New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1876-09-16

age will occur to houses In the neghborhoOd beyond the
SCATTERING Of few window-panes The ledge OF ROCK.
Of the ground various places between there and the
landing for the Harlem boats, passes under the East
River and makes its appearance again upon the upper
end Of Blackwes Island. Along this line the shock
will be the most severely felt.
ooer-iam constructed upon the reef In the form
Of half OF an irregular poygon Us longest De
feet out upon the rock shaft was sunk TO the depth OF
33 feet below mean low waterinark It's shape ~ con-
fOrmabe shape OF the DAM and ten tunnels aver
aging at their portals 90 feet in big and 10 in Width
radate from IL through the rock traverse gaheTles
excayated the tunnels were carried forward,
and the distance between the latter increased sub
sidiary tunnels were exeayated between te the WHO'S
forming network OF IS tunnels and III traverse gal.
leres. The tunnels and galleries were carried forward
on down grade, and their hlgntS were lessene.l
20 CONFORM 10 me upper surface OF s ane nSl
they lost the dignity OF tunnels and became mere
feet lower than the others and ditch running around
the breast" the further circumference OF the
cavatiOns, empes the water drained from the other
headings into the basin thus formed. From here 1t Is
pumped Into the river From all these excavations ABOUT
M 10 the time has been little short 81 600
The work has been done with Buregh drills the AR com
pressos being above ground In buildings constructed lr
the purpose The compressed AR was condcten 70 ne
drills through iron and rubber tubes Nitroglycerme,
S Gers nsea IN basng aecorns to the nature
rock Great had TO be used III making the uscrnl-
great explosion might have broken tile roof ana
let ia the water.
PRESENT CONDITION or THE WORK.
At last the work has reached its final stage Workmen
are busy engaged at present loading the holes which
367s in NUMBER The columns or supporting pillars
numbering IT, are pierced from floor to roof with no es
and the roof ALSO The holes arranged in groups OF
90 and each one IA flied with white pine plug, ON the
end CT which Is piece OF tin with nmber-froD 10
20-samped upon All the plugs in group are con-
nected with string which passes from on5 to the other
thus preventing any confusion IN separating group rom
group Each group has its designating n1rk, anu thus
they easily referred to as are the docks OF houses
The cartridges are delivered at the Government works
by the contractors, packed in boxes IBcy are nn cans
from 13s 25 inches in diameter and about ~ lnchcs
long, Gled with explosive material. There are bnFee
casses OF these cartridges OF three different deGees OF
strength and they all packed In boxes FOOT square
by "a inches long These boxes delivered at the
Government wharf handled IN the most careIhi
manner The late accident has caused the 10 ap
precate the power OF the material they handling In
the tunnels where the work is done 10y the means 81 tue
ordinary mining lamps the same care Is 3DserVaDIe
force inserted THIS pushed back TO Its pce by means
OF long pole another OF higher power follows H. anu
then another Of still higher grade after which tie pug
il returned to its place The plugs will be taken out when
all OF the holes have been thus ed ana small exploring
cartridges Of dynamite, with Illuminating CAPS WIZ 'hhe
their places. The dynamite being the hardest 70 eA
plOde placed next the Illuminating mercury COhtDeo
In the caps, which Is the greatest det0nntor vi an
All the exploding charges OF group VIII ne cOnnected
nv wire running from to another, which Will lake
the place the cord connecting the plugs Inc chs
will he connected with the electric battery
by two wires called "lead wires The battery wil DC
placed in bombprOof structure only short distance
from tho shaft The circuit will be connected, ut me
Iasf minute by Gen. Newton in person. Be, with his
staff, will position back ot the mine on s
point OF land aud the circuit will be closed by means VI
siuul In terry aud connecting wires that place and
the following manncri He VIII send by operating ms
small battery electric spark TO small torpedo on inc
ton OF the b0nbprOOf When the torpedo ex
plOdes t will the string ny winch the plates OF lne
battery insids the building suspended Ihcsc plates
falling into te fluids send Otner electrical currents
along the wires which lead to the holes IN the mine be-
low causing the simultaneous explosion OF the charges