DIGGING of veins I have written of, and the timbering of shafts, tunnels, drifts, and other excavations, and the art of surveying. I will now speak first of all, of the iron tools with which veins and rocks are broken, then of the buckets into which the lumps of earth, rock, metal, and other excavated materials are thrown, in order that they may be drawn, conveyed, or carried out. Also, I will speak of the water vessels and drains, then of the machines of different kinds,' and lastly of the maladies of miners. And while all these matters are being described accurately, many methods of work will be explained.
There are certain iron tools which the miners designate by names of their own, and besides these, there are wedges, iron blocks, iron plates, hammers, crowbars, pikes, picks, hoes, and shovels. Of those which are especially referred to as " iron tools " there are four varieties, which are different from one another in length or thickness, but not in shape, for the upper end of all of them is broad and square, so that it can be struck by the hammer. The lower end is pointed so as to split the hard rocks and veins with its point. All of these have eyes except the fourth. The first, which is in daily use among miners, is three-quarters of a foot long, a digit and a half wide, and a digit thick. The second is of the same width as the first, and the same thickness, but one and one half feet long, and is used to shatter the hardest veins in such a way that they crack open. The third is the same length as the second, but is a little wider and thicker; with this one they dig the bottoms of those shafts which slowly accumulate water. The fourth is nearly three palms and one digit long, two digits thick, and in the upper end it is three digits wide, in the middle it is one palm wide, and at the lower end it is pointed like the others; with this they cut out the harder veins. The eye in the first tool is one palm distant from the upper end, in the second and third it is seven digits distant; each swells out around the eye on both sides, and into it they fit a wooden handle, which they hold with one hand, while they strike the iron tool with a hammer, after placing it against the rock. These tools are made larger or smaller as necessary. The smiths, as far as possible, sharpen again all that become dull.
A wedge is usually three palms and two digits long and six digits wide; at the upper end, for a distance of a palm, it is three digits thick, and beyond that point it becomes thinner by degrees, until finally it is quite sharp.
The iron block is six digits in length and width; at the upper end it is two digits thick, and at the bottom a digit and a half. The iron plate is the same length and width as the iron block, but it is very thin. All of these, as I explained in the last book, are used when the hardest kind of veins are hewn out. Wedges, locks, and plates, are likewise made larger or smaller.
Hammers are of two kinds, the smaller ones the miners hold in one hand, and the larger ones they hold with both hands. The former, because of their size and use, are of three sorts. With the smallest, that is to say, the lightest, they strike the second "iron tool; " with the intermediate one the first " iron tool; " and with the largest the third " iron tool "; this one is two digits wide and thick. Of the larger sort of hammers there are two kinds; with the smaller they strike the fourth " iron tool; " with the larger they drive the wedges into the cracks; the former are three, and the latter five digits wide and thick, and a foot long. All swell out in their middle, in which there is an eye for a handle, but in most cases the handles are somewhat light, in order that the workmen may be able to strike more powerful blows by the hammer's full weight being thus concentrated.
The iron crowbars are likewise of two kinds, and each kind is pointed at one end. One is rounded, and with this they pierce to a shaft full of water when a tunnel reaches to it; the other is flat, and with this they knock out of the stopes on to the floor, the rocks which have been softened by the fire, and which cannot be dislodged by the pike. A miner's pike, like a sailor's, is a long rod having an iron head.
The miner's pick differs from a peasant's pick in that the latter is wide at the bottom and sharp, but the former is pointed. It is used to dig out ore which is not hard, such as earth. Likewise a hoe and shovel are in no way different from the common articles, with the one they scrape up earth and sand, with the other they throw it into vessels.
Now earth, rock, mineral substances and other things dug out with the pick or hewn out with the " iron tools " are hauled out of the shaft in buckets, or baskets, or hide buckets; they are drawn out of tunnels in wheelbarrows or open trucks, and from both they are sometimes carried in trays.
Buckets are of two kinds, which differ in size, but not in material or shape. The smaller for the most part hold only about one metreta; the larger are generally capable of carrying one-sixth of a congius; neither is of unchangeable capacity, but they often vary. Each is made of staves circled with hoops, one of which binds the top and the other the bottom. The hoops are sometimes made of hazel and oak, but these are easily broken by dashing against the shaft, while those made of iron are more durable. In the larger buckets the staves are thicker and wider, as also are both hoops, and in order that the buckets may be more firm and strong, they have eight iron straps, somewhat broad, four of which run from the upper hoop downwards, and four from the lower hoop upwards, as if to meet each other. The bottom of each bucket, both inside and outside, is furnished with two or three straps of iron, which run from one side of the lower hoop to the other, but the straps which are on the outside are fixed crosswise. Each bucket has two iron hafts which project above the edge, and it has an iron semi-circular bail whose lower ends are fixed directly into the hafts, that the bucket may be handled more easily. Each kind of bucket is much deeper than it is wide, and each is wider at the top, in order that the material which is dug out may be the more easily poured in and poured out again. Into the smaller buckets strong boys, and into larger ones men, fill earth from the bottom of the shaft with hoes; or the other material dug up is shovelled into them or filled in with their hands, for which reason these men are called " shovellers. " Afterward they fix the hook of the drawing-rope into the bale; then the buckets are drawn up by machines-the smaller ones, because of their lighter weight, by machines turned by men, and the larger ones, being heavier, by the machines turned by horses. Some, in place of these buckets, substitute baskets which hold just as much, or even more, since they are lighter than the buckets; some use sacks made of ox-hide instead of buckets, and the drawing-rope hook is fastened to their iron bale, usually three of these filled with excavated material are drawn up at the same time as three are being lowered and three are being filled by boys. The latter are generally used at Schneeberg and the former at Freiberg.
That which we call a cisium is a vehicle with one wheel, not with two, such as horses draw. When filled with excavated material it is pushed by a workman out of tunnels or sheds. It is made as follows: two planks are chosen about five feet long, one foot wide, and two digits thick; of each of these the lower side is cut away at the front for a length of one foot, and at the back for a length of two feet, while the middle is left whole. Then in the front parts are bored circular holes, in order that the ends of an axle may revolve in them. The intermediate parts of the planks are perforated twice near the bottom, so as to receive the heads of two little cleats on which the planks are fixed; and they are also perforated in the middle, so as to receive the heads of two end-boards, while keys fixed in these projecting heads strengthen the whole structure. The handles are made out of the extreme ends of the long planks, and they turn downward at the ends that they may be grasped more firmly in the hands. The small wheel, of which there is only one, neither has a nave nor does it revolve around the axle, but turns around with it. From the felloe, which the Greeks called ayBFa, two transverse spokes fixed into it pass through the middle of the axle toward the opposite felloe; the axle is square, with the exception of the ends, each of which is rounded so as to turn in the opening. A workman draws out this barrow full of earth and rock and draws it back empty. Miners also have another wheelbarrow, larger than this one, which they use when they wash earth mixed with tin-stone on to which a stream has been turned. The front end-board of this one is deeper, in order that the earth which has been thrown into it may not fall out.
The open truck has a capacity half as large again as a wheelbarrow; it is about four feet long and about two and a half feet wide and deep; and since its shape is rectangular, it is bound together with three rectangular iron bands, and besides these there are iron straps on all sides. Two small iron axles are fixed to the bottom, around the ends of which wooden rollers revolve on either side; in order that the rollers shall not fall off the immovable axles, there are small iron keys. A large blunt pin fixed to the bottom of the truck runs in a groove of a plank in such a way that the truck does not leave the beaten track. Holding the back part with his hands, the carrier pushes out the truck laden with excavated material, and pushes it back again empty. Some people call it a "dog ", because when it moves it makes a noise which seems to them not unlike the bark of a dog. This truck is used when they draw loads out of the longest tunnels, both because it is moved more easily and because a heavier load can be placed in it.
Bateas are hollowed out of a single block of wood; the smaller kind are generally two feet long and one foot wide. When they have been filled with ore, especially when but little is dug from the shafts and tunnels, men either carry them out on their shoulders, or bear them away hung from their necks. Pliny is our authority that among the ancients everything which was mined was carried out on men's shoulders, but in truth this method of carrying forth burdens is onerous, since it causes great fatigue to a great number of men, and involves a large expenditure for labour; for this reason it has been rejected and abandoned in our day. The length of the larger batea is as much as three feet, the width up to a foot and a palm. In these bateas the metallic earth is washed for the purpose of testing it.
Water-vessels differ both in the use to which they are put and in the material of which they are made; some draw the water from the shafts and pour it into other things, as dippers; while some of the vessels filled with water are drawn out by machines, as buckets and bags; some are made of wood, as the dippers and buckets, and others of hides, as the bags. The water-buckets, just like the buckets which are filled with dry material, are of two kinds, the smaller and the larger, but these are unlike the other buckets at the top, as in this case they are narrower, in order that the water may not be spilled by being bumped against the timbers when they are being drawn out of the shafts, especially those considerably inclined. The water is poured into these buckets by dippers, which are small wooden buckets, but unlike the water-buckets, they are neither narrow at the top nor bound with iron hoops, but with hazel,--because there is no necessity for either. The smaller buckets are drawn up by machines turned by men, the larger ones by those turned by horses.
Our people give the name of water-bags to those very large skins for carrying water which are made of two, or two and a half, ox-hides. When these water-bags have undergone much wear and use, first the hair comes off them and they become bald and shining; after this they become torn. If the tear is but a small one, a piece of smooth notched stick is put into the broken part, and the broken bag is bound into its notches on either side and sewn together; but if it is a large one, they mend it with a piece of ox-hide. The water-bags are fixed to the hook of a drawing-chain and let down and dipped into the water, and as soon as they are filled they are drawn up by the largest machine. They are of two kinds; the one kind take in the water by themselves; the water pours into the other kind when it is pushed in a certain way by a wooden shovel.
