The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1871-04-18
BRooKLYNs BRIDGE.
The Mammoth Caisson for the
New York Tower.
Ih Advanced State Of Construction How 1t
Looksd Yssterday-The Day Of Launching
Determined Upon-The Improvements
Suggested by Experience Where
It Will be Located aud the
Excavations to be Made.

street. East river. filling up within few feet the en-
tire water front OF the shipyard wherein 1t ID being
constructed, Is designed for the caisson on wnicn
the New York tower OF the East River Dridgc VIII
be built. one hundred and twenty-five men are
busIy engaged In various capacities ABOUT IT, ana
earnest and ever watchful. hitting mere ana there
among this small army OF artzans, are noticed tho
superintendents or the work. Upon superficial ex-
animation this monster specimen Of tho highest
order
appears nearly alike the calsson In position
the Brooklyn side OF the RIVER the filing in OF which
Is progressing very satisfactorily; and, indeed In
Its general dimensions anu details there is bu little
difference, yet theses differences are notifications
and Improvements taught the engineers IN charge
by experience, which viii make the present calsson
Just what is required for this grand undertaking.
The length OF the Is four feet more than that
or The Brooklyn structure, making the Size at the
base lO2 by l72 feet. The walls Of timber slope
slightly inward from bottom to top which ut the
bottom but eight inches IN thickness, yet 80 rap
Idly do they increase In this particular that at the
height CT nine feet they fully eight feet through
Above these the courses OF timber pass entirely
across from wall to wall, thus covering the air
chamber, which Is Of rectangular shape and where,
In a few months, the
HARDY MEN OF MUsCLH
Will. nlSnt diter Hlgut, ana hlItr Jay DtHeuth
the bed OF the river. dig and delvc until the casson
has found suitable and everlasting resting place.
This air chamber and tine improvement IS worthy OF
NOTICES. plated over :hc whole interior with boiler
irOn built up with small sheets in sections, which
are joined together with light angle iron at the
edges. THIS popularity OF placing it in position Is
necessitated by the future effect or neat and cold,
which, IL Is assumed, will produce total change in
the length or the lining OF nearly two inches The
object Of the
LINING or PLATE IRON
u twofod-the first to secure absolute protection
against fire. which, unfortunately. was incident TO
the Jklyn structure and so We'll remembered by
our citizens and second 20 prevent the compressed
air from escaping through the seams OF the timber
courses. These seams are only partially calEed,
wherein there Is another difference as COM
pared with the first calsson. those were tho
roughly caulked. The Inning Is thus q great i'm
pr0vemcnt, as fire cannot in anywlse be cOmmuni-
cate to the timber The danger from this element
Of course increases d the depth grows greater,
this being due TO the increased quantity Of oxygen
brought into contact with name when 1t Is once
started than would be In air OF ordinary
density. The danger Of timber structure IN
this particular Is much greater also in
consequence OF the enormous draught caused by the
pc OF air at pressure Of forty pounds through
eGccd, ex plains Colonel W. II. Paine, The superin.
tenuing engineer oi the works, in
DISTINGUISHING TIE FIRE
IN the roof OF the Brooklyn Cal5on, the pressure
or AR was abouL eighteen pounds per square inch,
and 1t carried the lame with Iurious blast, wind
ing and twisting II about wherever there was the
least chance OF escape No large amount OF timber
was burned, however, yet the fire, In thin, narrow
Ribbons uited out TO The distance Of twenty or more
iect from the po.nt OF starting, aud no stream oil
water could pos iDiy reach IL.
There are Nil ABOUT elghly-1ve tons OF this lining
OF boiler plate ron and II Is held firmly IN post
on the side walls ~ heavy bars OF iron. with long
bolts running through them and the walls. These
are being fastened To the r0oi Dy bolts at distances
OF two feet in e,thcr direction. These bolts pass
through three 70 hive feel or TIMBER ami serve the
s"S.lasr utner bolts, Twelve feet In length, hold
the partition walls and roof together and. In addi.
ton to these, 80 many screw bolts aud shorter bolts
are being used that, wnen ready Tor launching,
about
THREE HUNDRED And TEN THOUSAND PoUNDs
OF iron bars OF his character VIII have been worked
into the structure.
