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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 of 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 212 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. It 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
