The picturesque effect of this scenery is not a little heightened by the bold elevation of Carn-breh Hill, which, crowned with the mouldering remains of past ages, rises, as if in mockery of the boasted prowess of art, and forms a most striking and impressive contrast to the active scene before us.
Redruth is a very populous town of high antiquity, situated in the bosom of the mining district, and capable of affording very excellent accommodation to the mineralogist who may be desirous of remaining some days for the purpose of inspecting, at his leisure, the numerous mines by which it is surrounded. The general level of this metalliferous district is from 350 to 450 feet above the sea; and being frequently intersected by vallies, great opportunities are presented for the advantageous construction of Adits.
We next proceed to visit the great Steam-Engine of Chacewater mine, situated three miles south of Redruth. It was erected about the year 1813, and was at that period the most powerful machine in the world. It is a double engine upon the improved principle of Bolton and Watt, and the style and elegance with which its different parts are finished, reflect no inconsiderable credit upon the engineer. The following are its dimensions; the cylinder is 66 inches, the box 19, in diameter. The depth of the engine shaft is 128 fathoms. From the Adit to the bottom 90 fathoms. It makes eight strokes in a minute, and at every stroke it raises 108 gallons of water to the Adit;[112] and, at the same time also, 60 gallons, 10 fathoms high, for the purpose of condensing the steam. The quantity of coals consumed in twenty-four hours is estimated at about eight chaldrons. To give at once a popular idea of its immense power, it may be stated that, if it were applied as a mill, it could grind a Winchester bushel of wheat every minute. Notwithstanding the immensity of its force, and complexity of parts, so completely is it under the discretion and guidance of the engineer, that in one instant he is able to stop its motions by the mere application of his finger and thumb to a screw.—"We put a hook in the nose of the Leviathian;—play with him as a child, and take him as a servant for ever."
From Chacewater we proceed southward about two miles to visit the extensive Copper mines, called "The Consolidated Mines," the working of which has been lately resumed. Here we shall find two immense Steam Engines, with cylinders of 90 inches in diameter, constantly at work; the interior of which is kept as clean as a drawing-room. The capital expended in setting these mines at work was not less than £65,000, and under the arrangement of Mr. William Davey, the concern has proved so profitable, that shares are now selling in London at £100 per cent. profit.
Near the Consolidated Mines are Huel Unity and Poldice; the former is a Copper mine; the latter produces both Copper and Tin. The most beautiful specimens of Arseniate of Copper, and Arseniate of Lead have been found in these mines.
Having concluded our account of the mining district, it remains for us to offer to the mineralogical tourist a few observations upon the subject of Cornish Minerals, and upon the best method of procuring them; before the stranger, however, attempts to purchase any specimens, it will be well for him to inspect the several splendid cabinets in the county; besides that in the museum of the Royal Geological Society, at Penzance, he should see those in the possession of William Rashleigh, Esq. M. P. of Menabilly;[113] John Williams, Esq. of Scorrier House, and Joseph Carne, Esq. of Penzance. The one in possession of Mr. Rashleigh, if not the most accessible to the mineralogist, must be confessed to be without comparison, the most splendid. Its chief excellence consists in the magnificence and variety of the Oxide of Tin,[114] Fluors, Malachite, and some of the rarer varieties of Sulphuret of Copper, from mines which have long since ceased to be worked. Among the more remarkable specimens are those of Oxide of Tin (from Saint Agnes) some of the more interesting varieties of which present the following forms,—very large octohedrons with, and without, truncations;—the crystal described by Klaproth as one of the rarest occurrence, viz.—the four-sided prism, with a four-sided pyramid at each extremity; this is to be seen in its simple form, and also with a rich variety of truncations;—a group of four-sided pyramids covered with a thin coating of Calcedony, which, being hydrophanous, shews the form of the crystal very distinctly after immersion in water; Wood-tin forming a vein in a matrix of quartz, to one side of which adheres a fragment of rock; it is hardly necessary to remind the mineralogist of the importance of this specimen in a geognostic point of view;[115] Tin crystals having a coating of black hæmatite; Sulphuret of Tin, a mineral which has never been found in any part of the world except at Huel Rock, in Saint Agnes, Stenna-gwyn, in Saint Stephen's, and Huel Scorrier in Gwennap.[116] In the collection of Tins may be seen several small blocks[117] of that metal, as prepared by the Jews, for commerce, during the early workings of the Cornish mines, among which is a fraudulent one consisting of a mass of stone covered with a thin coating of metal. In the collection of Coppers may be noticed Yellow Copper ore with Opal (from Roskeir); the triple Sulphuret of Antimony, Copper, and Lead in various forms; Ruby Copper in cubes; Quartz containing globules of water; the Hydrargyllite or Wavellite, in a plumose form accompanied by Apatite in a matrix of Quartz (from Saint Stephen's), Topazes of considerable lustre (from Saint Agnes), Green Fluor in crystals of twenty-four sides (Saint Agnes). A most beautiful and instructive cube of Fluor, the surface of which reflects a delicate green hue, but upon being held to the light the crystal exhibits its octohedral nucleus of a purple colour. The mineralogist should also notice a superb octohedron of Gold, and a mass of Stalactitical Arragonite from the grotto of Antiparos. Before quitting Menabilly he ought to visit the grotto, built in a beautiful and secluded part of the grounds, near the shore in the port of Polredmouth. It stands at the extremity of a large grove, and is constructed with the finest species of marble and serpentine, with brilliant crystals, pebbles, and shells; its form is that of an octagon, two of the sides of which are appropriated to the door and window which front each other, while the six remaining sides form receptacles for minerals, four of which contain specimens of ores found in the county, and two are filled with organic fossils, polished agates, and jaspers; the intermediate spaces are occupied by shells, coralloids, and various other substances. The roof is composed of Stalactites of singular beauty, and which produce a very striking effect as they are seen through the roughly formed arch which composes the entrance. In this grotto are preserved two links of the chain which were found in Fowey harbour by some fishermen in the year 1776; they are of a triangular form, incrusted with shells and corals, and are supposed to have formed a part of the chain which extended from tower to tower, for the ancient defence of the harbour. Among the mineralogical specimens in this place there is one of Calcedony which deserves particular notice for its beauty as well as magnitude. In the centre of the grotto is a table inlaid with thirty-two polished specimens of granite, all found in the county of Cornwall.
The Cabinet of John Williams, Esq. is at Scorrier House, about two miles east of Redruth, and may therefore be visited by the mineralogist in the present excursion. This collection stands unrivalled in the magnificence of its specimens of Red Oxide of Copper, in octohedrons, cubes, and capillary crystals; it also contains the finest specimens of Arseniate of Copper in very perfect obtuse octahedrons;—a mass of Uranite, which in size and beauty is superior to any specimens ever discovered;—Blende, in octohedrons and cubes;—Native, and Ruby Silver; and a specimen of the Muriate of that metal (Horn Silver) so well known for its value, that it may be said to constitute one of the most interesting objects in the collection. The Arseniate of Lead, in six-sided prisms, a most beautiful mineral, which was first analysed by Mr. Gregor, and has been found only in Huel Unity, may be seen in this cabinet in its most perfect forms.
The collection of Mr. Carne has been already noticed in our account of Penzance, at page [31].