IMPROVEMENTS IN THE FURNACES OF STEAM 5332 ADDIED TO OTHER FURNACES
Year: 1866

page_text: LETTERS PATENT to Thomas Bridges, of Wolverhampton, in the County
of Stafford, Engineer, and Joshua Bigwood, of Wolverhampton, aforesaid,
Machinist, for the Invention of "IMPROVEMENTS IN THE FURNACES OF STEAM
5332
ADDIED TO OTHER FURNACES"
Sealed the 17th May 1867, and dated the 5th December 1866.
PROVISIONAL SPECIFICATION left by the said Thomas Bridges and Joshua
Bigwood at the Office of the Commissioners of Patents, with their
Petition, on the 5th December 1866.
We. THOMAS BRIDGES, of Wolverhampton, in the County of Stafford,
Engineer, and JOSHUA BIGWOOD, of Wolverhampton, aforesaid, Machinist, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
FURNACES OF STEAM BOILERS, WHICH IMPROVEMENTS MAY ALSO BE APPLIED TO OTHER
FURNACES," to be as follows:--
Our Invention has for its object, firstly, the introduction of jets of heated
air at the furnace door, or at the front of the furnace; and, secondly, the
introduction of jets of heated air at the bridge of the furnace.
We will describe our Invention in connection with the furnace of a steam-
boiler.
In carrying the first part of our Invention into effect we make the furnace
door at which the fuel is introduced hollow, or in the form of a box; the said
hollow door is perforated at front and back, and in the said perforations tube's

page_text: are fitted, the said tubes running horizontally from front to back of the hollow
door; the said tubes are also perforated with a number of small holes. On
the front of the hollow door is a perforated sliding plate, having in it per-
forations corresponding to the tubes in the door. By sliding the said perforated
plate which is worked with a lever or handle the outer openings of the tubes
in the door can be closed, or partially or wholly opened, and the amount of air
entering the furnace at the door thereby regulated. The back plate of the
hollow door has a series of perforations made in it in addition to those in
which the inner ends of the tubes fit; perforated plates may also be fixed
between the tubes. When the sliding perforated. plate is so situated as to
permit of the introduction of air through the door the said air entering by the
tubes passes out in great part through the perforations in the said tubes into
the hollow door, and from thence through the perforations in the perforated
plates in the box and those in the back of the door into the furnace. By
thus making the air which enters the furnace through the door circulates
through the tubes and hollow door and plates, which are heated by radiation
from the fire, the said air becomes heated as well as divided into small jets.
In order still more effectually to heat and divide the air entering the furnace
by the door a perforated plate (which we call a discharge plate) may be fixed
parallel to the back plate of the door. The air in this case after leaving the
door passes through the perforations in the discharge plate and becomes more
highly heated and divided. Where it is inconvenient to give the requisite
thickness to the hollow door, as in the furnaces of locomotive, marine, and
other boilers, a whollow perforated and tubulated box, similar to that herein-
before described as the hollow door, may be placed within the fire-box of the
furnace, and made capable of sliding backwards and forwards in the fire-box.
When it is required to fire the furnace the door is opened, and the perforated
tubulated box is pushed by means of a lever in connection with the said door
and tubulated box to the back of the fire-box; fuel is then introduced, and
the said box drawn forward, so that on the closing of the door it is situated
immediately behind the door. When, however, the furnace door can be made
hollow, in the manner first described, we prefer to employ that arrange-
iment. This part of our Invention besides being applicable to all kinds of
steam boiler furnaces may be applied to various other furnaces, such, for
example, as the furnaces or fire-places of puddling furnaces, cooking stoves,
or ranges.
In carrying the second part of our Invention into effect we make the bridge
of the furnace hollow, so as to form an air chamber, and fix on the top of the
said bridge a discharge plate having a number of small perforations made in

