New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1879-12-26

notwithstanding tle nasnitnde ~ be- wori.-1ud
II ~ easy 10 real the rafh ~ SIT Thomas Il urll-
remark that il win he grand brvoni dsscriptinnif
~. IN his OpiTion. less q fiirut under. kfnE
than the building OF the 10y BriCg.. The asou oil
this Is that their VIII he trpu l. wtn The istsr-
datons. Such difficulties pres nt til smselves ran
To great extent be calculated uDon and IN case
they vii be Visible and above ground. while those
arising IN connection with the T@y Bridge were
under the bed Of fhe river. and unexpected.
The bed Of the + rth has been thoroughly exafr-
med. and It IL almost nnDOssIble that any con-
tin2eucY can arise IN building tine supporting col
umns between the southern shore and the firsf
tower hat cannot Re readily met. The land piers
or columns on the southern side will be built on
bottom Of gravel. The first three river rirrs VIII
stand on foundation OF rock. The bottom here
dps very gradually. and further ouf tine columns
VIII he founded a very hard cOnQlOmeraIe or
boulder clay. underlying several feet of surface mud
ami clay. The auchoring and southern suspension
towers wiiThave q similar foundation. 10 the norm
Of the latter the bottom makes the rapid Dip already
referred 70, and then rises more gradually, although
still AT a steep gradient. 70 the rock comprising
lnchgarvie. On sloping bank on the side Of the
island the southern central tower Will stand. Here
all dinculty about the foundations may be said to
end
THE TOWERS AND GIRDERs.
In order to insure the requisite sodty. FOUR feet
of concrete resting upon the gravel bottom Will
form the foundation of the land piers. which will re
buit OF brick up the giriers. The latter viii be
eighteen feet hlgh and constructed upon the single
brace lattice principle according TO which the bars
cross each other oiagOnally. Two Of these grders
will be placed upon the supporting brickwork So rs
10 run parallel at n distance Of sixteen feet from
each other. They will he bound togct her BY means
of cross Orders. and upon the iafter u platform
twenty-five feet IN width VIII rest, along VIII Oh the
doublf line Of rails will b. laid. The bridge viii be
constructed in thIs manner a. tar ~ the anchorlng
towers. with this exception. that the f0un-
suit the altered nature of the bottom. Gals
sons Of wrought iron will be sunk in the
rver. and on the water being removed by air pres
sure, rhe interior will be dug out. the caIssOn sink
In 4 "a Hp o. al
When the mud and soft clay have been removed,
and the hard congiOmerate Is reached, the interior
VIII be built no with brick aud cement concrete.
the latter forming the core. The anchoring piers,
TO which the suspension chains are 10 be attached,
are placed one AT either side OF the roadway ana
are necessarily Of a very massive character As 10
the lofty suspension towers. a DESCRIPTION OF the
construction OF the southern Queen Ferry tower,
NAV be taken, except IN the matter Of the founda-
tIOn, applying to all 1t ia necessary 20 premise
that the tower will consist OF group of four piers,
each one of which will support four steel eyndri-
cal pillars. The piers will be each thlrtytwo feet
square, and will be placed at distances from each
other measured from their INSIDE edges, of about
sixtyve feet east and vest and tortyx feet north
and south. In other words the piers will stand at
the corners of a paralleiOqram, measuring about
100 feet by / 10 tact. In building them. eaissons
fifty feet in diameter will be employed. and the
hard cougomerate beng reached n the manner
already described, II viii be followed out 10 n
further depth OF eight feet. Resting upon cIrcu-
lar foundation. a square of brick, with walls eight
feet thick. will then be built and the hollow cham
Der inside will be filled with concrete In this way
the wOrk viii be carried up TO high-water mark,
where stone plinth of about two feet in thickness
will be land Above the pnrh, the per will be car
ued "A solid mass of brick. TWENTY-FIVE feet above
high water mark. Upon this viii be- raised four
lofty steel tables or columns three feet six inches in
diameter. placed at the corners Of a square
OF about twenty three feet, and securely
bound together with horizontal struts aud
diagonal ties. The columns VIII rise perpendlcu-
larry NJ TO the ROADWAY. and above 1t those on the
OUTSIDE will converge gradually as the top Is APP
preached. The four piers and sixteen steel tubes
composing the tower will all he built and placed IN
the manner described. Diagonal struts will bInd
the tour groups of pillars firmly together mp 70 the
line of the roadway. The lattice girders already
described viii carry the road by means of cross
grders. Above the roadway the groups of col
umns viii be secured 10 each other by hori-
zlntal struts and diagonal u.s. 50 as to form IN
effect one stupendOus tower 900 feet n heignr
TIE ROADWAY.
Having seen that the two lines Of rails from the
shore 10 the anchorng towers laid side by side
IN the usual way, upon platforms resting upon the
top of the lattice grders It IL necessary 70 fol-
low them further ont. At the anchoring towers the
lines diverge. until at the suspension tower they
are 100 feet apart. measuring from the middle Of
one line TO tnat OF the other. They parallel ut
that distance until the tower the Fife shore Is
reached, when they begin to converge and come
together again az the northern anchOring towers
The object attained by separating the lines Ia
greater security against the lateral pressure of high
winds Each line passes through the groups of pill
left.
In the great central spans the roadway viii be
laid along the bottom Of the huge lattice girders
which Will rest at either end upon the main towers
They Will rise from nineteen feet at the ends to be-
tween forty and fifty feet In the middle. aud will
thus have the appearance Of great arched fences.
To support these Rirders, heavy steel chains VIII
be passed from the archOriug tOwers-twO from
each--Over the tops of the steel towers, and from
them the grders viii he suspended by of per-
pendicuar supporting bars and traverse tension
bars radiating from the points where the lattice
girders rest upon the towers. IL VIII thus be seen
that each line of rails and ts supporting glrder
are hung uDOn two chains, the links of which take
hold Of pin resting IN casting at the top or the
towers II need only be added that 20 give greater
stability to the two central towers on Inchgarvie
the top Of each is anchored 20 the bottom Of the
other.
As 10 the material employed and mode of con-
structiOn mild steel was selected by the engineer
for the towers aud chains, firstly. for the sake OF
its comparative ghtuess. and. secondly. that equal
ity Of contraction and expansion might thus be
secured. When the towers and chains are IN reldi-
ness the great central spans Will be hoated ont IN
sections which, having been finished shore. VIII
simply need TO be hung IN their places upon the
CHAINS
the completeness Of the railway system of the cOun-
try and particularly 20 that Of the North British
Railway Company. When II is finished there will
be an unbroken route from London 70 Wick. The
distance between Edinburgh and Montrose, Aber-
deem and other towns along the northeast coast Will
as compared with the stirling route be lessened by
between thirty and forty miles. A further advan-
tage of great moment to those no are familiar with
the discOmfOrts OF "A in sQualy weather
will be the avoidance of the ferry between Granton
and Burntlsiand.
NOTES FROM yEWPORT