CXXX. DISCUSSION. 
Dredge “Neptune,” 18/11/96.—Sand Pump Tests. 
Boiler pressure 75ibs.2 Pressure at pump, pure water Ths.4 
300’ 
Vac. engines 24” 9 2ibs.9 
Revs. of engines 134 Pressure at pump, full nae silt 9ibs.2 
Diam. of spinner 6’ 62” 53 300’ ” 3}Ibs.9 
Cylinders 20” and 36” stroke 2’ Vac. on pump, pure water 6” 
full bore silt 10” 
9 
Material dredged sand and mud. “Vength of pipe line 800’. 
‘Pressure on “Groper’s” Discharge Pipes. 
soot aay — \ with clear water 130 revolutions per minute. 
20Ibs. at i S side 
13Ibs. 300’ 
Distance to eal of pipes 2,500’ ; 5’ rise of tide. 
Boiler pressure 100 Ibs, per square inch. 
Cylinders 20” and 36” stroke 2’. 
Mr. Houghton’s question as to power was practically answered 
by the information just given, the work done and power expended 
when dredging and discharging at a distance of 1,250’ being 
quoted. In practice it was found that the difference in power was 
inconsiderable as between dredging by pump at 10’ or 20’ depths. 
Height and distance after leaving the pump were the chief factors 
to reckon with. Mr. Houghton would see by again referring t0 
the paper read, that 300 h. p. was not quoted as the power 
developed when the “Neptune’s” 500 tons hopper was filled in 
nineteen minutes. Cards were not taken at that time, the power 
was considerably less than the 300 obtained under other conditions. 
Respecting the point of cut off in the sand pump compound 
engines referred to by Mr. Barraclough, it was between $ and 3 
of the stroke, and although the triple expansion engines with 160% 
of steam designed by the Department were more sconce than 
the compound ones, which were purchased, there was little to 
complain about in the latter as a pair of them having cylinders 
12” and 24” developed with 120ibs. of steam, and with moderate 
consumption of coal over 200 horse power. 
ai with sand and shell 130 revolutions per min. 
