De Re Metallica Part 7

The mines were worked by slaves. Even the overseers were at times apparently slaves, for we find (Xenophon, _Memorabilia_, II., 5) that Nicias paid a whole talent for a good overseer. A talent would be about 837 Troy ounces of silver. As wages of skilled labour were about two and one half pennyweights of silver per diem, and a family income of 100 ounces of silver per annum was affluence, the ratio of purchasing power of Attic coinage to modern would be about 100 to 1. Therefore this mine manager was worth in modern value roughly 8,000. The mines were the property of the State. The areas were defined by vertical boundaries, and were let on lease for definite periods for a fixed annual rent. More ample discussion of the law will be found on p. 83.

[7] Xenophon. (Essay on The Revenues, IV., 30). "I think, however, that I am able to give some advice with regard to this difficulty also (the risk of opening new mines), and to show how new operations may be conducted with the greatest safety. There are ten tribes at Athens, and if to each of these the State should a.s.sign an equal number of slaves, and the tribes should all make new cuttings, sharing their fortunes in common, then if but one tribe should make any useful discovery it would point out something profitable to the whole; but if two, three, or four, or half the number should make some discovery, it is plain that the works would be more profitable in proportion, and that they should all fail is contrary to all experience in past times." (Watson's Trans. p.

258).

[8] Agricola here refers to the proposal of Xenophon for the State to collect slaves and hire them to work the mines of Laurion. There is no evidence that this recommendation was ever carried out.

[9] _Partes._ Agricola, p. 89-91, describes in detail the organization and management of these share companies. See Note 8, p. 90.

[10] This island in the northern aegean Sea has produced this "earth"

from before Theophrastus' time (372-287 B.C.) down to the present day.

According to Dana (System of Mineralogy 689), it is cimolite, a hydrous silicate of aluminium. The Ancients distinguished two kinds,--one sort used as a pigment, and the other for medicinal purposes. This latter was dug with great ceremony at a certain time of the year, moulded into cubes, and stamped with a goat,--the symbol of Diana. It thus became known as _terra sigillata_, and was an article of apothecary commerce down to the last century. It is described by Galen (XII., 12), Dioscorides (V., 63), and Pliny (x.x.xV., 14), as a remedy for ulcers and snake bites.

[11] _Magister Metallorum_. See Note 1, p. 78, for the reasons of the adoption of the term _Bergmeister_ and page 95 for details of his duties.

[12] _Ramenta_. "Particles." The author uses this term indifferently for fragments, particles of mineral, concentrates, gold dust, black tin, etc., in all cases the result of either natural or artificial concentration. As in technical English we have no general term for both natural and artificial "concentrates," we have rendered it as the context seemed to demand.

[13] A certain amount of bitumen does float ash.o.r.e in the Dead Sea; the origin of it is, however, uncertain. Strabo (XVI., 2, 42), Pliny (V., 15 and 16), and Josephus (IV., 8), all mention this fact. The lake for this reason is often referred to by the ancient writers by the name _Asphalt.i.tes_.

[14] _Excoctor_,--literally, "Smelter" or "Metallurgist."

[15] This reference should be to the _De Natura Fossilium_ (p. 230), although there is a short reference to the matter in _De Ortu et Causis_ (p. 59). Agricola maintained that not only were jet and amber varieties of bitumen, but also coal and camphor and obsidian. As jet (_gagates_) is but a compact variety of coal, the ancient knowledge of this substance has more interest than would otherwise attach to the gem, especially as some materials described in this connection were no doubt coal. The Greeks often refer to a series of substances which burned, contained earth, and which no doubt comprised coal. Such substances are mentioned by Aristotle (_De Mirabilibus_. 33, 41, 125), Nicander (_Theriaca_. 37), and others, previous to the 2nd Century B.C., but the most ample description is that of Theophrastus (23-28): "Some of the more brittle stones there also are, which become as it were burning coals when put into a fire, and continue so a long time; of this kind are those about Bena, found in mines and washed down by the torrents, for they will take fire on burning coals being thrown on them, and will continue burning as long as anyone blows them; afterward they will deaden, and may after that be made to burn again. They are therefore of long continuance, but their smell is troublesome and disagreeable. That also which is called the _spinus_, is found in mines. This stone, cut in pieces and thrown together in a heap, exposed to the sun, burns; and that the more, if it be moistened or sprinkled with water (a pyritiferous shale?). But the _Lipara_ stone empties itself, as it were, in burning, and becomes like the _pumice_, changing at once both its colour and density; for before burning it is black, smooth, and compact.