When the water has been drawn out from the shafts, it is run off in troughs, or into a hopper, through which it runs into the trough. Likewise the water which flows along the sides of the tunnels is carried off in drains. These are composed of two hollowed beams joined firmly together, so as to hold the water which flows through them, and they are covered by planks all along their course, from the mouth of the tunnel right up to the extreme end of it, to prevent earth or rock falling into them and obstructing the flow of the water. If much mud gradually settles in them the planks are raised and the drains are cleaned out, for they would otherwise become stopped up and obstructed by this accident. With regard to the trough lying above ground, which miners place under the hoppers which are close by the shaft houses, these are usually hollowed out of single trees. Hoppers are generally made of four planks, so cut on the lower side and joined together that the top part of the hopper is broader and the bottom part narrower.
I have sufficiently indicated the nature of the miners' iron tools and their vessels. I will now explain their machines, which are of three kinds, that is, hauling machines, ventilating machines, and ladders. By means of the hauling machines loads are drawn out of the shafts; the ventilating machines receive the air through their mouths and blow it into shafts or tunnels, for if this is not done, diggers cannot carry on their labour without great difficulty in breathing; by the steps of the ladders the miners go down into the shafts and come up again.
Hauling machines are of varied and diverse forms, some of them being made with great skill, and if I am not mistaken, they were unknown to the Ancients. They have been invented in order that water may be drawn from the depths of the earth to which no tunnels reach, and also the excavated material from shafts which are likewise not connected with a tunnel, or if so, only with very long ones. Since shafts are not all of the same depth, there is a great variety among these hauling machines. Of those by which dry loads are drawn out of the shafts, five sorts are in the most common use, of which I will now describe the first. Two timbers a little longer than the shaft are placed beside it, the one in the front of the shaft, the other at the back. Their extreme ends have holes through which stakes, pointed at the bottom like wedges, are driven deeply into the ground, so that the timbers may remain stationary. Into these timbers are mortised the ends of two cross-timbers, one laid on the right end of the shaft, while the other is far enough from the left end that between it and that end there remains suitable space for placing the ladders. In the middle of the cross-timbers, posts are fixed and secured with iron keys. In hollows at the top of these posts thick iron sockets hold the ends of the barrel, of which each end projects beyond the hollow of the post, and is mortised into the end of another piece of wood a foot and a half long, a palm wide and three digits thick; the other end of these pieces of wood is seven digits wide, and into each of them is fixed a round handle, likewise a foot and a half long. A winding-rope is wound around the barrel and fastened to it at the middle part. The loop at each end of the rope has an iron hook which is engaged in the bale of a bucket, and so when the windlass revolves by being turned by the cranks, a loaded bucket is always being drawn out of the shaft and an empty one is being sent down into it. Two robust men turn the windlass, each having a wheelbarrow near him, into which he unloads the bucket which is drawn up nearest to him; two buckets generally fill a wheelbarrow; therefore when four buckets have been drawn up, each man runs his own wheelbarrow out of the shed and empties it. Thus it happens that if shafts are dug deep, a hillock rises around the shed of the windlass. If a vein is not metal-bearing, they pour out the earth and rock without discriminating; whereas if it is metal-bearing, they preserve these materials, which they unload separately and crush and wash. When they draw up buckets of water they empty the water through the hopper into a trough, through which it flows away.
The next kind of machine, which miners employ when the shaft is deeper, differs from the first in that it possesses a wheel as well as cranks. This windlass, if the load is not being drawn up from a great depth, is turned by one windlass man, the wheel taking the place of the other man. But if the depth is greater, then the windlass is turned by three men, the wheel being substituted for a fourth, because the barrel having been once set in motion, the rapid revolutions of the wheel help, and it can be turned more easily. Sometimes masses of lead are hung on to this wheel, or are fastened to the spokes, in order that when it is turned they depress the spokes by their weight and increase the motion; some persons for the same reason fasten into the barrel two, three, or four iron rods, and weight their ends with lumps of lead. The windlass wheel differs from the wheel of a carriage and from the one which is turned by water power, for it lacks the buckets of a water-wheel and it lacks the nave of a carriage wheel. In the place of the nave it has a thick barrel, in which are mortised the lower ends of the spokes, just as their upper ends are mortised into the rim. When three windlass men turn this machine, four straight. levers are fixed to the one end of the barrel, and to the other the crank which is usual in mines, and which is composed of two limbs, of which the rounded horizontal one is grasped by the hands; the rectangular limb, which is at right angles to the horizontal one, has mortised in its lower end the round handle, and in the upper end the end of the barrel. This crank is worked by one man, the levers by two men, of whom one pulls while the other pushes; all windlass workers, whatsoever kind of a machine they may turn, are necessarily robust that they can sustain such great toil.
The third kind of machine is less fatiguing for the workman, while it raises larger loads; even though it is slower, like all other machines which have drums, yet it reaches greater depths, even to a depth of 180 feet. It consists of an upright axle with iron journals at its extremities, which turn in two iron sockets, the lower of which is fixed in a block set in the ground and the upper one in the roof beam. This axle has at its lower end a wheel made of thick planks joined firmly together, and at its upper end a toothed drum; this toothed drum turns another drum made of rundles, which is on a horizontal axle. A winding-rope is wound around this latter axle, which turns in iron bearings set in the beams. So that they may not fall, the two workmen grasp with their hands a pole fixed to two upright posts, and then pushing the cleats of the lower wheel backward with their feet, they revolve the machine; as often as they have drawn up and emptied one bucket full of excavated material, they turn the machine in the opposite direction and draw out another.
The fourth machine raises burdens once and a half as large again as the two machines first explained. When it is made, sixteen beams are erected each forty feet long, one foot thick and one foot wide, joined at the top with clamps and widely separated at the bottom. The lower ends of all of them are mortised into separate sills laid flat upon the ground; these sills are five feet long, a foot and a half wide, and a foot thick. Each beam is also connected with its sill by a post, whose upper end is mortised into the beam and its lower end mortised into the sill; these posts are four feet long, one foot thick, and one foot wide. Thus a circular area is made, the diameter of which is fifty feet; in the middle of this area a hole is sunk to a depth of ten feet, and rammed down tight, and in order to give it sufficient firmness, it is strengthened with contiguous small timbers, through which pins are driven, for by them the earth around the hole is held so that it cannot fall in. In the bottom of the hole is planted a sill, three or four feet long and a foot and a half thick and wide; in order that it may remain fixed, it is set into the small timbers; in the middle of it is a steel socket in which the pivot of the axle turns. In like manner a timber is mortised into two of the large beams, at the top beneath the clamps; this has an iron bearing in which the other iron journal of the axle revolves. Every axle used in mining, to speak of them once for all, has two iron journals, rounded off on all sides, one fixed with keys in the centre of each end. That part of this journal which is fixed to the end of the axle is as broad as the end itself and a digit thick; that which projects beyond the axle is round and a palm thick, or thicker if necessity requires; the ends of each miner's axle are encircled and bound by an iron band to hold the journal more securely. The axle of this machine, except at the ends, is square, and is forty feet long, a foot and a half thick and wide. Mortised and clamped into the axle above the lower end are the ends of four inclined beams; their outer ends support two double cross-beams similarly mortised into them; the inclined beams are eighteen feet long, three palms thick, and five wide. The two cross-beams are fixed to the axle and held together by wooden keys so that they will not separate, and they are twenty-four feet long. Next, there is a drum which is made of three wheels, of which the middle one is seven feet distant from the upper one and from the lower one; the wheels have four spokes which are supported by the same number of inclined braces, the lower ends of which are joined together round the axle by a clamp; one end of each spoke is mortised into the axle and the other into the rim. There are rundles all round the wheels, reaching from the rim of the lowest one to the rim of the middle one, and likewise from the rim of the middle wheel to the rim of the top one; around these rundles are wound the drawing-ropes, one between the lowest wheel and the middle one, the other between the middle and top wheels. The whole of this construction is shaped like a cone, and is covered with a shingle roof, with the exception of that square part which faces the shaft. Then cross-beams, mortised at both ends, connect a double row of upright posts; all of these are eighteen feet long, but the posts are one foot thick and one foot wide, and the cross-beams are three palms thick and wide. There are sixteen posts and eight cross-beams, and upon these cross-beams are laid two timbers a foot wide and three palms thick, hollowed out to a width of half a foot and to a depth of five digits; the one is laid upon the upper cross-beams and the other upon the lower; each is long enough to reach nearly from the drum of the whim to the shaft. Near the same drum each timber has a small round wooden roller six digits thick, whose ends are covered with iron bands and revolve in iron rings. Each timber also has a wooden pulley, which together with its iron axle revolves in holes in the timber. These pulleys are hollowed out all round, in order that the drawing-rope may not slip out of them, and thus each rope is drawn tight and turns over its own roller and its own pulley. The iron hook of each rope is engaged with the bale of the bucket. Further, with regard to the double cross-beams which are mortised to the lower part of the main axle, to each end of them there is mortised a small piece of wood four feet long. These appear to hang from the double cross-beams, and a short wooden block is fixed to the lower part of them, on which a driver sits. Each of these blocks has an iron clavis which holds a chain, and that in turn a pole-bar. In this way it is possible for two horses to draw this whim, now this way and now that; turn by turn one bucket is drawn out of the shaft full and another is let down into it empty; if, indeed, the shaft is very deep four horses turn the whim. When a bucket has been drawn up, whether filled with dry or wet materials, it must be emptied, and a workman inserts a grappling hook and overturns it; this hook hangs on a chain made of three or four links, fixed to a timber.
