. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. h,and in the empty space below, which is shaded black, he transports in his wagons orwheelbarrows the ores towards the mouth of the mine. Fig. 726 is the cross section ofthe gallery. In the two figures, a represents the rock, and b the timbering; round whichthere is a garniture of small spars or lathes for the purpose of drainage and ventilation,with the view of promoting the durability of the wood-work. MINES. 853 The working of minerals by the mass is well exemplified a few league
. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. h,and in the empty space below, which is shaded black, he transports in his wagons orwheelbarrows the ores towards the mouth of the mine. Fig. 726 is the cross section ofthe gallery. In the two figures, a represents the rock, and b the timbering; round whichthere is a garniture of small spars or lathes for the purpose of drainage and ventilation,with the view of promoting the durability of the wood-work. MINES. 853 The working of minerals by the mass is well exemplified a few leagues to the north ofSiegen, near the village of Miisen, in a mine of iron and other metals, called Stahlberg,which forms the main wealth of the country. The plan of working is termed the excava-tion of a direct or transverse mass. It shows in its upper part the danger of bad mining,and in its inferior portion, the regular workings, by whose means art has eventually pre-vented the destruction of a precious mineral deposite. Fig. 727 is a vertical section of the bed of ore, which is a direct mass of spathose 727. iron, contained in transition rock (graywacke). a, a, a, are pillars of the sparry ore,reserved to support the successive stages or floors, which are numbered 1, 2, 3, &c.;b, b, b, are excavations worked in the ore; which exhibit at the present day severalfloors of arches, of greater or less magnitude, according to the localities. It may beremarked, that where the metallic deposite forms one entire mass, rich in spathose ironore of good quality, there is generally given to the vaults a height of three fathoms ;leaving a thickness over the roof of two fathoms, on account of the numerous fissureswhich pervade the mass. But where this mass is divided into three principal branches,the roof of the vaults has only a fathom and a half of thickness, while the excavation isthree fathoms and a half high. In the actual state of the workings, it may be estimatedthat from all this direc
Size: 2156px × 1159px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1840, booksubje, booksubjecttechnology
