New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-07-19

otherwise DO the owing 70 WIS Isos IN ehenvs
S%p Witch aVP Spss run II into ss' ss ssys
apparatus very powerful and T. Kept een ,s o.
work II ordinarily pumps about Loo esIions per
minute, but has capacity for pumping i'"" KA'i'"'
W. METHODS or DRrLLNa
The drifting done by compressed air, which s sup
piled from res4rvor above which ~ kept filed By i've
compressng engines OF four horfe power Only three OF
these usually nc work ct time The pressure ofair
is 30 pounds per square inch Air for such is more
expensive than steam but in this work IL almost In
dspensable for tho following reasons:
In carrying steam through such long pipes much OF
It's force would be lost through condemnation especially
under temperature low as that OF the tunneb The
escape OF steam from the drills would soon MI the
tunnels with mist which would blind the sight. s. The
steam would greatly heat the tunnels, whereas the con-
densed DIR tends TO cool them rather than otherwise
The condensed air affords excellent means OF venti-
lstng the tunnels clearing them from the smoke or the
blasting, &C. In the use OF steam through hose NJ IA
necessary In working movable drills there 10 constant
danger OF the hose becoming Oosene and OF the con
sequent seadng OF the operators Of the drill whereas,
in tho Of the escape of cold air. no damage Is done
The diamond drill has been used 70 some extent in the
excavation This drill consists of tube an inch or two
In diameter Into the circumference Of the end Of the
tube several diamonds introduced, and the tube,
when given rotary notion grinds away into the r9es,
leaving OF rock within the tube The great dlfii
Guilty with drills Of which two were used that
the diamonds would sometimes gee loose ana grind
upon one another to their mutual desruGon ln meg
Burleigh drills used in their place Six OF these drills
now employed The ohisel OF this drill Is driven In
by successive forward movements OF the machine, ~
being turned trifle between the successive blows
The explosive mostly used In blasting rs nroglycer-
magazine on Flood Rock It is brought thence In small
quantities boats and taken TO the laboratory con-
nectod with the works though removed from the other
buildings by quite stretch of marsh land and reached
by causeway. Here y Is made up into elgnt OF ten
an inch and half In diameter They are made OF thick
brown paper and the liquid gyoerine Is poured INTO
them when the top Is closed up and fuse which VIII
hmm ahnut attached.
end OF which percussion cap These cartridges are
and are exploded By percussion system OF signals
warns the workmen away from the points where expo
the use of this explosive; and although from 10
$1,000 pounds OF have been used during the last thr9e
Is said to be doubtful IL much can be said where
similar amount OF powder has been used during "a long
hs the root Be- CRACKED ad @ let
in. In consequences. explosions may be heard every
few sna 20 os nSyos ~ sSe pean Ths SIp
svs pound es ont 5& cen 81
pound or for eight pounds, o. CO. as against 81 TO- the
Of pound Of nitroglycerine The amount oil nitro
ton Is about II pounds. Powder is, however, used IN
part, about 800 pounds OF powder, and about l,oSo
pounds Of nitroglycerine being required every onn'
MINOR DETAILS OF THB WORK.
little railway runs into each tunnel, and the cars
which run on them drawn out TO turn-taoe COM
mon 20 all the tracks, near the center Of the great pit
and Just under great turnsble derrick which stands
on the edge OF the pit BY this derrick mules are let
down in kind OF crate to the railways beneath, where
they used draw the cars in and out oil the tunnels
There is intensely udicrous in seeing these
ANIMALS swung out In midair and let rapidly down Tor
distance OF 40 feet. The derrick is used Tor drawing
ont the excavaed rock we'll, and is operated by an
engine the brink OF the pit which swings the der
rick and draws up the loads the operators OF the engine
being guided In moving 1t by system OF signals from
watchmsn near the brink. The rock drawn out IS TO
81 that So Of a
almost no use except for 1lling IN oulsheadS
or other low places at present 9lssin
serves as kind Of breakwater- The tunnels have thus
far been extended TO perhaps an average length OF 400
ing the gallery outtngs about $500 feet and total
Of about $500 cubic yards OF ekcnttngs have been
tunneling I per month. AZ this rate Gen. Newton
is confident that the excavation win be finished by the
sion has not been announced He states that the expO
sion will be less violent than one would expect rom 50
In the neighborhood OF the excavation are the works
OF the establishment which include engine house for
pressing engines general tool shop the laboratory an
office, DC Thee are cheapiy Out wei oniit; ana are
along the shore for distance, aud small locomo
tive Carries OF the fragments by the carload. Capt.
b. r. Heuer OF the corps of Army Engineers is supern-
tendent In charge About 100 men arc now employed,
thoagh about $50 hired abouttwo years ago The
iaborers the tunnels divided into two gangs one
Of which works from 3 m n D. M: ana tas ota tss
entire "A hours, were formerly employed, but It has
been decided that the present system is the better one
The laborers receive 81 per day. and the miners y go
Work Is discontinued on Sunday, although the pump
Is kept constantly at work. Except at certain hours
FREQ access Is granted TO the tunnels and on 1ne
days the visitors said to average about 200
per day, and about 5000 on pleasant Sundays Armed
with torch and umbrella the adventures plunge into the
dark oayerns and despite the triekiBg seawater and
the closeness OF the tunnels well rewarded Indeed
few places the vicinity Of New York will better repay
visit The Astoria boats afford tho best access from
New-York while from Williamsburgh accommodate
citizens neghborhoOd 1t Is worthy OF note that
A model OF the work, about by feet IN extent and
made so that top be taken OF and the interior
exhibited has been sent TO the Vienna Exposition, with
subscription OF the plan and methods used And in this
hereis singular ftuess, since the work prove sue
cessfu IL will be Of international importance At this
point il may be worth while 70 add that, beside this
work, Gen Newton has charge or Government Work at
Sandy Hook, Fort Hamilton, Governors island, Bedloes
Island, ROndout Harbor the Hudson, Albany. Troy
Lake Champlan, and .at Burlington PlattsburR, otter
Creek and ROuse's Point near tho Canada frontier.
AS 70 the Pot Rock excavations, considerable progress
had been made In blasting that away, up to the time
scows obsructng the channel led to serious complaint
and Q temporary interruption OF the work The drill
scOw Is furnished With great inverted hemisphere or
sheet rOn which let down upon tho rock and, owing
to peculiar shape Is held TO the bottom the harder III
proportion to swiftness OF the current There
a number OF tubular openings through this, through
which the drills passed down TO the rock the henri
sphere serving to steady the drills which are worked
nom the above. Large charges or Rlycerine are
inserted In the holes thus formed divers aud then
exploded The work Is presently TO be resumed, and
will not be discontinued TIL depth OF 10 feet shall have
been reached.