IMPROVEMENTS IN CONSTRUCTING BEAMS, GIRDERS, BRIDGES, AND VIADUCTS
Year: 1862

page_text: LETTERS PATENT to Douglas Symonds Sutherland, of Rio de Janeiro,
at present of Crosby Square, in the City of London, Civil Engineer, for
the Invention of "IMPROVEMENTS IN CONSTRUCTING BEAMS, GIRDERS, BRIDGES,
AND VIADUCTS."
Sealed the 6th April 1863, and dated the 10th October 1862.
PROVISIONAL SPECIFICATION left by the said Douglas Symonds Suther-
land at the Office of the Commissioners of Patents, with his Petition,
on the 10th October 1862.
I, DOUGLAS SYMONDS SUTHERLAND, of Rio de Janeiro, at present of Crosby
Square, in the City of London, Civil Engineer, do hereby declare the nature
of the Invention for "IMPROVEMENTS IN CONSTRUCTING BEAMS, GIRDERS, BRIDGES,
AND VIADUCTS," to be as follows:-
The object of my Invention is the construction of a beam girder bridge or
viaduct that shall be self-contained while retaining the distinctive features of
a suspension bridge, that is to say, the power exerted by means of the
anchorage or otherwise in the maintenance of a suspension bridge is applied
and diverted by me in another form and direction, videlicet, within the
structure itself. I effect this by means of a combination of compression or
straining beams and of suspension bars or tension rods, whose arrangement
may be described as follows:-There may be two or more main beams,

page_text: girders, or. suspension trusses tied together and kept apart by cross beams
which divide the structure in its length into a certain even or uneven number
of bays or panels. The ends of these cross beams are round pins. Between
and butting against these pins are the horizontal compression or straining beams,
and working on and about the same pins as a centre are the lesser or vertical
compression or straining beams. The ends of these vertical straining beams
are in elevation double-headed, i.e., on each side of the centre line of the
piece is a round hole for the reception of a pin, or they may be in line exactly
in the vertical axis of the beam; thus there are two pins in each end of
each vertical straining beam; these pins secure a double and parallel line of
suspension bars or tension rods, which unite the opposite ends of the straining
beams diagonally throughout the construction. From the action of the mathe-
matical figures involved in this double-headed arrangement of the vertical
straining beams and of the double parallel tension rods one set become main
and the other counter suspension bars. The vertical straining beams working
on the cross beams which rest on the abutments may, in view of the trans-
verse strain upon them, be reduced in length or increased in dimension, but
where more than one span of like opening is needed the system may be con-
tinuous over the pier or piers. The vertical straining beams may or may not
be double-headed in cross section. The horizontal compression beams may be
single in pairs (for each main truss), or of greater number. Each suspension
and counter-suspension bar may be of a single piece, or it may be subdivided
in length and section; also the adjustments of their lengths may be made by
means of right and left handed screws, wedges, keys, or other known methods.
The superstructure may either rest upon or be fastened between the cross
beams, and a connection may or may not be made with the horizontal com-
pression beams, or it may have no connection with the cross beams and rest
solely upon the horizontal compression beams.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Douglas Symonds Sutherland in the Great Seal Patent
Office on the 10th April 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DOUGLAS
SYMONDS SUTHERLAND, of Rio de Janeiro, at present of Crosby Square, in
the City of London, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters

