Safety electric switches for mines
By: by H.H. Clark.
Series: [U.S.] Bureau of mines. Technical paper; 44
Publisher: Govt. print. off.
Published: 1913
Place of publication: Washington
Language: eng
Subjects: Electric switchgear.; Electricity in mining.
Notes: "Publications on mine accidents and methods of mining": p.7-8.
At head of title: Department of the interior. Bureau of mines. Joseph A. Holmes, director.
On verso of t.-p.: First edition, March, 1913.