Year: 1888

page_text: I, JAMES FREDERICK BLYTH of Hill House, Nayland, Suffolk, Engineer do hereby
declare the nature of this invention to be as follows:-
My invention relates to hot air cooking apparatus and more especially to apparatus
of that kind or class described in the Specifications of former Letters Patent granted
to David Grove viz. :-No. 7454 dated the 3rd June 1886, and No. 5358 dated the
9th November 1882.
Cooking apparatus of the kind or class described in the said Specifications as
hitherto constructed, has been found in practice, owing to the unequal distribution in
the cooking chambers or ovens of the apparatus, of the heat generated in the
combustion chamber or furnace, to burn the bread or other substance placed in the
said cooking chambers or ovens, and moreover whilst one portion of the bread or
other substance placed in the said cooking chambers or ovens of the apparatus, is
burned or overdone, another portion of the said bread or other substance is not
sufficiently cooked, thus necessitating the removal of the said bread or other
substance from the apparatus and changing it or turning it end for end. That part or
portion of the said bread or other substance nearest to the furnace door or front of the
apparatus being found in practice to be exposed to less heat than the part or portion
furthest from the said furnace door.
Moreover the draught of the said apparatus is defective.
The main object of my said invention is to obviate the above defects and to provide
an apparatus in which the heat from the combustion chamber or furnace will be equally
distributed in the cooking chambers or ovens.
My said invention comprises moreover various other improvements hereinafter set
forth.
In carrying my said invention into practice I form upon the front part or portion
of the furnace flue or flues a series of circular ribs or gills. Any number of these

page_text: circular ribs or gills may be employed so as to extend for any desired distance upon
the said flue or flues, and the said circular ribs or gills may be of any suitable
diameter or distance apart upon the said flue or flues. By means of these circular
ribs or gills I cause the heat from the flue or flues to be radiated from the front part
or portion of the said flue or flues. I place moreover a baffle plate (in addition to
those already used which run the whole length of the oven) over the smoke box end,
or the extremity of the combustion chamber furthest from the furnace door or front
of the apparatus and continue the said baffle plate for a suitable distance over the fire
clay retort. The said baffle plate is preferably composed of sheets or plates of metal
having between them an internal space filled with any suitable non-conducting
material.
In order to increase the draught in the combustion chamber or furnace, I provide a
suitable number of holes or apertures in the fire door or furnace door with or without
plates or slides or other means for closing or partially closing the said holes or
apertures. I morcover provide holes or apertures in the baffle plate, on the furnace
side of the said door. Instead of the vertical baffle plate usually employed I
sometimes moreover provide a baffle plate placed at an angle to the furnace door
so as to cause the current of air entering the said furnace, through the herein-
before mentioned holes, or apertures, to be thrown downward.
I prefer to construct the bridge or check in the furnace in one piece with the
retort, so that the said bridge or check, cannot be displaced by an injudicious use
of the firing tools. The said bridge or check is moreover provided with as many
holes or apertures as the dimensions of the said bridge or check will admit of thus
materially increasing the draught.
thus
I prefer moreover to form the longitudinal bracings carrying the cooking
chambers, or ovens, of T irons, instead of angle irous as heretofore employed,
increasing the stiffness or rigidity and strength of the apparatus.
I
Moreover the said chambers or ovens are firmly secured to the front of the apparatus
so as to render it impossible or extremely difficult for them to get disconnected by a
shock or otherwise. The T irons on which they rest are turned over at the rear
extremity so as to clutch the bottoms of the chambers or ovens thus obviating
any chance of the said chambers or ovens moving and at the same time allowing
ample room for expansion. The ends of all the said chambers or ovens are dished
so as to allow a longer tray to be employed in the said chambers or ovens.
moreover form the sides of the casing of the apparatus of plates or sheets of metal
running the whole length of the said apparatus, and I camber or curve the top or
upper part of the casing and bend the edges of the same so that the said top or
upper part can be attached to the sides of the said casing by means of bolts
or otherwise. I thus entirely dispense with or considerably reduce the number of
bolts or screws placed in the top or upper part of the casing, as hitherto constructed,
and moreover by cambering or curving the said top or upper part of the casing
it is better adapted to throw off rain, thus in the event of the apparatus being
employed in the open air without any shelter to protect it from the weather, there
is less liability to the temperature of the cooking chambers or ovens situated in
the upper part or portion of the apparatus, being reduced by rain falling upon
the outside of the top or upper part of the casing.
In order to provide means for lengthening the funnel or chimney of the
apparatus, when it may be found desirable or necessary to do So, for the purpose
of increasing the draught, I prefer to construct the said funnel or chimney in one
or more telescopic sections.
In some cases moreover in order to equalize the temperature of the cooking
chambers or ovens that are placed in the same horizontal line in the apparatus,
connect the said cooking chambers or ovens by means of two or any other suitable
number of pipes or tubes.
The other parts of the apparatus are substantially the same as described in the
specification of the former Letters Patent hereinbefore referred to.

