t cost
of the plant, notwithstanding that the material has to be taken 10 m.
from the Bristol Dock. She can lift 400 tons of stiff clay per hour from
a depth of 36 ft. below the water line, and the power required varies
from 120 i.h.p. to 150 i.h.p., according to the nature of the material.
The speed is 9 knots, and 4 propellers are provided, two at the head and
two at the stern, to enable the vessel to steam equally well either way,
as the river Avon is too narrow to permit her to be turned round.

The hopper dredger "La Puissante" (Plate I. fig. 4), constructed by
Messrs Wm. Simons & Co. for the Suez Canal Co. for the improvement of
Port Said Roads, is a fine example of this class of dredger. She is
275 ft. long by 47 ft. beam by 19 ft. deep. The hopper capacity is
2000 tons, and the draught loaded 16 ft. 5 in. The maximum dredging
depth is 40 ft., and the minimum dredging depth is only limited by the
vessel's draught, she being able to cut her own way. The bucket ladder
works through the well in the stern and weighs with buckets 120 tons.
The buckets have each a capacity of 30 cub. ft. and raised on trial
1600 tons per hour. The dredger is propelled by two sets of
independent triple expansion surface-condensing engines of 1800 i.h.p.
combined, working with steam at 160 lb. pressure, supplied by two mild
steel multitubular boilers. Each set of engines is capable of driving
the buckets independently at speeds of 16 and 20 buckets per minute.
The bucket ladder is fitted with buffer springs at its upper end to
lessen the shock when working in a seaway. The dredger can deliver the
dredged material either into its own hopper or into barges lying on
either side. The vessel obtained a speed of 9-3/4 knots per hour on
trial. The coal consumption during 6 hours' steaming trial was 1.66
lb. per i.h.p. hour. Fig. 9 (Plate I.) shows a still larger hopper
dredger by the same constructors.

_Dredgers fitted with Long Shoot or Shore Delivering Apparatus._--The
first instance of dredgers being fitted with long shoots was in the Suez
Canal. The soil in the lakes was very variable, the surface being
generally loose mud which lay in some places in the sand, but frequently
more or less on hard clay. Resort was had to shoots 230 ft. long,
supported on pontoons connected with the hull of the dredger. The sand
flowed away with a moderate supply of water to the shoots when they were
fixed at an incl