IMPROVEMENTS IN FUR- NACE OR FIRE-BARS
Year: 1860

page_text: LETTERS PATENT to John Blackwood, of the Town and County of Banff,
North Britain, Engineer, for the Invention of "IMPROVEMENTS IN FUR-
NACE OR FIRE-BARS."
Sealed the 29th May 1860, and dated the 21st March 1860.
PROVISIONAL SPECIFICATION left by the said John Blackwood at the
Office of the Commissioners of Patents, with his Petition, on the
21st March 1860.
I, JOHN BLACKWOOD, of the Town and County of Banff, North Britain,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN FURNACE OR FIRE-BARS," to be as follows, that is to say:-
This Invention relates to the arrangement and construction of furnace or
fire-bars in such manner as to ensure the bar lasting much longer than those
of the ordinary kind, as well as obtaining other advantages in the combination
of the fuel. Under one modification this improved furnace bar is cast hollow,
that is to say, there is an opening extending longitudinally through the bar.
The bar is by preference cast of an elliptical or egg-shaped figure in its trans-
verse section, the wider portion of the egg-shaped figure forming the upper
part of the bar, and the external convex surface the part on which the fuel
rests when fitted in the furnace.
bar are made with the
usual recessed or notched part, to
resting upon the cross
The ends of the
admit of the bar

page_text: bearers or supporters which are fitted at each end of the furnace. Below the
bearing ends of the bar are the openings which admit of a current of air con-
tinually passing through the bar from end to end, the metal of the bar forming
as it were a shell to this air chamber or thoroughfare. The metal at the
ends of the air passage is shaped so as to curve away in an angular direction,
in order that nothing may interfere with the free admission and emission of
the air to and from the bar. The currents of air passing through the several
bars of a furnace carry off a large portion of the heat imparted to the furnace
bar by the burning fuel, and in this manner the destructive effect of the
intense beat is counteracted by the cooling influence of the air. The result
of this arrangement is that these furnace bars last five times as long as those of
the ordinary kind, whilst the action of the furnace itself is greatly improved in
consequence of the introduction thereto of a body of air which has been pre-
viously heated in passing through the bars. These bars may, if preferred,
be made with the upper surface flat, but preference is given to the convex
figure. The bars are adapted for the furnaces of stationary, locomotive, or
marine engines, without requiring any alteration in the internal arrangement
of the same.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Blackwood in the Great Seal Patent Office on the 2
20th September 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BLACKWOOD, of the Town and County of Banff, North Britain, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters 2
Patent, bearing date the Twenty-first day of March, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Blackwood, Her special license that I, the said John Black-
wood, my executors, administrators, and assigns, or such others as I, the said 3
John Blackwood, 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 3
FURNACE OR FIRE-BARS," upon the condition (amongst others) that I, the

page_text: said John Blackwood, 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 John Blackwood, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying Drawings, and to the
letters and figures marked thereon, that is to say:-
My said Invention relates to the arrangement and construction of furnace
or fire-bars in such manner as to ensure the bar lasting much longer than
those of the ordinary kind, as well as obtaining other advantages in the com-
bustion of the fuel. Under one modification this improved furnace bar is cast
hollow, that is to say, there is an opening extending longitudinally through
the bar. The bar is by preference cast of an elliptical or egg-shaped figure in
its transverse section, the wider portion of the egg-shaped figure forming the
upper part of the bar, and the external convex surface the part on which the
fuel rests when fitted in the furnace. The ends of the bar are made with
the usual recessed or notched part to admit of the bar resting upon the cross
bearers or supporters which are fitted at each end of the furnace. Below the
bearing ends of the bar are the openings, which admit of a current of air
continually passing through the bar from end to end, the metal of the bar
forming as it were a shell to this air chamber or thoroughfare. The metal at
the ends of the air passage is shaped so as to curve away in an angular direc
tion, in order that nothing may interfere with the free admission and emission
of the air to and from the bar. The currents of air passing through the
several bars of a furnace, carry off a large portion of the heat imparted to the
furnace bar by the burning fuel, and in this manner the destructive effect of
the intense heat is counteracted by the cooling influence of the air. The result
of this arrangement is, that these furnace bars last five times as long as those
of the ordinary kind, whilst the action of the furnace itself is greatly improved
in consequence of the introduction thereto of a body of air which has been
previously heated in passing through the bars. These bars may, if preferred,
be made with the upper surface flat, but preference is given to the convex
figure. The bars are adapted for the furnaces of stationary, locomotive, or
marine engines, without requiring any alteration in the internal arrangement
of the same.
And in order that my said Invention of improvements in furnace bars may

