A NEW INVENTION OF A PERPETUAL OVEN FOR THE BAKING OF ALL KINDS OF BREAD
Year: 1810

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, Sir ISAAC
COFFIN, Baronet, Vice Admiral of the Blue Squadron of His Majesty's Fleet,
send greeting.
WHEREAS His most Excellent Majesty King George the Third, by
His Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Fifteenth day of May, in the fiftieth year of His.
reign, did give and grant unto me, the said Sir Isaac Coffin, my executors,
administrators, and assigns, His special licence, full power, sole privilege
and authority, that I, the said Sir Issac Coffin, my executors, administrators,
and assigns, and every of them, during the term of fourteen years therein
expressed, should and lawfully might make, use, exercise, and vend the
Invention therein mentioned, to wit, "A NEW INVENTION OF A PERPETUAL OVEN
FOR THE BAKING OF ALL KINDS OF BREAD," within that part of the United
Kingdom of Great Britain and Ireland called England, the Dominion of
Wales, and Town of Berwick-upon-Tweed, in such manner as to me, the said
Sir Isaac Coffin, my executors, administrators, and assigns, or any of them,
should seem meet; to have, hold, exercise, and enjoy the said licence, powers,.
privileges, and advantages therein granted or mentioned to be granted unto
me, the said Sir Isaac Coffin, my executors, administrators, and assigns, for
and during, and unto the full end and term of fourteen years from the date
of the said Letters Patent next and immediately ensuing, and fully to be
complete and ended, according to the Statute in such case made and provided;
in which said Letters Patent there is (amongst other things) contained a

page_text: proviso that if I, the said Sir Isaac Coffin, should not particularly describe
and ascertain the nature of my said Invention, and in what manner the same
is to be performed, by an instrument in writing under my hand and seal, and
cause the same to be inrolled in His Majesty's High Court of Chancery
within two calendar months next and immediately after the date of the said
Letters Patent, that then the said Letters Patent, and all liberties and
advantages whatsoever thereby granted, should utterly cease, determine, and
become void, as in and by the said recited Letters Patent, reference being
thereunto had, will more fully appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Sir Isaac Coffin, do hereby declare that the said Invention of a perpetual
oven for the baking of all kinds of bread, consists of, and is constructed and
used, as follows:-
It is called a perpetual oven because the operation of baking may be
continued for any length of time uninterruptedly. It is best made of an
oblong form, as shown in the annexed Drawing, of sufficient length and
breadth for the work contemplated, and is constructed of brick, stone, iron,
or of any other proper and convenient material for the construction of ovens.
A chamber A, B, in which the bread, &c. is baked, extends from end to end
of the oven, and is open at both ends; the one in the annexed Drawing,
intended for baking sea biscuits, is twenty feet long and four feet wide; it is
ten inches in height at the end farthest from the grate or grates on which the
fire is made, and decreases to six inches at the end where the fire-places
are; but these dimensions vary with the nature of the articles to be baked.
The chamber is heated by means of flues C and D, one of which passes under s
its bottom and the other over its top; these flues proceed from two fire-
places or grates E and F below, one of which is situated on each side of the
same end of the oven, and are of such form and dimensions as are in propor-
tion to the heat required and the nature of the fuel used.
In the oven
represented in the annexed Drawing, where wood is intended to be used, the s
arches for the fire-places are five feet long, eighteen inches wide, two feet high,
and are provided with iron doors and grates and an ash-pit below. The heat
ascends from one of these fire-places E through proper openings into a flue
or space C under the floor of the chamber to be heated, which extends the
length and width of it, so that the heat spread, underneath the whole floor 3
of the chamber from the end where the fire-place is to the other, where it, or
part of it, ascends with the smoke into a flue G, carried immediately under
the top of the oven, by which is conveyed to a chimney at the end where
the fire-places are, and there passes off. The heat from the other fire-place F

page_text: ascends into a flue or space D immediately above the ceiling or roof of the
heated chamber, extending also the whole length and width of it, so that, after
heating the said upper floor or ceiling of the chamber, the smoke, &c. ascends
and returns along the same highest flue or passage G to the chimney with
the smoke, &c. of the other fire-place; or this highest flue G may be divided
longitudinally into two parts, and the one half serves to convey away the
smoke, &c. of the fire-place E, and the other that of the fire-place F. By
means of this highest flue or returning chimney G, the upper exterior surface
of the oven is always kept warm, for seasoning the bread, &c. which may be
laid upon it. For the moro equal diffusion of the heat in the flues imme-
diately below and above the heated chamber, pieces of cylindric or square
bricks, stone, or metal, from two and a half to three inches in thickness, arc
placed in them at regular distances from each other, which may serve like-
wise to support the floors above them. The floor and ceiling of the heated
chamber may be of tiles made of fire-clay, or of fire-stone, or of cast or sheet
iron, or other metal, or of any material which stands fire and readily transmits
heat; if of well-made tile the thickness need not exceed one to one and a half
inch, but should be thickest at the ends nearest the fires; the joints must be
close, and may be rebated and laid in cement so as not to admit smoke from
the under and upper flues. The floor of the heated chamber may be supported
on props, as already mentioned, or it may rest on transverse iron bars, whichi
latter must at all events be used to support its ceiling or roof, placed at such
distances that each tile may rest upon them. The bottom of the lower flue C
is supported by an arch of bricks, or of whatever other material is used in the
construction of the oven, which arch is of the same width as the heated
chamber, and extends the whole length of the oven, and is open at both
ends, having under it the passage H. Near each end of the oven is a roller
or cylinder I and K, of cast iron or of wood cased with sheet iron, of about
three feet in diameter, and as long as the heated chamber is wide; the axis of
which cylinders are supported upon frames of iron or wood, as shewn in the
Drawing. Over these cylinders passes an endless web of wire cloth, of iron
or other metal L, L, of somewhat open mash and rather course and strong,
of nearly the width of the heated chamber, which it traverses near the floor,
and returns below through the passage H between the two fire-places; it is
kept from rubbing on the floor of the chamber by iron friction rollers of two
to three inches diameter, and from six to twelve inches apart, lying across the
When this oven is used
chamber, and having their axes upon an iron frame.
for baking, it is first brought to a sufficient heat by means of the fires and
flues above described; the biscuits or bread is then placed upon the endless

