A new signaling device for shaft mines

Author:	Stewart, L. D.
Additional Authors:	Potter, E. V.,
Year:	1931
Document Type:	USBI
Issuing Agency:	U.S. Dept. of Commerce, Bureau of Mines,
SUDOC:	C 22.11:6487
Series:	Information circular / Bureau of Mines ;
Report Number:	6487
Subject:	Mine safety
Link:	https://hdl.handle.net/2027/mdp.39015077576547