page_text: be properly understood, I shall now proceed to describe the several illustrative
Figures on the explanatory Sheet of Drawings which I have hereunto
appended for the purpose of showing certain modifications under which my
improvements may be judiciously carried out in practice, that is to say:-
Figure 1 on the accompanying Drawings is a partially sectional elevation of
one modification of my improved furnace bar, and Figure 2 is a transverse
vertical section of the same; Figure 3 is a half sectional end elevation of a
furnace fitted with my improved bar; Figure 4 is a longitudinal section, and
Figure 5, a plan corresponding to Figure 3. The furnace bar A, Figures 1
and 2, is cast or rolled hollow, that is to say, it has an opening extending
longitudinally throughout its length. The external portion of the bar is by
preference formed of an elliptical or egg-shaped figure, as shown in Figure 2.
The wider portion of the egg-shaped figure forms the upper part of the bar,
and the fuel rests upon the rounded upper surface B when the bar is fitted in
the furnace. The ends of the bar are notched or recessed at C in the ordinary
manner to admit of the bar resting on the cross bearer or supporters which
are fitted at each end of the furnace; and there are the usual laterally pro-
jecting parts D, which preserve the necessary longitudinal openings between
the fuel bearing portions of the bar. Below the bearing ends of the bar the
metal is curved at E, so as to leave a good opening at each end for the
admission of air. When fitted in the furnace, these openings admit of a
current of air passing through each bar, and these currents of air are highly
beneficial as regards the preservation of the bar, for by this means a large
proportion of the intense heat imparted to the bar by the burning fuel is
carried away, and its destructive effect upon the iron is counteracted by the
cooling influence of the air flowing through the bar.
In fitting these bars in furnaces, preference is given to the arrangement
delineated in Figures 3, 4, and 5, for stationary engines. The brickwork F is
constructed in the ordinary manner; the bars A rest upon the dead plate G,
at the front ends, and at the back on the hollow bearer H; this bearer is
built into the brickwork I, which forms the back part of the ash-pit and the
fire bridge. The hollow bearer H extends across the furnace, and has opening
into it at each side a pipe J, which is carried upwards in an angular direction,
as indicated by the dotted lines in Figure 4, the extremity of each pipe termi-
nating in the furnace above the fire-bars. The air which flows through the
hollow bars being heated in its passage, passes into the chamber or hollow
bearer H, and flows from it into the pipes J. The heated air issues from the
pipes J, where it mingles with the smoke arising from the burning fuel, where
its presence serves to render inflammable the greater portion of the evolved

page_text: gaseous matters, which are thus flashed into flame and utilized by imparting
heat to the boiler K. The flame and gaseous current, after passing round the
boiler by the flue L, are conveyed into the chimney. Instead of the fore-
going arrangement, the heated air from the pipes J, or from the bearer H,
may be allowed to escape either behind the fire-bridge, or be carried by means
of a short pipe up through it, so as to ignite the combustible gases at the
backward part of the furnace before they are allowed to escape to the
chimney. By this mode of arranging and constructing furnace bars, a large
body of air is carried into the furnace, which serves, in the first place, to
preserve the furnace bars, and, secondly, to economise the consumption of fuel
by not reducing the temperature of the furnace, and thus preventing, or nearly
so, the escape of visible smoke from the chimney.
Having now described and particularly ascertained the nature of my
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 consider novel and
original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent, is,―
First, the general arrangement and construction of furnace or fire-bars, as
herein-before described and shown in the accompanying Drawings.
Second, the system or mode of constructing furnace or fire-bars of the
peculiar figure or hollow form herein-before described and shown in the accom-
panying Drawings, or any mere modification of the same.
Third, the system or mode of arranging the said furnace or fire-bars in
furnaces, as herein-before described and delineated in Figures 3, 4, and 5 of
the accompanying Drawings, with a view of utilizing the currents of air passed
through the hollow bars.
In witness whereof, I, the said John Blackwood, have hereunto set my
hand and seal, this Nineteenth day of September, One thousand eight
hundred and sixty.
JOHN BLACKWOOD. (L.S.)