Chicago : Engineering and Contracting Pub. Co. · leaf 473
271.5 ft. The circumference of the inside ofthe concrete lining is 47 ft., with a clear open-ing of 165 sq. ft. The two main airways are V … Fig. 5—Steel Shoe Used for Ventilating Shaft. to the lower seam. This section measures 17ft.Xll ft. 4 in. in the clear on the center lines• if the axes, and has a depth of 100 ft. from
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Internet Archive · University of Illinois Urbana-Champaign · Public Domain Mark 1.0. Free to use for anything.
