and Salts, is dry and tedious; but as it was thought a neceffary addition to the preceding chapters, it could not be omitted. With respect to the nature and hiftory of Minerals, 1 confine myself to those of Cornwall only; and as they occur in the course of my work, have defcribed each in its incidental place. My readers will eafily perceive, that if I had fyftematically obferved those rules of genera, clafs, and order, laid down by Hill, Da Cofta, Cronstedt, and others, I fhould have spun out my treatise in a needlefs detail of matters foreign to the profeffed fubject of it. The second book treats of the theory and natural hiftory of Strata, Fiffures, and Lodes, with refpect to their formation, direction, inclination, interruption, elevation, and depreffion. The theory advanced in the first and third chapters was adopted by the reverend Dr. Borlafe, and as it has been well received by the criticks of his time, it is hoped that it may ftill pass till a better can be found and after all the opinions of the feveral naturalifts are collated, and che most probable are felected, the matter will still remain a meer poftulatum; fo that we would prefume to judge of these only from their vifible effects in the Mines of Cornwall. The fecond chapter contains little or no theory, being only a natural history of the contents of Lodes, according to their outward appearance; and any perfon a little converfant with Mineral Ores, may form a tolerable judgment of their contents from the description here given of them. The third book contains the practical part of Mining; the methods of difcovering and working Mines, the particular procefs for digging and raifing of Ores, and the machinery for drawing water. Though in this part the reader may find a fund of information that he has never feen opened before; yet it can be confidered only as a fummary of Mining, it being endlefs to enter into all its different modifications. The firft chapter treats of the difcovery of Mines by the Virgula, Shoding, and Cofteaning, especially the former; and gives an improved idea of a fcience in difcovering Mines very little understood out of Cornwall. The merit of the effay on the Virgula Divinatoria is due to Mr. William Cookworthy, of Plymouth; and though the virtues of the rod may not be eafily allowed by the incredulous, yet for my own part, I want no further evidence of its properties than I have already obtained to fix my opinion of its virtues. At least, the memoir is curious, and the fubject deferves to be further enquired into. In the method of Shoding, I have been more full than any preceding writer; and, I hope, with a judgment that will rescue this fcience from the darkness with which it was enveloped. The fecond chapter contains an account of the methods of Streaming in its prefent improved ftate. This immediately follows the chapter on Shoding, becaufe of its near affinity to that fubject. The practical part of Shoding and Streaming is founded upon a belief of the Noachian deluge and its effects, which are inconteftably verified in Shode and Stream works. In the third chapter, the effectual working of a Mine is exhibited in the finking of Shafts, driving Adits, digging and raifing of Ores, drawing the water, and every other operation under-ground. This is intended to explain the feveral parts of a Mine, and their dependency on each other; and to evince that fuch contingencies must be in all Mines, although varied in their fituations according to the different circumftances of different Mines. To this is added, a parallel fection of the greatest Mine now at work in Cornwall, to illuftrate the whole. The chapter following relates to the management of a Mine when in a proper courfe of working; wherein fuch maxims are laid down, that a novice in conducting a Mine may understand some matters indifpenfably connected with that art. The laft chapter of this book treats of Damps, Dialling, and Levelling, with practical inftances and remarks, fupported by experience, and altogether neceffary. The fourth book treats of the feveral manuductions used in dreffing of Tin, Copper, and Lead Orcs, and contains fome brief remarks upon dreffing Gold, Silver, &c. Though the general manner of dreffing Copper Ore was first taken from the methods used in the Lead Mines, yet there are so great a variety of Copper Ores requiring very oppofite treatment in their drefling, that I hope the fubject will be found greatly improved. The dreffing of Tin is indeed an art confined to the ftannaries only; yet the curious delicate manner in which it is manufactured in the drefling, may furnish many improvable and beneficial hints for the cleansing of other Minerals from their fordes. I have been very accurate in defcribing the manner of dreffing Tin Ore, as I have had ample experience in that business; and I doubt not of its proving a useful and general ftandard in that branch of Mineralogy. The beginning of the fifth book confifts of a memoir upon affaying, and more particularly upon a part of the Docimaftick art, which has never been fo experimentally treated of before, viz. How to affay Mundicks and Tin for Gold or Silver; by which proceffes the curious may judge how far the Mundicks of one place are fuperior to thofe of another for the precious Metals, or whether they contain any Silver or Gold. The proceffes for affaying Copper Ores by calcination, and by the regule way, are both infallible, if the operator will be attentive to his business. These proceffes are little known out of the Cornish affay offices, and have been too long kept profoundly fecret, for purposes which the reader will readily comprehend. The method of affaying Tin Ore is very fimple and efficacious, from the easy fufibility of its Metal. An adept in trying Copper Ores will foon know how to manage in affaying Cobalt, by the mode presented to his view in this chapter. The laft and grand object, is the manufactory of Tin and Copper Ores into their respective Metals; and I have set forth, as fuccinctly and clearly as the materials I have obtained would allow, the proceffes of smelting and metallizing those products, without infringing too much upon the fecrets of private trade. And though I have not forgotten to point out the oppreffions of monopoly, yet it is with lefs feverity than is due to the magnitude of the evil, and its mifchievous effects. The Appendix treats of the great improvement in the steam fire engine by Mr. Watt; an invention of more confequence to the Mining intereft of Great-Britain, than any discovery that has been made for half a century; and I hope to fee its univerfal use established in a very short time. As the idioms and terms of Cornish Miners are mostly derived from the ancient Cornish British dialect, and therefore not eafily intelligible to gentlemen unaccustomed to Mining, who may have occafion to converse or correfpond with them; to prevent mifconception, I have fubjoined an explanation of those terms in alphabetical order, including the relation they bear to those of the Lead Mines and Collieries. CONTENTS. and known to the firft inhabitants of Britain, ii. From Shode or Stream, ii. Lode works about feven hundred years standing -Of the antiquity of Tin, iii. Few Veftigia of Tin in Scilly- Iflands, iv. Author's opinion, that Tin was anciently exported from Falmouth harbour, fupported by Strabo, Diodorus Siculus, Cornish M. S. v, vi, vii. Copper but lately discovered and how, viii. Tin Ore rich, yet expenfive to dress-Much skill in hy- draulicks and mechanicks required to work Copper Mines, ix. Corollary-Reflexion, x. Great increase, annual amount and value of Tin, x. Ditto of Copper Ore for the laft fifty years, xi. Profit and lofs in the Mines like political gaming, xii. Calculation that the nett profit upon £400,000 is not 5 cent. |