IM- PROVEMENTS IN TERRA COTTA STOVES AND FIRE-POTS
Year: 1877

page_text: LETTERS PATENT to Thomas Gemmell, of the City of Baltimore, State of
Maryland, one of the United States of America, for the Invention of "IM-
PROVEMENTS IN TERRA COTTA STOVES AND FIRE-POTS."
Sealed the 12th February 1878, and dated the 20th August 1877.
PROVISIONAL SPECIFICATION left by the said Thomas Gemmell at the Office
of the Commissioners of Patents on the 20th August 1877.
THOMAS GEMMELL, of the City of Baltimore, State of Maryland, one of the
United States of America. "IMPROVEMENTS IN TERRA COTTA STOVES AND FIRE-
POTS."
.
: This Invention relates, first, to a stove having its shell or outer body and its top
or cover of composite construction, they being formed of blocks of terra cotta, soap-
stone, or other substance having similar heat-retaining properties contained by a
metallic casing, frame, or skeleton.
The said Invention relates, secondly, to a fire-pot of composite construction, that
is to say, a fire-pot or fire-holder to be used in stoves or otlier apparatus in which
fire-clay, terra cotta, or other similar heat-retaining substance is combined with
metal to form a complete structure.
In the stove embodying the present improvements the fuel is consumed in the
fire-pot, which is placed in the interior of the composite shell, but separate there.
from;
and both the said shell and fire-pot rest upon a hollow base adapted to serve
as an ash receptacle, and as means for communication between the outer air and the
interior of the aforesaid fire-pot.
The said Invention consists, first, in adapting terra cotta, soapstone, or other like
heat-retaining substance in blocks as the outer casing for a stove.

page_text: The said Invention consists, secondly, in a novel method of constructing a sec-
tional sheet-metal casing or frame for securing together the blocks of terra cotta,
soapstone, or other heat-retaining substance, whereby a complete composite stove
body or outer casing is formed.
The said Invention consists, thirdly, in constructing the body or outer casing of
the stove of blocks of terra cotta, soapstone, or other heat-retaining substance
secured within and by a metallic frame or skeleton adapted to hold and retain
them in place. The construction of the stove body is such as to permit the
radiated heat from the fire-pot or fire-holder to impinge directly on the inner
surface of the terra cotta blocks, there being no intervening obstructive inner
metallic casing.
The said Invention consists, fourthly, in a top for the said stove, wherein a block
of terra cotta, soapstone, or other heat-retaining substance forms the outer and the
main portion thereof, it being contained by a metallic frame or ring, or secured to a
metallic plate adapted to serve as the means for connection between the said terra
cotta block and the stove body or casing.
The said Invention consists, fifthly, in the manner of securing the aforesaid com-
posite top or lid, or in hinging the same to the body or outer casing of the stove.
The said Invention consists, sixthly, in the manner of effecting a gas and air tight
joint between the said stove body and the hollow base thereof.
The said Invention consists, seventhly, in the composite construction of the fire-
pot or fire-holder, it being formed like the aforesaid stove body or outer casing; or
of a cylindrical case of sheet iron with a lining of fire-clay or other refractory sub-
stance, and perforated or imperforated, as may be preferred; or of cast or wrought
iron bars with spaces between them; and, further, in providing the said fire-pot
with a lip or projection at its upper edge to facilitate its removal from or its replace-
ment in the stove body or outer casing.
The said body or outer casing of the stove consists of sheet-iron strips flanged in
such manner as to allow them to be rivetted or otherwise fastened together to form
packets, into which blocks of terra cotta, soapstone, or other substance having
similar heat-retaining properties are inserted. The said blocks are secured within
the pockets formed by the sheet-metal strips by turning or flanging the vertical
edges of the said strips which project beyond the said blocks. This flanging may
be performed either before or after the insertion of the blocks in the pockets. The
latter method requires the blocks to be placed in the pockets from either of their
ends instead of from their outer faces.
Another method of constructing the body or outer casing of the stove is to place
an annular block of terra cotta or a series of blocks of the same material over a
sheet metal cylinder. This design requires no special fastening devices for the terra
cotta or soapstone blocks.
The stove body or outer casing, which is either polygonal or cylindrical, is pre-
ferably removable from the hollow base, but may be permanently attached thereto
if desired.
According to a modification of this Invention the body or outer casing of the
stove consists of blocks of terra cotta, soapstone, or other heat-retaining substance
confined within and by a metallic frame or skeleton formed of an upper and a lower
frame plate or ring connected by vertical ribs having their 'outer edges flanged or
beaded to form shoulders, by means of which the said blocks are held in place.
The stove is fitted with a heat-retaining lid or cover 'constructed of a block of
terra cotta, soapstone, or the like, contained by a ring or frame of metal, and it is
made either separate and removable, or, preferably, hinged to the said frame, 'as
shown.
A close joint is formed between the stove body or outer casing and the lid or
cover, either by providing the upper end of the stove body with a depression or
annular groove, into which asbestos, sand, or other yielding fire-proof material is
placed, and providing the under face of the lid or cover with an annular projection

