IM- PROVEMENTS IN THE CONSTRUCTION OF BRIDGES
Year: 1870

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of "IM-
PROVEMENTS IN THE CONSTRUCTION OF BRIDGES." -A communication from
abroad by Charles Shaler Smith, Charles Hazlehurst Latrobe, and
Frederick Henry Smith, all of Baltimore, Maryland, in the United
States of America.
Sealed the 20th December 1870, and dated the 20th October 1870.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition,
on the 20th October 1870.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF BRIDGES," a com-
munication from abroad by Charles Shaler Smith, Charles Hazelhurst
Latrobe, and Frederick Henry Smith, all of Baltimore, Maryland, in the
United States of America, to be as follows:-
1
This Invention relates to the construction of viaducts or bridges, in
which the superstructure is supported upon piers, either independent

page_text: of each other or connected so as to form a system of continuous
trestle.
In carrying out this Invention it is proposed to anchor the tops of
iron or steel piers of bridges by means of longitudinal diagonal stays to
the feet or pedestals of other piers or abutments, so that each pier can
be formed of only two columns and still have the great longitudinal
base afforded by the spread of the longitudinal diagonal stays to give it
stability under the action of temperature or a moving load.
In combination with this system of longitudinal diagonal stays it is
further proposed to use iron or steel piers stiffened by means of up-and-
down tension rods and cross struts at such point in the height of the
pier as will prevent flexure.
It is also proposed to stiffen iron or steel bridge piers by means of
longitudinal rods or struts anchored to or abutting against masonry, and
connecting therewith the piers at such point in their heights as will
prevent flexure.
The iron or steel piers of bridges with the before-mentioned longi-
tudinal diagonal stays, the up-and-down stiffening system, and the
longitudinal stiffening system, may also be combined together in one
structure.
It is also proposed to combine iron or steel columns with cast-iron
caps and feet or joists when used for forming bridge piers, whether these
piers be isolated or connected together, so as to form a system of
trestle.
When employing a system of piers or continuous trestle it is proposed
to combine cast-iron joint boxes interposed between and forming the
bearings for the column sections with longitudinal diagonal ties con-
necting the joints of any one tier with those of another tier, or with the
caps or feet of the columns.
It is further proposed to combine with the piers and system of longi-
tudinal diagonal ties connecting the same wooden chord sticks and a
longitudinal system of wooden struts for supporting the roadway and
stiffening the piers.
A series of independent or isolated bridge piers may also be com-
bined with an intermediate span or spans of truss connecting the
same.

page_text: The longitudinal diagonal ties are united with columns or boxes of
such columns by means of a yoke and screw nut attachment, so as to
admit of the ready adjustment of said ties.
It is also proposed to employ a system of continuous trestle for bridges
in which the longitudinal diagonal rods or ties which connect the caps
and feet or joints of the columns are combined with intermediate spans
of truss extending between the said columns.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 20th April 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County. of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twentieth day of October, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said John Henry Johnson, Her special license
that I, the said John Henry Johnson, my executors, administrators;
and assigns, or such others as I, the said John Henry Johnson, my
executors, administrators, or 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
THE CONSTRUCTION OF BRIDGES," a communication to me from abroad by.
Charles Shaler Smith, Charles Hazlehurst Latrobe, and Frederick Henry
Smith, all of Baltimore, Maryland, in the United States of America,
upon the condition (amongst others) that I, the said John Henry Johnson,
my executors or administrators, 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 per-
formed, 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.

page_text: NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of my said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the Drawing
hereunto annexed, and to the letters and figures marked thereon, (that
is to say) :-
The said Invention relates to the construction of viaducts or bridges,
in which the superstructure is supported upon piers, either independent
of each other or connected so as to form a system of continuous
trestle.
Figure 1 of the annexed Sheet of explanatory Drawings is an elevation
of one construction of bridge supported on independent piers, and made
in accordance with the said Invention; Figure 2 is a transverse elevation
of one of the channel piers of the same; and Figure 3 is a transverse
elevation of one of the land piers thereof. The same letters of reference
indicate corresponding parts in all the corresponding Figures on the
Sheet of Drawings.
In constructing the bridge shown in Figures 1, 2, and 3, foundation
piers A of masonry are first provided. The capstones a in the channel
piers are placed immediately above high-water mark, those upon the
land sides being only of sufficient height to insure a stable structure.
There are two foundation pedestals to each pier. The metal is concen-
trated in two columns B in each pier, thereby securing the greatest
diameter of column with consequent increased strength per square inch
of section and diminution of strutting and other stiffening work. These 2
two columns are connected with each other by braces or horizontal
cross struts f, b, b', and lateral diagonal bracing or tie rods c or g, the
intermediate cross struts being omitted where spans of superstructure
are put together on the ground and drawn into position, in which case
lateral stiffness is secured to the columns by vertical stiffening rods a
connecting opposite ends of the same column, and strutted apart at their
centres by struts e. The land piers may or may not have the vertical
stiffening rods. When the strut fis used the lateral diagonal bracing
rods g are employed, one pair above and one pair below the strut bar f.
(See Figure 3.) The vertical stiffening rods d and struts e may be 3
duplicated in order to give stiffness to the columns in the longitudinal
line of the bridge, their positions, as shown in Figure 1, being at right
angles to the stiffening system for the lateral action shown in Figure 2.
3

