IMPROVEMENTS IN FURNACES
Year: 1883

page_text: LETTERS PATENT to Alfred George Brookes of N° 59 Chancery Lane in the
County of Middlesex Patent Agent for an Invention of IMPROVEMENTS IN
FURNACES communicated to him from abroad by Lyman Pruden French of
Boston in the State of Massachusetts one of the United States of America
PROVISIONAL SPECIFICATION left by the said Alfred George Brookes at
the Office of the Commissioners of Patents on the 30th October 1883.
ALFRED GEORGE BROOKES of N° 59. Chancery Lane in the County of Middlesex
Patent Agent IMPROVEMENTS IN FURNACES " communicated to me from abroad
by Lyman Pruden French of Boston in the State of Massachusetts, one of the
United States of America)
This invention relating to furnaces say for instance in the case of the furnace of
the steam generator of a locomotive engine and has for its object to produce more
perfect combustion of the fuel and to increase the heating effect upon the steam
generator
The furnace is provided with an arch or bridge wall extending from the front of
the fire-box at a point between the flues and grate rearwardly and upwardly
towards the crown sheet, a portion of the said arch adjoining the rear wall of the
fire box above the door through which the fuel is introduced and extending across
the top of the door opening.
The said arch causes the products of combustion and unconsumed gases and
cinders to be directed towards the rear water leg and crown sheet of the fire box
instead of being carried directly forward into the flues and openings are provided
above the said arch at either side of the door through which openings the said
gases and materials pass forward towards the flues.
=
A deflecting wall is employed in front of the upper edge of the said arch, it
being inclined forward and downward and thus with the arch forming a somewhat
contracted throat through which the materials arising from the firo are forced with
great velocity so that the heavier solid materials or cinders are thrown with great
violence against the flue sheet of the fire-box below the flues and are broken in
pieces and consumed instead of entering and clogging the flues

page_text: The arch or inclined bridge wall is according to one arrangement composed of a
thin water chamber or table communicating with the water legs around the fire
box, and a partition or covering which may be composed of refractory material
supported a short distance above the upper sheet of the said water chamber or
table, thus forming a compound arch or bridge wall having an air space or chamber
within it
Inlet passages are made through the water legs from the outside of the fire-box
to admit air to the said air chamber.
The water table is provided with numerous tubular stay bolts or short transverse
tubes connecting the air spaces in the arch with the interior of the fire box, and
thus permitting the air that has entered the said chamber, and become heated
therein, to flow into and be distributed through the fire-box to mingle with the
gases arising from the fire and thus insure the perfect combustion thereof.
By making the lower portion of the arch that is exposed directly to the most
intense heat of the fire a water chamber or table, the heating surface of the steam
generator is increased and clinkers cannot accumulate upon the said arch as
sometimes happens when it is made entirely of masonry.
The openings through or at the upper end of the arch for the passage of the
products of combustion should be made large enough to permit a man to enter
when necessary for the purpose of operating upon the interior of the fire-box or
flues.
The inclined arch or bridge wall is according to another arrangement composed
wholly of masonry supported on water pipes and having an air space or chamber
within it, this form of wall being readily applied to existing furnaces at small
expense and being easily renewed when burnt out.
The deflecting wall has a longitudinal passage through it and outlet openings
from the said passage to the lower edge of the wall, and short pipes or air inlet
tubes pass through the side legs of tho fire-box and enter the ends of the said
passage thus admitting air and also affording a support for the wall.
Dampers or registers are provided for regulating the amount of air thus
introduced through the bridge wall above the fire.
Another object of this invention is to aid the fire of the usual solid fuel burning
upon the grate, at the times when needed, by the employment of auxiliary liquid
or gaseous fuel by means of which an adequate amount of steam is generated with
the least expenditure of fuel
In ordinary furnaces burning coal, when fresh coal is thrown upon the fire it
cools it below the point necessary for the perfect combustion of the smoke and
gases, thus wasting a large portion of the heat producing effect of the fuel and
reducing the steam generating power of the fire as a whole at the very time when
by adding fuel it is intended to increase its power.
This is obviated in the present instance by supplementing at the proper times
the heat produced by the usual solid fuel by injecting a gaseous fuel consisting
of steam and vaporized hydro carbon liquid in the furnace constructed as herein-
before described
The liquid or gaseous fuel is introduced by an injector in the form of a jet,
opposite the openings in or at the upper end of the bridge wall, it passing through
the said openings and the portion not consuined striking against the heated
deflecting wall where complete combustion takes place
The arrangement of the arches or of the bridge wall and deflecting wall is such
as to cause the products of combustion from the solid fuel to pass through a
contracted space or to condense them, as it were, at the point where the gaseous
fuel is introduced, and to thus cause a complete union of the said gases and perfect
combustion.
