, 1877-11-09
Bridging the BOsphOrus.

Captain James B. Eads, engineer of the
iron bridge at st. Louis, and who has So
successfully planned and constructed the
jetties at the delta of the Mississippi river,
has also made elaborate plans for grand
iron bridge across the Bosphorus, con-
Meeting Pera-European Constantinople
with the Asiatic shore. This project of
the distinguished engineer is now for the
first time made public through the cour-
tosy of Mr.. A. o. Lambert, civil engineer,
who has been largely connected with the
great works of railway and bridge con-
struction in several countries of the Old
World, and also in Nebraska, Montana,
Idaho, and particularly in the Southern
States. Mr.. Lambert, in conjunction
with Captain Eads, drew the plans, made
the calculations and assisted at the sur
vey. 1t will be seen that the work, when
constructed, will be the most important
of the kind ever completed, affording to
the Turks, if that day ever comes, ready
back door out of Europe, in which they
took up their residence some 400 years
ago. ......... .....,...
The bridge will be about 5000 feet
long-over mile--will have fifteen
spans; will be 100 feet wide, and save the
masonry and flooring, will be built of
iron. The height of the roadway above
the surface of the water will be 100 feet,
thus atfording ample passage-way be-
tween the arches for ingoing and outgo-
ing ships. The greatest feat of engineer
ing will be the bold central arch-750
feet span-over an eighth of mile. This
is the longest span ever contemplated,
and its construction will necessitate the
most careful lobor and no small outlay
Of money. In order to accomplish this
single portion of the work alone two
great caissons will have to be sunk in
over 100 feet of water, and this can only
be dsne by coffer-dams and special con-
trivances in their completeness yet un-
known to engineering. The current at
the points where these piers will rest is
very strong, coming through the Darda-
nelles from the Sea of Marmora and rush
ing to the Black Sea. The two central piers
constituting the back bone of the bridge
will be fifty feet thick, of solid granite
blocks locked together with iron braces
A side view of this bridge will present
below the highest points of the arches an
intricate system of reinforce braces. 1t
is in this part of the construction that
great ingenuity, nice mathematical cal
Culation, and delicate mechanical skill
must be employed. By an invention Of
Captain Eads new feature will be intro
duced, so that train of cars or any other
heavy burden will not superimpose its
weight at any one point over which it
may be at the moment, but will be dis
tributed throughout the 5000 feet of the
supports, thus practically making 1T an
easy task to build an arch of 750 feet.
This is accomplished by uniting all the
main bracing from pier head to pier head,
and connecting the minor rods, so that
the whole forms a complete system, max
ing one brace dependent on the other.
The action Of heavy weights, Of troops
marching to common step, of rapid To-
comotion by the cars, is thus instantly
communicated through every foot of the
supports, and every part is made to do
its duty. The magnitude of the under
taking may be understood when it is
stated that the main piers will be two
hundred and seventy feet high from the
foundation to the summit. The aggre-
gate height of the fifteen piers would
make single pier Of half mile in
height, or eight times the altitude of the
ball on the top of st. Paul's Cathedral,
London.
1t is estimated that the cost Of con-
struction will not exceed $25, 100000, and
the time to complete it six years.-N. Y.
Times ..