IMPROVEMENTS IN OVENS FOR BAKING BREAD
Year: 1865

page_text: LETTERS PATENT to John Dauglish, of Reading, in the County of
Berks, M.D., for the Invention of "IMPROVEMENTS IN OVENS FOR BAKING
BREAD"
Sealed the 7th November 1865, and dated the 15th May 1865.
PROVISIONAL SPECIFICATION left by the said John Dauglish at the
Office of the Commissioners of Patents, with his Petition, on the 15th
May 1865.
I, JOHN DAUGLISH, of Reading, in the County of Berks, M.D., do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN OVENS FOR
BAKING BREAD," to be as follows:-
These improvements relate to ovens, known as travelling or mechanical
ovens, in which the material to be baked is made to enter at one mouth or
opening, whilst the material after it has been baked is discharged at another
separate and distinct opening or tail; these ovens are usually constructed
with a moveable bottom, which by a slow, regular, but intermitting motion
passes from end to end of the oven in the manner of an endless chain placed
round two drums or rollers, one roller being placed at the entrance mouth or
opening, and one at the exit opening, by which means the material to be
baked can be conveyed from the mouth to the tail. Such ovens are con-

page_text: structed of considerable length, but narrow, the length being in some instances
as much as 10 or 11 times greater than their breadth, but in others not more
than twice or three times. On account of their great length, in proportion to
breadth, it bas been found very difficult to regulate the heating of these ovens
so that soft bread which requires to be well cooked and kept moist at the
same time shall be subjected to the necessary temperature during the period
of its entire passage through the oven from the mouth to the tail. Now I
find that this can be most effectually accomplished by constructing the oven, so
far as the heating is concerned, in several distinct compartments, each with its
separate furnace and flues, but so far as the baking chamber, in which the
bread is placed, is concerned, making this one continuous space. Thus in an
oven 20 feet long and 4 feet wide I would divide the heating into two, three,
or more compartments, which would be each a separate oven having its mouth
and tail, but the mouths and tails of all being placed end to end would make
one long continuous baking space or oven. Again, it has been found
extremely difficult to prevent the prejudicial escape of steam as well as heat
from the mouth and tail of these ovens owing to the fact that the supply of
fresh material to be baked, and the exit of the baked material, are going on
continuously whilst the material is being baked. Now I find that I can
prevent all prejudicial escape of steam and heat by the following arrangement,
viz., 1st, I place the drums or rollers carrying the travelling bottom as they
are usually placed, the one at the tail of the oven just inside the baking space
and the one at the mouth of the oven outside the baking space, but I place
this latter a little farther from the mouth than usual. At the tail I place an
inclined sheet of metal at an angle of 45 degrees, or nearly so, to receive the
loaves as they are tilted over by the revolution of the drum; this incline
passes down sufficiently low that its lower edge shall be several inches below
the bottom of the baking space. Over this incline I place a metal hood,
having its upper edge fastened to and continuous with the crown of the baking
space and its lower edge on a level with the lower edge of the inclined plate,
these two being made continuous at the sides by plates of metal form a close
shoot having its mouth downwards and below the bottom of the oven. To
this mouth a door is fitted like a valve opening downwards and kept shut by
balance weight so regulated that as the baked material slides down the shoot
it falls upon the door, and immediately its weight causes the door to open
downwards and discharge the loaves into a basket, when the door immediately
closes again. At the mouth or entrance into the oven I place two doors, one
close to the mouth, which is made to open and shut by sliding up and down
vertically, the other outside of this, moving on a hinge (or in any convenient

