Sullivan republican. [volume] (Laporte, Pa.) 1883-1896, 1890-01-03
A Bridge from England to France.

A Bridge from England to France.
A great steel bridge across the Eng
lish channel is projected. The bridge
will sire tch over the shsllowest and mar
rowest part of the channel between Cape
Girls Nez and Folkestone, and will be
supported by columns resting on the
bottom of the sea. The amount OF
metal and machinery to be provided
would represent an aggregate weight OF
about 1000, 900 tons, the assumption
being that each country viii. have to
supply one half of this amount. Re-
gardng the cost of the work rough
calculation gives, with reas enable Ger
tainty, $780, 600, 000f for masonry SUP
ports, and 4SO, 600, ,oOOf. for the
metallic uperstructure-in all, S60,-
600, 000f. or e34, 400, 900. The
time required for the undertak-
ing may be fixed at about 10 years. The
whole of the pillars will occupy little
over one twelfth of the section of the
ch annel. The distance between the
piers, fixed at 500 and 800 metres for
the large spans, will not be less than
200 and 100 metres respectively for the
small ones, and will be sufficient TO
prevent the ir proving an obstacle to the
free navigation Of sailing vessels. As
for the metallic super-structure, the
metal columns firmly placed upon the
platforms of the supporting piers of ma
sonry are of a distinctly cylindrical
shape, and vary in height between 40
and AZ. rs metres, and on them will DO
placed the main girders Of the bridge.
There will thus be between the lower
part of the beams and the level OF tho
sea at low water free space varying in
height between 81 and 63.7S metres,
which height at high water will be re-
duced to 81 and 567 rs metres, rejpec-
lively. This height is amply sutii-
cient for the passage of vessel,
of whatsoever description or tonnage.
BY placing the flooring upon vertical
cylindrical columns the minimum height
of 81 metres is kept throughout the
whole width of the span, result not
achieved in the bridge over the Forth.
The girders are to be simple, unlattced
and trussed, so as to ensure the proper
distribution of all stresses. The level
of the permanent way is ~ metres above
the low water level. There will be a
double set of rails, and the width of the
flooring proper will be eight metres.
The width of the bridge is variable,
the greatest distance being between the
axes of the main girders, 25 metres a
space necessary to ensure the stability
of the structure under the action of
violent gusts of wind. The roadways
are of the ordinary width of Is metres
between the axes and the rails, the
latter set in grooves to obviate ac-
cident. The floor, made of ribbed
sheet iron, is to cover the bridge
throughout its length so as to make
every part accessible to the men APP
pointed for its supervision. Between
and outside the roadways pavements are
provided for the men to stand on, and
| thus keep out of the way of passing
trains. On the flooring may be set up
refugees, stations for the guards, signal
boxes, switches, otc. All these ar.
rangements can be multiplied according
to the requirements OF the traffic, and
scattered over any convenient points
and spans on the peirs. Lighthouses
may be erected to indicate obstacles to
be avoided The various kinds of lights
used in lighthouses may also serve to in
dicate to shippers the distance from the
Colbart and Varne banks. To meet
mill tary objections arrangements could
be made for masfay the span a. either
end of the bridge unfit for use; the two
end spans, notably. which are in con
tact with the abutments, might be re-
movable or revolve.
CastrOpOmicoI Criticism.