The sun., 1889-11-10


development OF tho bridge and the geo.
logical cut OF the ground upon which the
masonry piles are to be constructed, and
also a set Of detailed drawings showing the
construction OF the pillars. columns. and the
bridge proper. BY glance at these plans 1t is
easy to get q general idea OF the enterprise. At
the same time two French constructors have
printed a work containing complete plans and
calculations and indicating in the most pre-
else fashion thor idea of how the gigantic OPP
Grafton should be carried out as we'll az the
ways and means to be employed. The title OF
this work is the " Pont sur la Manche. Prelim-
mary projects by Messrs. Schneider Co. OF
the Creusot Works. and NJ. Hersent contractor
Civil Engineers; Sir John Fowler and BenJa-
min Baker. chief engineers OF the Forth
Bridge Besides the ninety-seren pages OF
text. in Svo. there are twenty-five sectional
and profile drawings Some iafge PhotiGSranhss
of the bridge by NJ. Armengaud.
In ali railway construction engineers are
obliged to consider the nfrastructure and the
superstructure. In the present instance 1t is
NOT simply question OF establishing rallinGs
and trenches and laying tracks upon more or
less favorable ground; the problem consists Of
sinking huge masonry piles in the water and
OF launching metallic spans 800 metres long
that that work i OF Of similar magnitude has reesntly
been accomplished on the Forth. near Edn-
Iurgh. and That aR3other bridge Is being son,
20 90 down down to a depth OF 'fifty-flve metres This
In nowise diminishes the Interest In the studies
authorties @ critic s as Messrs. Hersent nj and Schneider
with the aid Of the accompappying m cuts the
hs "a on the
which We Will now proceed TO explain.
The position oi the bridge Is naturally in:
coast coast T' at point tic called Gran and Gufs near near
ut EOlkpStOue alter DuSSllE over tu0 tnrle
and !colbart hanks The distance, is about
IS not %s gs sF Rs s Sy to-
deep wafer and take advantage Of tho iounda-
toned. which are covered only by seven or
eight metIes OF water. The greatest difficult
found four between % the cobart bank and the French &C
coast where IN certain parts the sea bottom ls
Ct dePth Of httyiaye metres. I % or iSO feet feet;
have been accomplished in engineering and In
submarine masonry in the ports Of Toulon.
Brooklyn and the Forth and at the Paris Ex-
hibition in the machinery gallery and the EiTel
Tower, the project does not seem impossible
The bridge is composed. Of course, OF sup
ports and OF o roadway resting thereon; The
calcareous stones. and Portland cement rest
ing on the bed Of the channel on the white or
blue chalk which is found to be sufficiently rec
sistinR to bear weight OF 10 to IL kilo-
grammes per square centimetre. These pill
lars. Wnero the dentn is 90 metres, VIII nave hC
their base superflcies OF l.604 square metres.
The masonry will be strengthened at intervals
by layers OF granite and above the water level
the masonry will be entirely of granite. These
will vary with the breadth of the system OF
metallic columns which will rest upon them.
L. calculated at 10000 tons for the deepest
pillars. which will give Il pressure Of kilog-
granimes per square centimetre
enormous affair, necessitating the establish
ment of special ports at Fokostone In Eng