Creator: Bolmer, R. L.
Description: Report issued by the U.S. Bureau of Mines discussing sinking and excavation of large-diameter access shafts. As stated in the introduction, "this information circular describes the application of modern methods and equipment in sinking a vertical, 916-foot-deep by 16-foot-diameter, concrete-lined access shaft for the Harold D. Roberts tunnel near Montezuma, Colo." (p. 1). This report includes maps, tables, illustrations, and photographs.
Contributing Partner: UNT Libraries Government Documents Department