Photograph of the Series 90-S Mobile Spar. According to author Eric Orlemann, "the Mobile Spar was a diesel-electric transporter equipped with a folding 130-foot guy wire tower." It was built for hauling lumber up steep slopes. Only one unit was built and sold to a lumber company in McCall, Idaho.

Report issued by the U.S. Bureau of Mines discussing materials surveys conducted on mercury. As stated in the foreword, "the surveys dealing with metals and minerals summarize the demand-supply position in the United States and include information on production, imports, consumption, exports, substitutes, and pertinent history" (p. v). This report includes maps, tables, illustrations, and photographs.