De Re Metallica Part 18

[15] The strata here enumerated are given in the Glossary of _De Re Metallica_ as follows:--

_Corium terrae_ _Die erd oder leim._ _Saxum rubrum_ _Rot gebirge._ _Alterum item rubrum_ _Roterkle._ _Argilla cinerea_ _Thone._ _Tertium saxum_ _Gerhulle._ _Cineris vena_ _Asche._ _Quartum saxum_ _Gniest._ _Quintum saxum_ _Schwehlen._ _s.e.xtum saxum_ _Oberrauchstein._ _Septimum saxum_ _Zechstein._ _Octavum saxum_ _Underrauchstein._ _Nonum saxum_ _Blitterstein._ _Decimum saxum_ _Oberschuelen._ _Undecimum saxum_ _Mittelstein._ _Duodecimum saxum_ _Underschuelen._ _Decimumtertium saxum_ _Dach._ _Decimumquartum saxum_ _Norweg._ _Decimumquintum saxum_ _Lotwerg._ _Decimums.e.xtum saxum_ _Kamme._ _Lapis aerosus fissilis_ _Schifer._

The description is no doubt that of the Mannsfeld cupriferous slates. It is of some additional interest as the first attempt at stratigraphic distinctions, although this must not be taken too literally, for we have rendered the different numbered "_saxum_" in this connection as "stratum." The German terms given by Agricola above, can many of them be identified in the miners' terms to-day for the various strata at Mannsfeld. Over the _kupferschiefer_ the names to-day are _kammschale_, _dach_, _faule_, _zechstein_, _rauchwacke_, _rauchstein_, _asche_. The relative thickness of these beds is much the same as given by Agricola.

The stringers in the 8th stratum of stone, which fuse in the fire of the second order, were possibly calcite. The _rauchstein_ of the modern section is distinguished by stringers of calcite, which give it at times a brecciated appearance.

[16] The history of surveying and surveying instruments, and in a subsidiary way their application to mine work, is a subject upon which there exists a most extensive literature. However, that portion of such history which relates to the period prior to Agricola represents a much less proportion of the whole than do the citations to this chapter in _De Re Metallica_, which is the first comprehensive discussion of the mining application. The history of such instruments is too extensive to be entered upon in a footnote, but there are some fundamental considerations which, if they had been present in the minds of historical students of this subject, would have considerably abridged the literature on it. First, there can be no doubt that measuring cords or rods and boundary stones existed almost from the first division of land. There is, therefore, no need to try to discover their origins.

Second, the history of surveying and surveying instruments really begins with the invention of instruments for taking levels, or for the determination of angles with a view to geometrical calculation. The meagre facts bearing upon this subject do not warrant the endless expansion they have received by argument as to what was probable, in order to accomplish a.s.sumed methods of construction among the Ancients.

For instance, the argument that in carrying the Grand Ca.n.a.l over watersheds with necessary reservoir supply, the Chinese must have had accurate levelling and surveying instruments before the Christian Era, and must have conceived in advance a completed work, does not hold water when any investigation will demonstrate that the ca.n.a.l grew by slow accretion from the lateral river systems, until it joined almost by accident. Much the same may be said about the preconception of engineering results in several other ancient works. There can be no certainty as to who first invented instruments of the order mentioned above; for instance, the invention of the dioptra has been ascribed to Hero, _vide_ his work on the _Dioptra_. He has been a.s.sumed to have lived in the 1st or 2nd Century B.C. Recent investigations, however, have shown that he lived about 100 A.D. (Sir Thomas Heath, Encyc. Brit.

11th Ed., XIII, 378). As this instrument is mentioned by Vitruvius (50 -0 B.C.) the myth that Hero was the inventor must also disappear.

Incidentally Vitruvius (VIII, 5) describes a levelling instrument called a _chorobates_, which was a frame levelled either by a groove of water or by plumb strings. Be the inventor of the _dioptra_ who he may, Hero's work on that subject contains the first suggestion of mine surveys in the problems (XIII, XIV, XV, XVI), where geometrical methods are elucidated for determining the depths required for the connection of shafts and tunnels. On the compa.s.s we give further notes on p. 56. It was probably an evolution of the 13th Century. As to the application of angle- and level-determining instruments to underground surveys, so far as we know there is no reference prior to Agricola, except that of Hero.