This stone is found in the Pumices, separately in different places, as it were, in cells, nowhere continuous to the matter of them. It is said that in Melos the pumice is produced in this manner in some other stone, as this is on the contrary in it; but the stone which the pumice is found in is not at all like the _Lipara_ stone which is found in it.

Certain stones there are about Tetras, in Sicily, which is over against Lipara, which empty themselves in the same manner in the fire. And in the promontory called Erineas, there is a great quant.i.ty of stone like that found about Bena, which, when burnt, emits a bituminous smell, and leaves a matter resembling calcined earth. Those fossil substances that are called coals, and are broken for use, are earthy; they kindle, however, and burn like wood coals. These are found in Liguria, where there also is amber, and in Elis, on the way to Olympia over the mountains. These are used by smiths." (Based on Hill's Trans.).

Dioscorides and Pliny add nothing of value to this description.

Agricola (_De Nat. Fos._, p. 229-230) not only gives various localities of jet, but also records its relation to coal. As to the latter, he describes several occurrences, and describes the deposits as _vena dilatata_. Coal had come into considerable use all over Europe, particularly in England, long before Agricola's time; the oft-mentioned charter to mine sea-coal given to the Monks of Newbottle Abbey, near Preston, was dated 1210.

Amber was known to the Greeks by the name _electrum_, but whether the alloy of the same name took its name from the colour of amber or _vice versa_ is uncertain. The gum is supposed to be referred to by Homer (Od.

XV. 460), and Thales of Miletus (640-546 B.C.) is supposed to have first described its power of attraction. It is mentioned by many other Greek authors, aeschylus, Euripides, Aristotle, and others. The latter (_De Mirabilibus_, 81) records of the amber islands in the Adriatic, that the inhabitants tell the story that on these islands amber falls from poplar trees. "This, they say, resembles gum and hardens like stone, the story of the poets being that after Phaeton was struck by lightning his sisters turned to poplar trees and shed tears of amber." Theophrastus (53) says: "Amber is also a stone; it is dug out of the earth in Liguria and has, like the before-mentioned (lodestone), a power of attraction."

Pliny (x.x.xVII., 11) gives a long account of both the substance, literature, and mythology on the subject. His view of its origin was: "Certainly amber is obtained from the islands of the Northern Ocean, and is called by the Germans _glaesum_. For this reason the Romans, when Germanicus Caesar commanded in those parts, called one of them _Glaesaria_, which was known to the barbarians as _Austeravia_. Amber originates from gum discharged by a kind of pine tree, like gum from cherry and resin from the ordinary pine. It is liquid at first, and issues abundantly and hardens in time by cold, or by the sea when the rising tides carry off the fragments from the sh.o.r.es of those islands.

Certainly it is thrown on the coasts, and is so light that it appears to roll in the water. Our forefathers believed that it was the juice of a tree, for they called it _succinum_. And that it belongs to a kind of pine tree is proved by the odour of the pine tree which it gives when rubbed, and that it burns when ignited like a pitch pine torch." The term amber is of Arabic origin--from _Ambar_--and this term was adopted by the Greeks after the Christian era. Agricola uses the Latin term _succinum_ and (_De Nat. Fos._, p. 231-5) disputes the origin from tree gum, and contends for submarine bitumen springs.

[16] The statement in _De Veteribus et Novis Metallis_ (p. 394) is as follows:--

"It came about by chance and accident that the silver mines were discovered at Freiberg in Meissen. By the river Sala, which is not unknown to Strabo, is Hala, which was once country, but is now a large town; the site, at any rate, even from Roman times was famous and renowned for its salt springs, for the possession of which the Hermunduri fought with the Chatti. When people carried the salt thence in wagons, as they now do straight through Meissen (Saxony) into Bohemia--which is lacking in that seasoning to-day no less than formerly--they saw galena in the wheel tracks, which had been uncovered by the torrents. This lead ore, since it was similar to that of Goslar, they put into their carts and carried to Goslar, for the same carriers were accustomed to carry lead from that city. And since much more silver was smelted from this galena than from that of Goslar, certain miners betook themselves to that part of Meissen in which is now situated Freiberg, a great and wealthy town; and we are told by consistent stories and general report that they grew rich out of the mines."

Agricola places the discovery of the mines at Freiberg at about 1170.

See Note 11, p. 5.

[17] Diodorus Siculus (V., 35). "These places being covered with woods, it is said that in ancient times these mountains were set on fire by shepherds, and continued burning for many days, and parched the earth, so that an abundance of silver ore was melted, and the metal flowed in streams of pure silver like a river." Aristotle, nearly three centuries before Diodorus, mentions this same story (_De Mirabilibus_, 87): "They say that in Ibernia the woods were set on fire by certain shepherds, and the earth thus heated, the country visibly flowed silver; and when some time later there were earthquakes, and the earth burst asunder at different places, a large amount of silver was collected." As the works of Posidonius are lost, it is probable that Agricola was quoting from Strabo (III., 2, 9), who says, in describing Spain: "Posidonius, in praising the amount and excellence of the metals, cannot refrain from his accustomed rhetoric, and becomes quite enthusiastic in exaggeration.

