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DOCK ENGINEERING.
machine, constructed by Messrs. Stothert & Pitt, of Bath, illustrated in
fig- 41, used for constructing a breakwater at the port of Goa in India, is of
this kind. The overhang is 25 feet, measured from the front leg to the
extreme position of the load; the extreme range of cross travel is 18 feet
and the vertical range of lift 40 feet; the clear height under the cross
girder is 16^ feet and the working load 40 tons.*
Pig ' 41. —Titan Overhead Traveller.
NEGATIVE APPLIANCES.
Excavators.—The varions classes of implements for the removal of earth-
work, in bulk and in the dry, from the site of a proposed dock may be
enumerated as
Land Dredgers.
Steam Navvies.
Grabs.
Land Dredgers are an adaptation of the principle of sea dredgers to land
work. They are a foreign product, and subdivisible into two types, which
may be distinguished as the French and the German respectively, according
to the country of their origin. Both, however, are one in mode of action,
and the distinction between them simply lies in the fact that the former
discharges its load into waggons entirely to the rear, while the latter
discharges into waggons which pass underneath its framing. This arrange-
ment gives the German machine a wider base and greater stability. Tliere
* Pitt on “ Plant for Harbour and Sea Works,” Min. Proc. Inst. C.E., vol. exiii.