Chicago : Engineering and Contracting Pub. Co. · leaf 80
Fig. 1—Loetchberg Tunnel Carriage BroughtForward After Mucking. … Fig. 3—Showing Horizontal Adjustment ofDrills. about the same. The increased average gainin the rate of advance has been concurrentwith the improvement in the machinery em-ployed in the headings. Where a great thickness of rock overlies atunnel, it is necessary to do the work whollyfrom the two…
Buildings
Internet Archive · University of Illinois Urbana-Champaign · Public Domain Mark 1.0. Free to use for anything.
