Chicago : Engineering and Contracting Pub. Co. · leaf 242
Rock Line At least I? Concretearound Thimble … The drifting was continued immediately fol-lowing the bottoming of the shaft. The northheading was started and was prosecuted fora distance of 11.9 ft. from the shaft centerand the south heading was prosecuted to itsjunction with the main tunnel, a distance of73 ft. from shaft center to tunnel…
Buildings
Internet Archive · University of Illinois Urbana-Champaign · Public Domain Mark 1.0. Free to use for anything.
