The Republican journal. [volume] (Belfast, Me.) 1829-current, 1883-05-31

GREAT MECHANICAL AND ENGINEERING
ACHIEVEMENT. DETAILS OF ITS CONSTRtC-
TION AND THE MATERIALS USED.

tic and difficult engineering enterprises ever
undertaken by trained and skillful human in
tellects. On that day the great bridge which
unites the cities of New York and Brooklyn
was formally opened to the public. The great
bridge was conceived in the mind of William
c. Kingsley of Brooklyn, who, as long ago as
1860 matured project and had plans drawn
by a competent engineer In about two wears
charter was obtained from the legislature and
company organized to carry on the undertake
ing, the capital being fixed at So 100000. John
a. ROebliDg, the engineer who built the first
suspension bridge at Niagara and the bridge
across the Ohio at Cincinnati, was engaged bv
the company. He at once went to work max
ing surveys, estimates and detailed plans, and
in September 1867, submitted report in which
he placed the probable cost of the bridge prop
er at 81 900 900, and of land for the approaches
and other incidentals at S3,S00,00O, making
$40, 800 900 in all. He also thought that the
work could be finished in five years. As mat
ter of fact the cost is upward of S15,000,000
and it has taken nearer sixteen than five years
to complete the structure. 1t should be said in
justice to Mr.. Roebing, however, that there
were in the way many difficulties involving de-
lay and extra cost which the most acute engin-
eering intelligence could not have foreseen.
Moreover, the plans have been altered, the di-
mensions enlarged and other changes made,
vastly enhancing the expense, for which the
engineer is i'll no way responsible. After the
work was well under way the company gave
place to board Of trustees representing the
two cities, including the Mayors and other mu
nicpa tunctiOnarieS acting TX offcio.
The preparatory abors having been accom-
pliShed, work on the bridge itself began by the
sinking of the caisson or huge crib of timber
on which the tower was to rest, on the Brook
lyn side in May, 1870. This method of con-
struction was marvellous piece of ingenuity
Upon the framework Were laid with matht
matica nicely the huge blocks Of granite of
which the tower is composed, while beneath
TO- I,oJa
mass to sink uniformly and steadily until the
bed rock was reached, and the tower rested on
the solid stone formation untold ages old. 1t
was absolutely necessary both that this founda-
ton should be reached and that the caiSsOn and
the masonry resting on ii should sink 50 gradu-
ally that it should not sweryc Il hairs breadth
from the lines marked out in advance. The
fact that this was done and that the towers to-
day do not vary the shadow of a shade from
the positions originally fixed is the highest trib
ute to the mastery skill of the engineers and
the care and caution of the workmen. The
Brooklyn caisson WAS finally adjusted in March,
1871. work having been delayed by several ac-
cidcnts. the worst being fire which cost SD,
600 and neccssitated the flooding of the interior
The New \ Ork calsson was placed in position
in October, 1871. and finally sunk in May 1872
The difficulties of getting a foundation were
greater on that side than on the other, owing to
the nature of the river bottom. The caiSSons
in place. the erection Of the towers and the lp-
prOaches was steadily pushed. 1t would be a
greater task than we can here assume to deS-
cribe in detail all the later steps. 1t must suf-
flee TO say that the towers are each 216i feet
high, the roadway being is feet above high
water mark. AT this elevation the towers are
divided by two archwayS 81! feet wide and
l205 feet high through which will pass the
streams Of humanity and the current of traffic
destined to lind the bridge Il useful thorough
fare III the coming years. At the top of the
towers are large movable iron plates. On these
SADDLE plates" as they are called, rest the
huge cables, nearly sixteen inches thick, which
sustain the weight of the central span. These
extend back on each side to the enormous an
chOrages, great masses of masonry in which
are embedded the huge anchor plates and the
iron links to which the cables are attached. BY
this system the tremendous ''pull' of the ca
bleS does not come upon the towers themselves,
but these merely stand as supports or fulcrumS,
and the cables. adjusting themselves to the
tension by the movable saddles, become the
means Of holding the towers in place instead of
eNerting strain upon them. The anchOrageS
are $50 feet inland, and the distance from an
chOrage to anchorage is 3460 feet. Other fig
ures which serve to give an idea of the struct-
ure are as follows: Distance between termin,
59S9 feet; between the towers, 1885! feet :;
height of roadway in the centre, l35 feet; at
the towers 11S feet. The following is tabu-
lated statement showing the weight of the sus-
pended structure and the transtory load it is
estimated as capable of bearing.
WEIGHT OF SUSPENDED STRUCTURE
Tons.
Between anchorages, 1850 fcet............... 6O20
Main span 1888 L feet. ...-......... ...... 1880
Wrirht carried III trussps 24S fee, , 10
WEIGHT OF sUsPENDERs.
p,,,.,,,,, ,,oI,,uo,. 30
Main snan " IA
Main .pan by cable. .............. $50
WEIGHT OF CABLES.
nv, etm ''''''''''''-' 2too o
Main ei,'m III cabins ia 3s0
,,.r,I,.,,r u, .,r,,,,,,, ,,,,n,,r>,,.
- 'i''i'i'i'
net"tth "h'ii"f"Sts''' ''''''''' ':' tno
Mi i"in sp',, i, ~ ,ii '1So 6S0
Carried III tIussrs.. ... 300
y,.,,.,,, IL, s,,,r,
IT ''>'''7 80 'N'S
netWech ahch"fageS 6"o to"
NAN spar NV rihirs S30 Sg0
By trnsSes, ns,,a, ~ ~
,,,.,,',,-, -. ,,,,,,.1,
i"iAh 81 "fi''''1 'r nh'i'"h,
Between ahchorageS' GSO
Main Wain pan sfami ~. ,a. '''' 3'-to 'fo
r. f. tr,ISn. 80 ~ "'a0 o0o
-
loiAH i"NNollohi LOAD
between ahchofaSea' ..:...'...- 5,ioo
NAN @ sptn.i .;ti,.'''''''' Observation-Disclosures -" @
Rv ."'ir tr11,a np,'a. "s '1o0 1o0
..,,,,,,,
po.,,.,,,. ..,,.,,,. ,so
between ancholages. es...................... .l1,1sO
Nam span by cables '.'.'....... 692o
,.,.,...., .,o71
cry si''''' ~ 'f'0''
The approach 10 the bridge begins at Chatham
street in New York and at the corner Of Sands
and Washington streets in Brooklyn. The
bridge will be divided into two driveways, one
for vehicles going and the other for those COM
ing, these drlveways taking up the outer sides.
Between these will be tracks for cars. similarly
arranged, and between these again an elevated
pathway for pedestrians, enabling passengers to
have full and unobstructed view of the Won
derful view beneath and around them.
Well may the completion of this great task
excite the admiration of the world. Its coun-
terpart has never yet been seen. 1t has cost a
great price in cash, in loss of life by accident
and in the illness and crippIing which have re-
suited TO many employees. Engineer Roebling