The fifth machine is partly like the whim, and partly like the third rag and chain pump, which draws water by balls when turned by horse power, as I will explain a little later. Like this pump, it is turned by horse power and has two axles, namely, an upright one-about whose lower end, which descends into an underground chamber, there is a toothed drum-and a horizontal one, around which there is a drum made of rundles. It has indeed two drums around its horizontal axle, similar to those of the big machine, but smaller, because it draws buckets from a shaft almost two hundred and forty feet deep. One drum is made of hubs to which cleats are fixed, and the other is made of rundles; and near the latter is a wheel two feet deep, measured on all sides around the axle, and one foot wide; and against this impinges a brake, which holds the whim when occasion demands that it be stopped. This is necessary when the hide buckets are emptied after being drawn up full of rock fragments or earth, or as often as water is poured out of buckets similarly drawn up; for this machine not only raises dry loads, but also wet ones, just like the other four machines which I have already described. By this also, timbers fastened on to its winding-chain are let down into a shaft. The brake is made of a piece of wood one foot thick and half a foot long, projecting from a timber that is suspended by a chain from one end of a beam which oscillates on an iron pin, this in turn being supported in the claws of an upright post; and from the other end of this oscillating beam a long timber is suspended by a chain, and from this long timber again a short beam is suspended. A workman sits on the short beam when the machine needs to be stopped, and lowers it; he then inserts a plank or small stick so that the two timbers are held down and cannot be raised. In this way the brake is raised, and seizing the drum, presses it so tightly that sparks often fly from it; the suspended timber to which the short beam is attached, has several holes in which the chain is fixed, so that it may be raised as much as is convenient. Above this wheel there are boards to prevent the water from dripping down and wetting it, for if it becomes wet the brake will not grip the machine so well. Near the other drum is a pin from which hangs a chain, in the last link of which there is an iron hook three feet long; a ring is fixed to the bottom of the bucket, and this hook, being inserted into it, holds the bucket back so that the water may be poured out or the fragments of rock emptied.
The miners either carry, draw, or roll down the mountains the ore which is hauled out of the shafts by these five machines or taken out of the tunnels. In the winter time our people place a box on a sledge and draw it down the low mountains with a horse; and in this season they also fill sacks made of hide and load them on dogs, or place two or three of them on a small sledge which is higher in the fore part and lower at the back. Sitting on these sacks, not without risk of his life, the bold driver guides the sledge as it rushes down the mountain into the valleys with a stick, which he carries in his hand; when it is rushing down too quickly he arrests it with the stick, or with the same stick brings it back to the track when it is turning aside from its proper course. Some of the Noricians collect ore during the winter into sacks made of bristly pigskins, and drag them down from the highest mountains, which neither horses, mules nor asses can climb. Strong dogs, that are trained to bear pack saddles, carry these sacks when empty into the mountains. When they are filled with ore, bound with thongs, and fastened to a rope, a man, winding the rope round his arm or breast, drags them down through the snow to a place where horses, mules, or asses bearing pack-saddles can climb. There the ore is removed from the pigskin sacks and put into other sacks made of double or triple twilled linen thread, and these placed on the pack-saddles of the beasts are borne down to the works where the ores are washed or smelted. If, indeed, the horses, mules, or asses are able to climb the mountains, linen sacks filled with ore are placed on their saddles, and they carry these down the narrow mountain paths, which are passable neither by wagons nor sledges, into the valleys lying below the steeper portions of the mountains. But on the declivity of cliffs which beasts cannot climb, are placed long open boxes made of planks, with transverse cleats to hold them together; into these boxes is thrown the ore which has been brought in wheelbarrows, and when it has run down to the level it is gathered into sacks, and the beasts either carry it away on their backs or drag it away after it has been thrown into sledges or wagons. When the drivers bring ore down steep mountain slopes they use two-wheeled carts, and they drag behind them on the ground the trunks of two trees, for these by their weight hold back the heavily-laden carts, which contain ore in their boxes, and check their descent, and but for these the driver would often be obliged to bind chains to the wheels. When these men bring down ore from mountains which do not have such declivities, they use wagons whose beds are twice as long as those of the carts. The planks of these are so put together that, when the ore is unloaded by the drivers, they can be raised and taken apart, for they are only held together by bars. The drivers employed by the owners of the ore bring down thirty or sixty wagon-loads, and the master of the works marks on a stick the number of loads for each driver. But some ore, especially tin, after being taken from the mines, is divided into eight parts, or into nine, if the owners of the mine give " ninth parts " to the owners of the tunnel. This is occasionally done by measuring with a bucket, but more frequently planks are put together on a spot where, with the addition of the level ground as a base, it forms a hollow box. Each owner provides for removing, washing, and smelting that portion which has fallen to him. (Illustration p. 170).
Into the buckets, drawn by these five machines, the boys or men throw the earth and broken rock with shovels, or they fill them with their hands; hence they get their name of shovellers. As I have said, the same machines raise not only dry loads, but also wet ones, or water; but before I explain the varied and diverse kinds of machines by which miners are wont to draw water alone, I will explain how heavy bodies, such as axles, iron chains, pipes, and heavy timbers, should be lowered into deep vertical shafts: A windlass is erected whose barrel has on each end four straight levers; it is fixed into upright beams and around it is wound a rope, one end of which is fastened to the barrel and the other to those heavy bodies which are slowly lowered down by workmen; and if these halt at any part of the shaft they are drawn up a little way. When these bodies are very heavy, then behind this windlass another is erected just like it, that their combined strength may be equal to the load, and that it may be lowered slowly. Sometimes for the same reason, a pulley is fastened with cords to the roof-beam, and the rope descends and ascends over it.
Water is either hoisted or pumped out of shafts. It is hoisted up after being poured into buckets or water-bags; the water-bags are generally brought up by a machine whose water-wheels have double paddles, while the buckets are brought up by the five machines already described, although in certain localities the fourth machine also hauls up water-bags of moderate size. Water is drawn up also by chains of dippers, or by suction pumps, or by " rag and chain " pumps. When there is but a small quantity, it is either brought up in buckets or drawn up by chains of dippers or suction pumps, and when there is much water it is either drawn up in hide bags or by rag and chain pumps.
First of all, I will describe the machines which draw water by chains of dippers, of which there are three kinds. For the first, a frame is made entirely of iron bars; it is two and a half feet high, likewise two and a half feet long, and in addition one-sixth and one-quarter of a digit long, one-fourth and one-twenty-fourth of a foot wide. In it there are three little horizontal iron axles, which revolve in bearings or wide pillows of steel, and also four iron wheels, of which two are made with rundles and the same number are toothed. Outside the frame, around the lowest axle, is a wooden fly-wheel, so that it can be more readily turned, and inside the frame is a smaller drum which is made of eight rundles, one-sixth and one twenty-fourth of a foot long. Around the second axle, which does not project beyond the frame, and is therefore only two and a half feet and one-twelfth and one-third part of a digit long, there is on the one side, a smaller toothed wheel, which has forty-eight teeth, and on the other side a larger drum, which is surrounded by twelve rundles one-quarter of a foot long. Around the third axle, which is one inch and one-third thick, is a larger toothed wheel projecting one foot from the axle in all directions, which has seventy-two teeth. The teeth of each wheel are fixed in with screws, whose threads are screwed into threads in the wheel, so that those teeth which are broken can be replaced by others; both the teeth and rundles are steel. The upper axle projects beyond the frame, and is so skillfully mortised into the body of another axle that it has the appearance of being one; this axle proceeds through a frame made of beams which stands around the shaft, into an iron fork set in a stout oak timber, and turns on a roller made of pure steel. Around this axle is a drum of the kind possessed by those machines which draw water by rag and chain; this drum has triple curved iron clamps, to which the links of an iron chain hook themselves, so that a great weight cannot tear them away. These links are not whole like the links of other chains, but each one being curved in the upper part on each side catches the one which comes next, whereby it presents the appearance of a double chain. At the point where one catches the other, dippers made of iron or brass plates and holding half a congius are bound to them with thongs; thus, if there are one hundred links there will be the same number of dippers pouring out water. When the shafts are inclined, the mouths of the dippers project and are covered on the top that they may not spill out the water, but when the shafts are vertical the dippers do not require a cover. By fitting the end of the lowest small axle into the crank, the man who works the crank turns the axle, and at the same time the drum whose rundles turn the toothed wheel of the second axle; by this wheel is driven the one that is made of rundles, which again turns the toothed wheel of the upper small axle and thus the drum to which the clamps are fixed. In this way the chain, together with the empty dippers, is slowly let down, close to the footwall side of the vein, into the sump to the bottom of the balance drum, which turns on a little iron axle, both ends of which are set in a thick iron bearing. The chain is rolled round the drum and the dippers fill with water; the chain being drawn up close to the hanging-wall side, carries the dippers filled with water above the drum of the upper axle. Thus there are always three of the dippers inverted and pouring water into a lip, from which it flows away into the drain of the tunnel. This machine is less useful, because it cannot be constructed without great expense, and it carries off but little water and is somewhat slow, as also are other machines which possess a great number of drums.