page_text: it. A series of perforated plates may be fixed in the said bridge or air
chamber to retard or heat the said air, so as to facilitate combustion. The
lower part of the said hollow bridge opens into the ash-pit, and is provided
with a regulating slide, by means of which the quantity of air entering the
said hollow bridge or air chamber and passing out at the discharge plates at
the top of the said bridge may be regulated at pleasure. By means of a
handle or lever in connection with the said slide the air passing through the
hollow bridge or air chamber and discharge plates is heated and divided before
mixing with the combustible gases passing over the bridge. By the use of
our Invention the combustion of the fuel in steam boiler and other furnaces is
made very perfect, the formation of smoke prevented, and the said fuel
thereby economized.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
.by. the said Thomas Bridges and Joshua Bigwood in the Great Seal
Patent Office on the 31st. May 1867..
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS
BRIDGES, of Wolverhampton, in the County of Stafford, Engineer, and JOSHUA
BIGWOOD, of Wolverhampton, aforesaid Machinist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of December, in the year of our Lord
One thousand eight hundred and sixty-six, in the thirtieth year of Her reign.
did, for Herself, Her heirs and successors, give and grant unto us, the said
Thomas Bridges and Joshua Bigwood, Her special licence that we, the said
Thomas Bridges and Joshua Bigwood, our executors, administrators, and
assigns, or such others as we, the said Thomas Bridges and Joshua Bigwood,
our executors, administrators, 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 THE FURNACES
OF STEAM BOILERS, WHICH IMPROVEMENTS MAY ALSO BE APPLIED TO OTHER
FURNACES," upon the condition (amongst others) that we, the said Thomas
Bridges and Joshua Bigwood, our executors or administrators, by an instru-
ment in writing under our or their hands and seals, or under the hand and
seal of one of us or them, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-

page_text: 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.
NOW KNOW YE, that we, the said Thomas Bridges and Joshua Bigwood,
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, that is to say:-
Our Invention has for its objects, firstly, the introduction of jets of air
at the furnace door, or at the front of the furnace; and, secondly, the intro-
duction of jets of heated air at the bridge of the furnace.
We will describe our Invention in connection with the furnace of a steam
boiler.
In carrying the first part of our Invention into effect we make the furnace
door at which the fuel is introduced hollow, or in the form of a box; the
said hollow door is perforated at back and front, and in the said perforations
tubes are fitted, the said tubes running horizontally from front to back of the
hollow door; the said tubes are also perforated with a number of small holes.
On the front of the hollow door is a perforated sliding plate, having in it
perforations corresponding to the tubes in the door; by sliding the said perfo-
rated plate, which is worked with a lever or handle, the outer openings of the
tubes in the door can be closed, or partially or wholly opened, and the amount
of air entering the furnace at the door thereby regulated. The back plate of
the hollow door has a series of perforations made in it in addition to those in
which the inner ends of the tubes fit. Perforated plates may also be fixed
between the tubes. When the sliding perforated plate is so situated as to
permit the introduction of air through the door the said air entering by the
tubes passes out in great part through the perforations in the said tubes into
the hollow door, and from thence through the perforations in the perforated
plates in the box. and those in the back of the door into the furnace; or the
air may pass directly into the spaces between the tubes in the hollow door
instead of by the perforations in the tubes, as described. By thus making
the air which enters the furnace through the door circulate through and about
the tubes and hollow door which are heated by radiation from the fire, the
said air becomes heated as well as divided into small jets. In order,still more
effectually to heat and divide the air entering the furnace by the door a per-
forated plate (which we call a discharge plate) may be fixed parallel to the
back plate of the door. The air in this case after leaving the door passes
through the perforations in the discharge plate and becomes more effectually
divided into jets. Where it is inconvenient to give the requisite thickness to
the hollow door, as in the furnaces of locomotive, marine, and other boilers, a

