The New York herald., 1870-10-15
A MAmMorH cAYsoN.

| Description or the Immcnso Calsson Tor
| the New York Shore of the East River
| Brid1c--rts Cost ard tho Quantity Of
Material In 1t.
| Messrs Webb & Bell. Engineers, OF Crcenpoint.
I. l., have In process OF construction colossal
caisson, desisnel to form portion OF the founda-
tton on the New York shore or the East river bridge,
and upon which the tower on that side
| WIN rest 1t viii be in form nnd con-
! strucli0n sira liar to the one launched nom
their snipyard In March last. witch has since
been placed IN position and Is now being built upon
| on the Brooklyn side Of the river. The magnitude
Of these cassons and the combination In them OF tho
various improvements which have from timo to
| time been suggested by eminent men thoroughly
couversant with the work render them at once struc-
lures OF the highest Interest and importance to the
! engineering profession. The success which has at
| tended The launching and fixing Of the previous
caisson, as well as its special adapability for
| the parpose for Which It was designed, leaves
little doubt but that this one Will also answer the
end desired. There will be also q few slight I'M
provcinents In this one which were observed TO be
wanting hi tho other. although 10 the ordinary OBJ
server no difference In its construction VIII be no
, teed, tho new suggestions having been made by
Colonel Roebling with reference to the additional
Strengthening bolts to be used In fastening On the
iron angle at the base OF The inner bottom edge.
The developments Of these plans left to Colonel
Pain, who has placed them in the working drawing
from which the structure is to be made.
This caissou will be sunk on the New York SIDE
opposite the old cast slip OF the Fulton ferry for
which space s being cleared by means OF dredging
machines, and 1t Is hoped that with an ordinary
amount Of energy on the part or the contractors the
srace win be cleared and the calsson placed in posi-
ton In November next.
THE cAIssoN
Is in reality an immense chest and when the term Is
applied to bridge building 1t suggests wooden
box or frame Of strong and massive tim
bers intended for laying the foundations OF
bridge in such situations ana In positions
where the ordinary Golfer dam cannot be used. In
tue present CASE there being rock foundation OF
suitable nature on the New York shore for the EN-.
poyment o. the dam, this structure will form part
OF the foundation of the tower itself. The system
adopted In its construction Involves, In addition 10
the ordinary one, the principe OF the pneumatic
rllc, which, in most cases. Is cylinder Of largo
size forced down into position by atmospheric pres
sure IN lhe present Instance the Atmospheric pres
sure VIII be assisted ~ the continual excavation OF
the earth rocks ana other matter from beneath the
mass Of the caissCn.
The principle o the diving bell Is suggested I'M
mediatc!y one looks upon she drawing and tracngs
which Co'onel ram mas prepared. The caiss0n pro-
per, or the enurinOuS chamber within which the
WORK OF EXCAVATION
will be carried on, is rectangular in shape, 1T2 feet
long, 1o2 feet wide outside. and IA feet inches hgl
sides are wedge saaped In section, the lower edge
being eight and q hali Inches and the upper eight
these sides is Ave feet IN thickness, which leaves
the dimensions OF roof and sides ing al,eYed for
WORKING chamber or about ljj feet by ninety eight
feet ground area ana nine feet In Height or space for
about eighty men TO WORK. The Whole Is composed
OF oak ana yeiow pine timber, twelve inches square,
the seams OF which are payedo with vegetable tar,
In order TO render them iinpervious to water, while
between the outside layers OF timber IL a slicahng
OF tin between the two sheatnngs Of felt which rem
ders them also MrtigIt. The sharp lower cages OF
ihc caisson are made very massive and strong
of timber is entirey OF OAK, ana TO this Is
boci cast iron Oya-raced shoe eight inches wide
ana tnrcc inches IN thickness at its Around
this shoe VIII be placed al armor Of boier plates OF
ca IRON extending three ce above on both sides
OF the Chamber wall, the whole being strengthened
the sc onl course oi timber VIII be inscr ell knee,
Or "oend,n Of hardwood which IS TO extend twenty
feet each way
The tmbers OF tho caisson are to be alI bol.ed to-
galher vertically. horizontally and diagonally with
one and hall inch bolts varying IN length from
more than fifteen inches apart throughout the whole
structure, the heads ana mus iigheued by means
As tins structure - sunk in Its desired position
Sixty iect below low tide mark, when Is tie same
as tbs depth Of the rivers channel, additional
courses OF timber VIII be placed on the top to the
height OF twenty feet and then flied in win
It's final resting PLACE the tower VIII be built on the
solid foundation thus formed.
SIX shafts OF boiler plates pass through tho roof
yatlng shafts, Rectangular shape, anu about seven
feet In diameter. Next are two supply shafts. circu
lar In form, fortylve inches In diameter through
which the worxnien arc TO pass TO tile working
chamber beneath. The last are TWO air shafts. or
locks, also circular, and twcnty0ne inches IN d.
aneter, all the shafts beng constructed specially
with the view o. safety and convenience. Through
the air shafts the air VIII be supplied forced, be-
low by means oil force pumps; the ar Will expel The
water and enable tie w0rKmen to descend to the
bottom Of the river. complete idea Of the magn
ude Of this caisson can e readily had from tine Iol.
fIDIie9-tNe Iaft,
feet; height, "a feet inches; including superincnn-
bent tl'lDeis aid concrete 8, feet inches; total
quantity OF timber employed In its construction
10000 cube feet; total weight OF casson befo Q
launching about 1000 tons weight OF wrought iron
boos 10 be used 100000 ounds weight OF frocd boiler
require about $4,000 thousand feet OF timber In
order to launch IL from the ways. A great number
OF men are working at 1t, ana it will probably be
finished before the time xed FOR placing Ii in posi
tion. 1t VIII cost, when delivered 10 the BTidge
Company, about $685. ....t.