The next machine of this kind, described in a few words by Vitruvius, more rapidly brings up dippers, holding a congius; for this reason, it is more useful than the first one for drawing water out of shafts, into which much water is continually flowing. This machine has no iron frame nor drums, but has around its axle a wooden wheel which is turned by treading; the axle, since it has no drum, does not last very long. In other respects this pump resembles the first kind, except that it differs from it by having a double chain. Clamps should be fixed to the axle of this machine, just as to the drum of the other one; some of these are made simple and others with triple curves, but each kind has four barbs.
The third machine, which far excels the two just described, is made when a running stream can be diverted to a mine; the impetus of the stream striking the paddles revolves a water-wheel in place of the wheel turned by treading. With regard to the axle, it is like the second machine, but the drum which is round the axle, the chain, and the balance drum, are like the first machine. It has much more capacious dippers than even the second machine, but since the dippers are frequently broken, miners rarely use these machines; for they prefer to lift out small quantities of water by the first five machines or to draw it up by suction pumps, or, if there is much water, to drain it by the rag and chain pump or to bring it up in water-bags.
Enough, then, of the first sort of pumps. I will now explain the other, that is the pump which draws, by means of pistons, water which has been raised by suction. Of these there are seven varieties, which though they differ from one another in structure, nevertheless confer the, same benefits upon miners, though some to a greater degree than others. The first pump is made as follows. Over the sump is placed a flooring, through which a pipe-or two lengths of pipe, one of which is joined into the other-are let down to the bottom of the sump; they are fastened with pointed iron clamps driven in straight on both sides, so that the pipes may remain fixed. The lower end of the lower pipe is enclosed in a trunk two feet deep; this trunk, hollow like the pipe, stands at the bottom of the sump, but the lower opening of it is blocked with a round piece of wood; the trunk has perforations round about, through which water flows into it. If there is one length of pipe, then in the upper part of the trunk which has been hollowed out there is enclosed a box of iron, copper, or brass, one palm deep, but without a bottom, and a rounded valve so tightly closes it that the water, which has been drawn up by suction, cannot run back; but if there are two lengths of pipe, the box is enclosed in the lower pipe at the point of junction. An opening or a spout in the upper pipe reaches to the drain of the tunnel. Thus the workman, eager at his labour, standing on the flooring boards, pushes the piston down into the pipe and draws it out again. At the top of the piston-rod is a hand-bar and the bottom is fixed in a shoe; this is the name given to the leather covering, which is almost cone-shaped, for it is so stitched that it is tight at the lower end, where it is fixed to the piston-rod which it surrounds, but in the upper end where it draws the water it is wide open. Or else an iron disc one digit thick is used, or one of wood six digits thick, each of which is far superior to the shoe. The disc is fixed by an iron key which penetrates through the bottom of the piston-rod, or it is screwed on to the rod; it is round, with its upper part protected by a cover, and has five or six openings, either round or oval, which taken together present a star-like appearance; the disc has the same diameter as the inside of the pipe, so that it can be just drawn up and down in it. When the workman draws the piston up, the water which has passed in at the openings of the disc, whose cover is then closed, is raised to the hole or little spout, through which it flows away; then the valve of the box opens, and the water which has passed into the trunk is drawn up by the suction and rises into the pipe; but when the workman pushes down the piston, the valve closes and allows the disc again to draw in the water.
The piston of the second pump is more easily moved up and down. When this pump is made, two beams are placed over the sump, one near the right side of it, and the other near the left. To one beam a pipe is fixed with iron clamps; to the other is fixed either the forked branch of a tree or a timber cut out at the top in the shape of a fork, and through the prongs of the fork a round hole is bored. Through a wide round hole in the middle of a sweep passes an iron axle, so fastened in the holes in the fork that it remains fixed, and the sweep turns on this axle. In one end of the sweep the upper end of a piston-rod is fastened with an iron key; at the other end a cross-bar is also fixed, to the extreme ends of which are handles to enable it to be held more firmly in the hands. And so when the workman pulls the cross-bar upward, he forces the piston into the pipe; when he pushes it down again he draws the piston out of the pipe; and thus the piston carries up the water which has been drawn in at the openings of the disc, and the water flows away through the spout into the drains. This pump, like the next one, is identical with the first in all that relates to the piston, disc, trunk, box, and valve.
The third pump is not unlike the one just described, but in place of one upright, posts are erected with holes at the top, and in these holes the ends of an axle revolve. To the middle of this axle are fixed two wooden bars, to the end of one of which is fixed the piston, and to the end of the other a heavy piece of wood, but short, so that it can pass between the two posts and may move backward and forward. When the workman pushes this piece of wood, the piston is drawn out of the pipe; when it returns by its own weight, the piston is pushed in. In this way, the water which the pipe contains is drawn through the openings in the disc and emptied by the piston through the spout into the drain. There are some who place a hand-bar underneath in place of the short piece of wood. This pump, as also the last before described, is less generally used among miners than the others.
The fourth kind is not a simple pump but a duplex one. It is made as follows. A rectangular block of beechwood, five feet long, two and a half feet wide, and one and a half feet thick, is cut in two and hollowed out wide and deep enough so that an iron axle with cranks can revolve in it. The axle is placed between the two halves of this box, and the first part of the axle, which is in contact with the wood, is round and the straight end forms a journal. Then the axle is bent down the depth of a foot and again bent so as to continue straight, and at this point a round piston-rod hangs from it; next it is bent up as far as it was bent down; then it continues a little way straight again, and then it is bent up a foot and again continues straight, at which point a second round piston-rod is hung from it; afterward it is bent down the same distance as it was bent up the last time; the other end of it, which also acts as a journal, is straight. This part which protrudes through the wood is protected by two iron washers in the shape of discs, to which are fastened two leather washers of the same shape and size, in order to prevent the water which is drawn into the box from gushing out. These discs are around the axle; one of them is inside the box and the other outside. Beyond this, the end of the axle is square and has two eyes, in which are fixed two iron rods, and to their ends are weighted lumps of lead, so that the axle may have a :greater propensity to revolve; this axle can easily be turned when its end has been mortised in a crank. The upper part of the box is the shallower one, and the lower part the deeper; the upper part is bored out once straight down through the middle, the diameter of the opening being the same as the outside diameter of the column pipe; the lower box has, side by side, two apertures also bored straight down; these are for two pipes, the space of whose openings therefore is twice as great as that of the upper part; this lower part of the box is placed upon the two pipes, which are fitted into it at their upper ends, and the lower ends of these pipes penetrate into trunks which stand in the sump. These trunks have perforations through which the water flows into them. The iron axle is placed in the inside of the box, then the two iron piston-rods which hang from it are let down through the two pipes to the depth of a foot. Each piston has a screw at its lower end which holds a thick iron plate, shaped like a disc and full of openings, covered with a leather, and similarly to the other pump it has a round valve in a little box. Then the upper part of the box is placed upon the lower one and properly fitted to it on every side, and where they join they are bound by wide thick iron plates, and held with small wide iron wedges, which are driven in and are fastened with clamps. The first length of column pipe is fixed into the upper part of the box, and another length of pipe extends it, and a third again extends this one, and so on, another extending on another, until the uppermost one reaches the drain of the tunnel. When the crank worker turns the axle, the pistons in turn draw the water through their discs; since this is done quickly, and since the area of openings of the two pipes over which the box is set, is twice as large as the opening of the column pipe which rises from the box, and since the pistons do not lift the water far up, the impetus of the water from the lower pipes forces it to rise and flow out of the column pipe into the drain of the tunnel. Since a wooden box frequently cracks open, it is better to make it of lead or copper or brass.
The fifth kind of pump is still less simple, for it is composed of two or three pumps whose pistons are raised by a machine turned by men, for each piston-rod has a tappet which is raised, each in succession, by two cams on a barrel; two or four strong men turn it. When the pistons descend into the pipes their discs draw the water; when they are raised these force the water out through the pipes. The upper part of each of these piston-rods, which is half a foot square, is held in a slot in a cross-beam; the lower part, which drops down into the pipes, is made of another piece of wood and is round. Each of these three pumps is composed of two lengths of pipe fixed to the shaft timbers. This machine draws the water higher, as much as twenty-four feet. If the diameter of the pipes is large, only two pumps are made; if smaller, three, so that by either method the volume of water is the same. This also must be understood regarding the other machines and their pipes. Since these pumps are composed of two lengths of pipe, the little iron box having the iron valve which I described before, is not enclosed in a trunk, but is in the lower length of pipe, at that point where it joins the upper one; thus the rounded part of the piston-rod is only as long as the upper length of pipe; but I will presently explain this more clearly.
The sixth kind of pump would be just the same as the fifth were it not that it has an axle instead of a barrel, turned not by men but by a water-wheel, which is revolved by the force of water striking its buckets. Since water-power far exceeds human strength, this machine draws water through its pipes by discs out of a shaft more than one hundred feet deep. The bottom of the lowest pipe, set in the sump, not only of this pump but also of the others, is generally enclosed in a basket made of wicker-work, to prevent wood shavings and other things being sucked in.
