Tunneling, Explosive Compounds, and Rock Drills

Tunneling, Explosive Compounds, and Rock Drills

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Description

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. 1878 edition. Excerpt: ...seen that the principles of English bar-timbering were never fully applied in this country, until the bars were drawn and saved at the Musconetcong Tunnel (pp. 301 to 309) in enlarging through heavy soft ground; moreover, we know that the constant experience of the past thirty or thirty-five years has justified this measure in similar nraterial in England. In taking out timber where it is deemed advisable to do so, some especial cautions should be observed. 1. Where timber is to be removed, the centres must be made sufficiently strong to stand the strain that will be put on them, as, until the arch is keyed, they will have the constantly growing load to support, not only of the masonry as it goes up, but also of the ground itself. 2. As we have previously emphasized, the work of taking put timber should never, in any case, be left to the masons, but the miners should always be summoned, even for comparatively small pieces of work. 3. The greatest care must be observed, in removing timber, not to take out too much at a time, as a break may easily be induced. It is, on the other hand, hardly necessary to remark that it is an object to save the timber in as good shape for future use as possible. 4. In Fig. 501, p. 552, the method is indicated by which several centres may be firmly connected together by a longitudinal tie-beam. The same bar, if made sufficiently etrong, can serve to hold the caps of a rafter set abb by a prop I, should the legs of the set be removed. In this connection, we would call especial attention to the advantages of the 5. Bars along the centres (as in Fig. 501) must not be spared. 6. Props between the new roof-timbers and the centres should be placed not vertically, but radially, and the propping and pressure, as noted in 2, ..show more

Product details

  • Paperback | 390 pages
  • 187.96 x 243.84 x 17.78mm | 680.39g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • Illustrations, black and white
  • 123659309X
  • 9781236593092