn; but there is scarcely a valley in which the operation has not been conducted on a small scale. [111] In the Ordnance Map of Cornwall, a spot marked "THE GOLD MINE" is noticed, near Liskeard. This name serves only to commemorate one of the many ruinous speculations into which the inhabitants of this County have repeatedly fallen, from a want of mineralogical knowledge. A mass of Pyrites having been discovered in this place, its brilliancy induced a belief that it was GOLD, in consequence of which workings were immediately commenced, and the sanguine adventurers, urged forward no doubt by those who derived an interest from the undertaking, could not be convinced of their error, until the complete ruin of their fortunes obliged them to abandon every hope.