Copper was as well known to be in Terra incognita, as in Cornwall, we ought to proceed to the discovery of the Lode: but as this has been defcribed elsewhere, we fhall now fet forth the first arrangements for working a Mine; in order to which, the principal thing to be thought of is a Shaft to cut the Lode, at twenty or thirty fathoms deep, if it is poffible to be done. Here it is neceffary to form fome judgment of the inclination or underlye of the Lode, before we attempt to fink a Shaft: for inftance, if the Lode underlies to the north about three feet in a fathom, and a Shaft is defigned to come down upon the Lode in twenty fathoms finking, the Miner muft go off north from the back of the Lode full ten fathoms, and there pitch his Shaft; by which means he is certain to cut the Lode in the Shaft about twenty fathoms deep; because for every fathom the Lode defcends in a perpendicular line, it is alfo gone three feet to the north of the perpendicular.

But to render this the more confpicuous, let the line E W represent the back or surface of a Lode pointing east and weft, and whose underlie is north: by finking a Shaft upon this back, it will foon be deferted by the Lode, which is gone further north three feet for every fathom that is funk upon that line; fo that when the Lode is twenty fathoms deep, it must be gone north to the imaginary line N, where another Shaft must be funk to cut the Lode at that depth.

N

W

E

A proper working Shaft, upon which a Whym may be erected if neceffary, fhould be fix feet long and four feet wide, or more where large water barrels may be wanted; and the harder the ground is, the longer and wider the Shaft ought to be, that the men may have the more liberty to work and break it, the area of a large fhaft being more easy to rip up where the ground is hardeft, than of a small one where it is more confined together, and breaks in fhreds of ftone, &c.

In

In many parts of the Mining diftrict, the north or the fouth channel appears to full view; and it is a maxim among the Miners, when they erect their windlafs upon a Shaft, to place it true to the horizon; in order to which they make an obfervation in a line to the fartheft diftance they can fee, which is always the fame height as the eye of the obferver, either upon the highest hill, or with the edge of the water.

A Shaft that is defigned for a water engine, may ferve, if it is of the fize of the largeft working Shaft; but a fire engine Shaft ought to be, at least, nine feet fquare, or ten feet by eight, or in fact to contain three Shafts in one, which muft be partitioned into three compartments, all the way down from grafs to the deepeft bottom of the Mine. One half is divided for the pumps and engine work; three feet in length of the other is proportioned for a foot way, to go down and rectify the pumps when amifs; and the remainder is divided alfo by a partition of boards, for a whym Shaft to draw the Deads and Ore from the Sump of the Mine. If the ground is hard and very wet, or the water very quick upon the men in finking, there ought to be eight men employed to fink a working Shaft; that is, two men in a corps of every fix hours; and in a fire engine Shaft, there fhould be fixteen employed in the fame manner : but if the ground is tender, and there is no hindrance by water, fix men in the firft, divided into three corps every eight hours, are reckoned fufficient; yet I have known four and twenty men put to fink an engine Shaft upon a great emergency.

The working Shaft being funk downright until it cuts the Lode, they open the Vein, or fink the body of the fhaft through it; and if they think the Vein is worth following, they fink the fame Shaft deeper in the body of the Lode, upon its inclination or underlie; whence the Shaft becomes, and bears the name of, an Underlier at the fame time they turn house, as they call it, from the bottom of their perpendicular, or from the top or beginning of the underlie. So that when the Lode is well impregnated, they turn houfe by driving or working horizontally on the courfe of the Vein, either to the caft or to the west, or both, as they find it most likely to answer their expectations, in order to make a fuller trial and discovery. Where the Lode anfwers well in thus driving upon it, they continue to do so, till they are prevented by want of air; or till the end of their workings is too far from the Shaft, and the expence of rolling back the ftuff to the Shaft is great and incommodious;

