IMPROVEMENTS IN SUSPENSION BRIDGES AND SUSPENDED GIRDER BRIDGES
Year: 1858

page_text: LETTERS PATENT to Rowland Mason Ordish, of No. 18, Great George
Street, Westminster, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN SUSPENSION BRIDGES AND SUSPENDED GIRDER BRIDGES."
Sealed the 30th September 1858, and dated the 10th April 1858.*
PROVISIONAL SPECIFICATION left by the said Rowland Mason Ordish
at the Office of the Commissioners of Patents, with his Petition, on the
10th April 1858.
I, ROWLAND MASON ORDISH, of No. 18, Great George Street, Westminster,
in the County of Middlesex, do hereby declare the nature of, the said Inven-
tion for "IMPROVEMENTS IN SUSPENSION BRIDGES AND SUSPENDED GIRDER
BRIDGES," to be as follows:-
Suspension bridges, as now constructed, usually consist of chains hung in
curves over and between towers or piers, and fixed or anchored to abutments
at the ends of the bridge, and supporting the roadway by means of vertical
or inclined rods running from the curved chains to the platform; or they con-
sist of straight inclined chains anchored to abutments and passing over towers
or piers to the platform, or intersecting and connected at their intersections to
the platform; or they consist of straight inclined chains anchored to abut-
ments, and passing over towers or piers, and connected to the platform by ties
and struts; or they consist of combinations of these methods of construction,
the principle being in every case that abutments and land ties are substituted
for the upper compressile member required in girders. Wire ropes, metal

page_text: plates, bolted and rivetted together, or metal rods are sometimes substituted
for the chains, and girders are sometimes added to the platform to distribute
a load over a length of the chains. If these bridges consist of more than one
span when one span is loaded and the others at the same time unloaded, the
equilibrium of the structure is usually disturbed, the platform of the loaded
span is depressed, and that of the unloaded spans elevated. It has been pro-
posed to obviate this defect by combining girders with the suspension chains
in such a manner as to resist the upward tendency of the chains of the
unloaded spans and to support a part of the load in the loaded spans. In this
case it is found that the extension or deflection of the chains from increase of
temperature being much greater than the deflection of the girders from the same
cause, the girders would be sometimes deprived of the support of the chains,
and thereby exposed to injurious strains upon the bridge being loaded.
I construct suspension bridges of more than one span by adding to or com-
bining with any of the before-mentioned forms of bridges, or any modification
thereof, chains running from tower to tower in straight or nearly straight lines,
anchored to abutments at each end, and supported by struts or ties from curved
chains, also anchored to abutments, and which carry the straight chains and
prevent any strain in them from their own weight. The straight chains are
connected with the chains supporting the roadway at the towers, and transmit
any strain caused by loads on the platform directly to the abutments, thus
preventing any disturbance of the equilibrium of the unloaded spans, with the
exception of that due to the extension of the metal of the chains, either from
its elasticity or from increase of temperature..
In bridges of one or more than one span, instead of anchoring the straight
chains to abutments in the ordinary manner, I sometimes also connect them to
heavy weights at one or both ends of the bridge in such a manner that tlie
chains are always stretched by the weights. The effect of this is that when
the bridge is loaded and the strain produced by the load is transmitted through
the straight chains to the abutments, these chains being already stretched by the
mooring weights cannot be further stretched by the load, and deflection from
the elasticity of these chains is thus prevented; and moreover, when the chains
are extended from increase of temperature the action of the mooring weights
keeping the straight chains stretched increases the distance between the points
at which the straight chains are connected to those carrying the platform and
which compensates for the lengthening of these chains. Deflection from
increase of temperature being thus to a great extent prevented, I am enabled
o combine suspension chains and girders without danger to the latter.
In lieu of straight chains running from tower to tower, I sometimes connect

page_text: the chains for carrying the load with the longitudinal girders or bearers in
such a manner that by applying weights to produce a strain on the girders or
bearers so that they are always stretched, the same effect is produced as by
the combination of straight chains and weights, as before described.
I also sometimes construct suspension bridges by combining with curved.
chains, suspended from tower to tower, straight or nearly straight chains con-
nected with the curved chains at various points and running to the lower parts
of the towers, these chains being retained in straight or nearly straight lines
by being suspended or supported by the curved chains or by the platform, the
platform being suspended from the curved chains.
The straight chains resist the tendency there is in the curved chains to alter
their form by moving or unequally distributed loads. The straight and curved
chains may be of any material of which suspension bridge chains are usually
composed. By these means rigid -suspension bridges are produced, which are
adapted for railway traffic and other purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Rowland Mason Ordish in the Great Seal Patent Office on
the 9th October 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROWLAND
MASON ORDISII, of No. Eighteen, Great George Street, Westminster, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of April, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unlo
me, the said Rowland Mason. Ordish, Her special licence that I, the said
Rowland Mason Ordish, my executors, administrators, and assigns; or such
others as I, the said Rowland Mason Ordish, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term 'therein expressed, should
and lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an In-
vention for "IMPROVEMENTS IN SUSPENSION BRIDGES AND SUSPENDED GIRDER
BRIDGES," upon the condition (amongst others) that I, the said Rowland
Mason Ordish, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly describe.