This invention consists in a bridge wall or arch of a locomotive fire-box extending
from the flue sheet at the lower front portion of the fire-box rearwardly and
upwardly and having a passage over its upper edge for the products of combustion,
combined with a deflecting wall depending from the crown sheet and set in contact

page_text: therewith and inclined forward and downward and approaching the bridge wall,
its lower edge being nearest to the surface of the bridge wall whereby a contracted
throat is formed causing the products of combustion to sweep over the upper surface
of the said arch.
Also in the combination of the bridge wall or arch extending from the lower
front portion of the fire-box rearward and upward with the deflecting wall
inclined forward and downward from the crown sheet in front of the upper end
of the said arch having an internal passage communicating with inlet openings
from the external air and provided with outlet openings into the combustion
chamber.
Also in the combination with the bridge wall or arch extending from the lower
front portion of the fire-box rearward and upward and provided with an internal
air space or chamber having inlet openings communicating with the external air
and outlet openings into the fire-box, of the deflecting wall depending from the
crown sheet of the fire-box downward and forward in front of the upper edge of
the said bridge wall, the said deflecting wall being in contact with the crown
sheet whereby the products of combustion are caused to pass beneath its lower
edge and sweep along the upper surface of the bridge wall.
Also in the combination of the bridge wall or arch extending from the lower
front portion of the fire-box rearward and upward, with the deflecting wall,
depending from the crown sheet at the front of the upper portion of the said bridge
wall, both the said bridge wall and deflecting wall being provided with internal
passages having inlet openings from the air outside of the fire-box and outlet
openings within the fire-box
Also in the combination of the bridge wall extending rearward and upward from
the lower front portion of the fire-box and provided with internal passages having
inlet openings from the external air and outlet openings in the fire-box, with means
for injecting liquid fuel into the fire-box
Also in the combination of the bridge wall and deflecting wall provided with
internal passages, communicating with the external air and with the interior
of a fire box, with means for introducing liquid fuel into the fire-box above the
bridge wall.
Also in the combination of the bridge wall inclined rearward and upward
from the lower front end of the fire-box, and having a passage above it with
the deflecting wall in front of its upper edge and means to project gaseous fuel
over the upper edge of the said bridge wall, and against the said deflecting wall.
Also in the combination with the grate and inclined bridge wall having a passage
above it, with an injecting apparatus located as described for projecting gaseous
fuel into the said passage.
Also in a bridge wall inclined from the lower front wall of the firebox rear-
wardly and upwardly the said wall being composed of two layers of bricks separated
by an air space which opens into the furnace at the upper edge of the wall and
communicates with the air at the outside of the furnace at the lower portion of the
said wall.
Also in a bridge wall inclined from the lower front wall of the fire box
rearwardly and upwardly the said wall being composed of two layers of bricks
separated by an air space which opens into the furnace at the upper edge of the
wall and communicates with the air at the outside of the furnace at the lower
portion of the said wall, combined with the deflecting wall depending from the
crown sheet in front of the upper edge of the said bridge wall, the lower edge of
the said deflecting wall being below the level of the upper edge of the said
bridge wall.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alfred George Brookes in the Patent Office on the 10th April
1884.
"
ALFRED GEORGE BROOKES of N° 50 Chancery Lane in the County of Middlesex
Patent Agent "IMPROVEMENTS IN FURNACES' (communicated to me from 5
abroad by Lyman Pruden French of Boston in the State of Massachusetts one of
the United States of America)
This invention relating to furnaces is shown as embodied in the furnace
of the steam generator of a locomotive engine and has for its object to produce
more perfect combustion of the fuel and to increase the heating effect upon the 1
steam generator.
The furnace is provided with an arch or bridge wall extending from the front of
the fire-box at a point between the flues and grate rearwardly and upwardly
towards the crown sheet, a portion of the said arch adjoining the rear wall of the
fire box above the door through which the fuel is introduced and extending across 1
the top of the door opening
The said arch causes the products of combustion and unconsumed gases and
cinders to be directed towards the rear water leg and crown sheet of the fire box
instead of being carried directly forward into the flues and openings are provided
above the said arch at either side of the door through which openings the said 2
gases and materials pass forward towards the flues.