page_text: or ring, which imbeds itself in the said material when the cover is closed; or by
inserting between the lid or cover and the stove body a gasket of lead or other soft
metal, or of asbestos, felt, or other similar substance.
The joint between the stove body or casing and the hollow base may be made by
means of a gasket in like manner to the joint above described.
The aforesaid hollow base has a central aperture in the upper plate thereof, over
which the fire-pot or fire-holder is supported. The said fire-pot is provided with a
perforated bottom to admit air to the burning fuel contained therein, and its body
is either formed of sheet iron lined with fire-clay to prevent the burning and wasting
of the metal, or of wrought or cast iron bars. forming a framework, the spaces
between the bars permitting heat to freely radiate from the fuel to the stove body or
outer casing of the stove.
The said fire-pot is however preferably constructed as follows, that is to say, of
blocks of fire-brick, or hardened refractory clay, or other heat-retaining substance
contained by a metallic framework, and in this respect the construction corresponds
very closely with that of the stove body or outer casing above described.
In all cases it is desirable to perforate the fire-pot to quicken the heat-radiating
action of the fire upon the inner surface of the stove body without interfering
materially with the heat-retaining properties of the fire-pot.
The stove is further furnished with dampers or registers to regulate the admission
of air to the interior of the hollow base, and thence to the interior of the fire-pot;
and also with a smoke pipe fitted with a damper to carry off the products of com-
bustion to a flue or chimney.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Geinmell in the Great Seal Patent Office on the 16th February
1878.
THOMAS GEMMELL, of the City of Baltimore, State of Maryland, one of the
United States of America. "IMPROVEMENTS IN TERRA COTTA STOVES AND FIRE-
POTS."
This Invention relates, first, to certain improvements in a stove having its shell
or outer body and its top or cover of composite construction, they being formed of
blocks of terra cotta, soapstone, or other substance having similar heat-retaining
properties contained by a metallic casing, frame, or skeleton.
The said Invention relates, secondly, to a fire-pot of composite construction, that
is to say, a fire-pot or fire-holder to be used in stoves and in other ways in which
fire-clay, terra cotta, or other similar heat-retaining substance is combined with
metal to form a complete structure, as will herein-after fully appear.
In the stove above referred to the fuel is consumed in the fire-pot, which is
placed in the interior of the composite shell, separate therefrom; and both the said
shell and fire-pot rest upon a hollow base adapted as an ash receptacle and as
means of communication between the outer air and the interior of the fire-pot
aforesaid.
The said Invention relates, thirdly, to the application of my improved composite
construction to stoves wherein the fuel is consumed in a fire-pot formed by a portion
of the stove body, as herein-after described.