page_text: and ascertain the nature of the said Invention, and in what manner the saine
was to be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Rowland Mason Ordish, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement :-
Suspension bridges as now constructed usually consist of chains hung in
curves over and between towers or piers, and fixed or anchored to abutments
at the ends of the bridge, and supporting the roadway by means of vertical or
inclined rods running from the curved chains to the platform; or they consist
of straight inclined chains anchored to abutments, and passing over towers or
piers to the platform, or intersecting and connected at their intersections to
the platform; or they consist of straight inclined chains anchored to abutments
and passing over towers or piers, and connected to the platform by ties and
struts; or they consist of combinations of these methods of construction; the
principle being in every case that abutments and land ties are substituted for
the upper compressile member required in girders. Wire ropes, metal plates;
bolted and rivetted together, or metal rods are sometimes substituted for the
chains, and girders are sometimes added to the platform to distribute a load
over a length of the chains.
If these bridges consist of more than one span, when one span is loaded and
the others at the same time unloaded, the equilibrium of the structure is
usually disturbed; the platform of the loaded span is depressed, and that of
the unloaded spans elevated. It has been proposed to obviate this defect by
combining girders with the suspension chains in such a manner as to resist
the upward tendency of the chains of the unloaded spans, and to support a
part of the load in the loaded spans. In this case it is found that the extension
or deflection of the chains from increase of temperature being much greater
than the deflection of the girders from the same cause, the girders would be
sometimes deprived of the support of the chains, and thereby exposed to
injurious strains upon the bridge being loaded.
:
I construct suspension bridges of more than one span by adding to or com-
bining with any of the before-mentioned forms of bridges, or any modification
thereof, chains running from tower to tower in straight or nearly straight
lines anchored to abutments at each end, and supported by struts or ties from
curved chains, also anchored to abutments, and which carry the straight chains,
and prevent any strain in them from their own weight. The straight chains

page_text: are connected with the chains supporting the roadway at the towers, and
transmit any strain caused by loads on the platform directly to the abutments,
thus preventing any disturbance of the equilibrium of the unloaded spans, with
the exception of that due to the extension of the metal of the chains, either
from its elasticity or from increase of temperature.
In bridges of one or more than one span, instead of anchoring the straight
chains to abutments in the ordinary manner, I sometimes also connect them
to heavy weights at one or both ends of the bridge in such a manner that the
chains are always stretched by the weights. The effect of this is that when
the bridge is loaded, and the strain produced by the load is transmitted through
the straight chains to the abutments, these chains-being already stretched by
the mooring weights, cannot be further stretched by the load, and deflection
from the elasticity of these chains is thus prevented; and moreover, when the
chains are extended from increase of temperature, the action of the mooring
weights keeping the straight chains stretched, increases the distance between
the points at which the straight chains are connected to those carrying the
platform, and which compensates for the lengthening of these chains; deflection
from increase of temperature being thus to a great extent prevented, I am
enabled to combine suspension chains and girders without danger to the
latter.
In lieu of straight chains running from tower to tower, I sometimes connect
the chains for carrying the load with the longitudinal girders or bearers in
such a manner, that by applying weights to produce a strain on the girders or
bearers so that they are always stretched, the same effect is produced as by
the combination of straight chains and weights, as before described.
I also sometimes construct suspension bridges by combining with curved
chains, suspended from tower to tower, straight or nearly straight chains
connected with the curved chains at various points, and running to the lower
parts of the towers, these chains being retained in straight or nearly straight
lines by being suspended or supported by the curved chains or by the plat-
form, the platform being suspended from the curved chains. The straight
chains resist the tendency there is in the curved chains to alter their form by
moving or unequally distributed loads. The straight and curved chains may
be of any material of which suspension bridge chains are usually composed..
By these means suspension bridges are produced, which are adapted for
railway traffic and for other purposes.
Figure 1 is a diagram shewing a portion of my improvements applied to
one form of my patent suspension bridge, (patented 7th March 1857). The
inclined straight chains a, a, a,support the roadway and loads passing over the