page_text: manner) leaving a space between the two doors capable of receiving one or
more rows of loaves to be baked in the moveable bottom which passes from
the roller outside immediately under these doors into the oven. These doors
are made to open and shut by an arrangement of apparatus actuated by the
same power that gives motion to the moveable bottom, so that the opening
and shutting of these doors, and the movement of the bottom, exactly
harmonize. Thus the bottom is made to move during a certain number of
seconds and to remain still or at rest for a given number of seconds. Whilst
the bottom is moving forward the inner door remains at rest open, and the
outer door remains at rest shut. Immediately the chain stops and rests the
inner door is made to sbut followed immediately by the opening of the outer
door. The chain and the two doors (the inner shut, the outer open) all
remain at rest for a few seconds, during which time the loaves to be baked
are placed on the bottom between the two doors, the outer door then shuts,
the inner opens; these then remain at rest whilst the bottom moves forward,
carrying the loaves placed between the two doors into the oven, when the
inner door again shuts, and the movements continue to be repeated. By this
means it will be seen that the mouth of the oven is never open, as it is always
closed by one or the other of the two doors. In order to give facility for
ascertaining the manner in which the baking is being performed, and for
regulating the heat and speed of the oven I place small glazed windows at
intervals along the sides of the oven through which light can be reflected and
the baking can be watched in its progress.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Dauglish in the Great Seal Patent Office on the 15th
November 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN.
DAUGLISH, of Reading, in the County of Berks., M.D., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of May, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-eighth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Dauglish, Her special licence that I, the said John
Dauglish, my executors, administrators, and assigns, or such others as
I, the said John Dauglish, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time, and at all

page_text: 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 " IM-
PROVEMENTS IN OVENS FOR BAKING BREAD," upon the condition (amongst others)
that J, the said John Dauglish, 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 John Dauglish, do hereby declare
the nature of the 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 thereof, reference being had to the Drawings hereunto annexed,
that is to say :-
Figure 1 shows an external elevation of one side of the two ends of an
oven constructed according to my Invention; Figure 2 shows a longitudinal
section of Figure 1; and Figure 3 shows a transverse section taken on the
dotted line z, z, in Figure 2. This oven is constructed long in proportion to
its width, and is divided into several sections, with a furnace or fire-place and
flues, with apparatus for regulating the heat of each section. There are also
glazed openings on one or both sides at intervals, in order that the progress
of the baking may be observed, and where necessary gas or other artificial
lights are applied exterior of such openings so as to light the interior of the oven.
One end of the oven is so arranged that the loaves or such like articles to be
baked, either in tins or shapes, or on trays or surfaces, which may be readily
moved into the receiving chamber at the mouth of the oven when the hood
or cover is raised. The mouth of the oven is also provided with a sliding
door, which is arranged to be closed when the hood or cover of the receiving
chamber is open as hereafter explained; within the oven is an endless chain
of plates of sheet iron, or it may be of other material, which is periodically
moved a short distance after the hood or cover to the receiving chamber is
closed, and the sliding door at the mouth of the oven is open. This endless
chain of plates is similar to what has been before used in ovens.
Ovens constructed according to my Invention may be divided into any
desired number of sections according to the purpose to which they may be
applied. The arrangement shewn in the Drawing is such as is employed in
baking 2 lb. loaves of aerated bread, and is about 50 feet long and 10 feet
wide, and is divided into five sections, each section having its fire-place or

page_text: urnace and flues with glazed light and sight oven or openings. At the
further or tail end of the oven there is formed a descending passage, which is
losed by a weighted valve which opens when a quantity of the bread descends
thereon. By these arrangements it will be seen that the bread is periodically
received into the oven and discharged therefrom, whilst the vapours interior of
the oven are prevented from escaping prejudicially from the oven, whilst the
heat of each section of the oven being capable of regulation enables the baker
to vary the heat of different sections according as he may from time to time
observe the progress of the baking as it is going on, and he can judge at what
part of the oven it is desirable to get such a top heat as may be desired in
order to produce crust in the upper surfaces of the bread.
In ordinary aerated bread much of the rising of the dough takes place
before the loaves are introduced into an oven, whilst ordinary bread made
with yeast rises considerably after it is introduced into an oven, and such is
the case in respect to aerated bread, the dough for which is drawn under
pressure, and the loaves are immediately conveyed into an oven; it is de-
sirable that these latter classes of bread should be subjected to a bottom heat
during the rising, whilst the upper parts of the loaves are not subjected to a
heat which will quickly produce crust to such an extent as to prejudice the
rising. By having a long oven heated in sections, with power to regulate the
heat in each section, the baker can modify or regulate the application of the
heat so as to get more or less top heat to any of the sections, and thus retard
or advance the period of forming the crust on the upper surfaces of the loaves
according as he may judge desirable.
In Figures 1 and 2 the one section, and the parts of two other sections
of an oven, constructed according to my Invention, are shewn, that is, the
whole of the first section A into which the bread is first received, a part of
the second section B, and a part of the last section Z, at the end of which the
baked bread is discharged down the inclined passage. All the intermediate
sections are made or constructed like the second section B. It is desirable
that the periodical movement of the endless chain of plates, and the periodical
opening and closing of the hood or cover of the receiving chamber of the
oven, and also the periodical opening and closing of the door at the mouth of
the oven should be derived from one motion, so that these movements may
be correctly timed one to the other. This may be done in various ways
by suitable gearing. I, however, prefer the arrangement which is partly
shown in the Drawings, and the action of which I will now describe.
a is an axis or stud, on which is placed and turns the spur or cog wheel b
which gears into the intermediate wheel c, by which motion is communicated

