The Natural History of the Mineral Kingdom, (1)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1810 edition. Excerpt: ...run paiallel, and sometimes very near to one another. When they run parallel, and near to each other, the ase then generally Hatter than a single one, and approach something near to the figure and description of the streeks or flat veins, which -re to come next under consideration; and it sometimes happens, that in particular places the skirts or sides of two parallel pipes approach so near to one another as to ccme into contact; and in this case, when the ore is wrought out of both, '4 hole or communication is formed between them. This generally happens only whcn one of them flies out wider than ordinary into the side next the other. The bearing of such pipes as continue between the strata is exactly the same as the declivity of the strata; but, properly speaking, pipes have no horizontal bearing whatever: Their bearing is in a declining or sloping line, and is towards the tame point of the compass as the declivity or dip of the strata. The slope of one of these pipe veins is the same as the declivity of the strata in the mining field, and even in that part of the field where they are found; and as the declivity of the strata is extremely various, so the slope of these pipes must be equally various. With respect to the other species of pipe veins which have burst their way up through the strata, it is more difficult to point out their bearing, as they generally dip down precipitately, and may be said to have no bearing at all, as the one end dips down towards the centre, and the other end points up towards the surface; and such of them as do not stand so near the perpendicular, seldom or never run in any straight line whatever, but wind downwards in a sloping and in an oblique di rection. Some parts of this sort of pipe will sometimes put...