New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1881-11-28
UNDER THE HUDSON.


CHANGES IN METHoDs-tcENEs IN 1hh i''
MEL -, 1,- +rn
The noint Of interest at the Hudson hlNer 'ui i
mel at present Is the connection VI 'n0 -,
cal shaft with the caisson at 'ho VP ~,
of the tunnels proper After the acoiucnr " ,sio,
OF 1880. n pneumatic caissOn was sum- 'no -.
were recovered and the old air-lock in'o 'io 80,
;,o shaft was reopened, while Work was W.
on the other side in the tunnels Inc pioDl'ni ~
nresent is how to replace this dishSeu a"-io'N' nv"
.Io onIv means Of entering, by COLI
.i.ian % the tunnel Assistant Engineer
II Finch has suggested q plan which may
y, aaorted He suggests that an air-tight diaphragm
10 inserted in the middle Of the old air-loek, ana
another at its opening into the caSson In inc SoV
or-loek thus formed the work OF excavatng can zoe
carried on on each side by the use OF compressor
air. As the height and the horlZoh'ai
distance are reached corresponding 10 the arci
of the tunnel iron plates are to be msorteu an"
further supported by brickwork. In other "orus'
the same method will I've followed WORKING OH e'c"
side from this ar-lock that has been pursued III INC
funnel When in advancing the WORK inc oii'n
,or Of the vertical or working shaft is reached 1t
will be carefully taken down and sent OUT ike 'ho
Cher material. The iron plating and masonry
work will be kept so far along that comnunlca-
tion can be readily effected with the out
side The result of this will be that
the small hole leading into the tunnel at present
from the bottom of the working shaft Will Oe re-
placed by the circular arch Of the tunnel ITSELF
For the months previous, to the last week or two
the Norkmen at the headings far under the river
have been cOntending against the sottest slit Eet
encountered. ut was Oozy as molasses' Salu
Assistant Engineer Finch. Il have seen
moments of the most intense e&cl'e'hen'
in tbs narrow space mt the headings Planks were
fla soft
silt But the work must 90 on: so mover thihg
was done. Excavations were made without TAXING
ANYTHING out This was the way. In the planks
ocioss fine heading a hole was sawn large enoughto
admit n mans hand. Instantly the cone began 10
flow in. But workman STOOD IGaHy;
Rmud fonr TO six inches in diameter. These
were rapidly plasered INTO the soft ooze anu piesse
hack Thus the progress OF the soft slit was stayed
Carefully the wor kman inserted one piece aitet
backward until a kind of shell was formed. Tins
was made of this hard mud. the pieces being pressed
together until this concaVlty was air i,gn', lneI
the workman continued his gentle onward
motion until the opening assumed Mise
size and dimensions. Meanwhile the 9lheI
workmen were crOuched about, IN the mnd ana
on the timbe1s watching like tigers Tor their prey
Occasionally the soft silt would force ITS way past
the workmans hand. Then the compressed ar would
escape with report like pistol shot' anu at Tue
sound the wOrkmen leaped TO therteet. Above, pas
sengers on boats saw a jet OF water suIdeniV snool
ND six feet in the air little thinking thaU IL came
from the tunnel underneath. There was no danger,
however. of such accident as She former
one If the men lost control of this SOFT mud, when
is very unlikely. it would require three OF tour
minutes for the mass To crush down the tmbeTs
aud overflow the headings. This would DC ample
time for the men to reach the ar locks OF when
there are two, one being always open. nus ms
curious method of excavation went on ultll cnhlc
yard was removed yet no SIT was taken out lhen
an iron plate was put in and held III place by braces
and the work of making hole III mud without
taking anything out continued. 1T required lour
hours to make space for one plate.
An advance OF more than fifty feet has been made
since November ], and at present the work Is gong
on in silt hard and firm cutting like old cheese.
With tue regular features of the tunnel readers OF
THE TRIBUNE are familiar. But the points Will he
found of interest in which the methods under the
present management differ from those employed be-
The visitor on reaching the bottom Of the vertical
shaft finds the old lock used SIMPLY as means
OF entering the tunnel. bOth doors standing wi9e
open He passes over the spot where the heroic
Woodlands and his companions met their death, |
into the caisson now simply an open anle-clanDcT
to the arched openings of the tunnels Their roofs |
of brick covered with cement are family revealed bY
occasional lights. Not 80, however, with the car
track and tiubers over which lncautOus passers |
suffer many grievOus fall. Some 400 feet down, |
these tunnels the bulkheads and arlocks are reached
The bulkhead walls are of brick four eet III thlcG-
ness. backed by solid umbers twelve Inches tllck,
and strongly braced with tim Der supports In each |
bulkhead are two air locks one kept open |
toward the heading at all times These |
air locks. which are SIX feet III diameter, |
bv fifteen feet long believed to be the largest in
the world Their doors, which are undouDttdIy the
fouT feet six inches These air locks were brought
through the opening of the old lock III sections, and
are the first ever constructed III this III nner ,
After undergoing the painful purgatory OF the air |
locks the visitor finds himS If III the tunnel on the
other side. Here carpenters are buslly at work on
timbers, with brickayers and cementers, by the |
light of electric lamps. Beyond them the brick |
work Of the tunnel ends and there ensqes maze |
of crossing braces and inter-lOcinng umbers. In |
the centre is the pilot tunnel" another new |
feature a small tunnel six feet six inches ID diam
eer composed of the usual iron boiler plates ms
"A .,arl htycn in Intn a
the top far enough To admit plate, winch |
is supported by braces, until another cut allows
second plate be bolted 10 IL. After the pilot IS adj
vanced fifteen twenty feet by adding plate to |
plate the plates of the outer shell are put III posi-
ton in rings i'll the same way, and braced IN every
direction IRON the pilot by radlal braces The pl-
lot tunnel has a tendency to SINK down be- |
low the desired level, and often has 10 be |
uniointed at the rear that the front portions |
NAV be raised. When thus ten rings have |
been put in place in the outside shell they are |
lined with brick work and cement The lower three
fftns of the lining of concrete made III the pro
portion of one part Portland cement. two Of sand |
and four of broken stone The upper part Is brick
work. Ill which long strips oil hoop Iron are utter
woven to prevent cracking.
striking one. Brawny men half uaked and begrned |
shovel way the silt underneath the branching UNI
Der while others at work In the pilot tunnel above
The silt is longer ucdled and blown out by com |
pressed air but an Eads sand pump is used. A |
stream Of water is forced upon the silt, and in tie
half-liquid mass is the "perforatOr" of the pump
which sucks the ooze into the pump where there ~
an arrangement of hollow cones like the njec- |
tor Tor feeding steam boilers with water |
aloug the level of the tunnel and
lifted seventy feet into huge tank outside the
buildings whence it flows in a fume L. the flats
in the rear These the chief points of difference
i'm the present management of the work
William L.. Smith, the engineer Ia charge, George
F. Seward. General superintendent OF Construction
and other officers regard the of the methods
employed here as established. :" We want the pub
lie 70 understand" said Mr.. Seward that
this work is not an experiment. We have enc1un-
tered obstacles and have overcome them, and now
the correct ess OF the methods, and the completion
of the work early date are assured AT present
we invite inspection Of the tunnel that everyone