page_text: is connected at one
to the spur or cog wheel d on the shaft of the roller e, which gives motion to
the endless chain of plates f, f, f, which extends from end to end of the oven,
and is properly supported therein, as is well understood. g is a driver on the
lever h, one end of which turns freely on the axis or stud a; this driver by
taking in between the teeth of the spur or cog wheel b gives motion thereto,
and consequently each time the lever his raised the endless chain of plates
will be moved a distance sufficient to move the bread which is placed on to
that part of the endless chain which for the time is in front of the sliding
door i beyond the door when such door is open, and the hood or cover j of
the receiving chamber k is closed. The connecting rod
end to the lever h, and its position on that lever may be varied or adjusted by
the screw h¹, so as to cause the driver on the lever to take hold at a greater
or less distance on the wheel b. The other end of the rod I receives a suitable
up-and-down motion from a cam or other suitable means fixed on a shaft
driven by a steam engine or other power. m is another connecting rod, which
receives an up-and-down motion at the times desired from a cam or other suit-
able means on the same shaft which gives motion to the rod l. The movements
to the rods and m are so arranged that the one is at rest whilst the other is
open, and vice versa; the rod m is at its lower end pinjointed to the lever n,
which at its other end is pinjointed to the rod o, to which the sliding door i of
the oven is attached; p is a connecting rod, which is pinjointed to the lever n
at its upper end, whilst its lower end is pinjointed to the hood or cover j of the
receiving chamber; hence, immediately the hood or cover j is fully down the
sliding door at the mouth of the oven begins to rise, and immediately the
sliding door i is fully down or shut, then the hood or cover j begins to open;
there is, however, a slight pause in the motions of the rods and m when the
sliding door i is fully down and the hood or cover j is fully open to allow of
the bread to be baked being placed in the chamber between the sliding door i
and the hood or cover j. q, q, are fire-places, one to each section of the oven.
The heat and products of combustion first heat the bottom r of the oven, it
then rises up through the flues & into the space t above the oven. At the
upper part of the fluess there are slides v. If the slide v be closed and the
slide 1. open, all the products from the fire passing up the flues s, s, will pass
over the top of the oven, and thence through the opening covered by the
slide into the flue w, and thence into the passage w¹ leading to the chimney;
but if the slide v¹ be closed and the slide v open, then the products of com-
bustion will pass through the opening covered by the slide when closed, and
will pass off to the chimney, offering less heat to the top of the oven than
when the slide v is open and the slide v¹ is closed. If both slides be partially

page_text: open more or less of the products may be directed in one way or the other.
This system of separate fire flues and slides or valves is applied to each of the
sections of the ovens. By these means the mode of applying the heat in each
section of the oven will be thoroughly under the control of the baker, whilst
by the aid of the glazed openings x and light thrown into the oven the baker
will, without opening the end or mouth of the oven, readily ascertain what is
the progress of the baking in each section of the oven, and thus be enabled to
vary or modify the heat in any or all the sections of which an oven is con-
structed. y is a descending passage, down which the loaves descend on to the
door y', which then opens; but so soon as the loaves have passed through, the
door closes by the weight y³ acting thereon.
In the Drawings the oven is shown to be formed of fire-bricks or tiles sup-
ported by iron girders, but the materials employed, and the manner of putting
such materials together in building an oven, according to my Invention, may
be varied.
What I claim is, the combined arrangement or combination of oven herein
described.
In witness whereof, I, the said John Dauglish, have hereunto set my
hand and seal, this Eleventh day of November, in the year of our
Lord One thousand eight hundred and sixty-five.
JOHN DAUGLISH. (L.S.)