page_text: bridge; the straight chains b, b, transmit the strains caused by the loads to the
abutments A, A, in case of one span being loaded and the other span being
The curved
unloaded, thus preventing any disturbance in the unloaded span.
chain c, c, supports the weight of, and retains in straight lines the chains a, a, a,
b, b, by means of the suspenders d, d, d. In the event of both spans being
equally loaded, there will be no strain in the chains b, b.
1. Figure 2 is a diagram or side elevation shewing a portion of my improve-
ments applied to the combination of ordinary suspension chains with girders.
a, a, are the suspension chains supporting the platform p, p, and loads by
means of the suspenders b, b; c, c, are chains transmitting a portion of the
strains caused by the loads to the abutments A, A, in case of the spans being
unequally loaded. The curved chains d; d, d, support the weight of, and retain
the chains c, c, in straight lines by means of the suspenders e, e, and struts f,f.
Instead of anchoring the chains c, c, in the ordinary manner, they are in this
case anchored to weights w, w, so that the chains c, c, are always stretched by
the action of the weights w, w, and therefore cannot be further extended by
any strain induced unequal loading of the bridge. It is evident that the
effects of the weights w, w, are such, that when variations of temperature.
occur, the normal versed sines of the suspension chains a, a, are nearly
maintained on account of the chords of their ares varying by means of the
constant tension induced in the chains c, c, by the weights w, w. I am thus
enabled to combine ordinary curved suspension chains and girders, so as to
produce an efficient bridge.
Figure 3 shews an application of the last-mentioned improvement to
another form of my patent suspension bridge. a, a, a, are the chains
supporting the platform p, p, and loads; b, b, b, are straight chains extending
from tower to tower T, T, T, and from the towers to the abutments A, A;
c; c, c, are curved chains supporting the weight of the chains a, a, a, and b, b, b,
The chains b, b, b, and
by means of the suspenders d, d, d, and struts e, e, e.
the chains c, c, c, are connected to the weights w, w, in the abutments. The
chains b, b, b, transmit any strains caused by unequal loading of the bridge to
the weights w, w, which maintain the chains b, b, in a state of tension, and thus
provide against any injurious effects consequent on expansion or contraction
from variation of temperature, or on the elasticity of the material of which
the chains are composed.
Figure 4 shews a portion of my improvements applied to my patent sus-
pension bridge. The girders G, G, are connected to weights w, w, in the
abutments, so that a constant tension is maintained in the girders. Tlic
chains a, a, a, which support the platform and loads, are connected to..the

page_text: girders at the towers T, T, and abutments A, A. The curved chains b, b, b,
support the weight of the chains a, a, a, by means of the suspenders c, c, c.
The girders G, G, transmit any strain caused by unequal loads on the bridge
to the weights w, w. The weights also compensate for variations in the length
5 of the girders or chains caused by variations of temperature, and prevent-any
injurious effects that might be caused by the elasticity of the material of the
girders.
It is evident that the method of applying the weights w, w, may be varied.
They may be suspended from the angle formed by.the meeting of two chains,
as shewn by. Figure 2, at x, x; the chains g, g, in this case being anchored to
the abutments at h, h, or the weights may move on inclined planes formed in
the abutments, as shewn by Figures 3 and 4 at P, P, or they may be con-
nected to the chains in any other suitable manner. The weights may also in
certain cases be applied in the towers or piers as well as, or in lieu of, the
abutments. It is to be understood that when the chains are not mentioned
as being connected to the weights, they are anchored to the abutments in the
usual manner. The weights w, w, may be formed or constructed of brick,
stone, iron, or other suitable material.
"
Figures 5 and 6 are elevations or diagrams of bridges, shewing an arrange-
ment of chains according to another part of my Invention. a, a, is a chain
supporting the chains b, b, the platform p, p, and the load; this chain passes
over the towers T, T, and is anchored to the abutments A, A; ; b, b, are
straight chains connected at the points c, c, c, with the chain a, and extending
to the lower part of the piers T, T, where the chains b, b, b, are anchored.
The chains b, b, b, are supported and retained in straight lines by means of
the suspenders d, d, d, which also support the platform and loads, and are
attached to the chain a. When the bridge is unequally loaded, the straight
chains b, b, b, resist the tendency of the curved chain a to alter its form, and
convey the strains caused by such unequal loading to the anchorage at the
part of the piers or towers T, T, and a bridge of considerable rigidity is
thus produced.
lower
As already herein-before mentioned the construction of the chains may bo
varied, and they may consist of metal plates rivetted together, or of wire ropes,
if preferred.
The so-called straight chains may be slightly curved without materially
affecting the rigidity of the structures; but this curvature should never exceed.
that which would occur in them if they were unsupported by the curved
chains and sustaining their maximum strains, and I prefer to make them very
nearly or quite straight.

page_text: Having now described the nature of the said improvements, and in what
manner the same are to be performed, I wish it to be understood that I claim
the application to suspension bridges, in the manner herein-before described,
of straight or nearly straight chains supported by curved chains, and connected
or not to moveable weights in the abutments or other parts of the bridges, for
the purpose of resisting the disturbance of equilibrium induced by unequal
loading of any or several of the spans, or by variations of temperature; and
the constructing of suspension bridges with curved chains in combination with
inclined, straight, or nearly straight chains, extending from the bases of the
towers or piers, and connected with. the curved chains at various points; these
straight chains being supported by the curved chains, and resisting the ten-
dency of the curved chains to alter their form when unequally loaded.
In witness whereof, I, the said Rowland Mason Ordish, have hereunto
set my hand and seal, this Ninth day of October, in the year of our
Lord One thousand eight hundred and fifty-eight.
ROWLAND MASON (L.S.) ORDISH.
Witness,
WILLIAM HENRY LE FEUVRE.