CERTAIN IMPROVEMENTS IN THE CONSTRUCTION OF BAKING OVENS, AND ALSO CERTAIN MACHINERY FOR WORKING OR USING THE SAME
Year: 1849

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
HARRISON, of Liverpool, in the County of Lancaster, Merchant, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-eighth day of
March, One thousand eight hundred and forty-nine, in the twelfth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Thomas Harrison, my exors, admors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Thomas Har-
rison, my exors, adñiors, and assigns, and such others as I, the said Thomas
Harrison, my exors, admors, or assigns, should at any time agree with, and
no others, from time to time and at all times during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick upon Tweed, my Invention of
"CERTAIN IMPROVEMENTS IN THE CONSTRUCTION OF BAKING OVENS, AND ALSO CERTAIN
MACHINERY FOR WORKING OR USING THE SAME;" in which said Letters Patent is
contained a proviso that I, the said Thomas Harrison, should cause a particular
description of the nature of my said Invention, and the manner in which the

page_text: same is to be performed, by an instrument in writing under my hand and
seal, to be inrolled in Her said Majesty's High Court of Chancery within
six calendar months next and immediately after the date of the said in part
recited Letters Patent, as in and by the same, reference being thereunto
had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Thomas Harrison, do hereby declare that the nature of my said Invention,
and in what manner the same is to be performed, are fully described and ascer-
tained in and by the present Specification thereof, reference being had to the
Drawings hereunto annexed, that is to say:-
Figure 1 is a front elevation of a set of baking ovens constructed according
to my said improvements. Figure 2 is an end view of the front of the ovens;
and Figure 3 a plan of Figure 2. A, A, are the ovens, which are built one
over the other for the sake chiefly of economizing space and heat, and may be
of any convenient number, either more or less. They are of about six times
greater depth or length than breadth, and have each doors at both ends, one
through which the biscuits or other articles to be baked are introduced, and
the other through which the articles when baked are removed. Each of these
ovens is worked by means of an endless revolving bottom B, (Fig. 4,) which is
carried on side rollers C, C, throughout the length of the oven, and turns
round larger rollers D, D, at the two ends, which are driven by a steam engine
or other first mover. The articles to be baked are delivered directly from a
cutting or dividing machine, such as is ordinarily used in biscuit baking
machinery on to the endless bottom B, which takes them in at one end and
turns them out at the other.
A plan of this bottom is given in Figure 5. M, M, is one of two sides
chains, each of which is formed of single and double links a and b connected
by pins c, c, like the chain of a watch spring. N, N, are a series of wires, which
are inserted crosswise into the links of the chains M, M, at a distance of about
three quarters of an inch apart, and rivetted thereto. P, P, are wire chains,
of the same length as the side chains M, M, but formed of single links, which
are connected lengthwise to the middle of the cross wires, in order to prevent
the latter from bending or springing, and to keep them at their assigned dis-
tances from each other. The links a and b of the main chains M, M, are
three inches and three eighths of an inch long, by five eighths of an inch in
breadth; the double ones are a quarter of an inch, and the single ones a
three sixteenths of an inch in thickness. The cross wires N, N, are made
alternately of round wire of an eighth of an nch diameter, and of flat wire of

page_text: an eighth of an inch in breadth by a quarter of an inch in thickness. I find
that a revolving bottom made of chains and wires of the above-specified dimen-
sions and connected together in the manner described, is amply sufficient to
carry biscuits or any other articles of like weight, and will maintain an even
surface and run true for a great length of time. But where the articles
required to be baked are of a heavier description, such as loaves, cakes, &c.,
I propose to substitute an endless chain of solid iron plates hinged together.
The side rollers which bear up the revolving bottom are mounted in frames
secured to the floor of the oven, as represented in Figuro 6 (a side view of
one of these frames), Figure 7 (an end elevation), and Fig. 8, a plan. Aª is
a basement plate, which is sunk into a recess made in the floor F of the oven
close by the side wall G. F is a pedestal raised on the basement A, and
secured to it by bolts E, E. C, C, represent a set of rollers, one placed above
the other, which have their bearings in the pedestal, and turn freely on their
axles. The rollers are flanged, in order to keep the revolving bottom from
swerving as it passes over them, and the flanges are sunk in the faces of the
frames to prevent the chains from getting entangled by them. B', B', are
wedges used to raise the rollers as may be required. The large driving
rollers D, D, are made six-sided, and each side of a breadth corresponding with
the length of the links a, b, and P, of the endless bottom. No studs or spurs
are used to take hold and carry round the endless bottom, the strain of the flat
links on the hexagonal sides being found quite sufficient for the purpose.
Driving rollers of a circular or other plain form with studs or spurs may,
however, be used if preferred. The rollers (of whatever shape) are placed
inside the ovens, and their axles carried out at one end through the side
walls, as shewn in the front elevation, Figure 1, the pulleys by which they
are worked from the steam engine being attached to these outward prolonga-
tions of the axles. The working of the ovens being thus effected with closed
doors, there is as little loss of heat as may be attending the operation. In order
that the revolving bottom may be tightened or slackened as may be required,
the axles of the driving rollers D, D, are secured in slides moved by screws, in
the manner represented in Figure 9. A is a slide frame, attached to the door
frame of the oven; B, a slide; C, the axle of one of the rollers; D, a clutch
plate, to fasten the axle with; E, a screw pin; F, a nut, by which the screw G
is worked, which moves the slide B; H is the line of the oven wall.
A longitudinal section of one of the ovens, shewing how the articles are
A is the oven;
delivered into it and how discharged, is given in Figure 4.
R¹, front door; R2, back door; B, the endless bottom, which revolves round

