PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION
ILLUSTRATION FOR THE MENTOR. VOL. 6, No. 6, SERIAL No. 154
COPYRIGHT, 1918. BY THE MENTOR ASSOCIATION, INC.
THE MENTOR · DEPARTMENT OF SCIENCE
MAY 1, 1918
Courtesy of Brown Hoisting Machinery Co.
COAL-HANDLING MACHINERY ON PITTSBURGH COAL CO. DOCKS, DULUTH, MINN.
An electric trolley, with 5½-ton bucket, travels on each bridge, carrying coal from the boat to storage, or to railroad car, or to screening apparatus in the rear
THE STORY OF COAL
By CHARLES FITZHUGH TALMAN
Editorial Writer for the Scientific American