page_text: By my improvements I obviate or greatly reduce the herein before mentioned defects
and inconveniencies that have been found to attend the use of the said portable cooking..
apparatus upon practical service, and I provide an apparatus that is strong, and
efficient, and well adapted for the purposes for which portable cooking apparatus are:
usually employed.
Dated thin 7th dove flul 1000
I, JAMES FREDERICK BLYTH, of Hill House, Nayland, Suffolk, Engineer, 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:-
My Invention relates to portable ovens or hot air cooking apparatus and more
especially to apparatus of the kind or class described in the Specifications of former Letters
Patent, granted to Edwin Ambrose Brydges :-No. 5358 dated the 9th November,
1882, and to David Grove No. 1780 dated 19th January, 1884, and No. 7454 dated
the 3rd June, 1886.
U
.1
It has been found in practice that in cooking apparatus of this kind or class as
hitherto constructed the bread or other substance placed in the cooking-chambers
or ovens is liable, by reason of the unequal distribution of the heat generated in the
combustion-chamber or furnace, to be burned or overdone at one side or portion
thereof, whilst another side or portion thereof, viz.:-that portion situated nearest to the"
furnace-loor or front of the apparatus is insufficiently cooked. It has therefore
been necessary to remove the breal or other substance from the apparatus and change
its position therein or turn it end for end. Moreover, the draught in the combustion-
chamber or furnace of the said apparatus as heretofore constructed is defective.
The object of my said Invention is to obviate the above defects, and to provide.
an apparatus in which the heat from the combustion-chamber or furnace will be
uniformly distributed in the cooking-chambers or ovens. And my said Invention
comprises various improvements hereinafter set forth.
In the accompanying Drawings I have. shown how my said Invention may 'be'
coneniently and advantageously carried into practice.
Figure 1 is a front elevation.
:

page_text: flues and
Figure 3 is a transverse section on the line y, y Figure 2, showing one form of my
improved portable oven or cooking apparatus.
Figure 4 is a front elevation.
Figure 5 is a side elevation, and
Figure 6 is an underside view, all drawn to an enlarged scale showing my improved
tray hereinafter described.
Like letters indicate corresponding parts throughout the Drawings.
A is the outer casing of the apparatus; B B are the cooking-chambers or ovens ;
B¹, B¹ are the oven-doors; C is the combustion-chamber or furnace which is provided
with a door C. D D are the furnace-flues. E is the uptake or chimney. F is the
ash-pan or ash-pit.
a, a are circular ribs, gills or flanges either firmly attached to, or forming part
of the front part of the upper furnace-flues D. Any number of the circular ribs
gills or flanges a may be employed extending for any desired distance upon the
said flues D, and the said circular ribs, gills or flanges a may be of any suitable
diameter and placed at any suitable distance apart upon the said flues. al, a¹ are
other ribs or gills which 1 sometimes' provide upon the smoke-box end of the said
upper flues D and upon the rear extremity of the combustion-chamber C. By means
of these circular ribs or gills a, a¹, I greatly augment the heating surface and
consequently increase the radiation of heat from the flue or flues, and by the
employment of these ribs or gills around the front portions of the flues D, I
provide for ensuring a more uniform heating of the ovens than heretofore. Moreover,
I place over the smoke-box end of the combustion-chamber or furnace C, that is
to say, the end thereof furthest from the furnace-door or front of the apparatus, a
baffle-plate 6 which is preferably formed of sheets or plates of metal having between
them an internal space filled with any suitable non-conducting material. 6' is a shield
or heat-separator formed of similar material to the said baffle-plate and extending over
the combustion chamber or furnace C. The said shield and baffle plate are intended
to protect the rear extremities of the ovens or cooking-chambers from excessive heat
and thus more effectually ensure uniform heating of the ovens.
To increase the draught in the combustion-chamber or furnace C, I provide a
suitable number of holes c in the fire-door or furnace-door C' with or without plates
or slides or other means for closing or partially closing the said holes or apertures.
I also provide on the furnace side of the said door, a baffle-plate or dead-plated having
perforations d¹. Instead of placing the said baffle-plate or dead-plate in a vertical
position I sometimes arrange the same at an angle to the furnace-door so as to
cause the current of air entering the said furnace through the holes in the said
door to be thrown or deflected more or less in a downward direction.
e is a bridge or check provided in the furnace C, which is preferably formed in one
piece with the walls of the said furnace so that it cannot be displaced by an
injudicious use of the firing-tools. Holes e¹ are formed in this bridge or check for
allowing heated air to pass through the said bridge or check. e², e², are vertical
bars intended to form a guard for preventing the coals or other fuel from passing
or being forced over the said bridge or check e to the back of the furnace. In
some instances I form these bars of fire-clay. ff are the longitudinal bracings which
carry the cooking chambers or ovens B and which are preferably formed of T-irons
instead of angle irons as heretofore, thus increasing the stiffness or rigidity and
strength of the apparatus. The said ovens B moreover are provided upon the sides
directly over the furnace or combustion-chamber C, with a double casing B² the space
between which is filled with some suitable non-conducting material, and they are
secured rigidly in position in the apparatus by means of set-screws clip-bearers and
square brackets bolted thereto.
I form the sides of the casing A of the apparatus of plates or sheets of metal
running the whole length of the said apparatus the space between the said plates of
sheets being filled up with any suitable non-conducting material, and 1 camber or

