New-York tribune., 1900-09-16

dredges to preserve the depth Of the harbor OF
Port Arthur, where the basin is gradually be-
coming sIlted by the detritus from the denuded
hills. The Government Of Tasmania. has also
adopted the American dredge system for Mac
Qnarie Harbor. where great mining district is
hsmpered because shipments must be sent out
over an eight foot bar to Melbourne, and there
tRansferred to deep sea craft The American
dredges VIII enable the ore TO be sent from
MacQuarie Harbor without reshipment. The
Queensland Government has ordered four
dredges 10 deepen the tidal inlets Of the Great
Barrier Reef which defends Northeastern AUS
traHa from the long surges Of the Pacific.
The American high power hydraulic dredge
was unknown abroad until the year 1896, when
the attention Of European engineers was at
tractsd by the great engineering feat of clear
ing the bar Of the Mississippi River. The sub
ject was discussed at the International Congress
Of Navigation. where the American delegates,
]. a Ockerson Of the Mississippi River Com
mission, and Ltrdon ". Bates, read some highly
interesting papers illustrated by lantern slides
describing the protection Of the banks OF the
Mississippi River and the methods adopted for
securing q navtgable channel during the low
water season. American dredges on the Volga
are now performing the work which their pro
totypes did the Mississippi
est development Of the American hydraulic
dredger. The craft has just been completed at
the shipyard Of SIR ". G. Armstrong. Whit
worth & Co. after the designs Of Lindon W.
Bates, civil engineer. The general design and
the appearance Of the vessel have beeh much
influenced by It's having TO perform the Journey
70 Queensland under It's own steam. 1t is one
ot the four dredges aggregating 1000 horse
power, ordered by the Queensland Government.
The present vessel was specially designed for
use on the F1tzroy River, which drains water
shed Of over fifty thousand square miles and
meets the sea at the port of Northampton.
The dredging mechanism Of the vessel con-
taius all the elements Of the Mississippi dredE-
ers with many important improvements. The
most striking OF these improvements is the hol-
low rotary milling cutter The present dredger
has two Of these mounted at the ends Of two
suction ladders" which. by means Of circular
telescope joints are so connected to the suction
Of the main sand pump as TO allow Of vertical
movement, and therefore OF work at variable
Depths, the extreme in the present instance be
ing "a feet below water level Another feature
is the method Of disposing Of the spoil" which
is discharged through a system Of pipes, buoyed
by pontoons Of elliptcal shape. and heNbly
connected by a metallic joint. This Is a com
bnation Of q ball and socket joint. with GIN
%! Joint surrounding II, and is packed in with
ing been found much superior TO the flexible
rubber or leather Joint pieces hitherto employed.
Ihe dredger is adapted for working either
Straight ahead or for dredging radially. When
tns latter method IS adopted the vessel Is an
chored by one Of two vertical anchors or
spuds" alternately, and is swung through the
arc required 70 form channel of the desired
width.
The principal dimensions of the hull are 230
teet in length over all, 80 feet beam and IL
Ieet in depth The main engine is triple eX-
pansion, with variable cutoff and IS capable OF
developing 800 indicated horse power when
running at 100 revolutions minute. By means
OF three bevel clutch gears this engine drives
also the twin screws. Steam is supplied TO all
engines Oh board from four boilers with three
furnaces each and having combined heating
surface Of II 400 square feet The boilers are
sS@pted for using Queensland coal. The whole
oI ths dredging and navigating mechanism is
controlled from q large operating room placed
Al me forward end Of the upper deck
ne model Of this dredger occupies prom
Iheht position IN the United States exhibit in
ne engineering section Of the Worlds Fair, ana
Z < special report upon il has been made by the
1IIecHon OF the French Institution OF Civil En-
sLheers. The Mississippi River Commission.
th "iLch displays the American dredging models.
LIS n@s received two grand prizes and 2 dozen gold
ana silver medals c. l. 4.