IMPROVEMENTS IN IRON BRIDGES
Year: 1853

page_text: LETTERS PATENT to Thomas William Kennard, of Duke Street,
Adelphi, in the County of Middlesex, Civil Engineer, for the
Invention of "IMPROVEMENTS IN IRON BRIDGES."
ealed the 6th October 1853, and dated the 6th July 1853..
PROVISIONAL SPECIFICATION left by the said Thomas William
Kennard at the Office of the Commissioners of Patents, with his
Petition, on the 6th July 1853.
I, THOMAS WILLIAM KENNARD, do hereby declare the nature of the.
said Invention for "IMPROVEMENTS IN IRON BRIDGES" to be as follows:-
My Invention is applicable to iron bridges constructed with a top
and bottom rail united by diagonal or other ties and struts. I con-
struct the top rail, which has to resist compression, of two plates or flat
bars placed horizontally one above the other. I bolt or rivet two angle
irons to the upper side of the lower plate or bar, and two other angle
irons to the lower side of the upper plate or bar. I connect these
angle irons together by means of joint plates placed at intervals or
extending the whole length of the rail. I fix the struts and ties by
means of pins passed through these joint plates. The extra strength

page_text: given by the joint plates to this part of the rail prevents it from being
too much weakened by the holes which receive the pins.
I construct the bottom rail or main tie of two flat bars, or of two
series of flat bars, placed on edge, and one over the other. These bars
are united by joint plates, in which are holes for receiving pins for
securing the struts and ties. By placing the two bars or the two series
of bars at a distance apart equal to or greater than the diameter of the
pins, it is not necessary to make any holes in the bars for the reception
of the pins, which are then fixed in the joint plates only, and the
weakening of the bars is thus avoided.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas William Kennard in the Great Seal
Patent Office, on the 5th January 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
THOMAS WILLIAM KENNARD, of Duke Street, Adelphi, in the County of
Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixth day of July, in the year of our
Lord One thousand eight hundred and fifty-three, in the seventeenth
year of Her reigu, did, for Herself, Her heirs and successors, give and
grant unto me, the said Thomas William Kennard, Her special licence
that I, the said Thomas William Kennard, my executors, administrators,
and assigns, or such others as I, the said Thomas William Kennard, 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 Invention for "IMPROVEMENTS
IN IRON BRIDGES," upon the condition (amongst others) that I, the said
Thomas William Kennard, by an instrument in writing under my hand
and seal, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed,

page_text: 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 Thomas William Kennard, 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 thereof, reference being had to the
accompanying Drawing, and to the figures and letters marked thereon,
that is to say:
The Invention is applicable to iron bridges constructed with a top
and bottom rail united by diagonal or other ties and struts. Figure 1,
is an elevation or side view of a portion of one of the main girders or
principals of such a bridge constructed entirely of wrought iron. A, is
the top rail; B, is the bottom rail or main tie; C, C, are diagonal
struts; and D, D, are diagonal ties. Figure 2, is a transverse section
on a larger scale of the top rail A, which is constructed of two flat
plates or bars a, b, to each of which two angle irons c, c, and d, d, are
rivetted. e, e, e, e, are plates rivetted to the angle irons c, c, and d, d,
so as to unite the whole together. Figure 3, is a section of the top
rail at one of the joints where the struts and ties are united to it. A
circular aperture is made through the sides of the rail to receive a
round pin which secures the strut and tie. A portion of the lower
plate b, is removed to allow the strut and tie to pass through, and two
short plates or bars f, f, are rivetted to the lower plate to strengthen it
at this part. Figure 4, is a section of the bottom rail or main tie,
which consists of two upper bars 9, 9, and two lower bars h, h, with an
interval between them. Figure 5, is a section of the bottom rail at one
of the joints; i, i, i, i, are short deep plates, which are rivetted to the
bars 9, and h, and perforated with a circular aperture for the reception
of the joint pin. By this arrangement the weakening of the tie bars
g, h, by passing the pin through them is avoided. This arrangement
may be employed with only two bars g, and h, or with two pairs of
bars, as shewn in the Drawing, or with two series or sets of bars of
any suitable number in each set. Figure 6, is a transverse section of one
of the struts C. It is composed of four plates or bars j, j, k, k, united

page_text: by four angle irons 1, 1, 1, 1; rivetted to them so as to form a cross.
Figure 7, is a section of the strut at the joint. The plates k, k, are pro-
longed beyond the plates j, j, and are strengthened by two plates m, m,
rivetted to them. A circular aperture, is made through the plates for
the reception of. the joint: pin. Figure 8; is a section of one of the
ties D. It consists of two flat bars or plates n, n. Figure 9, is a sec-
tion of the tie at the joint; p, p, are two plates, rivetted to eacli of the
barsin, to 'strengthen the tie at this part, where it is perforated for the
reception of the joint pin. A sufficient space is left between these tie
bars for the introduction of the end of the strut; Figure 7: Figure:10,
is a side view, and Figure 11, is a section of one of the joints by which,
the ties and struts are, connected to the top rail: The same letters refer
to similar parts in all the Figures. The end of the strut C, is inserted
between.the two bars of the, tie D, and both strut, and tie are passed
through the aperture in the bottom plate of the top rail A; and secured
by the joint pin, E. Figure 12, is a side view, and Figure 13, is a
section of one of the joints by which the ties and struts are connected
to the bottom rail. The end of the strut C..is inserted between the two
bars n, of the tie D, and both strut and tie-are introduced between the
bars g, g, h, h, and the joint plates i, i, of the bottom rail B, and secured
by the joint pin: E. The joint pins may be kept in their places by
means of nuts or keys, or a cap affixed by a screw or screws, or other-
wise, as may be preferred. When the bridge is heavily and unequally,
loaded some of the diagonal ties near the centre of the bridge may be
exposed to a compressing force and have to act as struts. The ties D
and struts C, near the centre, of the bridge are therefore all made of the
cross section.shewn in Figure 6, and their ends are made as shewn in
Figure 7. Figure. 14, is a side view, and Figure 15, is a section of
onci of the joints in the top rail near the centre of the bridge. The
ends of the struts or ties are introduced into the top rail A, and secured
by the joint pin E. A collar or filling piece q, is inserted between the
two-struts or ties. In lieu of, placing the struts. and ties in diagonal
positions, the struts may be placed vertical and the ties diagonal, or, the
ties vertical and the struts diagonal
...Having now.described the nature of my Invention.. and-in: what:

page_text: manner the same is to be performed, I wish it to be understood that
what I claim is,
Firstly, the constructing the top rails of iron bridges of two plates
or bars, and four angle irons, united or combined in manner herein-
before described.
Secondly, the constructing the bottom rails of iron bridges of two
flat plates or bars, or two series or sets of flat plates or bars,
placed one above the other, with an interval between them, and con-
nected by joint plates, and having joint pins for securing the struts and
ties, passing through the joint plates and through the interval between
the two bars or sets of bars, as herein-before described.
Thirdly, the constructing iron bridges by the combination of top and
bottom rails and ties and struts of the respective sections herein-before
described, connected together in manner herein-before described.
In witness whereof, I, the said Thomas William Kennard, have
hereunto set my hand and seal, this Fourth day of January, in
the year of our Lord One thousand eight hundred and fifty-
four.
20 Witness,
THOMAS WILLIAM KENNARD. (L.S.)
A. H. NEVILLE,
35, Bridge Street, Blackfriars.