page_text: curve the top or upper part of the casing A and bend the edges of the same as shown
at A¹ Figure 3, so that the said top or upper part can be attached to the sides of the
said casing by means of tap-bolts 'g, which are preferably formed of gun metal, instead
of the ordinary bolts, studs or rivets heretofore employed. The apparatus is, moreover
provided with especially strong bearers and transverse angle and tee-irons. By my
improvements, I can dispense with or considerably reduce the number of bolts, studs
or rivets placed in the top or upper part of the casing as hitherto constructed, and,
moreover by cambering or curving the said top or upper part of the casing, I provide
for throwing off rain or snow in a more efficient manner, so that, in the event of the
apparatus being employed in the open air without any shelter to protect it from the
weather there is less liability of the temperature of the cooking-chambers or ovens B
situated in the upper part of the apparatus being reduced by rain or snow falling and
lodging upon the outside of the top or upper part of the casing.
The sides and top being formed continuous, instead of in two or more parts or
sections as hitherto constructed, afford greater rigidity and add to the strength of the
apparatus. A2, A2 are supports upon which the apparatus rests when the travelling
wheels are removed and it is desired to use the apparatus in one place for any length
of time: When employed in this form, my improved portable oven or cooking
apparatus may be used as a stationary oven for use on board ship or elsewhere. A³ are
doors or covers which can be removed for the purpose of cleaning out the flues D.
h, Figures 4 to 6, is an improved tray which I prefer to employ for carrying the
bread or other substance intended to be baked in the cooking-chambers or ovens B.
The tray his formed slightly dished as shown and is provided with corner plates i
formed of manganese steel or other suitable material, and with a wire beading j_to
increase its strength and rigidity. k, k are forged or malleable cast iron handles
attached to the extremities of the tray h by means of plates k¹ riveted or otherwise
secured thereto or the said handles may be carried by the corner plates i. 1, 1 are gun-
metal or other suitable rollers arranged to rotate freely upon spindles l¹ carried by
angle-irons m rivetted and countersunk or otherwise secured to the underside of the
said tray h. The angle-irons m serve, moreover, to strengthen or stiffen the tray h
longitudinally. m', m' are other angle-irons secured transversely, in a similar manner
to the underside of the tray and intended to strengthen or stiffen the said tray
laterally.
In order to provide means for lengthening the funnel or chimney of the apparatus
when it may be found desirable or necessary to do so for the purpose of increasing the
draught, I sometimes construct the said funnel or chimney in one or more telescopic
sections.
The ash-pan or ash-pit F is preferably so constructed that it can he placed inside
the combustion-chamber or furnace C for convenience during transit.
In some cases, moreover, in order to equalize the temperature of the cooking-
chambers or ovens that are placed in the same horizontal line in the apparatus, I
connect the said cooking-chambers or ovens by means of two or any other suitable
number of pipes or tubes.
The other parts of the apparatus are substantially the same as described in the
Specifications of the former Letters Patent herein before referred to.
By my improvements I obviate or greatly reduce the hereinbefore mentioned
defects and inconveniences that have been found to attend the use of the said portable
cooking-apparatus upon practical service, and I provide an apparatus that is strong,
efficient and well adapted to fulfil the purposes for which portable cooking-apparatus
are usually employed.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed I wish it understood that
I claim :-
First. The improved arrangement of the circulating flues whereby I provide for
the equal distribution throughout the apparatus of the heat engendered in the

page_text: combustion-chamber or furnace and for the uniform heating of the ovens, substantially
as set forth.
Second. The combination, with the ovens and the combustion-chamber or furnace
of the flues having the ribs, gills or flanges, substantially as and for the purposes,
set forth.
Third. The combination, of parts comprising the combustion-chamber or furnace
having a door provided with a perforated baffle-plate or dead-plate the perforated bridge
or check and the baffle-plate (with or without. the shield) placed above the said
combustion-chamber or furnace, substantially as described.
Fourth. The improved tray having the corner plates or strengthening plates of
inanganese steel or other suitable material, the wire beading, the stiffening pieces and
the rollers, substantially as and for the purposes set forth.
Fifth. The improved cooking apparatus constructed substantially as described with
reference to the accompanying Drawings.
Dated this 6th day of April 1889.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.