Omaha daily bee., 1903-03-15

pen. In a little dressing room Just off the
caisson top the men who come out of the
air chambers doff their muddy, wet cloth
ing and swallow hot coffee that is prepared
by a small boy.
Building the piers and their foundations
below the water is a subject that is in
teresting. Great engineering skill is in
volved and in the pneumatic caisson
method of sinking the foundations there is
great danger to the laborers. One of the
two foundation piers for the East Omaha
bridge has been finished, but the larger
one is in progress. and the river bed is
being removed below the surface of low
water. 1t will go eighty-four feet before
the work Is stopped. The smaller pier,
which Is close to the west shore OF the
river. was sunk only seventy-four feet, but
1t is two feet shorter and six feet narrower
than the pile Of concrete that is now going
down slowly day by day in the center of
the stream. N's'. ..-'
The oaissons for the bridge we're made
by constructing the working chamber OF
twelve-inch timbers, three thicknesses
being used for the walls and the ceiling.
The lower timbers are beveled to a eating
edge and reinforced and protected by iron
plates. Strong braces protect the working
chamber from possible collapse. There is,
OF course, no floor, as it is through this
cavity that the water and dirt and rocks
are sucked up, so that the foundation may
be lowered. IN top of the working cham
bers is built, section by section, a heavily
timbered framework OF the same dimen-
sions, also braced inside, and into which
is placed concrete and stone welded 50
Arr,Iy A-,thnu that a. r,.to.E,V ain I.,k
longer than solid rock. These layers are
called Golfer dams and are put on as the
caisson sinks into the river bed.
Piercing the solid mass is a four-foot
cylinder having two ladders to the working
chambers below. Through this the caisson
men enter and make their exit, and through
II is hoisted the debris that cannot be
forced through a four-inch pipe. Sand and
gravel are blown out through the pipe by
the force OF compressed air, by which
means, also, air is provided for the work
men. The top of the big vertical cylinder
is locked by mechanism so that no air can
get through 1t. II air did penetrate into
the working chamber, 1t and the cylinder
would soon be choked with dirt and water
from underneath.
OF course, it is dangerous for the men
to work in caissons. The history OF bridge
DullulnB Is Iull OF the ulsaStefS ana SUDDEN
death that have overtaken them. 1t is not
the liability of the thousands OF tons of
concrete above them falling in, or. any
thing Of that kind, but the tremendously
high air pressure, that counts. The deeper
they go under the water the higher the air
pressure becomes, averaging about one
pound to every twenty-seven inches of de-
scent. At seventy-four feet, OF the extreme
depth Of the caisson already in, it was about
thirty-twO pounds.
Men have worked in atmosphere that
weighed hfty-two pounds to the square
inch, but the thirty-twO-pound pressure
was enough to kill one deliver who worked
on the Omaha bridge and to make very
sick and patients in the hospital several
other men. The man who died was Stephen
Mattox, and the occurrence was chronicled
in the newspapers. He had been at the
business but two days when IT proved too
much for him. although to all appearances
he was a strong man.
Concerning the Mr.. George Adgate says:
"Mattox was the first man I lost, though /
have sunk hfty-fve pneumatic caissons. 1t
is dificult to guard against such cases.
Great size and physical strength seem to
make little or no difference in the work,
small, wiry men getting along better many
times than large ones. As a general propo-
sition men with weak hearts or weak lungs