A way to break easily and speedily the hardest Rocks, communicated by the same Person, as he received it from Monsieur Du Son, the Inventor.
Though the invention of breaking with ease, and dispatch, hard Rocks, may be useful on several occasions, the benefit is incomparably great, that may thereby accrue to those, who have Adits or Passages to cut through hard Rocks, for making passage for Water to run out by, in Mines of Lead, Tin, or any other whatsoever; these Adits appearing to be the surest, cheapest, and most advantagious way imaginable, for draining of the same.
That which is here to be described, was invented by one of the most Excellent Mechanicks in the World, Monsieur du Son, who lately put it in practice himself in Germany, at the desire of the Elector of Mentz. The manner is, as followeth.
The Mine or Adit is to be made seven or eight foot high, which though it seem to make more work downwards, yet will be found necessary for making the better dispatch by rendring the Invention more effectual.
There is a Tool or Iron well steeled at the end, which cuts the Rock, (of the shape shewed by Fig. 2. here annexed,) 20. or 22. Inches long or more, and some 2½ Inches Diameter at the steeled end, the rest being somewhat more slender. The steeled end is so shaped, as makes it most apt to pierce the Rock, the Angles at that end being still to be made the more obtuse, the harder the Rock is. This Tool is to be first held by the hand, in the place, where the Hole, to be made for the use, which shall here be shewed, is to be placed; that is, in the middle between the sides of the Rock, that is to be cut, but as near the bottom as may be. The Tool being placed, is to be struck upon with an Hammer, the heavier the better, either suspended by a Shaft turning upon a Pin, or otherwise, so as one man may manage the Hammer, while another holds the Tool or Piercer. If it be hung in a Frame, or other convenient way, he that manageth it hath no more to do, but to pull it up at first as high as he can, and let it fall again by its own weight, the motion being so directed, as to be sure to hit the Piercer right. After the stroke of the Hammer, he that holds the Piercer, is to turn it a little on its point; so that the Edges or Angles at the point may all strike upon a new place; and so it must still be shifted after every stroke, by which means small Chipps will at every stroke be broken off, which must from time to time be taken out, as need requires. And thus the work must be continued, till the Hole be 18. or 20. Inches deep, the deeper the better. This Hole being made as deep as is required, and kept as streight and smooth in the sides, as is possible, there is then a kind of double Wedge to be made, and
fitted exactly for it; the shape whereof is to be seen in the annexed 3. Figure.
This double Wedge, being 12. or 13. Inches long, each piece of it, and so made, as being placed in their due position they may make up a Cylinder, but Diagonal-wise. The two flat sides that are contiguous, are to be greased or oyled, that the one may slip the more easily upon the other; and one of them, which is to be uppermost, having at the great end a hollow Crease cut into it round about, for fastening a Cartridge, full of Gunpowder, to it with a thred, the round end of the Wedge being pared as much as the thickness of the Paper or Pastboard, that holds the Powder, needs to make the outside thereof even with the rest of the Wedge. This Wedge must have an Hole drilled through the longest side of it, to be filled with priming Powder, for firing of the Powder in the Cartridge; which needs have no more, than half a pound of Powder, though upon occasion a greater quantity may be used, as shall be found requisite.