He tells us we are not to disbelieve the fable that formerly the forests having been set on fire, the earth, which was loaded with silver and gold, melted and threw up these metals to the surface, for inasmuch as every mountain and wooded hill seemed to be heaped up with money by a lavish fortune." (Hamilton's Trans. I., p. 220). Or he may have been quoting from the _Deipnosophistae_ of Athenaeus (VI.), where Posidonius is quoted: "And the mountains ... when once the woods upon them had caught fire, spontaneously ran with liquid silver."

[18] Lucretius, _De Rerum Natura_ V. 1241.

[19] Agricola's account of this event in _De Veteribus et Novis Metallis_ is as follows (p. 393): "Now veins are not always first disclosed by the hand and labour of man, nor has art always demonstrated them; sometimes they have been disclosed rather by chance or by good fortune. I will explain briefly what has been written upon this matter in history, what miners tell us, and what has occurred in our times.

Thus the mines at Goslar are said to have been found in the following way. A certain n.o.ble, whose name is not recorded, tied his horse, which was named Ramelus, to the branch of a tree which grew on the mountain.

This horse, pawing the earth with its hoofs, which were iron shod, and thus turning it over, uncovered a hidden vein of lead, not unlike the winged Pegasus, who in the legend of the poets opened a spring when he beat the rock with his hoof. So just as that spring is named Hippocrene after that horse, so our ancestors named the mountain Rammelsberg.

Whereas the perennial water spring of the poets would long ago have dried up, the vein even to-day exists, and supplies an abundant amount of excellent lead. That a horse can have opened a vein will seem credible to anyone who reflects in how many ways the signs of veins are shown by chance, all of which are explained in my work _De Re Metallica_. Therefore, here we will believe the story, both because it may happen that a horse may disclose a vein, and because the name of the mountain agrees with the story." Agricola places the discovery of Goslar in the Hartz at prior to 936. See Note 11, p. 5.

[20] _Fragmenta_. The glossary gives "_Geschube_." This term is defined in the _Bergwerks' Lexicon_ (Chemnitz, 1743, p. 250) as the pieces of stone, especially tin-stone, broken from the vein and washed out by the water--the croppings.

[21] So far as we are able to discover, this is the first published description of the divining rod as applied to minerals or water. Like Agricola, many authors have sought to find its origin among the Ancients. The magic rods of Moses and Homer, especially the rod with which the former struck the rock at h.o.r.eb, the rod described by Ctesias (died 398 B.C.) which attracted gold and silver, and the _virgula divina_ of the Romans have all been called up for proof. It is true that the Romans are responsible for the name _virgula divina_, "divining rod," but this rod was used for taking auguries by casting bits of wood (Cicero, _De Divinatione_). Despite all this, while the ancient naturalists all give detailed directions for finding water, none mention anything akin to the divining rod of the Middle Ages. It is also worth noting that the Monk Theophilus in the 12th Century also gives a detailed description of how to find water, but makes no mention of the rod. There are two authorities sometimes cited as prior to Agricola, the first being Basil Valentine in his "Last Will and Testament"

(XXIV-VIII.), and while there may be some reason (see Appendix) for accepting the authenticity of the "Triumphal Chariot of Antimony" by this author, as dating about 1500, there can be little doubt that the "Last Will and Testament" was spurious and dated about 50 years after Agricola. Paracelsus (_De Natura Rerum_ IX.), says: "These (divinations) are vain and misleading, and among the first of them are divining rods, which have deceived many miners. If they once point rightly they deceive ten or twenty times." In his _De Origine Morborum Invisibilium_ (Book I.) he adds that the "faith turns the rod." These works were no doubt written prior to _De Re Metallica_--Paracelsus died in 1541--but they were not published until some time afterward. Those interested in the strange persistence of this superst.i.tion down to the present day--and the files of the patent offices of the world are full of it--will find the subject exhaustively discussed in M. E. Chevreul's "_De la Baguette Divinatoire_," Paris, 1845; L. Figuier, "_Histoire du Merveilleux dans les temps moderne II._", Paris, 1860; W. F. Barrett, Proceedings of the Society of Psychical Research, part 32, 1897, and 38, 1900; R. W.

Raymond, American Inst. of Mining Engineers, 1883, p. 411. Of the descriptions by those who believed in it there is none better than that of William Pryce (_Mineralogia Cornubiensis_, London, 1778, pp.

