. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. '""•miJIiijjilii'illiiillii^'^nm. It has been stated above, that the near end of the crown-bars is'at^first temporarily supported or propped from the square timbers in the shafts; it must however be observed, that, by so doing, a great weight is thrown upon the square timbers in addition to that of the brickwork of the shaft, which is all that it is designed to carry, and in which it is materially assisted bv the ianging-rods, or shaft-sills described in the precedi
. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. '""•miJIiijjilii'illiiillii^'^nm. It has been stated above, that the near end of the crown-bars is'at^first temporarily supported or propped from the square timbers in the shafts; it must however be observed, that, by so doing, a great weight is thrown upon the square timbers in addition to that of the brickwork of the shaft, which is all that it is designed to carry, and in which it is materially assisted bv the ianging-rods, or shaft-sills described in the preceding chapters; and, for this reason, the square timbers should be as speedily as possible relieved from the weight of tlie bars, and whatever pressure of earth they may be sustaining : —this is finally done, when the the top sill next the shaft is inserted in its ])lace, by propping every bar therefrom. When the ground is good, there is no danger in temporarily supporting the near ends of the crown bars from the square timbers; but where it is soft, or yielding, it is unsafe thus to load them; for under such circumstances, the ground, instead of steadying the square timbers, is liable to give under the pressure; and when once the square timbers get out of the perpendicular they would require no great additional weight to force them in, and the yielding or soft ground which would thus lead to the accident, would follow from behind the shaft, and in all proba- bility bring the shaft down with it. * * * The cost to the Contractors for excavating the side lengths at Blechiugley would, upon an average, be as follows: £ a. d. Miners . 96-2 days . at 6s. 28 17 2 Labourers, . 95-0 . at 3s. 6d. 16 12 6 Horses . 28-9 . at 7s. 10 2 4 Candles . 4 dozen . at 6s. Gd. 16 0 Gunpowder . IJ cwt . at 46s. 2 17 6 Tools, and sharpening picks, wedges, &c., . . 15 0 Contractors' Superintendence, . 22 days . at 7s. 7 14 0 Clearing up the work when completed, . per length 0 5 0 Total £68 19 6 T
Size: 1970px × 1268px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1800, booksubjectarchitecture, booksubjectscience