page_text: The said Invention consists, first, in adapting terra cotta, soapstone, or other like
heat-retaining substance in blocks as the outer casing for a stove.
The Invention consists, secondly, in a novel method of constructing a sectional
sheet-metal casing or fraine for securing together the blocks of terra cotta, soapstone,
or other heat-retaining substance, whereby a complete composite stove body or outer
casing is formed.
The Invention consists, thirdly, in constructing the stove body or outer casing of
the stove of blocks of terra cotta, soapstone, or other heat-retaining substance
secured within and by a metallic frame or skeleton adapted to hold and retain
them in place. The construction of this stove body is such as to permit the heat
radiated from the fire-pot or fire-holder to impinge directly on the inner surface of
the terra cotta blocks, there being no intervening inner metallic casing to serve as
an obstruction thereto.
The Invention consists, fourthly, in a top for the said stove, wherein a block of
terra cotta, soapstone, or other heat-retaining substance forms the outer and the
main portion thereof, it being contained by a metallic frame or ring, or secured to a
metallic plate adapted as the means of connection between the said terra cotta block
and the stove body or casing.
The Invention consists, fifthly, in the manner of securing the aforesaid composite
top or lid, or in hinging the same to the stove body or outer casing of the stove.
The Invention consists, sixthly, in the manner of effecting a gas and air tight joint
between the said stove body and the hollow base thereof.
:
The Invention consists, seventhly, in the composite construction of the fire-pot or
fire-holder, it being formed in like manner to the stove body or outer casing before
mentioned; or of a cylindrical case of sheet iron with a lining of fire-clay or other
refractory substance, and perforated or imperforated as may be preferred; or of cast
or wrought iron bars with spaces between them; and, further, in providing the
said fire-pot with a lip or projection at its upper edge to facilitate its removal from
or its replacement in the stove body or outer casing.
In the further description of the Invention which follows reference is made to the
accompanying Drawings, in which,—
Figures 1, 2, 3, and 4 are respectively a vertical section, a side elevation,
a sectional plan, and an exterior plan of an octagonal stove embodying my
improvements.
Figures 5, 6, 7, and 8 are similar views of a stove of substantially the same con-
struction, but hexagonal in shape.
Figures 9, 10, 11, and 12 are similar views of an octagon-shaped stove illustrating
some slight modification in construction; and Figures 13 and 14 are views of parts
of the said stove on an enlarged scale.
Figures 15, 16, 17, and 18 are views of a square or quadrangular stove made in
accordance with the present improvements; and Figures 19 and 20, details of the
said stove on an enlarged scale.
Figures 21 and 22 are respectively a vertical section and a sectional plan of the
.fire-pot, showing a construction thereof similar to that of the stove body or outer
casing illustrated in Figures 9 to 20 inclusive; and Figures 23 and 24 illustrate
parts of said fire-pot or fire-holder on an enlarged scale.
Figures 25, 26, and 27 are respectively a vertical section, an exterior elevation,
and a sectional plan of a composite stove in which the fuel is consumed in a fire-
pot formed by a part of the stove body; and Figure 28 is a plan of a part of the
.said stove.
Figures 29 and 30 represent respectively a vertical section and an exterior eleva-
tion of a stove, similar in construction to that shown in Figures 25, 26, and 27; and
Figures 31, 32, 33, 34, and 35 are views of portions of the said stove on an enlarged
scale.
Figures 36, 37, and 38 are respectively a sectional elevation, an exterior elevation,

page_text: and a sectional plan of a stove having heat-retaining pipes or columns of composite
construction adapted to convey gases and products of combustion of the fuel in an
indirect manner to the stove pipe; and Figures 39 and 40 are views of parts of
the said stove on an enlarged scale, showing certain modifications in their
construction.
Similar letters of reference indicate similar parts in all the Figures.
The stove body or outer casing of the stove, illustrated in Figures 1 to 8 inclusive,.
consists of sheet-iron strips A flanged in such manner as to admit of their being,
riveted or otherwise fastened together to form pockets, into which blocks B of terra
cotta, soapstone, or other substance having similar properties of retaining heat are
inserted. The blocks B are secured within the pockets formed by the sheet-metal,
strips A by turning or flanging the vertical edges of the said strips projecting
beyond the said blocks, which flanging may be performed either before or after,
the insertion of the blocks to the pockets. The latter method requires the blocks
to be placed in the pockets from either of their ends, instead of from their
outer faces.
Another method of constructing the stove body or outer casing of the stove is to
place an annular block of terra cotta, or a series of blocks of the saine material, over,
a sheet-metal cylinder. This design requires no special fastening devices for the terra
cotta or soapstone blocks.
The stove body or outer casing, which is either polygonal or cylindrical, is
preferably removable from the hollow base C, but it may be attached thereto if
desired.
The stove body or outer casing of the stove, illustrated in Figures 9 to 20 inclu-
sive, consists of blocks of terra cotta, soapstone, or other heat-retaining substance
confined within and by a metallic frame or skeleton formed of an upper and a lower
frame plate or ring, represented respectively by D and E, connected by vertical
ribs F, having their outer edges flanged or beaded so as to form shoulders by means
of which the blocks B are held in place.
The stove is fitted with a heat-retaining lid or cover G, constructed of a block of
terra cotta, soapstone, &c., contained by a ring or frame of metal, and it is made
either separate and removable, or, preferably, hinged to the said frame, as shown.
A close joint is formed between the stove body or outer casing and the lid or
cover G in two ways:-By providing the upper end of the stove body with a
depression or annular groove a, into which asbestos, sand, or other yielding fire-proof
material is placed, and the under face of the lid or cover with an annular projection
or ring, which imbeds itself in the said material when the cover is closed; or by
inserting between the lid or cover and the stove body a gasket b of lead or other
soft metal, or of asbestos, felt, or other similar substance.
The joint between the stove body or casing and the hollow base may be made by
means of a gasket in like manner to the joint above described.
The hollow base C before alluded to has a central aperture in the upper plate
thereof, over which the fire-pot or fire-holder H is supported. The said fire-pot is
provided with a perforate bottom to admit air to the burning fuel contained
therein, and its body is either formed with sheet iron lined with fire-clay to prevent
the burning and wasting of the metal, or of wrought or cast iron bars forming a
framework, the spaces between the bars permitting heat to freely radiate from the
fuel to the stove body or outer casing of the stove.
The preferred method of constructing the fire-pot is however that shown in
Figures 21, 22, 23, and 24, viz., of blocks of fire-brick, or hardened refractory clay,
or other heat-retaining substance contained by a metallic framework, and in this
respect the construction corresponds very closely with that of the stove body or
outer casing before described.
In all cases it is desirable to perforate the fire-pot to quicken the heat-radiating
action of the fire upon. the inner surface of the stove body without interfering
materially with the heat-retaining properties of the fire-pot.

