BOOK VIII.

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are placed two cross-beams joined together, one in front and one in the back,the ends of which are mortised into the upright posts already mentioned.Through each mortise is bored a hole, into which is driven an iron clavis ;one end of the clavis has two horns, and the other end is perforated in orderthat a wedge driven through, binds the beams more firmly ; one horn of theclavis turns up and the other down. Three and a half feet above the cross-great activity prior to 500 b.c. (see note 6, p. 27), it was quite feasible for the ancient minerto have smelted these argentiferous lead ores direct. However, at some period prior to thedecadence of the mines in the 3rd Century b.c., there was in use an extensive system of millingand concentration. For the following details we are indebted mostly to Edouard Ardaillon(Les Mines Du Laurion dans VAntiquite, Chap. iv.). The ore was first hand-picked (in1869 one portion of these rejects was estimated at 7,000,000 tons) and afterward it wasapparently crushed in stone mortars some 16 to 24 inches in diameter, and thence passed tothe mills. These mills, which crushed dry, were of the upper and lower millstone order, likethe old-fashioned flour mills, and were turned by hand. The stones were capable ofadjustment in such a way as to yield different sizes. The sand was sifted and the oversizereturned to the mills. From the mills it was taken to washing plants, which consistedessentially of an inclined area, below which a canal, sometimes with riffles, lead through aseries of basins, ultimately returning the water again to near the head of the area. Thesewashing areas, constructed with great care, were made of stone cemented over smoothly,and were so efficiently done as to remain still intact. In washing, a workman brushedupward the pulp placed on the inclined upper portion of the area, thus concentrating there aconsiderable proportion of the galena ; what escaped had an opportunity to settle in thesequence of basins, somewhat on the order of the buddle. A quotation by Strabo (in, 2, 10)from the lost work of Polybius (200-125 b.c.) also indicates concentration of lead-silver ores inSpain previous to the Christian era : “ Polybius speaking of the silver mines of New Carthage,“ tells us that they are extremely large, distant from the city about 20 stadia, and occupy a“ circuit of 400 stadia, that there are 40,000 men regularly engaged in them, and that they“ yield daily to the Roman people (a revenue of) 25,000 drachmae. The rest of the process“ I pass over, as it is too long, but as for the silver ore collected, he tells us that it is broken" up, and sifted through sieves over water ; that what remains is to be again broken, and the“ water having been strained off, it is to be sifted and broken a third time. The dregs which“ remain after the fifth time are to be melted, and the lead being poured off, the silver is" obtained pure. These silver mines still exist; however, they are no longer the property“ of the state, neither these nor those elsewhere, but are possessed by private individuals. The“ gold mines, on the contrary, nearly all belong to the state. Both at Castlon and other“ places there are singular lead mines worked. They contain a small proportion of silver, but“ not sufficient to pay for the expense of refining.” (Hamilton’s Translation, Vol. I., p. 222).While Pliny gives considerable information on vein mining and on alluvial washing, thefollowing obscure passage (xxxm, 21) appears to be the only reference to concentration ofores : " That which is dug out is crushed, washed, roasted, and ground to powder. This“ powder is called apitascudes, while the silver (lead ?) which becomes disengaged in the“ furnace is called sudor (sweat). That which is ejected from the chimney is called scoria" as with other metals. In the case of gold this scoria is crushed and melted again.” It isevident enough from these quotations that the Ancients by “washing” and “sifting,”grasped the practical effect of differences in specific gravity of the various components ofan ore. Such processes are barely mentioned by other mediaeval authors, such as Theo-philus, Biringuccio, etc., and thus the account in this chapter is the first tangible technicaldescription. Lead mining has been in active progress in Derbyshire since the 13th century,and concentration was done on an inclined board until the 16th century, when WilliamHumpfrey (see below) introduced the jigging sieve. Some further notes on this industry willbe found in note 1, p. 77. However, the buddle and strake which appear at that time, arebut modest improvements over the board described by Agatharchides in the quotation above.

The ancient crushing appliances, as indicated by the ancient authors and by the Greekand Roman remains scattered over Europe, were hand-mortars and mill-stones of the sameorder as those with which they ground flour. The stamp-mill, the next advance overgrinding in mill-stones, seems to have been invented some time late in the 15th or earlyin the 16th centuries, but who invented it is unknown. Beckmann (Hist, of Inventions,n, p. 335) says : “ In the year 1519 the process of sifting and wet-stamping was established“ at Joachimsthal by Paul Grommestetter, a native of Schwarz, named on that account" the Schwarzer, whom Melzer praises as an ingenious and active washer ; and we are" told that he had before introduced the same improvements at Schneeberg. Soon after,“ that is in 1521, a large stamping-work was erected at Joachimsthal, and the process“ of washing was begun. A considerable saving was thus made, as a great many metallic“ particles were before left in the washed sand, which was either thrown away or used as“ mortar for building. In the year 1525, Hans Portner employed at Schlackenwalde the