The seventh kind of pump, invented ten years ago, which is the most ingenious, durable, and useful of all, can be made without much expense. It is composed of several pumps, which do not, like those last described, go down into the shaft together, but of which one is below the other, for if there are three, as is generally the case, the lower one lifts the water of the sump and pours it out into the first tank; the second pump lifts again from that tank into a second tank, and the third pump lifts it into the drain of the tunnel. A wheel fifteen feet high raises the piston-rods of all these pumps at the same time and causes them to drop together. The wheel is made to revolve by paddles, turned by the force of a stream which has been diverted to the mountain. The spokes of the water-wheel are mortised in an axle six feet long and one foot thick, each end of which is surrounded by an iron band, but in one end there is fixed an iron journal; to the other end is attached an iron like this journal in its posterior part, which is a digit thick and as wide as the end of the axle itself. Then the iron extends horizontally, being rounded and about three digits in diameter, for the length of a foot, and serves as a journal; thence, it bends to a height of a foot in a curve, like the horn of the moon, after which it again extends straight out for one foot; thus it comes about that this last straight portion, as it revolves in an orbit becomes alternately a foot higher and a foot lower than the first straight part. From this round iron crank there hangs the first flat pump-rod, for the crank is fixed in a perforation in the upper end of this flat pump-rod just as the iron key of the first set of " claws " is fixed into the lower end. In order to prevent the pump-rod from slipping off it, as it could easily do, and that it may be taken off when necessary, its opening is wider than the corresponding part of the crank, and it is fastened on both sides by iron keys. To prevent friction, the ends of the pump-rods are protected by iron plates or intervening leathers. This first pump-rod is about twelve feet long, the other two are twenty-six feet, and each is a palm wide and three digits thick. The sides of each pump-rod are covered and protected by iron plates, which are held on by iron screws, so that a part which has received damage can be repaired. In the " claws " is set a small round axle, a foot and a half long and two palms thick. The ends are encircled by iron bands to prevent the iron journals which revolve in the iron bearings of the wood from slipping out of it. From this little axle the wooden " claws " extend two feet, with a width and thickness of six digits; they are three palms distant from each other, and both the inner and outer sides are covered with iron plates. Two rounded iron keys two digits thick are immovably fixed into the claws. The one of these keys perforates the lower end of the first pump-rod, and the upper end of the second pump-rod which is held fast. The other key, which is likewise immovable, perforates the iron end of the first piston-rod, which is bent in a curve and is immovable. Each such piston-rod is thirteen feet long and three digits thick, and descends into the first pipe of each pump to such depth that its disc nearly reaches the valve-box. When it descends into the pipe, the water, penetrating through the openings of the disc, raises the leather, and when the piston-rod is raised the water presses down the leather, and this supports its weight; then the valve closes the box as a door closes an entrance. The pipes are joined by two iron bands, one palm wide, one outside the other, but the inner one is sharp all round that it may fit into each pipe and hold them together. Although at the present time pipes lack the inner band, still they have nipples by which they are joined together, for the lower end of the upper one holds the upper end of the lower one, each being hewn away for a length of seven digits, the former inside, the latter outside, so that the one can fit into the other. When the piston-rod descends into the first pipe, that valve which I have described is closed; when the piston-rod is raised, the valve is opened so that the water can run in through the perforations. Each one of such pumps is composed of two lengths of pipe, each of which is twelve feet long, and the inside diameter is seven digits. The lower one is placed in the sump of the shaft, or in a tank, and its lower end is blocked by a round piece of wood, above which there are six perforations around the pipe through which the water flows into it. The upper part of the upper pipe has a notch one foot deep and a palm wide, through which the water flows away into a tank or trough. Each tank is two feet long and one foot wide and deep. There is the same number of axles, " claws," and rods of each kind as there are pumps; if there are three pumps, there are only two tanks, because the sump of the shaft and the drain of the tunnel take the place of two. The following is the way this machine draws water from a shaft. The wheel being turned raises the first pump-rod, and the pump-rod raises the first " claw," and thus also the second pump-rod, and the first piston-rod; then the second pump-rod raises the second " claw," and thus the third pump-rod and the second piston-rod; then the third pump-rod raises the third " claw " and the third piston-rod, for there hangs no pump-rod from the iron key of these claws, for it can be of no use in the last pump. In turn, when the first pump-rod descends, each set of " claws " is lowered, each pump-rod and each piston-rod. And by this system, at the same time the water is lifted into the tanks and drained out of them; from the sump at the bottom of the shaft it is drained out, and it is poured into the trough of the tunnel. Further, around the main axle there may be placed two water wheels, if the river supplies enough water to turn them, and from the back part of each round iron crank, one or two pump-rods can be hung, each of which can move the piston-rods of three pumps. Lastly, it is necessary that the shafts from which the water is pumped out in pipes should be vertical, for as in the case of the hauling machines, all pumps which have pipes do not draw the water so high if the pipes are inclined in inclined shafts, as if they are placed vertically in vertical shafts.
If the river does not supply enough water-power to turn the last-described pump, which happens because of the nature of the locality or occurs during the summer season when there are daily droughts, a machine is built with a wheel so low and light that the water of ever so little a stream can turn it. This water, falling into a race, runs therefrom on to a second high and heavy wheel of a lower machine, whose pump lifts the water out of a deep shaft. Since, however, the water of so small a stream cannot alone revolve the lower water-wheel, the axle of the latter is turned at the start with a crank worked by two men, but as soon as it has poured out into a pool the water which has been drawn up by the pumps, the upper wheel draws up this water by its own pump, and pours it into the race, from which it flows on to the lower water-wheel and strikes its buckets. So both this water from the mine, as well as the water of the stream, being turned down the races on to that subterranean wheel of the lower machine, turns it, and water is pumped out of the deeper part of the shaft by means of two or three pumps.
If the stream supplies enough water straightway to turn a higher and heavier water-wheel, then a toothed drum is fixed to the other end of the axle, and this turns the drum made of rundles on another axle set below it. To each end of this lower axle there is fitted a crank of round iron curved like the horns of the moon, of the kind employed in machines of this description. This machine, since it has rows of pumps on each side, draws great quantities of water.
Of the rag and chain pumps there are six kinds known to us, of which the first is made as follows: A cave is dug under the surface of earth or in a tunnel, and timbered on all sides by stout posts and planks, to prevent either the men from being crushed or the machine from being broken by its collapse. In this cave, thus timbered, is placed a water-wheel fitted to an angular axle. The iron journals of the axle revolve in iron pillows, which are held in timbers of sufficient strength. The wheel is generally twenty-four feet high, occasionally thirty, and in no way different from those which are made for grinding corn, except that it is a little narrower. The axle has on one side a drum with a groove in the middle of its circumference, to which are fixed many four-curved iron clamps. In these clamps catch the links of the chain, which is drawn through the pipes out of the sump, and which again falls, through a timbered opening, right down to the bottom into the sump to a balancing drum. There is an iron band around the small axle of the balancing drum, each journal of which revolves in an iron bearing fixed to a timber. The chain turning about this drum brings up the water by the balls through the pipes. Each length of pipe is encircled and protected by five iron bands, a palm wide and a digit thick, placed at equal distances from each other; the first band on the pipe is shared in common with the preceding length of pipe into which it is fitted, the last band with the succeeding length of pipe which is fitted into it. Each length of pipe, except the first, is bevelled on the outer circumference of the upper end to a distance of seven digits and for a depth of three digits, in order that it may be inserted into the length of pipe which goes before it; each, except the last, is reamed out on the inside of the lower end to a like distance, but to the depth of a palm, that it may be able to take the end of the pipe which follows. And each length of pipe is fixed with iron clamps to the timbers of the shaft, that it may remain stationary. Through this continuous series of pipes, the water is drawn by the balls of the chain up out of the sump as far as the tunnel, where it flows out into the drains through an aperture in the highest pipe. The balls which lift the water are connected by the iron links of the chain, and are six feet distant from one another; they are made of the hair of a horse's tail sewn into a covering to prevent it from being pulled out by the iron clamps on the drum; the balls are of such size that one can be held in each hand. If this machine is set up on the surface of the earth, the stream which turns the water-wheel is led away through open-air ditches; if in a tunnel, the water is led away through the subterranean drains. The buckets of the water-wheel, when struck by the impact of the stream, move forward and turn the wheel, together with the drum, whereby the chain is wound up and the balls expel the water through the pipes. If the wheel of this machine is twenty-four feet in diameter, it draws water from a shaft two hundred and ten feet deep; if thirty feet in diameter, it will draw water from a shaft two hundred and forty feet deep. But such work requires a stream with greater water-power.
The next pump has two drums, two rows of pipes and two drawing-chains whose balls lift out the water; otherwise they are like the last pump. This pump is usually built when an excessive amount of water flows into the sump. These two pumps are turned by water-power;. indeed, water draws water.
The following is the way of indicating the increase or decrease of the water in an underground sump, whether it is pumped by this rag and chain pump or by the first pump, or the third, or some other. From a beam which is as high above the shaft as the sump is deep, is hung a cord, to one end of which there is fastened a stone, the other end being attached to a plank. The plank is lowered down by an iron wire fastened to the other end; when the stone is at the mouth of the shaft the plank is right down the shaft in the sump, in which water it floats. This plank is so heavy that it can drag down the wire and its iron clasp and hook, together with the cord, and thus pull the stone upwards. Thus, as the water decreases, the plank descends. and the stone is raised; on the contrary, when the water increases the plank rises and the stone is lowered. When the stone nearly touches the beam, since this indicates that the water has been exhausted from the sump by the pump, the overseer in charge of the machine closes the water-race and stops the water-wheel : when the stone nearly touches the ground at the side of the shaft, this indicates that the sump is full of water which has again collected in it, because the water raises the plank and thus the stone drags back both the rope and the iron wire; then the overseer opens the water-race, whereupon the water of the stream again strikes the buckets of the water-wheel and turns the pump. As workmen generally cease from their labours on the yearly holidays, and sometimes on working days, and are thus not always near the pump, and as the pump, if necessary, must continue to draw water all the time, a bell rings aloud continuously, indicating that this pump, or any other kind, is uninjured and nothing is preventing its turning. The bell is hung by a cord from a small wooden axle held in the timbers which stand over the shaft, and a second long cord whose upper end is fastened to the small axle is lowered into the shaft; to the lower end of this cord is fastened a piece of wood; and as often as a cam on the main axle strikes it, so often does the bell ring and give forth a sound.