A deflecting wall is employed in front of the upper edge of the said arch, it
being inclined forward and downward and thus with the arch forming a somewhat
contracted throat through which the materials arising from the fire are forced with
great velocity so that the heavier solid materials or cinders are thrown with great 2
violence against the flue sheet of the fire-box below the flues and are broken in
pieces and consumed instead of entering and clogging the flues.
The arch or inclined bridge wall is shown in one instance as composed of a
thin water chamber or table communicating with the water legs around the fire
box, and a partition or covering which may be composed of refractory material 3
supported a short distance above the upper sheet of the said water chamber or
table, thus forming a compound arch or bridge wall having an air space or chamber
within it.
Inlet passages are made through the water legs from the outside of the fire-box
to admit air to the said air chamber.
The water table is provided with numerous tubular stay bolts or short transverse
tubes connecting the air spaces in the arch with the interior of the fire box,
and thus permitting the air that has entered the said chamber, and become heated
therein, to flow into and be distributed through the fire-box to mingle with the
gases arising from the fire and thus insure the perfect combustion thereof.
By making the lower portion of the arch that is exposed directly to the most
intense heat of the fire a water chamber or table, the heating surface of the steam
generator is increased and clinkers cannot accumulate upon the said arch as
sometimes happens when it is made entirely of masonry.
The openings through or at the upper end of the arch for the passage of the
products of combustion should be made large enough to permit a man to enter
when necessary for the purpose of operating upon the interior of the fire-box
or flues.
3
The inclined arch or bridge wall is shown in another instance as composed
wholly of masonry supported on water pipes and having an air space or chamber 5

page_text: within it, this form of wall being readily applied to existing furnaces at small
expense and being easily renewed when burnt out.
The deflecting wall has a longitudinal passage through it and outlet openings
from the said passage to the lower edge of the wall, and short pipes or air inlet
tubes pass through the side legs of the fire-box and enter the ends of the said
passage thus admitting air and also affording a support for the wall.
Dampers or registers are provided for regulating the amount of air thus
introduced through the bridge wall above the fire.
Another object of this invention is to aid the fire of the usual solid fuel burning
upon the grate, at the times when needed, by the employment of auxiliary liquid
or guseous fuel by means of which an adequate amount of steam is generated with
the least expenditure of fuel.
In ordinary furnaces burning coal, when fresh coal is thrown upon the fire it cools
it below the point necessary for the perfect combustion of the sinoke and gases,
thus wasting a large portion of the heat producing effect of the fuel and reducing
the steam generating power of the fire as a whole at the very time when by adding
fuel it is intended to increase its power.
This is obviated in the present instance by supplementing at the proper times
the heat produced by the usual solid fuel by injecting a gaseous fuel consisting of
steam and vaporized hydrocarbon liquid in the furnace constructed as herein before
described.
The liquid or gaseous fuel is introduced by an injector in the form of a jet,
opposite the openings in or at the upper end of the bridge wall, it passing through
the said openings and the portion not consumed, striking against the heated
deflecting wall where complete combustion takes place.
The arrangement of the arches or of the bridge wall and deflecting wall is such
as to cause the products of combustion from the solid fuel to pass through a
contracted space or to condense them, as it were, at the point where the gaseous
fuel is introduced, and to thus cause a complete union of the said gases and perfect
combustion.
This invention also consists in a furnace, a bridge wall or arch extending from
the front of the fire-box rearwardly and upwardly to the rear wall of the fire-box,
a portion of the said arch adjoining the said rear wall above the door opening
through which the fuel is introduced, and it having openings or passages at
either side of the said door opening for the products of combustion, as will be
described.
Also in a bridge wall or arch of a locomotive fire-box extending from the flue
sheet at the lower point or portion of the fire-box rearwardly and upwardly and
having a passage over its upper edge for the products of combustion, combined
with a deflecting wall depending from the crown sheet and set in contact therewith
and inclined forward and downward, and approaching the bridge wall its lower
edge being nearest to the surface of the bridge wall whereby a contracted throat
is formed causing the products of combustion to sweep over the upper surface of
the said arch.
Also in the combination of the bridge wall or arch, extending from the lower
front portion of the fire-box rearward and upward, with the deflecting wall
inclined forward and downward from the crown sheet in front of the upper end of
the said arch having an internal passage communicating with inlet openings
from the external air and provided with outlet openings into the combustion
chamber.
