IMPROVEMENTS IN FIRE-PLACES, GRATES, OR FURNACES."
Year: 1853

page_text: LETTERS PATENT to Malcolm Maclaren, of Johnstone, in the
County of Renfrew, North Britain, Surgeon, for the Invention of
"IMPROVEMENTS IN FIRE-PLACES, GRATES, OR FURNACES."
PROVISIONAL SPECIFICATION left by the said Malcolm Maclaren
at the Office of the Commissioners of Patents, with his Petition,
on the 28th October 1853.
I, MALCOLM MACLAREN, of Johnstone, in the County of Renfrew,
North Britain, Surgeon, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN FIRE-PLACES, GRATES, OR FURNACES."
This Invention relates to an arrangement of domestic or other fire
grate, which in its general external features resembles an ordinary
grate, and may be used as such at pleasure. The actual fire holder
directly above the grate bars is covered over by a flat top plate,
having a large central opening fitted with an adjustable plate or cover.
When this cover is off the draught current from the grate finds its

page_text: way up from the burning fuel therein through the open top, and thence
between the grate cheeks above to an opening or draught way at the
top of the grate casting, about the level of the mantel-piece to the
chimney. When, however, the additional heating power is to be brought
into action the cover plate above the burning fuel is placed upon the
opening which it has to guard, and thus the direct. passage away of the
heated current is cut off; at the same time the draught passage over
head is also closed, so that the current must pass away by a totally
different route. The grate is cast in metal with its front plate and two
open backed vertical side channels, and in this condition it is fitted into
its allotted recess in the wall of the room, the back of which recess is
composed of fire clay or fire brick work, or iron, and answers to fill up
or complete the two side channels. Each side of the grate containing
the fuel is formed with a lateral opening communicating with its corre-
sponding vertical channel, so that when the current is shut in by placing
the fuel or grate-cover on, a side current is diverted right and left into
the bottom of each side channel. The heat is thus carried up and diffused
over an extended area of metal, whence it can radiate into the room, and
the upper ends of the two side channels being made to open into the two
opposite ends of a back cross channel wherein the upper valved passage
is formed, the two currents are thus brought together and made to pass
off to the chimney through a corresponding passage on the upper side
of the horizontal junction channel. When so contrived no heat passes
directly from the top of the burning fuel, the current being made to
diverge into two branches, passing along immediately behind and in
contact with an extended surface of a large area of the inner side of
the grate front, so as to afford a very superior extent of heating, surface.
In addition to this superior heating power cast iron chimney pieces
may be adopted to work in conjunction with the arrangement, and thus
obtain a still more enlarged heating area. It is also, obvious that,
instead of working the grate either as a plain open fire-place or as a
shut up stove grate in the manner described, it may be used partially
in both ways, that is to say, part of the drauglit current may be allowed
to pass directly from the fuel, whilst a portion is diverted, as already
explained, by a suitable partial opening of the necessary draught doors

page_text: or covers. It is also obvious that. the fire-place or grate may be
economically adopted as a cooking range by placing cooking utensils
on the grate cover opening, instead of the door which has been
referred to.
SPECIFICATION in pursuance of the conditions of the Letters Patent;
filed by the said Malcolm Maclaren in the Great Seal Patent Offic
on the 28th April 1854:
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
MALCOLM MACLAREN, of Johnstone,: in the County of Renfrew, North
Britain, Surgeon, send greeting.
.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of October, in the
year of our Lord. One thousand eight hundred and fifty-three, in the
seventeenth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Malcolm Maclaren, Her special license
that I, the said Malcolm Maclaren, my executors, administrators, and
assigns, or such others as 1, the said Malcolm Maclaren, my executors,
administrators, or assigns; should at any time agree with, and no
others, from time to time and at all 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 "IMPROVEMENTS IN
FIRE-PLACES, GRATES, OR FURNACES," upon the condition (amongst others)
that I, the said Malcolm Maclaren, by an instrument in writing under
my hand and seal, should particularly describe and ascertain the nature
of the said, Invention, and in what manner the same was to be per-
formed, 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 Malcolm Maclaren, do hereby.
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and.