The third pump of this kind is employed by miners when no river capable of turning a water-wheel can be diverted, and it is made as follows. They first dig a chamber and erect strong timbers and planks to prevent the sides from falling in, which would overwhelm the pump and kill the men. The roof of the chamber is protected with contiguous- timbers, so arranged that the horses which pull the machine can travel over it. Next they again set up sixteen beams forty feet long and one foot wide and thick, joined by clamps at the top and spreading apart at the bottom, and they fit the lower end of each beam into a separate sill laid flat on the ground, and join these by a post; thus there is created a circular area of which the diameter is fifty feet. Through an opening in the centre of this area there descends an upright square axle, forty-five feet long and a foot and a half wide and thick; its lower pivot revolves in a socket in a block laid flat on the ground in the chamber, and the upper pivot revolves in a bearing in a beam which is mortised into two beams at the summit beneath the clamps; the lower pivot is seventeen feet distant from either side of the chamber, i.e., from its front and rear. At the height of a foot above its lower end, the axle has a toothed wheel, the diameter of which is twenty-two feet. This wheel is composed of four spokes and eight rim pieces; the spokes are fifteen feet long and three-quarters of a foot wide and thick; one end of them is mortised in the axle, the other in the two rims where they are joined together. These rims are three-quarters of a foot thick and one foot wide, and from them there rise and project upright teeth three-quarters of a foot high, half a foot wide, and six digits thick. These teeth turn a second horizontal axle by means of a drum composed of twelve rundles, each three feet long and six digits wide and thick. This drum, being turned, causes the axle to revolve, and around this axle there is a drum having iron clamps with four-fold curves in which catch the links of a chain, which draws water through pipes by means of balls. The iron journals of this horizontal axle revolve on pillows which are set in the centre of timbers. Above the roof of the chamber there are mortised into the upright axle the ends of two beams which rise obliquely; the upper ends of these beams support double cross-beams, likewise mortised to the axle. In the outer end of each cross-beam there is mortised a small wooden piece which appears to hang down; in this wooden piece there is similarly mortised at the lower end a short board; this has an iron key which engages a chain, and this chain again a pole-bar. This machine, which draws water from a shaft two hundred and forty feet deep, is worked by thirty-two horses; eight of them work for four hours, and then these rest for twelve hours, and the same number take their place. This kind of machine is employed at the foot of the Harz mountains and in the neighbourhood. Further, if necessity arises, several pumps of this kind are often built for the purpose of mining one vein, but arranged differently in different localities varying according to the depth. At Schemnitz, in the Carpathian mountains, there are three pumps, of which the lowest lifts water from the lowest sump to the first drains, through which it flows into the second sump; the intermediate one lifts from the second sump to the second drain, from which it flows into the third sump; and the upper one lifts it to the drains of the tunnel, through which it flows away. This system of three machines of this kind is turned by ninety-six horses; these horses go down to the machines by an inclined shaft, which slopes and twists like a screw and gradually descends. The lowest of these machines is set in a deep place, which is distant from the surface of the ground 660 feet.
The fourth species of pump belongs to the same genera, and is made as follows. Two timbers are erected, and in openings in them, the ends of a barrel revolve. Two or four strong men turn the barrel, that is to say, one or two pull the cranks, and one or two push them, and in this way help the others; alternately another two or four men take their place. The barrel of this machine, just like the horizontal axle of the other machines, has a drum whose iron clamps catch the links of a drawing-chain. Thus water is drawn through the pipes by the balls from a depth of forty-eight feet. Human strength cannot draw water higher than this, because such very heavy labour exhausts not only men, but even horses; only water-power can drive continuously a drum of this kind. Several pumps of this kind, as of the last, are often built for the purpose of mining on a single vein, but they are arranged differently for different positions and depths.
The fifth pump of this kind is partly like the third and partly like the fourth, because it is turned by strong men like the last, and like the third it has two axles and three drums, though each axle is horizontal. The journals of each axle are so fitted in the pillows of the beams that they cannot fly out; the lower axle has a crank at one end and a toothed drum at the other end; the upper axle has at one end a drum made of rundles, and at the other end, a drum to which are fixed iron clamps, in which the links of a chain catch in the same way as before, and from the same depth, draw water through pipes by means of balls. This revolving machine is turned by two pairs of men alternately, for one pair stands working while the other sits taking a rest; while they are engaged upon the task of turning, one pulls the crank and the other pushes, and the drums help to make the pump turn more easily.
The sixth pump of this kind likewise has two axles. At one end of the lower axle is a wheel which is turned by two men treading, this is twenty-three feet high and four feet wide, so that one man may stand alongside the other. At the other end of this axle is a toothed wheel. The upper axle has two drums and one wheel; the first drum is made of rundles, and to the other there are fixed the iron clamps. The wheel is like the one on the second machine which is chiefly used for drawing earth and broken rock out of shafts. The treaders, to prevent themselves from falling, grasp in their hands poles which are fixed to the inner sides of the wheel. When they turn this wheel, the toothed drum being made to revolve, sets in motion the other drum which is made of rundles, by which means again the links of the chain catch to the cleats of the third drum and draw water through pipes by means of balls,-from a depth of sixty-six feet.
But the largest machine of all those which draw water is the one which follows. First of all a reservoir is made in a timbered chamber; this reservoir is eighteen feet long and twelve feet wide and high. Into this reservoir a stream is diverted through a water-race or through the tunnel; it has two entrances and the same number of gates. Levers are fixed to the upper part of these gates, by which they can be raised and let down again, so that by one way the gates are opened and in the other way closed. Beneath the openings are two plank troughs which carry the water flowing from the reservoir, and pour it on to the buckets of the water-wheel, the impact of which turns the wheel. The shorter trough carries the water, which strikes the buckets that turn the wheel toward the reservoir, and the longer trough carries the water which strikes those buckets that turn the wheel in the opposite direction. The casing or covering of the wheel is made of joined boards to which strips are affixed on the inner side. The wheel itself is thirty-six feet in diameter, and is mortised to an axle, and it has, as I have already said, two rows of buckets, of which one is set the opposite way to the other, so that the wheel may be turned toward the reservoir or in the opposite direction. The axle is square and is thirty-five feet long and two feet thick and wide. Beyond the wheel, at a distance of six feet, the axle has four hubs, one foot wide and thick, each one of which is four feet distant from the next; to these hubs are fixed by iron nails as many pieces of wood as are necessary to cover the hubs, and, in order that the wood pieces may fit tight, they are broader on the outside and narrower on the inside; in this way a drum is made, around which is wound a chain to whose ends are hooked leather bags. The reason why a drum of this kind is made, is that the axle may be kept in good condition, because this drum when it becomes worn away by use can be repaired easily. Further along the axle, not far from the end, is another drum one foot broad, projecting two feet on all sides around the axle. And to this, when occasion demands, a brake is applied forcibly and holds back the machine; this kind of brake I have explained before. Near the axle, in place of a hopper, there is a floor with a considerable slope, having in front of the shaft a width of fifteen feet and the same at the back; at each side of it there is a stout post carrying an iron chain which has a large hook. Five men operate this machine; one lets down the doors which close the reservoir gates, or by drawing down the levers, opens the water-races; this man, who is the director of this machine, stands in a hanging cage beside the reservoir. When one bag has been drawn out nearly as far as the sloping floor, he closes the water gate in order that the wheel may be stopped; when the bag has been emptied he opens the other water gate, in order that the other set of buckets may receive the water and drive the wheel in the opposite direction. If he cannot close the water-gate quickly enough, and the water continues to flow, he calls out to his comrade and bids him raise the brake upon the drum and stop the wheel. Two men alternately empty the bags, one standing on that part of the floor which is in front of the shaft, and the other on that part which is at the back. When the bag has been nearly drawn up-of which fact a certain link of the chain gives warning-the man who stands on the one part of the floor, catches a large iron hook in one link of the chain, and pulls out all the subsequent part of the chain toward the floor, where the bag is emptied by the other man. The object of this hook is to prevent the chain, by its own weight, from pulling down the other empty bag, and thus pulling the whole chain from its axle and dropping it down the shaft. His comrade in the work, seeing that the bag filled with water has been nearly drawn out, calls to the director of the machine and bids him close the water of the tower so that there will be time to empty the bag; this being emptied, the director of the machine first of all slightly opens the other water-gate of the tower to allow the end of the chain, together with the empty bag, to be started into the shaft again, and then opens entirely the water-gates. When that part of the chain which has been pulled on to the floor has been wound up again, and has been let down over the shaft from the drum, he takes out the large hook which was fastened into a link of the chain. The fifth man stands in a sort of cross-cut beside the sump, that he may not be hurt, if it should happen that a link is broken and part of the chain or anything else should fall down; he guides the bag with a wooden shovel, and fills it with water if it fails to take in the water spontaneously. In these days, they sew an iron band into the top of each bag that it may constantly remain open, and when lowered into the sump may fill itself with water, and there is no need for a man to act as governor of the bags. Further, in these days, of those men who stand on the floor the one empties the bags, and the other closes the gates of the reservoir and opens them again, and the same man usually fixes the large hook in the link of the chain. In this way, three men only are employed in working this machine; or even-since sometimes the one who empties the bag presses the brake which is raised against the other drum and thus stops the wheel-two men take upon themselves the whole labour.