page_text: Whenever the length of space is not too great these longitudinal
stiffening systems can be replaced by longitudinal rods or struts k
(Figure 1) anchored at or near one end of the structure, and passing
thence from one pier to another through the joints, and thence to an
anchorage at the other end of the structure, unless long spans should
intervene, in which case they stop at the long span piers, as shown in
the Drawings. In order to keep these rods or struts straight they may
be supported by suspenders from above, and with a view to counteract
the effect of changes of temperature rubber or like washers may be
interposed between the columns and the nuts on the ends of the struts.
The piers are connected with one another by diagonal rods or stays h,
which extend from the top of one pier to the feet of the adjoining piers
(see Figure 1), thereby giving much greater stiffness and freedom from
longitudinal motion under the action of moving loads than in the case
of the independent pier, relying only upon its own base. These longi-
tudinal stays also tend to support any column in position in case its
masonry pedestal should settle or get knocked out. All the rods have
a screw adjustment, so that the bridge can be fully loaded in hot weather
and every thing secured to a full bearing. Wire, or wire rope, or other
suitable material may be used instead of rods. The superstructure can
be of any desired material, span, or system of trusses, either connected
together from end to end of bridge, or unconnected, the piers being
thoroughly anchored and self-supporting in all directions.
Figure 4 is a side elevation of a trestle bridge made in accordance
with this Invention; Figure 5 is a transverse section of the same. The
remaining Figures represent perspective views of detached parts. on an
enlarged scale.
I will first describe the construction of the piers.
The piers are formed of columns or shafts a of iron or steel of any
form of section, which (as shown in Figure 9) fit over tenons 6 formed
on the cast-iron foot boxes F (Figure 9).. These foot boxes are bolted
or otherwise suitable secured at c, c, to masonry, and to the said boxes
are pinned yokes d, d, which receive the lower ends of the longitudinal.
diagonal ties 4 (shown also in Figure 4): Running through the castings
and secured thereto by bolts are the transverse struts S³, formed each
of two channel bars, between which the lower ends of the lateral ties 2
are hung, as shown in Figure 9. The upper end of each column fits
over a tenon formed on the cast-iron post cap C, Figure 7, this cap

page_text: being adapted to receive and hold the chord sticks, the cross struts, the
truss chains, and the longitudinal diagonal ties. The chord sticks are
framed in pairs to the cap, one on each side of the rib that extends
across its top, and on each side of which are placed the plates or bars
which run through the cap and form the jaws, between which the longi-
tudinal diagonal ties take hold of the cap. These bars are held in place
by the pin upon which the truss chains are hung, the pin passing
through the hole formed for its reception in the cap, as represented in
Figure 7. The construction and arrangement of the cross strut S¹ in
no wise differs from that of the strut S³, already referred to in Figure 9.
The lateral ties 1 also take hold of the cap in the manner already
described with reference to the lateral ties 2. To unite the column
with its cap and foot all that is required is to slip its ends over the
tenons formed on the foot box and cap, so that the pier can be set up
with great ease and expedition.
In Figure 6, W represents the end box of chord provided with cuts
to take plates, which hold the longitudinal tie rods 3. These boxes W
are also shown in Figure 4.
To construct the piers of considerable height they are formed in tiers
or stories, and to this end cast-iron joint boxes are employed, such
as represented in Figure 8. This joint box J, which is interposed
between and forms the bearing for the contiguous ends of the sections
to be united has a tenon e on each end, over which fits the upper end
of the lower section and the lower end of the upper section to be joined
in one continuous pier, as, for instance, in Figure 4, the centre piers are
made in three stories or tiers AB, BC, CD, thus necessitating the
employment of a foot box, cap, and two joint boxes. The lower column
CD fits over the tenon of the foot box and the lower tenon of the first
joint box. The middle column B C fits over the upper tenon of the first
and the lower tenon of the second joint box, and so on. This method
of uniting the sections combines in itself strength and ease in fitting
the parts together. The contiguous ends of the cast sections united by
the joint boxes have no contact with each other, but take a direct
bearing on the boxes themselves, and the structure can be set up with
great rapidity and facility.
1
The cross strut S* (Figure 8) made of channel bars is secured in the
joint box in the manner already indicated with reference to the struts
S2, S3, and from between the channel bars the lateral ties 1, 2, extend

