Walter E. Lewis

• Bureau of Mines test procedures for rocks
• Carbide insert bit drilling at the Cleveland-Cliffs Iron Co. mines Ishpeming, Mich
• Hydraulic tunneling in St. Peter sandstone at Minneapolis, Minn
• Tunnel construction by peripheral sawing at the Fort Randall Reservoir, Pickstown, S. Dak
• Ventilation-air heating plants of the Menominee Range