Also in the combination with the bridge wall or arch extending from the lower
front portion of the fire-box rearward and upward and provided with an internal
air space or chamber having inlet openings communicating with the external air
and outlet openings into the fire-box, of the deflecting wall depending from the
crown sheet of the fire-box downward and forward in front of the upper edge of
the said bridge wall, the said deflecting wall being in contact with the crown sheet

page_text: whereby the products of combustion are caused to pass beneath its lower edge and
sweep along the upper surface of the bridge wall.
Also in the combination of the bridge wall or arch extending from the lower
front portion of the fire-box rearward and upward, with the deflecting wall,
depending from the crown sheet at the front of the upper portion of the said
bridge wall, both the said bridge wall and deflecting wall being provided with
internal passages having inlet openings from the air outside of the firebox, and
outlet openings within the fire-box.
Also in the combination of the bridge wall extending rearward and upward
from the lower front portion of the fire-box and provided with internal passages
having inlet openings from the external air and outlet openings in the fire-box,
with means for injecting liquid fuel into the fire-box.
.
Also in the combination of the bridge wall and deflecting wall, provided with
internal passages, communicating with the external air and with the interior of a
fire-box, with means for introducing liquid fuel into the fire-box above the
.bridge wall
Also in the combination of the bridge wall inclined rearward and upward
from the lower front end of the fire-box, and having a passage above it with
the deflecting wall in front of its upper edge and means to project gaseous fuel
over the upper edge of the said bridge wall, and against the said deflecting wall.
Also in the combination with the grate and inclined bridge wall having a passage
above it, with an injecting apparatus located as described for projecting gaseous
fuel into the said passage.
Also in a bridgo wall inclined from the lower front wall of the fire box
rearwardly and upwardly the said wall being composed of two layers of bricks
separated by an air space which opens into the furnace at the upper edge of the
wall and communicates with the air at the outside of the furnace at the lower
portion of the said wall.
Also in a bridge wall, inclined from the lower front wall of the fire box
rearwardly and upwardly the said wall being composed of two layers of bricks
separated by an air space which opens into the furnace at the upper edge of
the wall and communicates with the air at the outside of the furnace at the
lower portion of the said wall, combined with the deflecting wall depending
from the crown sheet in front of the upper edge of the said bridge wall, the lower
edge of the said deflecting wall being below the level of the upper edge of the
said bridge wall.
Figure 1, is a vertical longitudinal section of a locomotive fire-box embodying
this invention
Figure 2, a horizontal section thereof on line x-x Figure 1, a portion of the
refractory shell or portion forming the upper member of the bridge wall being
broken away to show the lower portion of the bridge wall or water space with its
air passage.
Figure 3, a detail showing the register for controlling the admission of air.
Figure 4, a vertical longitudinal section of a fire-box on a smaller scale showing
the bridge wall as composed wholly of masonry, and
Figure 5, a perspective view of one of the pairs of bricks of which the said wall
is made.
The fire-box a having a grate b and door or opening c for the introduction of
fuel may be of any suitable or usual construction the walls of the said fire-box
being shown in this instance as composed of water spaces or legs d, e, f, such as
commonly employed in the furnaces of locomotive boilers
The said fire-box is provided with an arch or bridge wall h extending from the
lower front portion of the fire-box in an inclined direction rearwardly and upwardly
it being shown in Figures 1 and 2 as terminating above the door c, where the said
arch is connected with or butts against the rear wall or water leg f of the furnace
The said wall is provided with openings 3 at its highest end at either side of the
door c, the said openings being bounded by the front and side walls e, f, of the

page_text: fire-box and affording a passage for the products of combustion to the flues F and
usual smoke stack or up-take of the furnace.
The said arch is shown in Figures 1 and 2, as composed of a water chamber or
table i included between two sheets or plates i¹ connected together by numerous
tubular stay bolts or short tubes, which constitute perforations or air passages
through the said water table or chamber which has above it a partition or covering
portion preferably made of refractory material supported a short distance above
the upper sheet of the water table so as to produce an air chamber m, between
the portions i, k, of the arch, the said perforations ; permitting air to flow from the
said chamber m to the fire-box above the fire.
The portion of the arch is shown as made of bricks the length of which is
equal to about one half the width of the fire-box, the said bricks having flanges k',
on the under side at their ends by which they are supported upon the water
table i, a sufficient distance above it to give the air space or chamber m sufficient
deptb.
Air is admitted to the chamber m through suitable tubes or openings n through
the walls of the fire-box the said openings being shown as provided with mouth
pieces n having gauze or perforated plates n³, to act as strainers, and containing
suitable dampers or registers n³, by which the amount of air entering through them
can be regulated, the said registers being operated by suitable mechanism such for
example as the rod n*, see Figure 3, from the interior of the cab.