page_text: hollow perforated and tubulated box, similar to that herein-before described
as the hollow door. may be placed within the fire-box of the furnace and, made
capable of sliding backwards and forwards in the fire-box. When it is
required to fire the furnace the door is opened and the perforated tubulated
box is pushed by means of a lever in connection with the said door and
tubulated box to the back of the fire-box; fuel is then introduced and the said
box drawn forward, so that on the closing of the door it is situated immediately
behind the door. When, however, the furnace door can be made hollow, in
the manner herein first described, we prefer to employ that arrangement.
In carrying the second part of our Invention into effect we make the bridge
of the furnace hollow so as to form an air chamber, and fix on the top of the
said bridge a discharge plate having a number of small perforations made in
it. A series of perforated plates or tubes may be fixed in the said bridge or
air chamber to retard or heat the said air so as to facilitate combustion. The
lower part of the said hollow bridge opens into the ash-pit, and is provided
with a regulating slide, by means of which the quantity of air entering the
said hollow bridge or air chamber and passing out at the discharge plates at
the top of the said bridge may be regulated at pleasure. The regulating
slide is worked by a handle or lever: the air passing through the hollow
bridge or air chamber and discharge plates is heated and divided before
mixing with the combustible gases passing over the bridge.
Having explained the nature of our Invention, we will proceed to describe,
with reference to the accompanying Drawings, the manner in which the same
is to be performed.
Figure represents in end elevation and Figure 2 in vertical longitudinal
section (partly in elevation) a steam boiler having an internal flue containing
our improvements for admitting jets of heated air at the door and bridge of
the furnace; Figure 3 is a vertical section on a larger scale of a door and its
frame for the furnace of an ordinary boiler, that is, a boiler heated from the
outside; Figure 4 is a front elevation and Figure 5 a hack elevation of the
same, and Figure 6 is a longitudinal section of the same and portion of a
furnace; Figure 7 is a front elevation of a furnace door and parts connected
therewith applied to the fire-box of a locomotive, marine, or similar boiler;
Figure 8 is a vertical section of the same, and Figure 9 is a plan (partly in
section) of the same, a portion being removed; Figure 10 is a plan and end
view of a perforated tubular bridge as herein-after explained.
We will first describe our improvements represented in Figures 1, 2, 3.
The same letters
4, 5, and 6 for admitting jets of air at the furnace door.
of reference indicate the same parts in Figures 1, 2, 3, 4, 5, and 0.

page_text: a is the furnace of the boiler: b, the fire-bars; and c. the ash-pit; the said parts
being of the ordinary construction. The furnace door at which the fuel is intro-
duced consists of a frame or box d. d. e. f, the front and back plates e, f, being
perforated with holes h. i. Across the hollow door or box and into the plates
e. f. tubes are fitted, the ends of the said tubes entering depressions in the said
plates e, f, coinciding with the holes has represented. On the front of the hollow
perforated and tubulated door thus made is a perforated sliding plate 1 having
in it perforations corresponding to the perforations h. i, in the front plate c.
The said perforated plate slides in grooves made in the ribs m. m, fixed on
"the front plate e of the door. The perforated sliding plate 1 is moved hori-
Zontally by means of the handle n. the said handle also serving to open and
close the door. By sliding the plate the proper distance, the holes h, i, in
the front plate e of the tubulated door can be closed or partly, or wholly
opened, and the amount of air entering the furnace at the door thus regulated.
When the perforated plate 1 is so situated that the perforations in it coincide
with those in the front plate e, air enters the tubes and the spaces between
the tubes passes through the said tubes and spaces and escapes in a divided
state by the perforations h, i, in the back plate f of the door into the furnace.
By this means the air entering the furnace passes through the interior, and
circulates about the exterior of the tubes , and also passes through the per-
forations in the front and back plates of the door, and as the said tubes and
plates are heated by radiation from the fire, the said air becomes heated as
well as divided into small jets. The tubes may be perforated if thought
necessary with a number of small holes, so that the air entering the said tubes
may in part pass into the spaces between them, and escape by the perforations
in the back plate, but we prefer to use the arrangement represented in the
Drawings. A perforated discharge plate may be fixed parallel with the back
plate of the tubulated door for the purpose of more effectually dividing and
heating the air entering the furnace by the door. The air in this case after
leaving the door passes through the perforations in the discharge plate, and
becomes more highly heated and divided. In applying this part of our Inven-
tion to the furnaces or fire-boxes of locomotive, marine, and other boilers, as
illustrated in Figures 7, 8. and 9, we make the perforated and tubulated door
in the manner herein-before described, and we prefer to apply to the back of
the said door a perforated plate n. the said plate n turning in a horizontal
plane upon a joint or hinge n° on the fire-box. The plate n carries a per-
forated hood or cover p (omitted in Figure 9). To the said plate na series
of curved tubes q are fitted in the manner best seen in Figure 8, the openings
in the said plate into which the said tubes q are fitted coinciding with the

