IMPROVEMENTS IN THE CONSTRUCTING OF FIREPROOF FLOORING AND ROOPING, ALSO APPLICABLE TO THE CONSTRUCTION OF VIADUCTS, AQUEDUCTS, CULVERT, &c.%
Year: 1848

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
NASMYTH, of Ebury Street, Pimlico, in the County of Middlesex, Civil
Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Fourth day of September, in the twelfth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said George Nasmyth, my exors, adñiors, and assigns, Her especial
license, full power, sole privilege and authority, that I, the said George
Nasmyth, my exors, adñiors, and assigns, or such others as I, the said George
Nasmyth, my exors, adiñors, and assigns, shall at any time agree with, and
no other, from time to time and at all times during the continuance of the
term of years therein expressed, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed, and
in the Islands of Guernsey, Jersey, Alderney, Sark, and Man, and in all Her
Majesty's Colonies and Plantations abroad, my Invention of "IMPROVEMENTS
IN THE CONSTRUCTING OF FIREPROOF FLOORING AND ROOPING, ALSO APPLICABLE TO
THE CONSTRUCTION OF VIADUCTS, AQUEDUCTS, CULVERT, &c.%;" in which said
Letters Patent is contained a proviso that I, the said George Nasmyth, do
cause a particular description of the nature of my Invention, and in what
manner the same is to be performed, by an instrument in writing under our
hand and seal, to be enrolled in Her Majesty's High Court of Chancery

page_text: within six calendar months next and immediately after the date of the same
in part recited Letters Patent, as in and by the same, reference being there-
unto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
George Nasmyth, do hereby declare that the nature of my said Invention and
the manner in which the same is to be carried into effect, are herein-after fully
described and ascertained by the following description thereof, reference being
had to the Drawings herewith annexed, and to the figures and letters marked
thereon, that is to say:
My Invention being a construction of fireproof flooring and roofing, and
which construction is also applicable to roadways of viaducts, or railways and
bridges, aqueducts and other similar purposes, the improvements consisting of
some of the most important parts used in such structures. I divide my
Invention into two parts. The first part being the flooring and roofing, &c.
The second. being the bearers, joints, or girders used for supporting such floors,
roofs, roadways, &c.
The general construction of the flooring and roofing is as follows, and is
set forth in the Drawings, appended hereunto :-I use plates of wrought iron,
steel, or other eligable metal, which are bent so as to form the segment of a
circle, or conical, polyagonal, or other shape, with a chord of the arched or
other shaped plate, which is another plate bent at the ends to retain the
segment or upper plate in its position. I also propose using two or more
bars of iron or steel bent up at the ends as a substitute for the chord plate,
and for the lighter descriptions of floors, I would always use them. Another
construction is by using T or other suitable shaped iron bent into any of the
forms before stated, and retained in such form before stated by a tension bar
bent over at the ends, the arch of T-iron to have the rib either underneath
or above. I place this combination of T-iron and tension bars between
the girders, at such distances apart as may be found necessary, the ends
resting on the flanges of such girders, and I then use thin sheet-iron or
other metal, which I bend so as to cover over and rest upon the upper
part of the arch formed of the T-iron, always allowing the ends of the covering
plates to pass underneath the turned-over ends of the tension bars; angle
iron may be also used in the same way. Where great stiffness or ridgedity may
be essential, combined with lightness, I fasten the thin sheets of metal to
the arches or other forms of T or other iron, so as to form a series of ribs on
the under sides of the plates, still using the tension bars as before described.
The floors are then made level by being covered with cement or concrete
upon the upper surface of the bent plates. There are many modifications