The furnace is provided with a deflecting arch or wall o, made of refractory
material and preferably having a longitudinal passage o¹, and outlet openings o³
leading therefrom to the lower edge of the wall.
The said longitudinal passage o¹ is connected at its ends with inlet tubes p,
passing through the side legs e of the fire-box and extending a short distance
into the said passage as shown and thus affording a support or bearing for the
said wall.
The middle portion of the wall o which may be made in two pieces is supported
by bolts r depending from the crown sheet and provided with lugs supported on
washers a for adjusting its height, and a cross pin t, the said lug entering a socket
in the brick or bricks of the wall.
The said bolts and lugs being at the front of the wall o are protected from the
direct action of the fire and burn away only after a long time.
The water table i has to be made as permanent part of the fire box and is of
considerable expense.
In order to avoid such increase in cost of making the fire-box, or in cases where
the present invention is to be applied to furnaces already in use, the bridge wall
may be made as shown in Figure 4, wholly of masonry supported on water pipes t¹
connected with the crown and flue sheets of the boiler by suitable couplings t¹.
Such a masonry wall is preferably composed of two layers k³, k³, of fire brick or
refractory material, the said layers being separated from one another by flanges on
the bricks as shown in Figure 5, or otherwise, to include an air space or chamber
between them, which space or chamber opens directly into the furnace at the upper
edge 4 of the arch and communicates with the openings n through the wall of the
fire-box, so that air is admitted to the interior of the said bridge wall heated
therein, and delivered at its upper edge into the furnace where it combines with
the gases.
A suitable space is left above the wall h for the entire width of the fire box for
the passage of products of combustion to the flues F.
The cinders that are raised from the bed of the fire have to follow a very devious
path before arriving at the tubes F, being thrown against the rear end of the fire-
box and crown sheet and the wall o, so that they are broken up and reduced in
size and are exposed for such a long time to the intense heat of the combustion
chamber that but very few arrive at or pass into the said tubes.
By having the arch h extended over the door c of the fire-box as shown. in
Figures 1. and 2, the. Ques. and. main beating..surface of the steam generator is
-

page_text: protected from the direct access of cold air, when the door c is opened for tho
introduction of fuel, and it also prevents the finer portions of the fuel being thrown
in from being carried by the draught over the bridge wall.
The deflecting wall arranged as shown with relation to the crown sheet and
arch its lower edge being below the level of the upper edge of the said arch / or
above the edges of the openings 3 therein, when constructed as shown in Figures 1
and 2, causes the products of combustion to rush with great velocity down the
upper surface of the said arch preventing any deposit thereon, and the few cinders
that are not previously consumed are caused to strike against the flue sheet at
the front of the fire-box below the flues instead of being thrown directly into the
said flues.
The escape of cinders from the smoke stack is thus almost wholly prevented, and
the combustion is rendered so perfect that scarcely any smoke is produced and the
heat is moreover throughly distributed over the surface of the fire box, so that
with a given quantity of fuel the generation of steam is considerably increased over
that of ordinary furnaces.
In some cases it is desirable to be able to increase the generation of steam still
further, which may be accomplished by the employment of gaseous fuel in addition
to the usual coal burning on the grate as follows:-
The gaseous fuel consisting of petroleum or other hydrocarbon fluid supplied to
the injectors u is projected by a jet of steam which combines with it into the
space above the passages 3 in the bridge wall hand strikes against the deflecting
wall o acting upon the said wall with a very intense heat.
The said gaseous fuel is comsumed in passing across the upper portion of the
fire-box, and the heat thus generated is sufficient to insure perfect combustion of
the gases arising from the solid fuel before arriving at the flues in which the beat
is always maintained above the condensation point, thus preventing the deposit of
soot therein.
It is not new to employ a rearwardly and upwardly inclined bridge wall either
made as a portion of the water space of the boiler or made of masonry supported
on water tubes, and it is also not new to employ in connection with such an
inclined bridge wall a deflecting wall at the front of its upper edge, but in those
cases in which two walls have been employed previous to the present invention
the upper wall has been so arranged as to form an obstruction to the flow of gases
and cinders towards the flues, the said gases being thrown into eddies and the
cinders deposited in large quantities on the upper surface of the bridge wall and in
the flues, and 'such arrangement is not herein claimed
Bridge walls have previously been made with passages for the introduction of
air to the furnace and are not in themselves hercin claimed.