Ano her feature not seen In the Brooklyn caisson
the "a o. y pG Se iar s san a. pn c s
cavatiOn 10 be made on the New YORK side. 1t was
grand work 81 blasting tho Solid rock on the
Brooklyn shore; tut this viii not be the here.
Fifty u these pumps. from three and han To four
incncs in diameter, WIN be in position, through
surface The pumps. OF powerful rotary descrip-
ton viii be placed above, and the work expected to
be done by them VIII be rapid ana or enormous
amount daily. BorIngS, with view oil asceraining
THE ENACT NATURE
the excavations be at the Ioot OIL kOOso-
Welt street. where the caisson Is TO be snnS, show
that depth OF seventy feet and from that to the
"bed rocA," winch IS at eighty aud ei2hty-two feet
the sand contains u lew bouldcrs. To remove these
1t was necessary 10 provide water shafts as noted
IN first construction. these shafts are cylIndri
cal instead OF OenJ square, as III the Brooklyn
Caisson, aud are eight feet IN diaMeter.
The supply shafts are four In number Instead OF
two, "a In the fist structure, and
TIE LOCKS
arc ba.t in an entirely different ana wholly novel
manner. In this caisson these are placed within the
ynf.a anh.k nd mi ont nm
into the timber. They are In two pairs, each pair
being Joined together by rectangular trough Of
iron. At the end Of TINS trough door Is placed,
opening into the cylinder once inside OF this
cylinder. the lock, there IL observed another door,
through which the interior OF the caisson il reached.
Each oil these cylinders as devised, Is q complete
ar ioSk within ITSELF SERVING 20 pas ID ann out the
the atmosphere 10 tue Increased pressure In the air
cnamber below. Each cylinder Will hold twenty
men comfortably aud
EIGHTY wORKMES
can 60 to and fro every i've minutes. Surrounding
each pair Of All locks L. large iron cylinder, which
serves as the bottom OF the wcllhole, by which to
reach them. TINS II intended to be joined above to
q wooden curb that Is to be carried up aud kept
Waier.,,vht as the caisson desccnds to iis position
Circular sralrcases are built IN this cJllnder, by
which 10 ascend and descend.
Another feature different rom the Brooklyn ca5-
son Is that the present Will have roof OF timber
ave feet IN thickness before launching and after
that accomplished fifteen leet more VIII be added,
FULLY TWENTY FEET
OF WOODWORK before the stoncwork VIII commence
to he land. The entire thickness oil roof or tic
Brooklyn structure is bur ten ieet.
should unforeseen diilcnty arise the con-
tractors OF this immense work, Messrs. WcOb Bell,
hope TO bave the caisson 80 ar advanced that 1t will
be
READY TO LAUNCH
about the 9th OF May: but II II 81 not hon In readi-
ness 1t win not he sent into the water unt the 10th.
To Lunch structure or tnis character seemed TO
he me insnrnlountable Difficulty TO all shipbuldcrs
whom the BROOKLYN catss0l was bein, prepared for
that purpose. They rcmemoeged the Ill iiculty at
I'm
weeks OF labor ana the lives II cost, and shook thcii
heads oninousiy. But after the preliminary worS
was done ana the w0rl was passed ina: the large
structure was moving II was
BUT THIRTY SECONDS
before the c8Isson struck the water and that without
the least connection among or harm to any Of
the aborcrs In tue present caisson, 10 make asaur
ancc doubly sure ia this matter OF Launching, there
has been constructed n0oring wnich passe5 nearly
bcrs within beng full OF air Il cannot escape unit
the structure reaches the water, which WIN onl,