incommodious; then it is proper to put down another Shaft as before defcribed, or more to the north, because it will be more convenient, the longer it continues downright. Mean while, they are mindful to fink their firft Shaft in order that they may work away the Lode from thence in Stopes, and have a little Sump or pit in that place as a bafon for receiving the water of the Lode, whence they discharge it to grafs by the cafieft method they can devife for moft Lodes have ftreams of water running through them; and when they are found dry, it seems to be owing to the waters having been forced to change their course, either because the Lode has ftopped up the old paffages, or because fome new or more cafy ones are made, whereby the Lode and ftrata adjacent to it are bleeded as we term it. However, they are often hindered from going down deep enough to find any great quantity of Ore, by the burden of water that moft Veins abound with; therefore, if the Mine is not encouraging, they give over any further purfuit; but if it seems likely to prove well, and the Lode lies in an afcending ground, they quit the Vein for the prefent, and go down to the moft convenient place in the valley, and from thence they bring a Trench, Drain, or Conduit, which they call an Adit, Tye, or Level; and fo they work and drive this paffage through the hill in a right line to the Lode, with very little lofs of the level they began from.

Where the Adit is intended only for the fake of unwatering one particular Vein, it is frequently adviseable to bring it home on the course of it, if the fituation of the ground will admit, because this is a continual trial of it at that depth: yet, if there are many Lodes not far afunder, an Adit brought home athwart them may fometimes be preferable, if it can be conveniently complied with; for the fituation of the ground must be well confidered, to judge how to drive home the most short, deep, speedy, and cheap Adit, with the most probable success.

If the hill takes its courfe eaft and weft a confiderable length, and the difcovery of the Vein is very far from a valley at either end of the hill, there may be no choice in the matter; for the shortest and cheapest Adit will of courfe be driven from the north or fouth, unless moorftone or ireftone ftrata intervene. It then behoves the adventurers to feek for a Crofs-Goffan, where it lies convenient in distance from the discovery, to bring home the Adit in; and provided the Goffan does not exceed three feet in width, it is reckoned very favourable, because the Adit

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Adit may be wrought through the body of it, without the ufe of timber and boards to fupport and keep it up. On the contrary, most Cross-Goffans are too wide to break down the whole breadth for an Adit; and therefore they drive on the eastern or western fide of it, which ever is most to their liking, and at the fame time break down a fmall thickness of its contiguous wall, so that they are fure to cut all Veins, and branches of metallick Veins, in their paffage to the Mine; by which means, as in driving levels across the country out of thofe cross-courses, many more valuable Lodes have been discovered, than those they were driving to unwater. Nevertheless that fide of the

Adit which is in the body of the Goffan, must be braced up, and bound with boards, as muft likewise its back or top, otherwife the hinder part of the level may fall in and occafion a choak in it. Yet there are fome few Goffans that will stand without any fupport.

These Adits are commonly fix feet high and about two feet and a half wide, so that there may be room enough both in height and breadth to work in them; and alfo room to roll back the broken deads in a wheel-barrow: but if the ground or rock be very hard, the Adit ought to be more fpacious or large each way, to give the greater liberty or room to work and break. the ftone. An Adit requires four men to work it constantly by day and night, and a boy or two to roll back the broken work, if they break it very faft.

The neceffity for Shafts in driving an Adit, occurs very frequently to fupply the workmen with air, and for the convenience of winding up the deads. Where the country is very hard, the Shafts fhould be forty fathoms diftant from each other; and where the ground is feasible or moderately tender, they may be twenty fathoms diftant; but in this, as in all other parts of Mining, the adventurers must be ruled by the varieties of place and other circumstances. An Adit Shaft should be fix feet long and three feet broad, which generally employs fix men to work it day and night.

When the Miners want air by being a great way under-ground, and cannot conveniently put down a new Shaft; then, if the Adit be high enough, they lay boards on the bottom of the Adit, from their laft Shaft along to the Adit end, and so stop them down closely with clay or earth, by which contrivance, called a

Saller,