IMPROVEMENTS IN PORTABLE OVENS
Year: 1876

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVEMENTS IN
PORTABLE OVENS." A communication from abroad by Eugène Paul Geneste,
Charles Georges Herscher, and Ernest Herscher, all of Paris, in the Republic of
France, Engineers.
Sealed the 9th March 1877, and dated the 5th October 1876.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 5th October 1876.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN PORTABLE OVENS." A communication from abroad
by Eugène Paul Geneste, Charles Georges Herscher, and Ernest Herscher, all of
Paris, in the Republic of France, Engineers.
This Invention relates to portable ovens intended more particularly for the use of
armies in campaign, and it consists of a peculiar arrangement and combination of
ovens mounted upon wheels, which enables the operation of baking to be as
efficiently and rapidly performed as in fixed ovens, whilst at the same time admitting
of a considerable saving being effected in the consumption of fuel. The arrange-
ment is moreover adapted to the use of any description of fuel, which constitutes a
great practical advantage over the ordinary portable ovens:
The apparatus is composed of two ovens placed one above the other and enclosed
in a metal case, which forms the body of a vehicle or carriage. This vehicle or
carriage suspended upon springs is mounted upon two axles and four wheels.
The two ovens are constructed with their mouths at the back of the carriage.
The interior of each oven is composed of a flooring of brickwork of heat-resisting
material, arranged in the manner herein-after described, and of a sheet-iron roof or
arch. Each arch is lined or covered with insulating incombustible material, such
for example as asbestos, or a layer or coating may be employed composed of silicate
of potash and asbestos in fibres in equal proportions.
In order to form an additional security against cooling a similar layer or coating
may be applied to the interior of the external casing of the carriage.
The two ovens are heated by means of wood placed upon the floor or hearth and
77

page_text: heating the roof or arch by direct action; the cinders are then withdrawn, and the
bread is introduced in the place previously occupied by the fuel.
The arches covered with asbestos impart to the bread the heat which they have
absorbed and the baking is accomplished. Two independent chimneys serve to
carry off the smoke from the ovens.
The general construction of the carriage is designed with a view to protect it
against the deterioration resulting from the direct action of the flame upon the
metallic surfaces. The rigid part is composed of two longitudinal pieces of sheet
metal, by which the carriage is suspended. Upon these longitudinal pieces thero
are placed parallel cross pieces of metal plate carrying at their extremities iron
uprights which form the external casing or framework of the carriage. Suitably
curved Tirons connect together all the external uprights; these T irons themselves
form part of the ribs supporting the floor of the upper oven.
The sheet-iron arches are placed a short distance below the curved T irons, and
are supported by or connected to the same by means of numerous iron rods, which
ensure the regularity of the space between the ribs and the arches. This space is
occupied by the asbestos, the uniform distribution of which is preserved by reason
of the number of the rods before mentioned. This arrangement has the advantage
of obviating all liability to the distortion of the roofs or arches, whatever may be
the action of the fire, as their rigidity depends upon that of the ribs, which are
placed at such a distance from the fire as to preclude all danger of injury. The
carriage is provided with a seat on the fore part, and is arranged to be drawn by
two or four, or any other required number of horses. It is also provided with a
movable metal hood which when required serves to form a shelter over the oven
mouths. This hood may be arranged to slide in grooves on the carriage or to be
lowered on hinges, so as to protect the oven mouths while travelling.
The paving of the oven is arranged in such a manner that a brick of any
description may suffice to replace temporarily a damaged square. It is composed by
preference of very light metal boxes each of which receives a separate brick, so as
to avoid the lateral wear of the bricks during the shaking of the journeys, and to
enable a damaged brick to be temporarily replaced by any ordinary brick under an
emergency.
The chimneys or funnels are arranged so as to be capable of being turned down
while the vehicle is in motion, and suitable means are provided for the adjustment
of the registers of the flues and for the working of the oven mouths and shutters
with which the oven mouths are fitted.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Henry Johnson in the Great Seal Patent Office on the 5th
April 1877.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN PORTABLE OVENS." A communication from abroad
by Eugène Paul Geneste, Charles Georges Herscher, and Ernest Herscher, all of
Paris, in the Republic of France, Engineers.
The said Invention relates to portable ovens intended more particularly for the
use of armies in campaign, and it consists of a peculiar arrangement and combination
of ovens mounted upon wheels, which enables the operation of baking to be as
efficiently and rapidly performed as in fixed ovens, whilst at the same time
admitting of a considerable saving being effected in the consumption of fuel. The
arrangement is moreover adapted to the use of any description of fuel, which
constitutes a great practical advantage over the ordinary portable ovens.
The apparatus is composed of two ovens placed one above the other and enclosed
in a metal case which forms the body of a vehicle or carriage. This vehicle or
carriage suspended upon springs is mounted upon two axles and four wheels,

