When the bore is intended to penetrate but a few fathoms, the whole work may be performed directly by the hands; but when the bore is to be of considerable depth, a lofty triangle of wood is set above the bore-hole, with a pulley depending at its summit angle, for conducting the rope to the barrel of a windlass or wheel and axle, secured to the ground with heavy stones. The loose end of the rope is connected to the rods by an oval iron ring, called a runner; and by this mechanism they may be raised and let fall in the boring; or the same effect may be more simply produced by substituting for the wheel and axle, a number of ropes attached to the rod-rope, each of which may be pulled by a man, as in raising the ram of the pile-engine.

In the Newcastle coal district there are professional master-borers, who undertake to search for coal, and furnish an accurate register of the strata perforated. The average price of boring in England or Scotland, where no uncommon difficulties occur, is six shillings for each of the first five fathoms, twice 6 shillings for each of the second five fathoms, thrice 6 shillings for each of the third five fathoms, and so on; hence the series will be—

1st five fathoms6s.each£110
2nd five fathoms12s.—30
3rd five fathoms18s.—410
4th five fathoms24s.—60
20 fathoms of bore£150

Thus the price increases equably with the depth and labour of the bore, and the undertaker usually upholds his rods. There are peculiar cases, however, in which the expense greatly exceeds the above rate.

The boring tools are represented in the following figures:—

Fig. 819.
1.The brace-head.
2.The common rod.
3.The double-box rod; intermediate piece.
4.The common chisel.
5.The indented chisel.
6.Another of the same.
7.The cross-mouthed chisel.
8.The wimble.
9.The sludger, for bringing up the mud.
10.The rounder.
11.The key for supporting the train of rods at the bore-mouth.
12.The key for screwing together and asunder the rods.
13.The topit, or top-piece.
14.The beché, for catching the rod when it breaks in the bore.
15.The runner, for taking hold of the topit.
16.The tongued chisel.
17.The right-handed worm screw.
18.The left-handed do.
19.The finger-grip or catch.

We shall now explain the manner of conducting a series of bores in searching ground for coal.