HANDLING COAL

Four-ton grab buckets operating on the four bridge-tramways pick up the

coal from the hold of lake steamers and deposit it either on the dock or

in cars. The four machines can be moved to any part of the dock to which

steamers are moored and four ships can be unloaded rapidly at one time.

The motive power is electricity.]

[Illustration: _Courtesy of the J. M. Dodge Co._

The Wonder Book of Knowledge The Marvels of Modern Industry and Invention, the Interesting Stories of Common Things, the Mysterious Processes of Nature Simply Explained · 第 33 / 162 题