662

THEORY ANI) PRACTICE OF ENGINEERING.

Rook II.

the match runs away, and after the shot has gone off' with much noise, smoke, and dust,the men return and find a chasm made ; then with hammers and picks they strike uponevery projecting piece of rock, and bring it down. The chamber where they work is filledwith smoke by every additional shot fired : if the rock be wet, the patent fuse, being a slowmatch inside a rope, is found convenient for blasting. When the miners have cut out theore which is near the level, it is arched over, and they proceed working upwards ; thedeads or rubbish, or the rock not containing the ore, is let down behind them, as theyascend ; different sets of men work above each other, protected by scaffolding. Whenthe ore is removed, it is let down a channel, through an opening called a hopper, into thecart or waggon in the level.

In some mines there is much work in the first level, and it is frequently necessary toascend and make another ; this is effected by drilling and blasting out the rock by gun-powder, and placing scaffolding, by which the miners climb to their work. In this upwardwork tliey make a small-landing place, and go from one stage to another, so that they areable to place ladders or pieces of wood from side to side, and afterwards climb up, havinghalting-places all the way. When arrived at the height thought best to fall in with the veins,they move forward horizontally, or in a line parallel to the first level driven in from theair ; it may be necessary to work upwards a second time, and form another flight ofladders, and, after getting to a certain height, again to move forward, and so on severaltimes, until the place of working be 500 or 600 feet above the first level.

The miner who works in such a remote situation walks into the level, as far as the firstdescent by the ladders, down which he goes, with a load of tools on his back. lie thenproceeds to the second flight of ladders, and descends to the third, until he comes to theplace where he has to perform his work : no air being admitted except from the level bywhich he has entered, there is nothing to produce a current; the air enters slowly abouthim, merely by the effect of a difference of temperature, and means are taken to diminishan evil which cannot be removed. Sometimes a body of air is forced by a fall of waterfrom the top surface of the hill, an opening being made for it to descend to the level withgreat violence, driving a body of air before it, and running out along the bottom of the levelfrom the mine. Machines or fanners, worked by boys, are used, and the air is carriedalong pipes to places to which it would otherwise very slowly penetrate. Forcing-pumpsare sometimes employed to drive it in a similar way, and a supply is obtained by runninga second level from the air into the hill, making a communication with the first; in this casethe air put in action enters at one level, and goes out by the other. Sometimes a shaft iscarried up or let down from the open air into the level, when a current is produced.Few mines have two levels communicating with the open air, or shafts from the outerair down to the levels, the sum required for the purpose being so great that the pro-prietor prefers to discontinue working rather than submit to the expense; but the menand boys, having no other means of existence, are often allowed to work in the mine withall these inconveniences. The ore dug out of the level, which is entered from the openair, is brought out by a horse and cart, the wheels of which run upon a railway ; butthat dug in the shafts, above the first levels, is let down holes or channels made for thepurpose from one to another, and down to the first or chief level, when it is brought out:when taken from the low levels it is hoisted up by whinseys from one to another, untilbrought to the first level, where it is carried out to the open day ; boys are employed todrive the horses for the whinseys and carts.

Tlie water is raised from great depths by steam-engines or by an hydraulic engineor great water-wheel, which works a pump ; that at the surface falls into the buckets ofthe wheel, and by its giaviiy causes it to revolve, the water being discharged into thelevel. The pump brings up the water from a great depth below, and discharges it intothe level, where it runs out. This machine is cheaper than the steam-engine, as itrequires no fuel, and very little attendance, and works day and night.

In the parish of Stanhope steam power is not used, but water power equal to that of120 horses: in the mines of Allendale, there are 14 water-wheels, possessing a powerequal to 300 horses. It is obvious that the hydraulic machine can be used only on theside of a hill, where there is a stream of water on the surface, which very often occurs inthe lead country. The lengths of the levels, driven into the hills, arc various : someare half a mile, and some double that distance ; there are some much longer, as that nearly5 miles in length, called the Kent Force Level; it begins near Alston, close by the fall ofthe Nent, and extends forward to Nent Head. For a long time there was water in thislevel deep enough to carry boats, by which the ore was brought out, which is now’ per-formed by carts, to the foot of a shaft near Nent Head, where it is hoisted up by awhimsey; several shafts, for the purpose of ventilation, are let dowm into this level.

Of Hushing -A quantity of ore is obtained by a method called hushing : where a

great ravine has been formed by the streams on the side of a hill, and water comes downover the stones, clay, and earth, if ore has been discovered, it is a good place for hushing.A dam is made at the upper part, with a channel for the water, some of the larger stones