CENTRIFUGAL PUMP DREDGING IN N.S.W. CXI, 
One of the first successful applications of the centrifugal pump 
(see Plate 5) for reclaiming was on the Amsterdam Canal in 
the year 1867. Before that time, the dredged material was 
shovelled from the barges into barrows, and wheeled on shore, 
but such slow progress was made, the canal having to be deepened 
from 3’ to 23’, that mechanical appliances became almost indis- 
pensable, and Messrs. Burt and Freeman fitted to one of the bucket 
dredges an improved “ Woodford ” centrifugal pump, the shaft of 
which worked vertically driving a spinner 3’ 6” in diameter, fitted 
near the bottom of an upright cylinder, about 12’ high, so arranged 
_ that the contents of the buckets, falling through it, were met by 
the ascending volume of water from the Woodford pump, and the 
dredgings, thus liquefied, forced through floating pipes to the 
Shore. The pipes were constructed of wood with leathern joints 
and were buoyed. As much as 2,000 tons of silt was sometimes 
thus disposed of in twelve hours and deposited at a height of 8’ 
above water level at a distance of 1,200’ from the dredge. Dual 
machines of this type were early in 1870 used in Russia for canal 
work near Cronstadt. Mr. Burt having further improved the 
machine by fitting knives on the vertical pump shaft, and by 
directing into the cylinder water jets under great pressure, 
Succceded in dealing with stiff clay, and introduced the machine 
thus perfected on the Danube. In 1880, the Barrow Ship Build- 
ing Company, constructed for that river a combined bucket and 
pump dredger 124’ long, 28’ beam, with buckets holding 18’ cubic 
each, and capable of working at a depth of 28’. The pump was 
4}’ in diameter, the pipes were 18”. The engines developed 180 
horse power when the buckets and pump were working ; how 
much for each is not stated, but judging from the power required 
to drive a pump of the size given, the division of horse power was 
Probably 55 for dredging and 125 for pumping. 
The machine referred to is, strictly speaking, not a sand pump, 
but an adjunct, and a most valuable one, to the ordinary 
ladder dredge. The first sand pump successfully used was em- 
ployed in Holland about thirty years ago. An old steamer was 
