We illustrate below a useful type of dredger made by Messrs. Rennie, of
Blackfriars, England. The drawing almost explains itself. The machine
consists of a double barge or pontoon, in which is erected a derrick.
This derrick works a "spoon" dredge at the end of a lever. The spoon, as
shown, is at its lowest position. It will make a forward stroke, through
about one-sixth of a revolution, and will thus become filled with
mud and be lifted above the surface of the water. The motion will be
imparted to it by the chain and pulleys seen at outer end of the derrick
jib. The jib will then be swung round over the bank on a hopper barge
and its contents delivered. The requisite power is supplied by the steam
engine at the end of the pontoon. Messrs. Rennie have made several of
these little dredgers, which are found very useful and handy in shallow
water.--_The Engineer_.
[Illustration: SINGLE BUCKET DIPPER DREDGER.]
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