Cx, A. B. PORTUS, 
CENTRIFUGAL PUMP DREDGING IN N. 8. WALES. 
‘By A. B. Portus, Assoc. M. Inst. C.E. 
[With Plates 5-14.] 
(Read before the Engineering Section of the Royal Society of N. 8. Wales, 
October 21, 1896. ] 
Commopious harbours and deep navigable rivers are such impor- 
tant factors in estimating a country’s material progress that any 
description of appliances employed for effecting their improvement 
must have some interest both for the scientific and commercial 
members of the community. It is not, however, the object of 
this paper to deal with the whole subject of harbour and river 
improvement by dredging, because in doing so the evolution of 
the ladder and bucket system of river deepening would have to be 
traced, and to do so would be to tell over again what has been so 
often and so well told before, viz., the story of the river Clyde, 
and how, by ladder dredging, it has been transformed from an 
insignificant stream to being one of the most important arteries of 
commerce in the British Empire. Readers of the history of the 
Clyde, the Tyne and the Wear, look in vain for any information 
about reclamation by sand pumps, because hitherto the centrifugal 
pump has not, on any of these rivers, been used for deepening 
purposes, nor had it, with the exception of at Lowestoft, been 
used at any port in the United Kingdom until the year 1890, 
when at the Mersey bar it was used with such conspicuous success 
that the Liverpool Harbour Board, had built, two hopper pumps 
each capable of lifting 4,000 tons of sand per hour. Some pal 
ticulars of these vessels will be given at the conclusion of this 
paper, and also of the leviathan of sand pumps built during the 
present year on the Mississippi and now pumping on shore silt at 
the rate of 3,500 tons per hour. . 
