The Kimball graphic. (Kimball, Brule County, Dakota [S.D.]) 1883-1905, 1884-12-05
UNDER FLOOR ROCK
Preparations for What will be the Great
est Explosion Known In History.

est Explosion Known In History.
New York Sun.-"There are four
miles of tunnels in this nine" said
Foreman Bernard Boyle as he con-
Quoted n visitor down into the excava-
tons under Flood Rock, which the
| Government has undertaken to blow
up rs it blewup Hallett's Reef, a short
distance above it in He'll Gate. "This
is all gneiss rock" the guide continued.
"Some of it is so soft that it can be cut
with a knife, and some of it is so hard
that it has to be blown up. The dip is
at an angle O fabout go deg. which favors
the entrance of water from the river
aboye u.s."
A dismal rain was pouring from the
rock and threatening to extiEgnish the
oil lamp which the explorer carried.
On stepping through o doorway he
found himself in water up to the knees
of his high rubber boots. In
the extreme northeast corner Of the
mine q roar was heard, and soon the
water was seen rushing down through 8
VIDE seam. A number of laborers were
busily engaged in %comenting and in
drilling test holes in new directions.
"We are working carefully, now,
guarding against any further outbreak"
said Mr.. BOYLE. "There is a million
dollars worth of work at stake here.
and we are exercising the greatest eau
ton. In case of q sudden flood the mi
ners would escape through the door
there and close it. Then the compress
sed air of this pipe would be let loose
and a pressure of sixty pounds to the
square inch would prevent this section
from filling. The pumps are well able
to take care of the present leaks. W.
might introduce the compressed air in
to the seams there aud stop it, nodoubt,
but as we don't know the width of the
orifice further back, we prefer the
slower process of cementing."
"When shall you be ready for the
great explosions"
Gin about one year from this month.
There are only ninety men engaged
here now, although we have had two
hundred or more in times past. Our
present force can complete the work by
the time we are ready for the explosion.
You would be surprised at the number
of men who apply for work in such a
mine. You see, we keep q uniform
temperature here the year round, and
plenty of good fresh air. Some of the
men have been here from the start, and
we keep the old hands as long as posi-
Bile. No n has ever contracted the
caisson disease here. The men are
temperate and we never allow the use
ofliquor.
Next September you may see and
hear the largest explosion known to his
tory. All of these holes you see there
with plugs in them will be filled with
explosives which will cost $500 900.
About 100, 900 cubic yards of rock have
already been excavated. Whatever we
can carry out now will not have to be
ished up by divers and grapplers in this
form of debris after the explosion.
Men are busy here night and day. II
you desire to count, you will find about
$50 900 two and three-inch holes drilled
for explosives already. The drills have
to be sharpened $4,000 times per year in
the shops overhead. The rock, after be-
ing mined, has to be hoisted, carried away
to deep water, and dumped. A hole
seventy feet deep, just north Of Black
wells Island, has served largely as our
dumping ground. The work requires
drilling, blasting, hauling, hosting,
dumping, pumping, timbering, trans
porting, surveying, sounding and many
other things. Every hole has to be
drilled with mathematical precision to
meet some other hole. We try to keep
twenty feet and upward of rock for q
roof, which requires an accurate knowl-
edge of the depth of water above it.
Ventilation is kept up by a fan twelve
feet in diameter, driven by an engine.
The large galleries ventilate themselves.
The pumping operations are necessarily
continuous. The average inflow from
leakage at low tide is TAO gallons per
minute, but the last great leak, which
you noticed q few minutes ago, has in
creased it to over a Thousand gallons.