page_text: And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the accompanying Sheet of Drawings, the same letters of
reference indicating corresponding parts in all the Figures.
Figure 1 of the accompanying Drawings represents a longitudinal sectional
elevation of the apparatus; Figure 2 is a transverse sectional elevation of the
same; and Figure 3, an end elevation viewed from behind.
The two ovens F, F1 are constructed with their mouths ff, at the back of the
carriage. The interior of each oven is composed of a flooring of brickwork A of
heat-resisting material, arranged in the manner herein-after described, and of a
sheet-iron roof or arch B. Each arch is lined or covered with non-conducting
incombustible materials, such for example as asbestos, which is preferred on account
of its relatively great calorific power, its low density, its quality of being a bad
conductor of heat, and its property of not becoming deteriorated to whatever
degree of heat it may be exposed, or a layer or coating may be employed composed
of silicate of potash and asbestos in fibres in equal proportions.
In order to form an additional security against cooling a similar layer or coating
may be applied to the interior of the external casing of the carriage.
The two ovens F, F1, may be beated in the usual manner by means of wood or
other fuel placed upon the floors or hearths and heating the roofs or arches by direct
action; the cinders are then withdrawn, and the bread is introduced in the place
previously occupied by the fuel.
The arches B covered with asbestos impart to the bread the heat which they have
absorbed, and thus the baking is accomplished. Two independent chimneys M, M',
serve to carry off the smoke from the ovens.
The general construction of the apparatus is designed with a view to protect it
against the deterioration resulting from the direct action of the flame upon the
inetallic surfaces. The rigid part is composed of two longitudinal metal girders p,
by which the apparatus is suspended, and upon which there are placed parallel cross
pieces g of metal plates, say about 8 inches apart, carrying at their extremities iron
uprights which form the external casing or framework of the apparatus. Suitably
curved Tirons & connect together all the external uprights, the Tirons of the lower
oven forming part of the ribs supporting the floor of the upper oven.
The sheet-iron arches B are placed at a distance of, say about 5 inches, below the
curved Tirons 8, and are supported by or connected to the same by means of
numerous iron rods or long bolts t, which ensure the regularity of the space between
the ribs and the arches. This space is occupied by the asbestos, the uniform
distribution of which is preserved by reason of the number of the rods or bolts
before mentioned. This arrangement has the advantage of practically preventing
the roofs or arches from becoming distorted, whatever may be the action of the
fire, as their rigidity depends upon that of the ribs s, which are placed at such a
distance from the fire as to preclude all danger of injury. The apparatus is
suspended upon springs S' carried upon axles S2, upon which are mounted the
running wheels S; it is provided with a seat S' on the fore part, and in the
example illustrated is arranged to be drawn by two or four horses. It is also
provided with a moveable metal hood T, which when required serves to form a
shelter over the mouths of the ovens. This hood may be arranged to slide in
grooves on the carriage or to be lowered on hinges, so as to protect the oven mouths
while travelling.
The paving of the oven is arranged in such a manner that a brick of any
description may suffice to replace temporarily a damaged square. It is composed by
preference of very light metal boxes, each of which receives a separate brick, so as
to avoid the lateral wear of the bricks by the shaking in the journeys, and to
enable a damaged brick to be temporarily replaced by any ordinary brick under an
emergency.
Figures 2 and 3 illustrate the arrangement adopted with regard to the chimneys
or funnels, which are constructed so as to be capable of being turned down while

page_text: J. HENRY JOHNSON. (L.S.)