Technical paper issued by the Bureau of Mines over the ventilation of copper mines in Michigan. Natural ventilation of the mines and mining conditions are discussed. This report includes tables, maps, and illustrations.

Technical paper issued by the Bureau of Mines over transportation of motor gasoline by pipe line. The locations and designs of the pipe lines are discussed. This paper includes tables, maps, photographs, and illustrations.

Technical paper issued by the Bureau of Mines over "the history of the craters in the Richland gas field. The data have been collected at various times over a period of four years. The equipment and methods of control are discussed, and photographs show the surface conditions at various intervals in the life of the craters" (p. 1). This paper includes tables, maps, photographs, and illustrations.