New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1885-10-04

HOW THE ROCK HAS BEEN UNDERMINED,
THE FINAL TOUCH LIKELY TO BE GIVEN o.
WEDNESDAY MORNING.

THE FINAL TOUCH LIKELY TO BE GIVEN o.
WEDNESDAY MORNING.
The accompanying cut is an exact representation
Of Flood Rock and the manner in which IT mas oeeO
undermined. The lines crossing each other at rlch'
auges are the centrelines of the galleries and are
twenty-five feet apart 1t was of course inpossol"
TO tender these galleries entirely regular owing to
the varying hardness of the rock. the seams
assures etc: but by looking at the little irregular
figures contained in tue squares II Will De seen
that they do not vary much IN shape OF area OF
section The irregular figures are the cross
sections of the pillars which help to support the
roof of rock. At the extreme right baud they are
absent thus showing the contour lines OF that por-
tiop of the reef more plainly Along the outer line
there is a depth at mean low water OF twenty-sM
feet al the next twenty feet aud at the inner
one of only eighteen. The same lines, with some
for twelve and six feet extend all over the drawing
INT they are difficult to distinguish among the ont
lines of the pillars. The galleries are now EXTENDED
out to the extreme northeastern tip OF the reel now
oyer and the whole :ock within the outside line
will he removed by the explosion and subsequent
dredging to depth of twenty-six feet at mean 10"
water The total of the reef inside the twenty
six feet contour line shown Ill the cut, is about
nine acres The portion included within the heavy
black line is out OF water anu IoThis 1no 'e"nu
visible to the passer-by.
II will give the non-professional reader a better
idea of the work if he eonceves the QUITO represent
the ground plan of an immense stone temple. lZoo
feet IN length and VARYING from 800 to go 1eet IN
bIeadth The roof is supported by 46| stone
pillars each fifteen feet square; so large aud
numerous that they take up over third OF the h"or
space The ceiling is only ten feet shove tue h0or
and the solid stone roof Is ten feet thck at ti'e
edges and slopes upward toward the centre until IL
reaches thickness of forty feet The flat surface,
thare ia fnrtv feet of h. a
little less than an acre in extent IL rs the Is ana
IN which reference has previously been made. II
visitor were TO wander about in this temple he would
have AT The outer edge ten Feet Of rock and thirty
feet of water over his head AS lie travelled hall
way toward the centre there would be twenty-iour
feet OF rock and sixteen feet of water over him,
while I'D the me- ghborIood of the shaft the galleries
would grow and merge into a cavern with roof OF
tho same thickness to protect him from the VagarIes
of the weather Every one of these pillars IS per-
forated with holes nine feet IN depth ana three
inches in diameter. pointing upward Mt various
angles The average distance between their centres
is i've feet and each contains its twenty -"dd
mounds of high explosives ready to pull the temple
down unon itself Scattered about the roof ut
intervals of four feet still more holes each With
its sptelul and eoergetic contents. able ana willing
TO assist 10 the crash OF matter and the wreck OF
nine acres of world. The entire number OF holes Is
l32s6 and their aggregate length twenty-five
miles Although the exact figures have not been
pnbllshed by General Newton and the officers in
charlie the OPINION OF expert engineers places the
amount of explosives to be used at 800 600 ponds
OF this about eight parts compound known
Inv this fitting title of ruckarock and the niath part
pure dynamite -, 49, r
pressed air drills the song of the minrr to his mules
and the heavy thug thug of the pumps have been
the forms of devotion during the past years 10
,s,A nlnlr MS lea SnHt
so 600 cuuic yards OF rock have been taken Out.
and 2 5000 cubic yards are still lett IN the I'M
meuse structure. Soon the pumps which Keep the
doors in "A halfway dry condition. will stop VOL
the water will steal in through tue innuinerah'e
little leaks. and pour N through TWO 49, nZ,noh
and corner Will be filled. Then at the touch al a
unger this temple OF industry viii DC rent asundcr
amid earthquakes anu darkness .
In tue of that portion of the cut marked oil
by "a heavy black line is shown u small blackcned
rectangle That represents the mouth of the main
shaft The smaller rectangle To the lelt indicates a
smaller shalt, which assists IN puinpihg ,ni yenti-
1ation; Connecting with these are the II go feet
OF galleries which have been hcwn out uf the rock
The nam shalt is siXty-ioar feet deep below mean
low water but the average gallery hoor is fourteen
feet higher The draining of the mine "a
difficult problem, as all the galleries must slope
downward away from the centre This will readily
be understood when u 10 remembered that
tie rock grows thinner out toward the
edges OF the reef, SO that ii the galleries
out OF level they would come
into opcn water. To collect the ". ter that leaks
through 1t il allowed 10 flow along the galleries
toward tho outer edge Of the reef There u Is col
lected by drainage bitches running along the edge.
and then taken down the centre III deep canal to
the at the foot of the shaft Here IT IS taken
in hand by pumps having capacity OF 1000
gallons a minute aud forced to the surface. The
leaks have always furnished supply OF water that
kept the pumps busy. The mary cracks and assures
through which the waters Of th5 Sound trlod to
force their way plugged up with woo len
wedges. This was the only way in which the
pressure of the water-abOut twenty-six pounds 20
the square inch-could be resisted. Tho most loaky
portion is that at the northeastern extremity,
shown in the cut without tunnels. This has an
area of about acre The rock was irregular
and badly assured. and ID Was delicate work %
drive the headings In places both roof ana sides
had to DO supported by ticlbers. Still further 10
guard against the possible consequences OF acct
deaf hsre, she whole section 10 separated fiom the
rest of the mine 10y water-tiEht door, opening
away from the shaft A rope leads from the door
70 the shaft and from the latter point OF vantage ali