New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1896-12-20

nor. IN the canal basin at Joliet a distance OF
four and one-third miles, the Desplaines has
sharp fall OF about for;y-two feet and In addluoh
to this an extreme huctuaton of thirteen feet In
the level OF Lake Michigan has to be taken into &C
count: so the controlling works must be elaborate
and powerful far beyond the capacity OF the ordi-
nary canal lock- In order to regulate the now.
which will exceed in volume that when the ONO
pours into the Mississippi at low water The con-
trolling works will. when completed. comprise a
bear-trap DAM next TO the south wall and beyond
1t a series Of sluce gates. set in mason
~ bukheads piers. upon which are built brick
towers.
The bear-trap dam, the main object Of which Is
TO afford an outlet for Ice. has opening OF lGo
feet and a vertical oscillation OF IL feet. II
consists of series Of metal plates forming two big
metal leaves. hinged together and working be-
tween masonry bulkheads. The downstream leaf
is hinged to a heavy foundation the upstream leaf
being so placed to present the barrier 10 the
water The structure is operated by admitting
water through conduits controlled by valves. be-
meath the leaves. The bulkheads for fifteen sluice-
gates have been finished, but only seven OF the big
metal gates are In place. that being many as
will be necessary, with the beartrap dam to regu-
late flow of 100000 cubic feet Of water minute.
These gateways have each opening OF 30 feet
and a height OF 20 feet. Each gate Is % feet 5
inches long and 20 feet high and the total weight
of the equipment OF each gateway will be 20 tons
The bed of the channel is Is feet below the bottom
of the gates, the total distance from the canal
bottom to the top OF the piers being GO feet The
water leaving the main channel through the suce-
gates and bear-trap dam will flow into great
rectangular BASIN formed by dixie OF earth fifteen
feet high, by which means the water will be con-
Quoted southwark OF the end of the controlling
works and into the Desplaines River.
MOST OF THE EXCAVATION COMPLETED.
Much difficult work remains 10 be done in max
ing connection between the new canal and the Chi
cago River al Robey-st. Chicago. and In arranging
for the carrying OF the water from the Lockport
end Of the canal into the Despaines and down the
steep grade OF Joliet yet the close OF this year sees
Sc per cent of the actual labor OF excavation accom-
plished Many Of the sections having been entirely
completed the visitor no longer see all the
various machinery at work. though all along the
. line OF the main channel the machines are still
standing upon the spoil banks" spoil" being the
| technical term for all the material excavated
| The first thing that the visitor notices In looking
at the rock sections Is the exceeding smoohncss OF
| the vertical planes OF solid limestone walls and he
thinks II must have been a great deal OF trouble
10 chip down the rock to such uniformity after the
blasting. But the work was done before the blast
| ing. by, an Ingenious little machSee known the
great chisel with Z-shaped Cutting edge o' "a
placed in such position that the chise will come
| the channeller moves backward and forward on It's
| section Of railroad track the chisel does its
work OF cutting groove three Inches wide and
| sinking downward ten feet into the course Of rock
| on which the machine stands. Then the drills OF
steam compressed air are set at work. dynamite
are set on breaking up ali the rock in that course
for the width OF the channel. the three-nch cleft
' on each side. however, preventing the dIshsurins