Chicago : Engineering and Contracting Pub. Co. · leaf 667
] 29 FngDConfg Fig. 5 Fig. 6. Fig. 7. terial resemble gravel in lack of firmnesseven where no water is present. It is impos-sible to mine it the ordinary way. Material such as broken rocks, dirt, gravel,etc., commonly known as wash, is generally,or often, met with in opening a tunnel orshaft. At… … EtiqfContg This false set should be 4 ins. higher and 8ins. wider than a common tunnel set to allow4 ins. on each of the three sides. Then thedrives should be driven about 2 ft. moreahead over the false set or to where the newset will be placed. This new set should beplaced after the top and side…
Buildings
Internet Archive · University of Illinois Urbana-Champaign · Public Domain Mark 1.0. Free to use for anything.