page_text: in the usual manner. The two longitudinal tie rods or stays 4, which
meet or cross each other on the same side of the joint box have their
straps hung upon the same pin f, as shown in Figure 8. The piers are
stiffened at their joints by means of a system of longitudinal wooden.
or metallic struts X, which are secured to or abut against masonry, or
its equivalent, at each end of the bridge, as shown in Figure 4, and fit
into the joint boxes, as seen in Figure 8.
In illustration of this Invention I have described the method preferred
of constructing the cast-iron caps, feet, and joints, and of uniting them
with the columns, but the construction of these parts may, however, be
varied to a great extent, according as circumstances require, and so far as
the method of uniting the parts is concerned, the columns may fit over
the caps, feet, and joints, or the latter may fit over the former, or the two
may be riveted or bolted together, as may be found necessary in using.
different sections of columns..
With regard to the longitudinal diagonal tie system, the manner in
which these ties 3, 4, can be used is shown in the diagram, Figure 4.
The upper end of one stay in this instance is anchored to the top of
one pier or post, and thence it extends diagonally downward, and is
anchored to the foot of the second, third, or further pier beyond, passing
through and being united with the joint boxes of the intermediate
columns.
The manner in which the ties 4 are united with the columns which
they intersect, is shown clearly in Figure 8. Their ends pass through
yokes d, d, pivoted to the boxes, and are there held by means of screw
nuts, by which the ties can be tightened and readily adjusted. This
system of tie rods is represented as continuous from the cap of one
column to the base of another, but it can also be used with just as
good effect to connect the joints of one tier with those of another-
tier, or with the caps or feet of the columns forming the piers, and
they may be also attached directly to the columns themselves or to the
longitudinal struts, as may be best in different situations.
'
The mode above described is adapted more particularly to the crossing
of dry ravines or valleys where there is no stream of any considerable size
to be bridged, but in case a large body of water must be spanned, or
other circumstances make it inconvenient or impracticable to employ
a continuous trestlework, the construction of independent piers upon
the same general plan may be-adopted, which can be connected. by one:

page_text: or more channel spans; for instance, suppose that the three centre
bents of the structure, shown in Figure 4, were removed, thus leaving
two independent piers. Between these two piers a channel span com-
posed of any suitable form of truss should be introduced, and by
counterbracing the end bents of the two piers a perfectly safe and
strong bridge would be produced.
In the bridge represented the piers or columns are set at such a
distance as to require the use of a truss, but they can be set at any
required distance apart, so as to dispense, if need be, with the truss.
The combined use of the intermediate spans and longitudinal ties
with the piers, as shown in Figure 4, is however productive of advantage,
for a strong and durable structure is obtained, while at the same time
the posts or columns can be set at a greater distance apart than has
heretofore been practicable, and so far as this portion of the Invention
is concerned the particular construction of the columns or posts is
immaterial though the construction herein-before described is preferred.
In place of the channel bars or iron of equivalent form inserted
in the boxes or caps, and used for the cross struts, small columns
may be used, which fit over tenons cast on the sides of the joint boxes,
foot boxes, or caps with which the struts require to be connected.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I con-
sider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,―
1. Anchoring the tops of iron or steel piers of bridges by means
of longitudinal diagonal stays to the feet or pedestals of other piers
or abutments, so that the pier can be formed of but two columns, and
still have the great longitudinal base afforded by the spread of the
longitudinal diagonal stays to give it stability under the action of
temperature or a moving load.
2. In combination with the said system of longitudinal diagonal
stays I claim iron or steel piers stiffened by means of up-and-down
tension rods and cross struts at such point in the height of the pier as
will prevent flexure.
•
3. Stiffening iron or steel bridge piers by means of longitudinal
rods or struts anchored to or abutting against masonry, and connecting

page_text: therewith the piers at such point in their heights as will prevent
flexure.
4. The combination of the iron or steel piers of bridges with the
longitudinal diagonal stays, the up-and-down stiffening system, and the
longitudinal stiffening system, substantially as set forth.
5. The combination, substantially as described, of iron or steel
columns with cast-iron caps and feet or joints when used to form bridge
piers, whether these piers be isolated or connected, so as to form a
system of trestle.
6. In a system of piers or continuous trestle, such as described,
I claim the combination with the cast-iron joint boxes interposed
between and forming the bearings for the column sections of longitu-
dinal diagonal ties connecting, substantially in the manner specified, the
joints of any one tier with those of another tier, or with the caps or feet
of the columns.
7. The combination with the piers and system of longitudinal
diagonal ties connecting the same of the wooden chord sticks and lon-
gitudinal system of wooden struts for supporting the roadway and
stiffening the piers.
8. The combination of a series of independent or isolated bridge
piers formed as described with an intermediate span or spans of truss
connecting the same.
9. Uniting the longitudinal diagonal ties with the columns or
boxes of the said columns by means of the yoke and screw nut
attachment, so as to admit of the ready adjustment of the said ties.
10. A system of continuous trestle for bridges, in which the
longitudinal diagonal rods or ties which connect the caps and feet or
joints of the columns are combined with intermediate spans of truss
extending between the said columns, as herein-before described.
In witness whereof, I, the said John Henry Johnson, have to this
my Specification set my hand and seal, this Nineteenth day of
April One thousand eight hundred and seventy-one.