The sun. [volume] (New York [N.Y.]) 1833-1916, 1902-01-19

floor Of a 2oO-foot bridge elevated 50 feet
above the ground on rolling towers at eaoh
end. Each Of the three belts was supported
on rollers followed a little In the centre.
like dice boxes. which made IL sufficiently
concave to retain the clay. like a trough.
They were driven at a speed Of about
seven. feet a second n ceaselessly car
ried the clay away from the shovel, up the
IL TO a ria point, where a diagonal
scraper was set across II, and pushed the
load of. TO fall through the bridge floor
and pile up on the ground underneath,
When the steam shovel completed a
cut across the canal. which perhaps re-
quired two days, its tracks, the belts and
the bridge were all moved ten feet ahead
and the process was kept up continuously.
Many Of the chunks Of clay were az large
as a mans head, and II was amusing TO
watch them ride quietly along until they
began the ascent Of the steep bank, and
then begin to roll and tumble and start
down with an evident determination not to
go up that slope under any circumstances
They would hurry and scramble as fast
as possible. but 1t was not steep enough
for them to fall quite ~ fast as the belt
travelled, and IL would keep picking them
up again and again, each time lifting them
a little higher before they would succeed
In starting down. until at last they were
AnOed on the level Delt on tOp.
Blasting n tunnel through the solid rock
IL usually considered an easy and a COM
paratively safe task; ~excavating IL In solid
clay with a good depth Of the same mate
rial overhead Is sometimes still easier.
Even quicksand may be pierced AZ the
expense Of sufficient time and money, but
when IL Ia necessary to tunnel through
soft mud and silt very near the river bottom
in deep water, the task is one Of the most
difficult, dangerous and costly that can be
attempted.
Such a tunnel with an inside diameter Of
ten feet was recently built in a very novel
manner. A huge concrete tube, 225 feet
long, lined inside and covered outside
with steel plates, wa built on shore on
regular inclined ways.
The ends being closed. the I,o0o-ton
mass was launched like a ship. towed thirty
piles driven on both sides OF IL. and one end
connected by divers to the shore tunnel pre-
viously built 10 join II. The most re-
markable feature OF the work was that a
storm arose and threatened TO injure the
floating tunnel before IL was quite COM
pleted.
Large valves were hastily opened and
IL was allowed to fill and sink TO a depth
below the storm action. When Il was
calm again tho water was pumped out
and the great pipe rose to the surface, was
completed, and again sunk, this time per-
HldiltIilll rtdliilk llctn Oh Int lOunCdflOn
Of piles cut on accurately by submerged
steam saws at the required level. far below
the surface Of the river.
In sinking deep shafts through quick
sand II il often impossible TO keep out
the water so men a work In the bot
tom. tn sides will cave in continuously,
quicksand will enter like water through
the smallest crevice in the lining, and
OF IL will flow from a long distance
underground, 40 as 10 cause depressions
In the surface at remote places.
Worst Of all. the san and water will rise
up in the bottom as fast a. il can be pumped
out, and this, added to the great pres
on the sides and the difficulty Of build
ing n watertight lining from the top down.
makes the work slow and difficult
Recently the %expedient OF freezing the
auckland far below the surface was
and after that was accomplished,
shaft could he ~excavated easily. The
is accomplished by the use Of the
modern refIigerating machine.
A shaft about Is feet qua and 100 feet
ieep was sunk in this manner through
water and quicksand TO solid rock az Iron
Mountain, Mich. n few years ago. Twenty
seven l0-inch iron pipes were arranged
about three feet apart on the sides OF a
-ectangle enclosing the shaft and sunk
vertically 20 rock by a water jet and steam
hammer.
An s-inch pipe, closed at the bottom.
was lowered inside each I0-inch pipe and
The latter withdrawn. A ik-inch pipe,
at the bottom. wa lowered inside
s-inch pipe. reaching nearly TO its
and extending through It's cap
On top.
The tops Of the inner pipes were con-
10 a pressure pipe. through which
brine from the refrigerating machine was
pumped at a temperature 81 about II de-
yrees Fahrenheit. and rising through the
pipes. escaped from their tops into
, connecting horizontal pipe. which served
~ the suction main Of the circulating
pump.
The cold brine thus moved around and
the circuit taking about twenty
minutes for zach trip, and rising In
hat time about one degree In temperature.
A. IL absorbed the heat from the quick
and and water hin ooatings 81 ioe formed
the outside 81 the s-inch pipas
md gradually Increased Ia thickness until
n ten days those on adiaoeni pipes united
md formed a solid wall ~ frozen water
quicksand. which. after forty days
.r-eziuE attained a thickness ~ ten feet
This excluded the water, ~ that the
shaft could b" eHcaNatsd through u AZ Ia
-Ock The material had indaed 10 ba
blasted and res-iHblsd sand -stons.
The shan was med with heavy tlmb.T
walls hung from a.. top and packed around
sith hay A watsr-tiRht Joint wus made
With the rpck The refrigeration vac stopped
md the ground allowed o. thaw which
: did ~ slowly that b. Ma nifty dAys b~-
tho water i-,gaH 60 enter tie shat
The outer edge ~ the frozen mass vas
a. d" q cylindrical surfAn. "a