New signaling device for shaft mines with comments and suggested modifications.

Saved in:

Bibliographic Details
Online Access:	Full Text (via ProQuest)
Other Authors:	Potter, Elmer Vernon, 1908-, Stewart, L. D.
Format:	Government Document eBook
Language:	English
Published:	Washington, D.C. : [s.n.], 1931.
Series:	Mines Bur. Info. Circ. No. 6487.
Subjects:	Signals and signaling.

Internet

Full Text (via ProQuest)

Holdings details from Online
Call Number:	C22.11-6487
C22.11-6487	Available