The two walls when having the peculiar arrangement herein described with
relation to one another are of great advantage to the furnace even when they are
not adapted to admit heated air thereto, and such walls are considered to be within
the scope of the present invention.
By making the bridge wall when of masonry in two separate layers the unequal
expansion of the upper and under surfaces does not destroy the bricks and it is
found in practice to be hetter to permit the air to escape at the upper open end of
the wall rather than through perforations, as the latter are apt to cause the rapid
destruction of the bricks owing to the rapidity of the flow through them and
also to the difference in temperature between the air and the heated surface of
the bricks.
Some portions of the apparatus herein described may be applied to the furnaces
of stationary boilers with good results.
Having thus described the nature of the said invention and means adapted for
carrying the same into practical effect, I would have it understood that What I
claim is
1. In a furnace the bridge wall or arch extending from the front of the fire-box
rearwardly and upwardly to the rear wall of the firo-box, a portion of the said arch
E

page_text: adjoining the said rear wall above the door opening through which the fuel is
introduced and it having openings or passages at either side of the said door
opening for the products of combustion, substantially as described.
2. In a locomotive fire-box a bridge wall or arch extending from the flue sheet at
the lower front portion of the fire-box rearwardly and upwardly and having a
passage over its upper edge for the products of combustion, combined with a
deflecting wall depending from the crown sheet and set in contact therewith and
inclined forward and downward and approaching the bridge wall, its lower edge
being nearest to the surface of the bridge wall, whereby a contracted throat is
formed causing the products of combustion to sweep over the upper surface of the
said arch, substantially as set forth.
3. The combination of the bridge wall or arch, extending from the lower front
portion of the fire-box rearward and upward, with the deflecting wall inclined
forward and downward from the crown sheet in front of the upper end of the said
arch having an internal passage communicating with inlet openings from the
external air and provided with outlet openings into the combustion chamber,
substantially as and for the purpose described
4. The combination with the bridge wall or arch extending from the lower front
portion of the fire-box rearward and upward and provided with an internal air
space or chamber having inlet openings communicating with the external air and
outlet openings into the fire box, of the deflecting wall depending from the crown
sheet of the fire box downward and forward in front of the upper edge of the said
bridge wall, the said deflecting wall being in contact with the crown sheet whereby
the products of combustion are caused to pass beneath its lower edge and sweep
along the upper surface of the bridge wall, substantially as described.
5 The bridge wall or arch extending from the lower front portion of the fire-box
rearward and upward, combined with the deflecting wall, depending from the crown
sheet at the frout of the upper portion of the said bridge-wall, both the said bridge
wall and deflecting wall being provided with internal passages having inlet openings
from the air outside of the fire-box, and outlet openings within the fire box,
substantially as described.
6 The combination of the bridge wall extending rearward and upward from the
lower front portion of the fire-box and, provided with internal passages having
inlet openings from the external air and outlet openings in the fire-box, with means
for injecting liquid fuel into the fire-box, substantially as described.
7. The combination of the bridge wall and deflecting wall, provided with internal
passages, communicating with the external air and with the interior of a fire-box
with means for introducing liquid fuel into the fire-box above the bridge wall
substantially as described.
8. The combination of the bridge wall inclined rearward and upward from the
lower front end of the fire box, and having a passage above it with the deflecting
wall, in front of its upper edge and means to project gaseous fuel over the upper
edge of the said bridge wall and against the said deflecting wall, substantially as
described.
9. In a furnace the grate and inclined bridge wall having a passage above it,
combined with an injecting apparatus located as described for projecting gaseous
fuel into the said passage, substantially as set forth.
10. The bridge wall inclined from the lower front wall of the fire box rearwardly
and upwardly, the said wall being composed of two layers of bricks separated by
an air space which opens into the furnace at the upper edge of the wall and
communicates with the air at the outside of the furnace at the lower portion of the
said wall substantially as described.
11. The bridge wall inclined from the lower front wall of the fire-box rearwardly
and upwardly the said wall being composed of two layers of bricks separated by an
air space which opens into the furnace at the upper edge of the wall and commu-
nicates with the air at the outside of the furnace at the lower portion of the said
wall, combined with the deflecting wall depending from the crown sheet in front

page_text: of the upper edge of the said bridge wall, the lower edge of the said deflecting wall
being below the level of the upper edge of the said bridge wall, substantially as
described.
In witness whereof I the said Alfred George Brookes have hereunto set my
hand and seal this tenth day of April in the year of our Lord one thousand
eight hundred and eighty four.