But enough of haulage machines; I will now speak of ventilating machines. If a shaft is very deep and no tunnel reaches to it, or no drift from another shaft connects with it, or when a tunnel is of great length and no shaft reaches to it, then the air does not replenish itself. In such a case it weighs heavily on the miners, causing them to breathe with difficulty, and sometimes they are even suffocated, and burning lamps are also extinguished. There is, therefore, a necessity for machines which the Greeks call puenmatikai and the Latins spiritales--though they do not give forth any sound-which enable the miners to breathe easily and carry on their work.
These devices are of three genera. The first receives and diverts into the shaft the blowing of the wind, and this genus is divided into three species, of which the first is as follows. Over the shaft-to which no tunnel connects are placed three sills a little longer than the shaft, the first over the front, the second over the middle, and the third over the back of the shaft. Their ends have openings, through which pegs, sharpened at the bottom, are driven deeply into the ground so as to hold them immovable, in the same way that the sills of the windlass are fixed. Each of these sills is mortised into each of three cross-beams, of which one is at the right side of the shaft, the second at the left, and the third in the middle. To the second sill and the second cross-beam-each of which is placed over the middle of the shaft-planks are fixed which are joined in such a manner that the one which precedes always fits into the groove of the one which follows. In this way four angles and the same number of intervening hollows are created, which collect the winds that blow from all directions. The planks are roofed above with a cover made in a circular shape, and are open below, in order that the wind may not be diverted upward and escape, but may be carried downward; and thereby the winds of necessity blow into the shafts through these four openings. However, there is no need to roof this kind of machine in those localities in which it can be so placed that the wind can blow down through its topmost part.
The second machine of this genus turns the blowing wind into a shaft through a long box-shaped conduit, which is made of as many lengths of planks, joined together, as the depth of the shaft requires; the joints are smeared with fat, glutinous clay moistened with water. The mouth of this conduit either projects out of the shaft to a height of three or four feet, or it does not project; if it projects, it is shaped like a rectangular funnel, broader and wider at the top than the conduit itself, that it may the more easily gather the wind; if it does not project, it is not broader than the conduit, but planks are fixed to it away from the direction in which the wind is blowing, which catch the wind and force it into the conduit.
The third of this genus of machine is made of a pipe or pipes and a barrel. Above the uppermost pipe there is erected a wooden barrel, four feet high and three feet in diameter, bound with wooden hoops; it has a square blow-hole always open, which catches the breezes and guides them down either by a pipe into a conduit or by many pipes into the shaft. To the top of the upper pipe is attached a circular table as thick as the bottom of the barrel, but of a little less diameter, so that the barrel may be turned around on it; the pipe projects out of the table and is fixed in a round opening in the centre of the bottom of the barrel. To the end of the pipe a perpendicular axle is fixed which runs through the centre of the barrel into a hole in the cover, in which it is fastened, in the same way as at the bottom. Around this fixed axle and the table on the pipe, the movable barrel is easily turned by a zephyr, or much more by a wind, which govern the wing on it. This wing is made of thin boards and fixed to the upper part of the barrel on the side furthest away from the blow-hole; this, as I have said, is square and always open. The wind, from whatever quarter of the world it blows, drives the wing straight toward the opposite direction, in which way the barrel turns the blow-hole towards the wind itself; the blow-hole receives the wind, and it is guided down into the shaft by means of the conduit or pipes.
The second genus of blowing machine is made with fans, and is likewise varied and of many forms, for the fans are either fitted to a windlass barrel or to an axle. If to an axle, they are either contained in a hollow drum, which is made of two wheels and a number of boards joining them together, or else in a box-shaped casing. The drum is stationary and closed on the sides, except for round holes of such size that the axle may turn in them; it has two square blow-holes, of which the upper one receives the air, while the lower one empties into the conduit through which the air is led down the shaft. The ends of the axle, which project on each side of the drum, are supported by forked posts or hollowed beams plated with thick iron; one end of the axle has a crank, while in the other end are fixed four rods with thick heavy ends, so that they weight the axle, and when turned, make it prone to motion as it revolves. And so, when the workman turns the axle by the crank, the fans, the description of which I will give a little later, draw in the air by the blow-hole, and force it through the other blow-hole which leads to the conduit, and through this conduit the air penetrates into the shaft.
The one with the box-shaped casing is furnished with just the same things as the drum, but the drum is far superior to the box; for the fans so till the drum that they almost touch it on every side, and drive into the conduit all the air that has been accumulated; but they cannot thus fill the box-shaped casing, on account of its angles, into which the air partly retreats; therefore it cannot be as useful as the drum. The kind with a box-shaped casing is not only placed on the ground, but is also set up on timbers like a windmill, and its axle, in place of a crank, has four sails outside, like the sails of a windmill. When these are struck by the wind they turn the axle, and in this way its fans-which are placed within the casing-drive the air through the blow-hole and the conduit into the shaft. Although this machine has no need of men whom it is necessary to pay to work the crank, still when the sky is devoid of wind, as it often is, the machine does not turn, and it is therefore less suitable than the others for ventilating a shaft.
In the kind where the fans are fixed to an axle, there is generally a hollow stationary drum at one end of the axle, and on the other end is fixed a drum made of rundles. This rundle drum is turned by the toothed wheel of a lower axle, which is itself turned by a wheel whose buckets receive the impetus of water. If the locality supplies an abundance of water this machine is most useful, because to turn the crank does not need men who require pay, and because it forces air without cessation through the conduit into the shaft.
Of the fans which are fixed on to an axle contained in a drum or box, there are three sorts. The first sort is made of thin boards of such length and width as the height and width of the drum or box require; the second sort is made of boards of the same width, but shorter, to which are bound long thin blades of poplar or some other flexible wood; the third sort has boards like the last, to which are bound double and triple rows of goose feathers. This last is less used than the second, which in turn is less used than the first. The boards of the fan are mortised into the quadrangular parts of the barrel axle.
Blowing machines of the third genus, which are no less varied and of no fewer forms than those of the second genus, are made with bellows, for by its blasts the shafts and tunnels are not only furnished with air through conduits or pipes, but they can also be cleared by suction of their heavy and pestilential vapours. In the latter case; when the bellows is opened it draws the vapours from the conduits through its blow-hole and sucks these vapours into itself; in the former case, when it is compressed, it drives the air through its nozzle into the conduits or pipes. They are compressed either by a man, or by a horse or by water-power; if by a man, the lower board of a large bellows is fixed to the timbers above the conduit which projects out of the shaft, and so placed that when the blast is blown through the conduit, its nozzle is set in the conduit. When it is desired to suck out heavy or pestilential vapours, the blow-hole of the bellows is fitted all round the mouth of the conduit. Fixed to the upper bellows board is a lever which couples with another running downward from a little axle, into which it is mortised so that it may remain immovable; the iron journals of this little axle revolve in openings of upright posts; and so when the workman pulls down the lever the upper board of the bellows is raised, and at the same time the flap of the blow-hole is dragged open by the force of the wind. If the nozzle of the bellows is enclosed in the conduit it draws pure air into itself, but if its blow-hole is fitted all round the mouth of the conduit it exhausts the heavy and pestilential vapours out of the conduit and thus from the shaft, even if it is one hundred and twenty feet deep. A stone placed on the upper board of the bellows depresses it and then the flap of the blow-hole is closed. The bellows, by the first method, blows fresh air into the conduit through its nozzle, and by the second method blows out through the nozzle the heavy and pestilential vapours which have been collected. In this latter case fresh air enters through the larger part of the shaft, and the miners getting the benefit of it can sustain their toil. A certain smaller part of the shaft which forms a kind of estuary, requires to be partitioned off from the other larger part by uninterrupted lagging, which reaches from the top of the shaft to the bottom; through this part the long but narrow conduit reaches down nearly to the bottom of the shaft.
When no shaft has been sunk to such depth as to meet a tunnel driven far into a mountain, these machines should be built in such a manner that the workman can move them about. Close by the drains of the tunnel through which the water flows away, wooden pipes should be placed and joined tightly together in such a manner that they can hold the air; these should reach from the mouth of the tunnel to its furthest end. At the mouth of the tunnel the bellows should be so placed that through its nozzle it can blow its accumulated blasts into the pipes or the conduit; since one blast always drives forward another, they penetrate into the tunnel and change the air, whereby the miners are enabled to continue their work.
If heavy vapours need to be drawn off from the tunnels, generally three double or triple bellows, without nozzles and closed in the forepart, are placed upon benches. A workman compresses them by treading with his feet, just as persons compress those bellows of the organs which give out varied and sweet sounds in churches. These heavy vapours are thus drawn along the air-pipes and through the blow-hole of the lower bellows board, and are expelled through the blow-hole of the upper bellows board into the open air, or into some shaft or drift. This blow-hole has a flap-valve, which the noxious blast opens, as often as it passes out. Since one volume of air constantly rushes in to take the place of another which has been drawn out by the bellows, not only is the heavy air drawn out of a tunnel as great as 1,200 feet long, or even longer, but also the wholesome air is naturally drawn in through that part of the tunnel which is open outside the conduits. In this way the air is changed, and the miners are enabled to carry on the work they have begun. If machines of this kind had not been invented, it would be necessary for miners to drive two tunnels into a mountain, and continually, at every two hundred feet at most, to sink a shaft from the upper tunnel to the lower one, that the air passing into the one, and descending by the shafts into the other, would be kept fresh for the miners; this could not be done without great expense.
