[96] Grass is the technical name for the surface on all occasions.
[97] The great Copper Mine, called Crennis, was discovered by some casual observers in the cliff.
[98] From Aditus, a passage?
[99] The application of this machine in the county is estimated as saving the labour of 10,000 men; whilst the powers of the different steam-engines are considered as at least equivalent to 40,000 more.
[100] See Dr. Forbes's Paper "On the Temperature of Mines," in the second volume of the Transactions of the Cornish Society.
[101] The annual cost of gunpowder, used in the mines of the county, amounts to more than thirty thousand pounds.
[102] Transactions of the Royal Geological Society of Cornwall, vol. 2, page 162.
[103] The quantity of water discharged by the pumps from many of the Cornish mines is very considerable; thus Huel Abraham discharges from the depth of 1440 feet, about 2,092,320 gallons every 24 hours; Dolcoath, from nearly the same depth, 535,173 gallons in the same time; and Huel Vor, from the depth of 950 feet, 1,692,660 gallons.
[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.