Page:Philosophical Transactions - Volume 001.djvu/88

 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, cut 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 to be uppermost, having at the great end a hol'ow Crease cut into it round about, for fastning 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 oven 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.

Then this Wedge, being first thrust into the Hole with the Cartridge, the round side, where the Priming-hole is, being uppermost, the other Wedge is to be thrust in, home to the due position, care being taken, that they fit the Hole in the Rock as exactly as may be. Then the end of the lower Wedge being about an Inch longer, than that of the upper outwardly, and flatned, priming Powder is to be laid upon it, and a piece of burning Match or Thread dipt in Brimstone or other such prepared combustible Matter, fastned to it, that may burn so long, before it fire the Powder, as he, that orders it, may have time enough to retire quite out of the Pit or Adit, having first placed a piece of Wood or Iron so, as one end thereof, being set against the end of the lower Wedge, and the other against the side-wall, so as it cannot slip. Which being done, and the Man retired, when the Powder comes to take fire, it will first drive out the uppermost Wedge, as far as it will go; but the flaunting figure of it being so made, as the farther it goes backward, the thicker it grows, till at the last it can go no farther, then the Rh