page_text: the rollers D, D, and is borne by the side rollers C, C; T is the endless cloth of
the cutting machine, from which the biscuits or other articles are delivered on
to an inclined plane of polished iron V₁, from which they pass forward to the
revolving bottom B; V" is another inclined plane (similar to V¹), which
receives the articles as they are turned from off the revolving bottom at the
back of the ovens, and conducts them forward to a basket or other suitable
receptacle.
Instead of employing an endless revolving bottom, and causing the biscuit or
other articles to go in at one end of the oven and go out at the other, a reci-
procating bottom may be used, and the articles turned out at the same end at
which they are introduced (one door being thereby dispensed with).
In that
case the reciprocating motion may be best obtained by means of a vertical
rack, working in pinions on the outward prolongations of the shafts of the
hexagonal driving rollers D, D.
The driving rollers may be also worked by continuous wheel gearing
(instead of either of the modes before pointed out), providing always that such
gearing is in correspondence with the motion of the cutting machinery.
The continuous rotary motion may be stated as being generally preferable
wherever the biscuits or other articles to be baked are supplied to the ovens by
machinery moved in like manner, and the intermittent motion as answering
best where the ovens are filled and emptied by hand.
The bottoms B, B, (whether revolving or reciprocating) may be also
extended beyond the front and back doors of the ovens, and the driving
rollers D, D, be also placed outside, and indeed in all cases where the articles
to be baked are of such a description that they can only be conveniently intro-
duced and taken out by hand into the ovens, this will be found the most
suitable arrangement. Great care, however, must be taken to make the doors
fit as close down as may be upon the (revolving or reciprocating) bottoms.
In working on either principle a set of four ovens, such as represented in
Figures 1, 2, and 3, and of twenty-six and a half feet in length by four and a
half feet in breadth, which gives an area equal to the placement of about one
and a half cwt. of hexagonal biscuit, the motive parts of the machinery are
stopped as soon as the ovens are filled, which occupies about a couple of
minutes. The doors are then closed for about twenty-six minutes, after which
the doors are re-opened and the motive power is applied at such a speed to
the revolving bottom that it shall deliver in about two minutes more the entire
quantities with which the ovens have been charged. I would prefer, however, to
have the ovens longer, and the bottom revolving continuously at such an

page_text: adjusted speed that the biscuits should be completely baked while passing
through from the front to the back of the oven. But in that case the driving
rollers must of necessity be placed outside of the oven doors, and these doors
must have apertures in them just sufficient to allow the revolving bottom and
biscuits to pass through, accompanied with as little cold air as may be.
The heating of the ovens is effected by the improved arrangements repre-
sented in Figures 10, 11, and 12, of the annexed Drawings. Figure 10 is a
sectional elevation; Figure 11 a ground plan, and Figure 12 a transverse
section of a set of four ovens (similar to that before described) shewing the
details of this part of my Invention. I discard altogether the direct applica-
tion of fire to the ovens, and make use of hot air only. The hot air is admitted
as equably as may be by inlet pipes A, A, into an air chamber B, which
extends the whole way under the floor of each oven, and each floor is made of
perforated tiles t, t, laid on bricks x, x, so placed as to allow the hot air to
ascend freely between them. Apertures C, C, of suitable dimensions are
made in the top of each oven for the escape of the used air, whence it flows
into an up shaft D, which is carried up alongside of the series of ovens and is
common to the whole. The up shaft terminates in a receiving chamber E³,
which extends the whole way along the top of the uppermost oven, and from
this chamber the hot air passes off finally into the atmosphere through the
chimney F. Both the inlet and outlet passages have valves attached to them,
which are worked by connected rods from the front of the ovens, whereby
complete controul is obtained over the quantities of air both admitted and dis-
charged.
Having now described the nature of my said Invention, and in what manner
the same is to be performed, I declare that what I claim as of my Invention is,
firstly, the constructing of baking ovens in tiers one above the other, having
each either one or two doors, and containing each revolving or reciprocating
bottoms worked from the outside, as beforo described.
Secondly, the heating of baking ovens by the circulation of hot air through-
out and around the same, as before described.
In witness whereof, I, the said Thomas Harrison, have hereunto set my
hand and seal, this Twenty-eighth day of September, in the year of our
Lord One thousand eight hundred and forty-nine.
THO (L.S.) HARRISON.

page_text: AND BE IT REMEMBERED, that on the Twenty-eighth day of September,
in the year of our Lord 1849, the aforesaid Thomas Harrison, came before
our said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and everything therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Enrolled the Twenty-eighth day of September, in the year of our Lord
One thousand eight hundred and forty-nine.