Mine Safety Appliances Co. Chamber of Commerce Bldg.Pittsburgh, Pennsylvania. Complete File on Rock-Dusting by Mine Safety,1924. Contents: Extracts from technical description of explosions, where propagation was actually stopped by rock dust installation. Various phases of Rock-dusting as described by the General Manager of a rock-dusted mine. "Efficacy, Methods and Costs of Rock-dusting Bituminous Coal Mines," by E. E. Steidle,Supervisor Cooperative Mining Course,Carnegie Institute of Technology. And more articles, GREAT photos. HAs soiling on cover. Overall Very Good Condition!