Mr. Bennett Brough (Cantor Lecture, London, 1892) points out that the _Nutzliche Bergbuchlin_ (see Appendix) describes a mine compa.s.s, but there is not the slightest reference to its use for anything but surface direction of veins.

Although map-making of a primitive sort requires no instruments, except legs, the oldest map in the world possesses unusual interest because it happens to be a map of a mining region. This well-known Turin papyrus dates from Seti I. (about 1300 B.C.), and it represents certain gold mines between the Nile and the Red Sea. The best discussion is by Chabas (_Inscriptions des Mines d'Or_, Chalons-sur-Saone, Paris, 1862, p.

30-36). Fragments of another papyrus, in the Turin Museum, are considered by Lieblein (_Deux Papyras Hieratiques_, Christiania, 1868) also to represent a mine of the time of Rameses I. If so, this one dates from about 1400 B.C. As to an actual map of underground workings (disregarding ill.u.s.trations) we know of none until after Agricola's time. At his time maps were not made, as will be gathered from the text.

[17] For greater clarity we have in a few places interpolated the terms "major" and "minor" triangles.

[18] The names of the instruments here described in the original text, their German equivalents in the Glossary, and the terms adopted in translation are given below:--

LATIN TEXT. GLOSSARY. TERMS ADOPTED.

_Funiculus_ -- Cord

_Pertica_ _Stab_ Rod

_Hemicyclium_ _Donlege bretlein_ Hemicycle

_Tripus_ _Stul_ Tripod

_Instrumentum cui _Compa.s.s_ Compa.s.s index_

_Orbis_ _Scheube_ Orbis

_Libra stativa_ _Auffsafz_ Standing plummet level

_Libra pensilis_ _Wage_ Suspended plummet level

_Instrumentum cui _Der schiner Swiss compa.s.s index Alpinum_ compa.s.s_

[19] It is interesting to note that the ratio of any length so obtained, to the whole length of the staff, is practically equal to the cosine of the angle represented by the corresponding gradation on the hemicycle; the gradations on the rod forming a fairly accurate table of cosines.

[20] It must be understood that instead of "plotting" a survey on a reduced scale on paper, as modern surveyors do, the whole survey was reproduced in full scale on the "surveyor's field."

BOOK VI.

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,[1] and lastly of the maladies of miners. And while all these matters are being described accurately, many methods of work will be explained.

[Ill.u.s.tration 150 (Iron tools): A--First "iron tool." B--Second.

C--Third. D--Fourth.[2] E--Wedge. F--Iron block. G--Iron plate.

H--Wooden handle. I--Handle inserted in first tool.]

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 acc.u.mulate 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, blocks, and plates, are likewise made larger or smaller.

[Ill.u.s.tration 151 (Hammers): A--Smallest of the smaller hammers.

B--Intermediate. C--Largest. D--Small kind of the larger hammer.

E--Large kind. F--Wooden handle. G--Handle fixed in the smallest hammer.]

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.

[Ill.u.s.tration 152a (Crowbars): A--Round crowbar. B--Flat crowbar.

C--Pike.]

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.

[Ill.u.s.tration 152b (Picks): A--Pick. B--Hoe. C--Shovel.]

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 sc.r.a.pe 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.

[Ill.u.s.tration 154a (Buckets for hoisting ore)]

[Ill.u.s.tration 154b (Buckets for hoisting ore): A--Small bucket. B--Large bucket. C--Staves. D--Iron hoops. E--Iron straps. F--Iron straps on the bottom. G--Hafts. H--Iron bale. I--Hook of drawing-rope. K--Basket.

L--Hide bucket or sack.]

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.[3] 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 das.h.i.+ng 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 bale 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.[4]" 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, subst.i.tute 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.

[Ill.u.s.tration 155 (Wheelbarrows): A--Small wheelbarrow. B--Long planks thereof. C--End-boards. D--Small wheel. E--Larger barrow. F--Front end-board thereof.]

That which we call a _cisium_[5] 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 [Greek: apsides], two transverse spokes fixed into it pa.s.s 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.

[Ill.u.s.tration 156 (Trucks): A--Rectangular iron bands on truck. B--Its iron straps. C--Iron axle. D--Wooden rollers. E--Small iron keys.

F--Large blunt iron pin. G--Same truck upside down.]

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"[6], 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.

[Ill.u.s.tration 157 (Batea): A--Small batea. B--Rope. C--Large batea.]