page_text: perforations in the back plate f of the door, which open into the tubes k. By
this arrangement the air passing through the spaces in the door between the
tubes escapes directly into the fire-box, while the air passing through the
tubes enters the curved tubes q. and is delivered by the said tubes into the
gases in the said fire-box. The perforated and tubulated door and perforated
and tubulated back plate n, q, are connected together by a lever or levers in
such a manner that when the door is opened by its handle r the said back
plate is turned aside on its hinge ³, and the opening in the fire-box thus left
free for the introduction of fuel into the said fire-box. On closing the door
after the introduction of the fuel the plate n is at the same time brought
inmediately behind the said door, as represented in Figure 8, and air may
pass into the fire-box in the manner herein-before described. The parts of
the perforated and tubulated door represented in Figures 7, 8, and 9 are
marked with the same letters as corresponding parts in Figures 1, 2, 3, 4, 5,
and 6.
When it is convenient to use in locomotive, .marine, and other boilers a
perforated and tubulated door of the construction herein-before described the
said door may be omitted, and the hinged perforated and tubulated plate n, q:
be employed in combination with the ordinary door; or instead of the
perforated and tubulated plate n. q. a perforated and tubulated box similar to
the door described and represented may be placed or hinged within the fire-box.
This part of our Invention, besides being applicable to all kinds of steam
boiler furnaces, may be applied to various other furnaces, such, for example, as
the furnaces or fire-places of puddling furnaces and cooking stoves or ranges.
When we apply our perforated and tubulated door to furnaces where an
intense heat is employed, such as in puddling furnaces, we prefer to line the
inside of the door with perforated fire-bricks.
We will now describe our improvements in introducing jets of heated air at
the bridge of the furnace with reference to Figures 1, 2, and 10. At the
back of the bridge plates represented in Figure 2 we form an air chamber t,
and at the top of the said air chamber we place a dividing or discharge plate
or tube 2 having a number of small perforations in it. The air chamber t
communicates with the discharge tube or plate by means of a slot or opening
at . The lower part of the air chamber t opens into the ash-pit c by means
of perforations made in the bridge plate s. In front of the perforations u is
a perforated slide for regulating the quantity of air entering the chamber or
hollow bridge, and passing out at the discharge plate or tube . The slide v
works in grooves in the ribs 2, and is moved the required distance so as to

page_text: open or close or partially close the perforations u in the bridge plate by means
of an arm engaging in a recess in the said slide (see Figure 1). The axis
of the arm is worked by a lever or handle passing along the ash-pit c to the
front of the furnace. A series of perforated plates or tubes may be fixed in the
hollow bridge or air chamber to retard or heat the air. By admitting air at
the bridge in the manner described and represented the said air is heated and
divided into jets before it mixes with the combustible gases passing over the
said bridge.
For boilers which are heated from the outside we use a tubular perforated
bridge of the kind represented in plan and end elevation in Figure 10 of the
Drawings. In this arrangement the end of the hollow perforated bridge a
is situated outside the furnace, and air passes into the said bridge by per-
forations in the said end, the admission of air being regulated by the perforated
slide y. The air passing along the heated bridge becomes heated in contact
therewith, and is delivered in the form of jets into the gases passing over the
said bridge.
By the use of our Invention the combustion of the fuel in steam boiler and
other furnaces is made very perfect, the formation of smoke prevented, and
the said fucl thereby economized.
Having now described the nature of our Invention, and the manner in
which the same is to be performed, we wish it to be understood that we do
not limit ourselves to the precise details herein described and illustrated, as
the same may be varied without departing from the nature of our Invention;
but we claim as our Invention of improvements in steam boiler and other
furnaces.
Firstly, introducing jets of air into the front of the furnace by means of a
perforated and tubulated door constructed, and the admission of air through
the said door regulated, substantially in the manner herein-before described
and illustrated in Figures 1, 2, 3, 4, 5, 6, 7, 8, and 9 of the accompanying
Drawings.
Secondly, introducing jets of air into the front of the furnace or fire-box by
means of a perforated and tubulated box or a perforated and tubulated plate
placed within the furnace or fire-box and immediately behind the door, the
said box and plate being constructed substantially in the manner herein-before
described with reference to Figures 7, 8, and 9 of the accompanying
Drawings.
Thirdly, introducing heated jets of air at the bridge of the furnace by means
of a hollow and perforated bridge or air chamber constructed substantially in

page_text: he manner herein-before described, and illustrated in Figures 1, 2, and 10 of
he accompanying Drawings.
In witness whereof, we, the said Thomas Bridges and Joshua Bigwood,
have hereunto set our hands and seals, this Twenty-eighth day of
May, in the year of our Lord One thousand eight hundred and sixty-
Witness,
T. W. BRIDGES.
Wolverhampton.
THOMAS BRIDGES. (S.)
JOSHUA BIGWOOD. (L.S.)