[54] To the elaborate memoir, by _Mr. Carne_, published in the second volume of the Transactions of the Royal Geological Society of Cornwall, and entitled "_On the Mineral Productions, and the Geology of the Parish of Saint Just_," we would especially direct the attention of the scientific traveller. [55] The quantity of Copper procured in this way at Botallack, says Mr. Carne, is about a ton in a year. This chemical process is now practised in most of the mines in which the "_Tin-stone_" is mixed with Copper ore, as in Dolcoath, Cook's Kitchen, Chacewater, and in some parts of St. Agnes. [56] The principal sub-marine mines on this part of the coast are _Levant_; _Tolvaen_; _Huel Cock_; and _Huel Castle_; Copper Mines; and _Praze_; _Little Bounds_; _Riblose_; _Huel St. Just_; Tin Mines; and _Botallack_ Tin and Copper Mine. [57] A miner of the name of _James Wall_, who resides in the village of _Carnyorth_, has generally a variety of these minerals for sale. [58] "_Crown Engine_," so named from its vicinity to three rocks called the "_Three Crowns_." It was our intention to have presented the reader with an engraving of this extraordinary scene, and indeed measures had been taken for its accomplishment, when we were induced to abandon the design on learning that a lithographic print had been published by a meritorious and self-taught artist at Penzance, the sale of which we were anxious not to diminish. [59] This apparatus is termed "_The Shammel Whim_." [60] A metalliferous vein is provincially called a _Lode_. [61] The tin and copper are in a state of _mechanical_ mixture, although _Dr. Boase_ has lately found amongst the heaps, a specimen of "_Tin Pyrites_," in which these metals are _chemically_ combined. [62] The miners always distinguish their mines by a _feminine_ appellation. [63] See a paper by Dr. John Davy, in the first volume of the Transactions of the Royal Geological Society of Cornwall, entitled "_On the Granite Veins of Porth Just_." [64] This rock is a binary compound of _Quartz_ and _Schorl_, without any, or scarcely any, admixture of the other constituents of Granite; and yet when we consider its various relations, it must be regarded as rather a variety of the latter than a distinct rock. The locality now mentioned and that singular group of rocks between Truro and Bodmin, known by the name of _Roach Rock_, are, as far as we know, the only places in Cornwall where this modification of granite is found _in mass_. In the form of veins its occurrence is not unusual, especially at the junction of granite and slate, where it would often seem to exist as an intermediate rock.