Published by Department of the Interior, Bureau of Mines, Washington, DC, 1922
Seller: Clausen Books, RMABA, Colorado Springs, CO, U.S.A.
First Edition
Wraps. Condition: Good. Photographs and Drawings (illustrator). First Edition. Humidity rippled, lightly character-soiled covers with very worn edges and corners; The geophone is actuated solely by means of sound waves transmitted through earth or rock; Its uses include locating trapped miners, detecting leaks in buried water mains, determining the limits of active fires in sealed areas, and predicting possible cave-ins and mining disasters before they happen; 33p. Size: 8vo - Over 7 3/4" - 9 3/4 " Tall. Paperback.