Electric blasting switches, underground mines, Lake Superior District.
- Creator Personal:
- Petersen, Max S., Cash, Frank E. (Frank Errette)
- Title:
- Electric blasting switches, underground mines, Lake Superior District.
- Call Number:
- P19460
- Date:
- 1946
- Description:
Serial issue. Issued as: United States. Bureau of Mines. Information circular, 7372 (1946:Sept.).
- Subject Topical:
- Ground control (Mining)--Lake States., Mine safety--Lake States., Iron mines and mining--Lake States--Safety measures.