page_text: by the use of other forms of iron, some of which are shewn in the Drawings.
But the peculiarity of this the first. part of my Invention is, the retaining the
upper or bent plate or bar in its curved or bent form, by the chord
or under plate or bars, without the use of bolts, rivets, or any fastening
whatever, but if preferred the same effect may also be produced by rivetting
on a joggle or joggles to retain the ends of the upper plate; or bolts or rivits
may be used in combination with the afore-mentioned modes, thus forming
a very strong, light, and perfectly fireproof floor, the plates thus formed,
being laid on girders, may be continued to any extent. But in the event
of the girders being placed so much apart as to exceed the length of the
plates which at present are usually manufactured, I use two or more plates,
rivitted or welded, or otherwise fastened together, so as to form them
of the desired length, always preferring one plate if they can be manu-
factured. I would only use the upper or curved plates, rivitted or otherwise
fastened together; the tension bars I prefer to have them made in one picce, but
if required they may be constructed of a chain of links or wire rope or
otherwise, of two or more pieces; and each plate, being retained in its curved
or bent form as before described, is perfectly free from all lateral action
on the beams, girders, or walls of the buildings on which they are supported.
The method of forming the several parts thus used will be understood by
the following description:-The upper plate is bent to the shape required to
constitute the arch or other form by any of the machines made use of for
the purpose of bending the iron plates commonly used in the construction
of steam boilers, also for wheel tyres, and well known as plate-bending
machines, or by any other convenient means; and another plate or requisite
number of bars of the proper length, bent or turned over at each end as
shewn at A, A, in Figure 1, Sheet A, the distance between the inner sides
of the turning of this plate or bars to be equal to the chord line of the
upper plate in its bent or curved state, as shewn by Figures 2, 3, 4, 5, so
that the arched plate will pass between the turned-up ends of the under or
chord plate or bars, and be there retained in its curved or ben state, without
the aid or intervention of rivets, bolts, or any fixing whatever, as shewn
at Figure 6. There are other methods of retaining the curved plate in
its form; this may be done by casting retaining pieces on the girders
where cast-iron girders are used, as shewn at B, B, Fig. 7, or, in
the event of wrought-iron beams being employed, by pieces fixed to the
girder, as B, B, Fig. 8, so as to retain the ends of the curved plate;
but in every case I would recommend the use of one or more retaining
or tension bars, so as to remove all lateral action. The retaining pieces may

page_text: be simple projecting pieces, as shewn at B, B. I sometimes employ corru-
gated plates in the construction of the flooring, the corrugations of the plates
being placed in the position shewn in Fig. 11, where they are supported in
their arched form by their bearing upon the arched or other shaped bars A;
these arched bars may be made of T-shaped or angle iron, as shewn in Fig. 9,
or of one or two angle iron bars, to which are rivetted a fin or strip of bar
iron, as represented at A, in Fig. 10. This Figure shews a section of a flooring
constructed of a series of arched bars A, and tension bars B, supported by
two cast-iron girders C of the ordinary construction; these arched bars are
placed a short distance apart, and support the flat plates D upon which the
concrete or other filling and the floor is laid; or in place of the concrete
cement or other filling above the plates, I sometimes use plates of thin metal
placed on edge and rivetted together, and wholly or partially filled up with
concrete and cement as before; this construction will be lighter.
The second part of my Invention being the construction of the beams
or girders for the support of floors, roadways, bridges, aqueducts, &c.; in the
formation of which I use wrought iron or a combination of wrought iron and
steel, or of wrought iron, cast iron, and steel, Fig. 13 representing a longi-
tudinal view of a wrought-iron girder, shown partly in elevation and partly in
section, and Fig. 14, a transverse section upon an enlarged scale through the
line z, z, Fig. 18.
Having determined the length of girder or beam, one or more bars of
wrought iron, steel, or other metal is bent so as to form a segment of a circle
or arched or other form A. Two or more other bars are bent or turned over
at the ends forming the chord B, so that the arched bar or bars A will pass
between the parts turned of the chord B up, and be there retained in their
arched form, as previously described in the first part of this my Invention. I
then have plate iron of the required strength, which may be either riveted,
welded, or fastened together by any of the ordinary methods, so as to form the
sides C', C', of the girder; such sides have riveted or otherwise fastened
between them a bar or bars of wrought iron D, which must correspond in
shape with the outside of the arch A, so that when the sides C', C, thus
fastened together are placed over the arched bar A, the bar D will bear on
the entire length of it; the arched bars A, and tension or chord bars B, will
be encased by the outside plates C, C, and trough-pièce D. I sometimes use
cast iron in place of the wrought-iron side plates. But I recommend the
wrought iron in preference; the same means may be applied as a truss for
wooden beams. Before this beam or girder is erected in a building or viaduct,
&c., attention must be paid as follows:-That the under side of the ends of

