CENTRIFUGAL PUMP DREDGING IN N.S.W. CXIII. 
to dredge out the basin between Bullock Island dyke and New- 
castle, the author urged Mr. Moriarty, the then Engineer-in-Chief 
for Harbours and Rivers, to convert the steam hoppers ‘‘ Neptune” 
and “‘Juno” into sand pumps, and to use them for pumping the 
sand in the basin on to the areas available for reclamation. 
The Government, on the recommendation of Mr. Hickson, acting 
for Mr. Moriarty, approved of plans of the vessels being sent to 
Sir John Coode, who arranged with Messrs. J. and K. Smit, of 
Holland, the principal builders of Dutch sand pumps, to supply 
the necessary machinery for the alterations. Before the pumps 
were fitted on board, Mr. Darley, who had succeeded Mr. Moriarty, 
had the hulls lengthened 12’, to give additional freeboard and to 
carry more silt, at the same time giving greater space for the 
machinery. The pump placed in front of the engines is, as will 
be seen by the drawing, of the simplest possible construction, 
being in design and action not unlike an ordinary fan or blower. 
As with all centrifugal pumps a chief element of success is ample 
driving power. The engines of the “Neptune” are capable fof 
developing 330 indicated horse power, and are of the compound 
surface condensing type, with cylinders 20 and 36” and 24” stroke. 
Steam is supplied at 80 bbs. pressure by a cylindrical multitubular 
boiler 11’ in diameter 10’ long, having three furnaces 2’ 6” in 
diameter, and one hundred and twenty-eight 4” tubes. Aft and 
forward of the engines, suitable clutches are fitted to enable the 
power of the engines to be almost instantaneously transferred 
from the propeller shaft to the pump spindle and vice versa. 
Between the engines and the pump a friction nave is fitted, and 
is adjusted to slip when large pieces of iron or stone are drawn 
up by the pump, endangering the arms of the spinner. The 
Suction and delivery pipes are 20” in diameter. The vessel’s 
hopper holds 500 tons of sand, and under favourable circum- 
stances has been filled in nineteen minutes, the engines making 
130 revolutions per minute, giving a periphery speed to the 
6’ 6}” spinner of 2,680’ per minute. These speeds are increased 
by about eighteen per cent., if the material dredged is sent 
8—Oct, 21, 1896, , : 
