316 MINING 



ployed in detaching the ores, in sorting them, taking them out, and preparing new 

 piles against the next Saturday. 



The labour of a week consists, for every man, of five posts during the day, each of 

 8 hours, and of one post of 4 hours for Saturday. Moreover, an extra allowance is 

 made to such workmen as employ themselves some posts during the night. 



The labour of one compartment, or atelier, of the mine consists, therefore, in 

 arranging the faggots, in detaching the ore which has already experienced the action 

 of the fire ; in breaking the blocks obtained ; in separating the ore from the debris of 

 the pile ; and, whenever it may be practicable or useful, in boring holes for blasting 

 with gunpowder. The heat is BO great in this kind of mine that the men are obliged 

 to work in it without clothing. 



We have already remarked that, besides the working by fire, which is chiefly used 

 here, recourse is sometimes had to blasting by gunpowder. This is done in order 

 either to recover the bottom part or ground of the vaults on which the fire can act but 

 imperfectly, to clear away some projections which would interfere with the effect of 

 the pile, or, lastly, to strip the surrounding rock from the mass of the ore, and thence 

 to obtain schist proper for the construction of the rubbish-terraces. 



The blasting-process is employed when the foreman of the workshop or mine- 

 chamber judges that a hole well placed may separate enough of ore to pay the time, 

 the repair of tools, and the gunpowder expended. But this indemnification is rarely 

 obtained. The following statement will give an idea of the tenacity which the mineral 

 deposit often presents : 



In a portion of the Kammelsberg mine, the ore, consisting of extremely compact 

 iron and copper pyrites, was attacked by a single man, who bored a mining-hole. 

 After 1 1 posts of obstinate labour, occupying altogether 88 hours, the workman, 

 being vigilantly superintended, had been able to advance the hole to a depth of no 

 more than 4 inches ; in doing which he had rendered entirely unserviceable 126 

 punches or borers, besides 26 others which had been re-tipped with steel, and 

 201 which had been sharpened ; 6 Ibs. of oil had been consumed in giving him 

 light ; and Ib. of gunpowder was required for blasting the bore. It was found 

 from a calculation made upon these facts by the administration of mines, that every 

 inch deep of this hole cost, at their low price of labour, nearly a florin, value two 

 shillings and sixpence. 



It is therefore evident that, though the timber, of which the consumption is pro- 

 digiously great, were much less abundant and dearer than it still is at Kammelsberg, 

 mining by fire would be preferable to every other mode of exploitation. It is even 

 certain that, on any supposition, the employment of gunpowder would not be practi- 

 cable for every part of the mine ; and if fuel came to fail, it would be requisite to 

 renounce the workings at Kammelsberg, although this mountain still contains a large 

 quantity of metals. 



If in all mines the free circulation of air be an object of the highest importance, 

 wo must perceive how indispensable it must be in every part of a mine where the 

 mode of exploitation maintains the temperature of the air at 112 Fahr., when the 

 workmen return into it after the combustion of the piles, and in which, besides, it is 

 necessary that this combustion be effected with activity in their absence. But, in 

 consequence of the extent and mutual ramifications of the workings, the number of 

 the shafts, galleries, and their differences of level, the ventilation of the mine is in a 

 manner spontaneously maintained. The high temperatur* is peculiarly favourable to 

 it. The aid of art consists merely in placing some doors judiciously, which may be 

 opened or shut at pleasure, to carry on the circulation of the air. 



In considering the Kammelsberg from its summit, which rises about 400 yards 

 above the town of Goslar, we observe, first, beds of slaty sandstone, which become 

 the more horizontal, the nearer they approach to the surface. At about 160 yards 

 below the top level there occurs, in the bosom of the slaty greywacke, a powerful 

 stratum of shells embedded in a ferruginous limestone. In descending towards the 

 face of the ore, the parallel stratification of the clay-slate, which forms its walls and 

 roof, grows more and more manifest. Here the slate is black, compact, and thinly 

 foliated. The inclination of the different beds of rock is considerable. 



The ores are argentifereus and auriferous, but very slightly so, especially as to 

 the gold. It is the ores of load and copper which contain the silver, and in the 

 latter the gold is found, but without its being well ascertained in what mineral it is 

 deposited. Sometimes the ore occurs in the native state, or as copper of cementation. 

 Beautiful crystals of sulphate of limo are found in the old workings. 



In figs. 1475, 1476, AB is the shaft of extraction, called the Kahncnkuhlcr ; N is 

 the ventilation-shaft, called Bre'itUngerwettcrschacht ; p is the extraction-shaft, called 

 Innier-schacht. 



B F JB a new extraction-shaft, called Neuertreibschackt t by which also the water is 



