Electric blasting switches, underground mines, Lake Superior District.

Creator Personal:

Cash, Frank E. (Frank Errette), Petersen, Max S.

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:

Mine safety--Lake States., Ground control (Mining)--Lake States., Iron mines and mining--Lake States--Safety measures.