IMPROVEMENTS IN ROLLED IRON JOISTS AND GIRDERS
Year: 1871

page_text: LETTERS PATENT to Julius Homan, of No. 17, Gracechurch Street,
in the City of London, for the Invention of "IMPROVEMENTS IN ROLLED
IRON JOISTS AND GIRDERS."
Sealed the 26th March 1872, and dated the 14th October 1871.
PROVISIONAL SPECIFICATION left by the said Julius Homan at the
Office of the Commissioners of Patents, with his Petition, on the
14th October 1871.
-
I, JULIUS HOMAN, of No. 17, Gracechurch Street, in the Oity of
London, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN ROLLED IRON JOISTS AND GIRDERS," to be as follows:-
-
In the rolled joist or girder of the ordinary kind the object sought is
to make a beam of iron having a web and flanges to resist the vertical
and lateral strains caused by the load, and the dimensions of these parts
are arranged chiefly with the view of providing sizes that shall be con-
venicnt in use. Such beams are too strong in some parts and too
M

page_text: weak in other parts, the excess of metal in the over strong parts being
wasted.
I find that to obtain the maximum amount of strength at the
minimum cost it is necessary to maintain a certain proportion between
all the parts, so that the beam shall be equally strong everywhere when
subjected to the transverse strains of the load. And I find these con-
ditions to be nearly that the depth of the beam shall be about four times
the width of the flanges, that the amount of metal in the flanges shall
be about the same as in the web, and that the shoulder or part where
the web is joined to the flange shall be strong enough to resist the 1
tendency to cant over, and shall taper gradually to the middle part of
the web, commonly known as the neutral axis of the beam. Rolled
joists and girders so made furnish nearly 30% more resistance, weight
for weight, when compared with ordinary beams.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Julius Homan in the Great Scal Patent Office
on the 12th April 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JULIUS
HOMAN, of No. 17, Gracechurch Street, in the City of London, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of October, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Julius Homan, Her special license
that I, the said Julius Homan, my executors, administrators, and
assigns, or such others as I, the said Julius Homan, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thercafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the

page_text: "
'
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
ROLLED IRON JOISTS AND GIRDERS," upon the condition (amongst others)
that I, the said Julius Homan, my executors or administrators,
by an instrument in writing under my, or their, or one of their
hands and seals, 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 Julius Homan, 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 tho
following statement thereof, that is to say :-
In the rolled joist or girder of the ordinary kind the object sought is
to make a beam of iron having a web and flanges to resist the vertical
and lateral strains caused by the load, and the dimensions of these parts
are arranged chiefly with the view of providing sizes that shall be con-
venient in use. Such beams are too strong in some parts and too
weak in other parts, the excess of metal in the over strong part being
wasted.
I find experimentally that to obtain the maximum amount of strength
at the minimum cost it is necessary to maintain a certain proportion
between all the parts, so that the beam shall be equally strong every-
where when subjected to the transverse strains of the load. And I find
these conditions to be nearly that the depth of the beam shall be about
four times the width of the flanges, that the amount of metal in the
flanges shall be about the same as in the web, and that the shoulder or
part where the web is joined to the flange shall be strong enough to
resist the tendency to cant over, and shall taper gradually to the middle
part of the web, commonly known as the neutral axis of the beam.
Rolled joists and girders so made furnish nearly 30% more resistance,
weight for weight, when compared with ordinary beams.
In order that my said Invention may be most fully understood, and
readily carried into effect, I will proceed to describe the Drawing
hereunto annexed.

page_text: DESCRIPTION OF THE DRAWING.
The Drawing shews a section of a rolled iron joist or girder made
according to my Invention. The depth is four times the width of the
flanges. The web or centre portion is thinnest in the middle, and it
tapers either way towards the flanges, which it meets with bold curves.
The sections are so proportioned, as the Drawing shows, that the metal
in the flanges is about the same as in the web (the flange being con-
sidered to terminate and the web to commence on a line drawn through
the middle of the connecting curves, as is indicated by the lines 1, 1, on
the Drawing).
It is not essential that these proportions should be exactly maintained,'
but a loss of strength is incurred by any considerable departure from
them, and when the departure in either of the proportions above set
forth amounts to as much as 30 per cent., the loss of strength is so
serious that I confine my claim within this limit.
In witness whereof, I, the said Julius Homan, have hereunto set my
hand and seal, this Eleventh day of April, in the year of our Lord
One thousand eight hundred and seventy-two.
.
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