page_text: Patent, bearing date the Tenth day of October, in the year of our Lord One
thousand eight hundred and sixty-two, in the twenty-sixth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Douglas Symonds Sutherland, Her special licence that I, the said Douglas
Symonds Sutherland, my executors, administrators, and assigns, or such others
as I, the said Douglas Symonds Sutherland, 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 CONSTRUCTING BEAMS, GIRDERS, BRIDGES, AND
VIADUCTS," upon the condition (amongst others) that I, the said Douglas
Symonds Sutherland, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-
ticularly describe and ascertain the nature of the said Invention, and in
what manner the same 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 Douglas Symonds Sutherland, 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, that is to say :-
The object of my Invention is the construction of a beam girder bridge or
viaduct that shall be self-contained while retaining the distinctive features of a
suspension bridge, that is to say, the power exerted by means of the anchorage
or otherwise in the maintenance of a suspension bridge is applied and diverted
by me in another form and direction, viz., within the structure itself. I
effect this by means of a combination of compression or straining beams and
of suspension bars or tension rods, whose arrangement may be described as
follows:-There may be two or more main beams girders, or suspension
trusses tied together and kept apart by cross beams, which divide the
structure in its length into a certain even or uneven number of bays or panels.
The ends of these cross beams are round pins. Between and butting against
these pins are the horizontal compression or straining beams, and working on
and about the same pins as a centre are the lesser or vertical compression or
straining beams. The ends of these vertical straining beams are in elevation
double-headed, i. e., on each side of the centre line of the piece is a round
hole for the reception of a pin, or they may be in line exactly in the vertical

page_text: change in the position of the vertical beams consequent on the deflection of
the bridge under load will shorten one set of diagonals and lengthen the
other, i.e., one set of rods will be relieved of the load while the other set will
support it entirely, these latter then are the main suspension rods, while if
the former be reduced to the new length of the diagonals they represent they
become counter rods, and upon the removal of the load receive the upward
thrust of the structure. Figures 8 and 9 are Diagrams representing the action
of the mathematical Figures composing Figures 4, 5, 6; the position of the
main suspension rods; with reference to the centre line of the bridge is shown
in Figure 8, that of the counter rods in Figure 9. In Figure 8 the movement
of A and C towards A¹ and C¹ lengthens the diagonal lines connecting D
and B, C, while a corresponding movement in the opposite direction shortens
them. The reverse is the case in Figure 9; here a movement of E and G
towards each other shortens the diagonals, while a corresponding movement in
an opposite direction lengthens them. If O, O', were placed on 0³, 0³, a
Diagram would be produced corresponding to a single panel of Figures 4, 5,
and 6; any change in the position of the vertical beams consequent on the
deflection of a bridge under load must shorten one set of these diagonals and
lengthen the other, i.e., as in Figures 1, 2, and 3, one set of rods will be
relieved of the load while the other set will support it entirely. These latter
then are the main suspension rods, and the former, if shortened to the new
length of the diagonal lines they represent, will become counter rods, and on the
removal of the load receive the upward thrust of the structure. Figure 10 is a
Diagram of a bridge composed of Figures 4 and 6; Figure A B, C D, E F, GH,
the main system, represents Figure 4 without the upper or counter rods, and
Figure A B, IJ, CK, LM, EN, OP, GH, the lesser system, is the
counterpart of Figure 6, the upward thrust being met by the counter rods
of the second Figure A B, I J, &c. alone, the counter rods of A B, C D,
&c. being dispensed with. Figures 11, 12, 13 show detail Drawings of a
bridge of this description in side and cross elevation and plan. The main
compression beams are in pairs, and are here shown of I section. The
lesser or vertical straining beams work on pins between these beams, and
the main and counter suspension bars or rods are divided in their length
by the short links for convenience of erection, and pass between the
main compression beams in pairs, the lesser system being within the greater.
The compression beams in this case are divided to obviate the necessity
of a joint at the pin, short beam of like section working on the pin
receiving the ends of the main beams covering plates, securing the double

page_text: jointing thus formed; this system may however be dispensed with, and the
beams of any convenient section may abut against the pins. In the plan,
Figure 13, one half shows the superstructure attached to the main compression
beams and depending on them alone, the other shows the cross beams at the
pins, and the longitudinal beams of the superstructure depending upon them;
the position of the covering plates at the junctions of the several beams is here
shown also.
In witness whereof, I, the said Douglas Symonds Sutherland, have here-
unto set my hand and seal, this First day of April, in the year of our
Lord One thousand eight hundred and sixty-three.
DOUGLAS S. SUTHERLAND. (L.S.)
DOUGLAS S. SUTHERLAND. (L.S.)