There are two different machines for operating, by means of horses, the above described bellows. The first of these machines has on its axle a wooden wheel, the rim of which is covered all the way round by steps; a horse is kept continually within bars, like those within which horses are held to be shod with iron, and by treading these steps with its feet it turns the wheel, together with the axle; the cams on the axle press down the sweeps which compress the bellows. The way the instrument is made which raises the bellows again, and also the benches on which the bellows rest, I will explain more clearly in Book IX. Each bellows, if it draws heavy vapours out of a tunnel, blows them out of the hole in the upper board; if they are drawn out of a shaft, it blows them out through its nozzle. The wheel has a round hole, which is transfixed with a pole when the machine needs to be stopped.
The second machine has two axles; the upright one is turned by a horse, and its toothed drum turns a drum made of rundles on a horizontal axle; in other respects this machine is like the last. Here, also, the nozzles of the bellows placed in the conduits blow a blast into the shaft or tunnel.
In the same way that this last machine can refresh the heavy air of a shaft or tunnel, so also could the old system of ventilating by the constant shaking of linen cloths, which Pliny has explained; the air not only grows heavier with the depth of a shaft, of which fact he has made mention, but also with the length of a tunnel.
The climbing machines of miners are ladders, fixed to one side of the shaft, and these reach either to the tunnel or to the bottom of the shaft. I need not describe how 'they are made, because they are used everywhere, and need not so much skill in their construction as care in fixing them. However, miners go down into mines not only by the steps of ladders, but they are also lowered into them while sitting on a stick or a wicker basket, fastened to the rope of one of the three drawing machines which I described at first. Further, when the shafts are much inclined, miners and other workmen sit in the dirt which surrounds their loins and slide down in the same way that boys do in winter-time when the water on some hillside has congealed with the cold, and to prevent themselves from falling, one arm is wound about a rope, the upper end of which is fastened to a beam at the mouth of the shaft, and the lower end to a stake fixed in the bottom of the shaft. In these three ways miners descend into the shafts. A fourth way may be mentioned which is employed when men and horses go down to the underground machines and come up again, that is by inclined shafts which are twisted like a screw and have steps cut in the rock, as I have already described.
It remains for me to speak of the ailments and accidents of miners, and of the methods by which they can guard against these, for we should always devote more care to maintaining our health, that we may freely perform our bodily functions, than to making profits. Of the illnesses, some affect the joints, others attack the lungs, some the eyes, and finally some are fatal to men.
Where water in shafts is abundant and very cold, it frequently injures the limbs, for cold is harmful to the sinews. To meet this, miners should make themselves sufficiently high boots of rawhide, which protect their legs from the cold water; the man who does not follow this advice will suffer much ill-health, especially when he reaches old age. On the other hand, some mines are so dry that they are entirely devoid of water, and this dryness causes the workmen even greater harm, for the dust which is stirred and beaten up by digging penetrates into the windpipe and lungs, and produces difficulty in breathing, and the disease which the Greeks call asthma. If the dust has corrosive qualities, it eats away the lungs, and implants consumption in the body; hence in the mines of the Carpathian Mountains women are found who have married seven husbands, all of whom this terrible consumption has carried off to a premature death. At Altenberg in Meissen there is found in the mines black pompholyx, which eats wounds and ulcers to the bone; this also corrodes iron, for which reason the keys of their sheds are made of wood. Further, there is a certain kind of cadmia which eats away the feet of the workmen when they have become wet, and similarly their hands, and injures their lungs and eyes. Therefore, for their digging they should make for themselves not only boots of rawhide, but gloves long enough to reach to the elbow, and they should fasten loose veils over their faces; the dust will then neither be drawn through these into their wind-pipes and lungs, nor will it fly into their eyes. Not dissimilarly, among the Romans the makers of vermilion took precautions against breathing its fatal dust.
Stagnant air, both that which remains in a shaft and that which remains in a tunnel, produces a difficulty in breathing; the remedies for this evil are the ventilating machines which I have explained above. There is another illness even more destructive, which soon brings death to men who work in those shafts or levels or tunnels in which the hard rock is broken by fire. Here the air is infected with poison, since large and small veins and seams in the rocks exhale some subtle poison from the minerals, which is driven out by the fire, and this poison itself is raised with the smoke not unlike pompholyx, which clings to the upper part of the walls in the works in which ore is smelted. If this poison cannot escape from the ground, but falls down into the pools and floats on their surface, it often causes danger, for if at any time the water is disturbed through a stone or anything else, these fumes rise again from the pools and thus overcome the men, by being drawn in with their breath; this is even much worse if the fumes of the fire have not yet all escaped. The bodies of living creatures who are infected with this poison generally swell immediately and lose all movement and feeling, and they die without pain; men even in the act of climbing from the shafts by the steps of ladders fall back into the shafts when the poison overtakes them, because their hands do not perform their office, and seem to them to be round and spherical, and likewise their feet. If by good fortune the injured ones escape these evils, for a little, while they are pale and look like dead men. At such times, no one should descend into the mine or into the neighbouring mines, or if he is in them he should come out quickly. Prudent and skilled miners burn the piles of wood on Friday, towards evening, and they do not descend into the shafts nor enter the tunnels again before Monday, and in the meantime the poisonous fumes pass away.
There are also times when a reckoning has to be made with Orcus, for some metalliferous localities, though such are rare, spontaneously produce poison and exhale pestilential vapour, as is also the case with some openings in the ore, though these more often contain the noxious fumes. In the towns of the plains of Bohemia there are some caverns which, at certain seasons of the year, emit pungent vapours which put out lights and kill the miners if they linger too long in them. Pliny, too, has left a record that when wells are sunk, the sulphurous or aluminous vapours which arise kill the well-diggers, and it is a test of this danger if a burning lamp which has been let down is extinguished. In such cases a second well is dug to the right or left, as an air-shaft, which draws off these noxious vapours. On the plains they construct bellows which draw up these noxious vapours and remedy this evil; these I have described before.
Further, sometimes workmen slipping from the ladders into the shafts break their arms, legs, or necks, or fall into the sumps and are drowned; often, indeed, the negligence of the foreman is to blame, for it is his special work both to fix the ladders so firmly to the timbers that they cannot break away, and to cover so securely with planks the sumps at the bottom of the shafts, that the planks cannot be moved nor the men fall into the water; wherefore the foreman must carefully execute his own work. Moreover, he must not set the entrance of the shaft-house toward the north wind, lest in winter the ladders freeze with cold, for when this happens the men's hands become stiff and slippery with cold, and cannot perform their office of holding. The men, too, must be careful that, even if none of these things happen, they do not fall through their own carelessness.
Mountains, too, slide down and men are crushed in their fall and perish. In fact, when in olden days Rammelsberg, in Goslar, sank down, so many men were crushed in the ruins that in one day, the records tell us, about 400 women were robbed of their husbands. And eleven years ago, part of the mountain of Altenberg, which had been excavated, became loose and sank, and suddenly crushed six miners; it also swallowed up a hut and one mother and her little boy. But this generally occurs in those mountains which contain venae cumulatae. Therefore, miners should leave numerous arches under the mountains which need support, or provide underpinning. Falling pieces of rock also injure their limbs, and to prevent this from happening, miners should protect the shafts, tunnels, and drifts.
The venomous ant which exists in Sardinia is not found in our mines. This animal is, as Solinus writes, very small and like a spider in shape; it is called solifuga, because it shuns (fugit) the light (solem). It is very common in silver mines; it creeps unobserved and brings destruction upon those who imprudently sit on it. But, as the same writer tells us, springs of warm and salubrious waters gush out in certain places, which neutralise the venom inserted by the ants.
In some of our mines, however, though in very few, there are other pernicious pests. These are demons of ferocious aspect, about which I have spoken in my book De Animantibus Subterraneis. Demons of this kind are expelled and put to flight by prayer and fasting.
Some of these evils, as well as certain other things, are the reason why pits are occasionally abandoned. But the first and principal cause is that they do not yield metal, or if, for some fathoms, they do bear metal they become barren in depth. The second cause is the quantity of water which flows in; sometimes the miners can neither divert this water into the tunnels, since tunnels cannot be driven so far into the mountains, or they cannot draw it out with machines because the shafts are too deep; or if they could draw it out with machines, they do not use them, the reason undoubtedly being that the expenditure is greater than the profits of a moderately poor vein. The third cause is the noxious air, which the owners sometimes cannot overcome either by skill or expenditure, for which reason the digging is sometimes abandoned, not only of shafts, but also of tunnels. The fourth cause is the poison produced in particular places, if it is not in our power either completely to remove it or to moderate its effects. This is the reason why the caverns in the Plain known as Laurentius used not to be worked, though they were not deficient in silver. The fifth cause are the fierce and murderous demons, for if they cannot be expelled, no one escapes from them. The sixth cause is that the underpinnings become loosened and collapse, and a fall of the mountain usually follows; the underpinnings are then only restored when the vein is very rich in metal. The seventh cause is military operations. Shafts and tunnels should not be re-opened unless we are quite certain of the reasons why the miners have deserted them, because we ought not to believe that our ancestors were so indolent and spiritless as to desert mines which could have been carried on with profit. Indeed, in our own days, not a few miners, persuaded by old women's tales, have re-opened deserted shafts and lost their time and trouble. Therefore, to prevent future generations from being led to act in such a way, it is advisable to set down in writing the reason why the digging of each shaft or tunnel has been abandoned, just as it is agreed was once done at Freiberg, when the shafts were deserted on account of the great inrush of water.
END OF BOOK VI.