page_text: web of of wire cloth, at the end farthest from the fires, and, by turning the
cylinder or roller next the fire-place slowly, it passes on with the web into the
heated chamber, and, by properly proportioning the slowness of the motion to
the degree of heat, which experience will soon teach, it will come out at the
end where the fire-places are, sufficiently baked, and may then either be taken
off or suffered to fall off; fresh biscuits or bread must be continually laid on
the wire cloth as it enters, so that a regular and constant succession is
kept up. A very light door of sheet iron or other metal may be hung at each
end of the chamber from the top, so as to prevent the escape of much heat;
and not to interfere with the entrance and exit of the wire cloth and
substances to be baked. The ceiling of the heated chamber rises gradually
from the end where the fire is made to the opposite end where the bread
enters, for the purpose of facilitating the issue of the steam from the bread or
biscuit at the end at which they enter; four to six inches in the whole length
is a proper rise in the chamber of an oven of the dimensions of that above
described and represented in the annexed Drawing, but may admit of variation
according to circumstances.
Cord wood is the best fuel to use upon the grates, but peat or coaks, or those
kind of pit coal which emit little smoke, may also be used; coals which
gencrate much soot would too soon choak up the flues, and prevent the heat
from penetrating the tiles.
A variation in the construction of the oven is made as follows:-A singlé
fire-place is made at one end of the arch under the heated chamber, the flamė
and heat of which pass through a flue immediately under the floor of the
chamber to the other end of the oven, where they-ascend-by-perpendicular_flues
to another horizontal flue carried immediately above the ceiling or roof of the
chamber, which returns to the end next the fire, and there opens to the air by
means of a small chimney on each side of the oven; and as by this construc-
tion the endless web is precluded from passing under the chamber, it is turned
upwards over a cylinder at each end and passes back over the top of the oven.
The bread, &c. is put in as before at the end, farthest from the fire, and when
.it arrives at the end nearest the fire is either taken off by hand, or pushed off
by sloping pieces of wood placed across the web, which slide into baskets at
the sides. In smaller ovens the endless web may be dispensed with, and the
wire cloth stretched upon a light iron-frame of the length of the oven, which,
with the bread, &c. placed upon it, is pushed in at the end farthest from the
fire and gradually advanced to the other, at which it is as gradually withdrawn.
By this mode of baking time, fuel, and labour are saved, and other advan-
tages are attained, for the bread, &c. when first put into the oven goes into

page_text: the lowest heat, and regularly advances to a hotter situation as it dries, and is
better able to endure it; the drying is also facilitated by the escape of the
steam at the end of the chamber where the bread enters, instead of being
confined as in the common oven, and the bread or biscuit lying upon an open
wire leaves the heat free to act upon all parts of it; by this means the biscuit,
&c. is dryer when it leaves the oven than in the old mode, and will keep
longer; the baker also has it in his power to roll the biscuit, &c. out of the
oven the moment he discovers it to be baked enough; and he may keep
the oven regulated at the proper heat by means of thermometers and a
judicious management of the fires.
In witness whereof, I, the said Sir Isaac Coffin, have hereunto set my
hand and seal, the Twenty-ninth day of May, in the year of our Lord
One thousand eight hundred and ten.
Sealed and delivered, being first duly
stamped, in the presence of
JOHN BLACKMAN.
Tam Ta
ISAAC (L.s.) COFFIN.
stamped, in the presence of
JOHN BLACKMAN.
JOHN TERSDALE.
AND BE IT REMEMBERED, that on the same Twenty-ninth day of May,
in the year above mentioned, the aforesaid Sir Isaac Coffin came before our
Lord the King in His Chancery, and acknowledged the Specification afore-
said, and all and everything therein contained, in form above written. And
also the Specification aforesaid was stamped according to the tenor of the
Statute in that case made and provided.
Inrolled the Thirtieth day of June, in the year above written.