113-123), who devotes much pains to a refutation of Agricola. When we consider that a century later than Agricola such an advanced mind as Robert Boyle (1626-1691), the founder of the Royal Society, was convinced of the genuineness of the divining rod, one is more impressed with the clarity of Agricola's vision. In fact, there were few indeed, down to the 19th Century, who did not believe implicitly in the effectiveness of this instrument, and while science has long since abandoned it, not a year pa.s.ses but some new manifestation of its hold on the popular mind breaks out.

[22] Exodus VII., 10, 11, 12.

[23] Odyssey XVI., 172, and X., 238.

[24] Odyssey XXIV., 1, etc. The _Caduceus_ of Hermes had also the power of turning things to gold, and it is interesting to note that in its oldest form, as the insignia of heralds and of amba.s.sadors, it had two p.r.o.ngs.

[25] In a general way _venae profundae_ were fissure veins and _venae dilatatae_ were sheeted deposits. For description see Book III.

[26] These mines are in the Erzgebirge. We have adopted the names given in the German translation.

[27] The quotation from Pliny (x.x.xIII., 31) as a whole reads as follows:--

"Silver is found in nearly all the provinces, but the finest of all in Spain; where it is found in the barren lands, and in the mountains.

Wherever one vein of silver has been found, another is sure to be found not far away. This is the case of nearly all the metals, whence it appears that the Greeks derived _metalla_. It is wonderful that the shafts begun by Hannibal in Spain still remain, their names being derived from their makers. One of these at the present day called Baebelo, furnished Hannibal with three hundred pounds' weight (of silver) per day. This mountain is excavated for a distance of fifteen hundred paces; and for this distance there are waterbearers lighted by torches standing night and day baling out the water in turns, thus making quite a river." Hannibal dates 247-183 B.C. and was therefore dead 206 years when Pliny was born. According to a footnote in Bostock and Riley's translation of Pliny, these workings were supposed to be in the neighbourhood of Castulo, now Cazlona, near Linares. It was at Castulo that Hannibal married his rich wife Himilce; and in the hills north of Linares there are ancient silver mines still known as Los Pozos de Anibal.

BOOK III.

Previously I have given much information concerning the miners, also I have discussed the choice of localities for mining, for was.h.i.+ng sands, and for evaporating waters; further, I described the method of searching for veins. With such matters I was occupied in the second book; now I come to the third book, which is about veins and stringers, and the seams in the rocks[1]. The term "vein" is sometimes used to indicate _ca.n.a.les_ in the earth, but very often elsewhere by this name I have described that which may be put in vessels[2]; I now attach a second significance to these words, for by them I mean to designate any mineral substances which the earth keeps hidden within her own deep receptacles.

[Ill.u.s.tration 45a (Vein in mountain): A, C--The mountain. B--_Vena profunda_.]

First I will speak of the veins, which, in depth, width, and length, differ very much one from another. Those of one variety descend from the surface of the earth to its lowest depths, which on account of this characteristic, I am accustomed to call "_venae profundae_."

[Ill.u.s.tration 45b (Vein in mountain): A, D--The mountain. B, C--_Vena dilatata_.]

Another kind, unlike the _venae profundae_, neither ascend to the surface of the earth nor descend, but lying under the ground, expand over a large area; and on that account I call them "_venae dilatatae_."

[Ill.u.s.tration 49 (Veins in mountain): A, B, C, D--The mountain. E, F, G, H, I, K--_Vena c.u.mulata_.]

Another occupies a large extent of s.p.a.ce in length and width; therefore I usually call it "_vena c.u.mulata_," for it is nothing else than an acc.u.mulation of some certain kind of mineral, as I have described in the book ent.i.tled _De Subterraneorum Ortu et Causis_. It occasionally happens, though it is unusual and rare, that several acc.u.mulations of this kind are found in one place, each one or more fathoms in depth and four or five in width, and one is distant from another two, three, or more fathoms. When the excavation of these acc.u.mulations begins, they at first appear in the shape of a disc; then they open out wider; finally from each of such acc.u.mulations is usually formed a "_vena c.u.mulata_."

[Ill.u.s.tration 50a (Veins in mountain): A--_Vena profunda_.

B--_Intervenium_. C--Another _vena profunda_.]

[Ill.u.s.tration 50b (Veins in mountain): A & B--_Vena dilatatae_.

C--_Intervenium_. D & E--Other _venae dilatatae_.]

The s.p.a.ce between two veins is called an _intervenium_; this interval between the veins, if it is between _venae dilatatae_ is entirely hidden underground. If, however, it lies between _venae profundae_ then the top is plainly in sight, and the remainder is hidden.