been empty spaces, and the other, that they have been filled from above.
I observed the first in the mine of Dolcoath, between Camborne and Redruth, where, at the depth of seventy fathoms below the adit level,[1] that is to say, according to my observations, one hundred and eighty-four feet below the level of the sea, there was found an empty space in the vein of some fathoms in length, and broad in proportion. The walls of it are smooth, which is seldom the case, as these cavities, called by the miners, druses, creaks, or pouches, are almost always lined with crystallisations; Werner observes, that we find these druses in places where the vein is of greatest thickness. It often very distinctly appears that they have been much longer and wider, but that they have been partly filled up by a new substance having been deposited in them.[2]
The second fact, I have alluded to, I observed in a coal—pit at Littry in Normandy, two leagues S.W. of Bayeux. In sinking the pit St. George, there was found in a vein at the depth of two hundred and fifty feet from the surface, a conglomerate formed of rounded pebbles, the greatest part of them flints, although the saalbande and the rock are of stratified limestone. A branch of a tree was also found, with the ligneous structure preserved.[3] Werner mentions
- ↑ The adit level is twenty-seven fathoms below the surface of the ground, where the entrance to the mine is situated, and which is, according to my observations, two hundred and thirty-six feet above the level of the sea.
- ↑ Nouvelle Theorie de Ia formation des filons, p. 80. One of the most singular caverns of this sort, is that which exists at Joachimstal, at the depth of two hundred and fifty toises. This cavern, from which a vast quantity of water ran out, is said to be eleven toises in length and nine in breadth. Its height, which is not yet known, considerably, exceeds twelve toises. Ibidem p. 115.
- ↑ Journal de Physique, Mars 1807, p. 225.
