IMPROVEMENTS IN CONSTRUCTING METAL BEAMS OR GIRDERS
Year: 1852

page_text: LETTERS PATENT to Henry McFarlane, of Lawrence Lane, in the
City of London, Merchant, for the Invention of "IMPROVEMENTS
IN CONSTRUCTING METAL BEAMS OR GIRDERS."-A communication."
Sealed the 12th January 1853, and dated the 13th October 1852.
PROVISIONAL SPECIFICATION left by the said Henry McFarlane
at the Office of the Commissioners of Patents, with his Petition,
on the 13th October 1852.
I, HENRY MCFARLANE, of Lawrence Lane, in the City of London,
Merchant, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN CONSTRUCTING METAL BEAMS OR GIRDERS" to be as
follows:-
My Invention consists of constructing beams or girders by corrugating
sheet metal deeply with nearly vertical and parallel corrugations longi-
tudinally of each beam or girder.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry McFarlane in the Great Seal Patent
Office on the 13th April 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
HENRY MCFARLANE, of Lawrence Lane, in the City of London,
Merchant, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of October, One
thousand eight hundred and fifty-two, in the sixteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Henry McFarlane, Her special licence that I, the said
Henry McFarlane, my executors, administrators, and assigns, or such
others as I, the said Henry McFarlane, my executors, adminis-
trators, 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 METAL BEAMS OR GIRDERS," upon the condition (amongst
others) that I, the said Henry McFarlane, 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, 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 Henry McFarlane, 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
Drawing annexed, which makes part of this Specification, and in which
Figure 1, is a view in perspective of a short section of beam suitable
for a bridge, made of a single plate, according to the method invented
by me; and Figure 2, is a transverse section of the same.
The object of my Invention is, to work laminar material possessing
great tensile strength, as sheet iron, for example, into such a form as

page_text: will adapt it to being used with great advantage for the beams of houses
and bridges, and for other purposes where great weights and strains are
to be resisted. I am aware that this material has been wrought into
various forms under the name of corrugated plates, but all such forms
are defective, and fail to develope the strength of the material because
they dispose the plate across instead of causing it to stand edgewise in
the line of the pressure.
It is well known that in a number of beams of unequal depth and
thickness, but each of the same depth of thickness throughout its whole
length, each containing an equal amount of material, and each being
properly stiffened to prevent buckling, that one will possess the greatest
amount of transverse strength, or support the greatest weight without
liability to fracture, which presents the greatest depth of material in the
line of pressure.
I have taken advantage of this theoretical principle in the construc-
tion of my laminar beam, and my Invention consists in disposing the
sheet or plate in parallel longitudinal strips, which are alternately flat
and arched in their transverse section, the flat strips being parallel or
thereabouts to each other, and standing edgewise, or nearly so, in the line
of pressure, and being stiffened laterally at both edges by the arches to
prevent them from buckling; by thus disposing so much of the sheet of
metal in a series of parallel plates standing on edge directly in the line
of pressure, instead of disposing the whole of it across the line of pres-
sure, as has heretofore been done, I develope a far greater proportion
of the strength of the material in resistance to fracture by a weight
resting upon it.
The Drawing annexed represents a beam made according to my
improved method of a single sheet of metal disposed in longitudinal
strips, which are alternately flat and arched; the flat strips or plates a,
being arranged parallel or thereabouts to each other, both transversely
and longitudinally, and the arches being alternately inverted. The
extremities of the inverted arches c, terminate in and give lateral stiff-
ness to the lower edges of the vertical plates, while the extremities of
the inverted arches b, terminate in and give lateral stiffness to the upper
edges of the vertical plates; the stiffness thus given to the edges of the
vertical plates being to prevent them from buckling.

page_text: The thickness of the sheet, the height and flatness and span of the
arches, and the depth and number of the plates must be proportionate
to the weight the beam is intended to support, and are matters of. calcu-
lation which must be left to the judgment of the engineer who super-
intends the construction; so also must the selection of the mode of
manufacture, whether by rolling, swedging, or otherwise, be left to his
judgement.
In a beam thus constructed the great depth of the parallel plates
gives it great strength with but little weight of material.
I have based my Invention upon the absolutely perpendicular position
of the flat strips of the laminar of my beam; but as it might be found
difficult in practice to construct a beam in which the laminar would
occupy the exact vertical and parallel position that theory assigns to
them, and which is the best, I have qualified the rigid exactitude and
inflexibility of the word "perpendicular" by the adverbs "thereabouts"
and "nearly."
I claim to have produced a new and useful laminar beam, composed
of sheet or plate metal, bent or disposed longitudinally into a series of
narrow strips alternately flat or thereabouts, and arched, the flat strips
being parallel or thereabouts, both longitudinally and transversely, and
held in this position, and united at the top and bottom alternately by the
intermediate arched strips, one of which is arranged between every two
of the flat strips, substantially as herein set forth.
In witness whereof, I, the said Henry McFarlane, have hereunto
set my hand and seal, this Eighth day of February, One
thousand eight hundred and fifty-three.
HENRY MCFARLANE. (L.S.)
Witness,
JNO. COOK,
12, Cursitor Street, Chancery Lane.