page_text: The stove is further furnished with dampers or registers to regulate the admission
of air to the interior of the hollow base, and thence to the interior of the fire-pot;
and also with a smoke pipe fitted with a damper to carry off the products of com-
bustion to a flue or chimney.
I also construct the stove without a fire-pot, and adapt a part of the stove body
or casing as a fire or fuel holder, as illustrated in Figures 25 to 40; and further I
construct the stove in sections, each one of which is a complete structure, and
capable of being substituted for the corresponding part or section of an ordinary
stove to increase its heat-retaining properties.
Various ways of applying an improved heat-retaining section to parts or sections
of ordinary construction to form a complete stove are shown in Figures 29 to 40.
Having thus described and ascertained the nature of my said Invention, what I
claim is substantially as follows :-
1st. A stove body consisting of a continuous, or nearly continuous, wall of terra
cotta or other heat-retaining substance provided at its inner surface with a metal
backing or casing conforming to the shape of and fitting to the said exterior wall.
2d. In combination with a stove casing of composite construction, as described,
a composite cover for the same, or one constructed of a metallic plate having an
outer cover of terra cotta or other heat-retaining material.
3d. A heat-retaining stove body or outer casing composed of blocks of terra
cotta, soapstone, or other heat-retaining substance contained by a metallic frame-
work consisting of an upper and a lower ring or plate connected by ribs, or a series
of metallic frames and rings or plates.
4th. In combination with a stove body or outer casing consisting of a metallic
frame containing blocks of terra cotta or other similar heat-retaining substance, and
the cover for the same, a hinge connecting them together, so that the cover may be
raised without removal.
5th. In combination with a composite stove body or outer casing, and the cover
and base for the same, gaskets of soft metal, or of asbestos, felt, or other suitable
substance, situated between the said casing and cover and between the said casing
and base.
6th. In combination with a hollow base of a stove, a fixed or a removable stove
body or outer casing constructed of a series of terra cotta, soapstone, or other heat-
retaining blocks confined in a metallic frame consisting of an upper and a lower
plate or ring connected by ribs.
7th. A heat-retaining cover for a stove consisting of a block of terra cotta, soap-
stone, or other heat-retaining substance secured to a metallic plate by means of a
flange surrounding the said plate.
8th. In combination with a stove body or outer casing of composite construction,
as described, and a hollow base for the same, a composite fire-pot or fire-holder, or
one composed of blocks of fire-clay or other heat-retaining substance contained by a
metallic frame.
9th. In combination with a hollow base of a stove and a heat-retaining body or
outer casing for the same, a removable fire-pot of perforated sheet iron lined with
fire-clay, or of cast or wrought bars having space between them.
10th. A movable fire-pot or fire-holder for a stove or for other purposes of com-
posite construction, the bottom being formed of a perforated plate or casting, and
the sides of blocks of fire-brick or hardened refractory clay or other heat-retaining
substance contained by a metallic framework in the manner described.
11th. A heating stove body divided into two or more sections, each one of which
is a complete structure formed of a series of blocks or slabs of terra cotta, soapstone,
or of fire-brick contained in and by a framework of metallic ribs or bars and rings
or annular plates connected in any suitable manner.
12th. In combination with the bars and top or cover of a stove, heating pipes or
columns connecting the same, the said heating pipes or columns being constructed of

page_text: terra cotta, soapstone, fire-brick, or other heat-retaining substance supported by a
sheet-metal inner casing, or by a metallic framework.
In testimony whereof, I have hereunto set my hand and affixed my seal, this
Eighteenth day of January, A.D. 1878.
In presence of
WT. HOWARD,
Solicitor of Patents,
Baltimore,
Maryland.
WOODRUFF W. WHARTON,
Baltimore,
Maryland.
THOMAS GEMMELL. (L.S.)