G76

THEORY AN1) PRACTICE OF ENGINEERING.

Book II.

tamping iron, a particular clay being used for wadding, a certain length of safety fusekeeping up the communication with the powder ; when fire is applied the miners retire tillthe explosion has taken place. It is not often that the safety fuse misses fire, but accidentsnow and then arise from its burning more slowly than usual, which may occur from tootight ramming down, when the impatience of the 'miner induces him too early toexamine into the cause of the delay, and the explosion takes place before he withdraws.After the blasting the/nc/t comes into requisition for the removal of the partially separatedangular pieces of rock ; in soft ground the use of gunpowder is only occasionally re-quired. These works are done by the piece; the miner contracts to excavate therock in a certain situation at so much per solid fathom ; this is denominated tut-worh ; orhe undertakes to excavate the vein, and to fit the ore for the market, at the price of so muchin the pound of the sum for which the ore is sold; then it is called tribute. Both thesecontracts are to a certain extent speculative; but whilst the former involves only the un-certainty of the nature of the ground, which in these strata is not ordinarily great, the latteris dependent on the character of the vein, as well as on its size and richness, which are ex-ceedingly variable in the majority of mines ; the consequence is, that while the tut-icorkmanreceives pay approaching, in the regularity of amount, to that of the daily labourer, thetributer is on one occasion absolutely a loser, and on another receives a sum unusually largefor a person in his rank of life ; he is in fact a co-adventurer with the owners, but one whorisks nothing but his time and labour.

.The methods by which the contracts are let tends, however, to equalise, in a greatmeasure, the average monthly earnings during periods of considerable length ; at certainstated times, generally at an interval of two months, the work to he done in differentlevels is put up to be contracted for. Each place of work (pitch) requires a certain numberof men and hoys, determined by the agent, the partnerships between the individuals beingentirely voluntary. The greater part of the men who are employed in a particular mineare generally present on these occasions; at any rate one of each parly is there to com-pete for the contract. The agent, who acts as auctioneer, commonly standing in thewindow of the counting-house of the mine, names a particular place of work, as the 110Jf r est of Doctor's Shaft; some one immediately names a price, and in a great majority ofcases this is one of the party who has been working in the place in question, and no oneunderbids him, but the agent states a lower price, which is accepted. Where the contractis taken by the party which had it before, it is generally throughout the mining districtsa rule not to disturb those who have been in possession of a pitch : it is the assurancespringing from this, which sometimes induces a party of miners when a new pitch, onewhich has not hitherto been worked, is set up, to take it for nothing, or next to nothing.They expect to establish themselves in the mine, and on the next setting day, they pro-bably obtain a remunerating price.

There is of course an opposition of interests between the owners, whom the agentrepresents, and the labourers, and the object of the latter is to make the former believe theground harder, and the veins poorer than they are. He, on the other hand, forms his ownjudgment on these points by an accurate examination within a day or two of the setting,and fixes his price for the most part so that average wages may be gained by the men.It is clear, however, that where a tribute pitch is at present poor, he must be cautious ingiving a higher price, as there is always a possibility of a rapid increase in the size of thelode, and the value of its produce. The contracts are generally good from one setting-dayto another, or for two months ; but longer terms are often given, where the work to bedone is known to be of equable value.

The setting-day -is usually the pay-day likewise; accounts are given to each party,stating the value of their work, and the deductions to be made from it. The sum due tothe concern is received by one of its members, and divided afterwards among them. Oneconsiderable item in these bills is what is called the subsist, which is an advance made onaccount at the end of the first month of the contract, for the subsistence of the men andpayment of the boys. Its amount is commonly determined by the value of the workalready done : but in some mines the sum advanced is always nearly the same, and wherethe men are relied upon for continuing at their work, this pay is allowed for a number ofsuccessive months, until at length their contract becomes more profitable, and they areenabled to discharge the arrears.

The most common ore of copper is the yellow sulphuret (bisulphuret), or rather copperpyrites, which is frequently combined with stony matter, blende, galena, mundic, oxide oftin, wolfram, and other substances in a smaller degree. The existence cf either of these ismatter of consideration for the smelter , in making a proper mixture of ores for the furnace.The smelting of copper ores in the West of England has been entirely discontinued, it beingfound more profitable to send them to Wales , as a return freight for the ships bringingcoals to the mines.

The Crushing Mill is not generally adopted on account of the difficulty of bringing theore to exactly the proper size. The average quantity of copper contained in the ore is