page_text: the tension or chord bars must rest upon supporting plates E, E; and before
such pieces of metal be finally fixed to the ends of the girders or beams, I put
a load equally distributed over the girder of at least one third more than the
weight the girder is even intended to sustain, the purpose of this being done is
to insure the casing or outer structure C, C, of the girder or beam bearing on
the encased arch or other form A, and causing the chord or tension bar B
being brought into action. The end pieces are now fastened firmly in their
places, and the girder ready for use. There must be a small space allowed to
permit of any expansion or stretching of the chord or tension bars. The flanges
for the support of the fireproof plates or joists, described in the first part of
this Specification, are formed by riveting or fastening angle iron to the side
plates; pieces of T or other shaped iron H, H, are also riveted to the
sides C, C, for the purpose of preventing the turn-over ends of the flooring,
tension bars, or plates resting upon the flange F from turning upwards. The
action of this girder will be as follows:-When the load is placed upon any
part of it there will be a tendency to deflection, which will at once be borne
by the encased arch, and the tendency to become a flatter arch or to change
its form will be counteracted by the action of the tension bars or chord, and
the deflection will thus be resisted by the construction, which results in a very
strong, light, and cheap girder, free from the danger arising from the use of
cast iron, and free from all lateral action. In the case of a great length
of chord or tension bar there may be a tendency to sagg downwards,
I counteract this by applying supports at the centre or other convenient
parts.
The combination of the first and the second parts of my Invention are
illustrated in Figures 15, 16, and 17, showing their application to the floor
of a building of about 25 feet square, and constituted of one girder, which
supports one end of the flooring plates or bars, the walls of the building
supporting the other ends, Fig. 15 being a section of the flooring through the
line X, X, Fig. 16 and 17.
Fig. 16 is a section through the line W, W, Fig. 15, and Fig. 17 a plan view
of the girder, with portions of the flooring plates or bars, but divested of the
concrete and flooring so as to shew fully its construction. The girder A is
supported upon the walls, and upon the flanges of which rests the flooring
bars B, B, carrying upon them the flooring plates C, C, upon which the
flooring is placed in any convenient manner, either by filling up with cement,
concrete, or other materials, or otherwise. The general proportions I would
recommend for a girder twenty feet between the bearings to support ten tons
on the centre will be as follows-Side plates 15 inches deep, 1/8th of an

page_text: inch thick; bar of trough iron between plates 3/8ths by 2"; bar of iron form-
the arch 8/8ths x 2"; and three steel bars, 2" x 3/8ths as the tension bars.
But I do not bind myself in carrying out this my Invention to the above
proportions, nor to any particular dimensions or form of the metal plates or
bars used. And in certain cases I use corrugated iron, galvanized or not;
nor do I state or specify, in the case of corrugated iron, any size or dimen-
sion of the corrugations, or in the plates or arches any particular curve, as
this varies with circumstances. And I wish it understood that I use for
the construction of the said flooring, roofing, &c., and also for the beams and
girders, plates or bars, bent or formed into any figure other than a straight
line, as a substitute for the simple bent or curved plates or bars, any form
in which pressure applied to the upper part will have the tendency to deflect,
and thereby bring the action of tension into use. From the strength of this
construction of girder depending on the action of tension, it will be evident
that the chord or tension bars must be of sufficient strength to bear any
load the girder is intended to sustain, either whether a permanent or moveable
And also the strength of this construction of girder may be increased
simply by separating the side: plates, so as to encase two or more arches and
chord or tension bars, as shewn at Fig. 18. I therefore increase the power
of my girder by making it of greater breadth, keeping the depth the same,
and thus in buildings and viaducts, save what is termed head room, the
peculiarity of my construction is the bearing on the upper side of the bow
or arch, and bringing the tension bars at once into action in the simplest
and most direct manner.
one.
Figs. 19 and 20 shews sections of girders of modified constructions.
Where floors are constructed on the principle already described by tension
plates below and arched plates above, such plates being continuous side
by side over the whole extent of the floor, hollows or recesses will be left
in the thickness of the floor, as between the floor and the ceiling, which
spaces may be usefully applied to the purposes of, warming and ventilation,
by causing currents of warm or cold air to pass through them, which may be
admitted into the apartments by perforations in the floors and perforations
may also be applied to the ceilings to carry off the vitiated air.
In conclusion I have to state that the floors, roadways, &c., are made
level with any good concrete or cement, or by other means, but I would
always recommend the use of Portland cement used as a concrete, 'with
bricks, flints, or any other incombustible. material; and in cases where
great lightness may be required, hollow earthernware pipes or drainage
tiles may be used with advantage to fill up the spaces formed by the curved

page_text: plates and the level floor; the intervening spaces may then be filled up with
Portland cement as a grout, the upper surface of the floor may be covered.
with plain or ornamental tiles, or wood if required; but I do not claim any of
the concluding remarks as part of my Invention.
Having now described the nature of my said improvements, I do hereby
declare that the said Inventions, whereof the exclusive use is granted to me by
the Letters Patent herein-before recited, consist of the following particulars:-
First, I claim the modes of constructing fireproof floors and roofs for
buildings, and girders for bridges, viaducts, and buildings, by means of a
metallic arch or other curved or angular figure, or both, supported by
a metallic chord constituting the abutment of the arch as herein-before
described.
Secondly, I claim the application of such flooring for the purposes of
warming, cooling, and ventilating buildings by currents of air made to pass
through the bollow spaces formed by the distance between the arched plates
and the chord plates, as herein-before described.
In witness whereof, I, the said George Nasmyth, have hereunto set my
hand and seal, the Third day of March, One thousand eight hundred