page_text: by the following statement, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon, that is
to say:
My said Invention principally relates to an arrangement of domestic
or other fire grates, which in its external features resembles an
ordinary grate, and may be used as such at pleasure. The actual fire
holder directly above the grate bars is covered over by a flat top grate,
having a large central opening fitted with an adjustable plate or cover.
When this cover is off' the draught current from the grate finds its way
up from the burning fuel therein through the open top, and thence
between the grate cheeks above to an opening or draught way at the
top of the grate casting, about the level of the mantel-piece to the
chimney. When, however, the additional heating power is to be
brought into action the cover plate above the burning fuel is placed
upon the opening which it has to guard, and thus the direct, passage
away of the heated current is cut off; at the same time the draught
passage over head is also closed, so that the current must pass away
by a totally different route. The grate is cast in metal with its front
plate and two open backed vertical side channels, and in this condition
it is fitted with its allotted recess in the wall of the room, the back of
which recess is composed of fire clay or fire brick work, or iron, and
answers to fill up or complete the two side channels. Each side of the
grate containing the fuel is formed with a lateral opening communicating
with its corresponding vertical channel, so that when the current is shut
in by placing the fuel or grate cover on, a side current is diverted right
and left into the bottom of each side channel. The heat is thus carried
up and diffused over an extended area of metal, whence it can radiate
into the room, and the upper ends of the two side channels being made
to open into the two opposite ends of a back cross channel wherein the
upper valved passage is formed, the two currents are thus brought
together and made to pass off to the chiinney through a corresponding
passage on the upper side of the horizontal junction channel.
so contrived no heat passes directly from the top of the burning fuel,
the current being made to diverge into two branches, passing along
immediately behind and in contact with an extended surface of a large
When

page_text: area of the inner side of the grate front, so as to afford a very superior
extent of heating surface. In addition to this superior heating power
cast iron chimney pieces may be adapted to work in conjunction with
the arrangement, and thus obtain a still more enlarged heating area.
It is also obvious that, instead of working the grate either as a plain
open fire-place or as a shut up stove grate in the manner herein-before
described, it may be used partially in both ways, that is to say, part of the
draught current may be allowed to pass directly from the fuel, whilst a
portion is diverted, as already explained, by a suitable partial opening
of the necessary draught doors or covers. It is also obvious that the
fire-place or grate may be economically adapted as a cooking range by
placing cooking utensils on the grate cover opening, instead of the door
which has been referred to.
And in order that my said Invention may be properly understood I
shall now proceed to describe the several Figures on the Sheet of
Drawings hereunto attached. Figure 1, on my Sheet of Drawings is a
complete front elevation of one form of domestic fire grate as arranged
according to my Invention. Figure 2, is a transverse vertical section
of the grate corresponding. Figure 3; is a back elevation of the grate,
partially sectioned to exhibit the draught passages. Figure 4, is a
horizontal section of the grate above the fire bars. Figure 5, is a com-
plete plan of the grate. When used as a common direct draught grate
the draught current passes from the fire bars directly up the central
passage or throat, as at A, and through the first central valvular passage
B to the upper adjustable thoroughfare C, leading at once into the
chimney. Under these circumstances the cover plate D of the burning
fuel is wholly removed from the grate. This cover D fits closely to the
top of the fuel-holding portion of the grate, as in Figures 1 and 2, and
when the current is to be diverted from its immediate course the plate
is placed over the fuel so as to cover it entirely in. In this state of
matters the draught current is diverted through the lateral openings
E in the body of the grate, and thus two separate streams or currents
are conveyed through the grate back and cheeks into the vertical
thoroughfare or thoroughfares F. Instead of using two lateral
openings E for this escape of the beated currents to the back of the
:

page_text: fire-place, any other convenient number may be used; and such holes
may either have their upper edge on a level with the top front bar of
the grate, or they may be disposed lower down in the grate; or, further,
the sides of the grate may be made quite open, with gratings or per-
forations, for example. In this particular example the grate is cast
with a duplex back to form the ascending passages for the heated
currents, which first of all pass from the grate by the openings E into
the cross flue recess G, and thence up the space H, and the sides F.
But it is not necessary that this duplex back should be used, for if the
grate is left open behind, the face of the masonry in the recess prepared
for it will afford the necessary back surface for the currents, and in such
case the central portion I of the grate back may be made to fit hard up
against the wall of the recess, the cross flue G opening at each end only
into the passage-spaces F. When the currents reach the level of the
horizontal division plate J, they pass through through the adjustable
slide valves K, which are worked from the front of the grate by but-
tons connected to rack and pinion movements. These valves K, in
addition to governing the apertures at M, are also capable of regulating
the passage through the central port B, for when they are drawn
towards the centre, so as to open the passages M, they correspondingly
close the port B. This route of the heated currents brings them up into
the inner cross passage N, beneath the division O, and from this space
the currents pass up through the central port C, surmounted by a slide
valve P, adjustable from the front of the grate by a button Q. In this
way the smoke, heated air, and gaseous vapour all pass into the
chimney above, without entering the surrounding space R. This space
answers as a species of heat reservoir; and contains nothing but heated
air, which can thus flow into the apartment to be warmed through the
open work in the front of the grate, as delineated in Figure 1, of my
Drawings. This external division may either have a surrounding edge
plate cast to it, or it may be left open to the surrounding wall surface.
By adopting metal, chimney or mantel pieces in conjunction with this
plan of fire-place a still more effective heating surface may be obtained.
The heated currents from the fire-place passages, as already described
herein, are in such case made to pass, behind the metal chimney-piece,

page_text: and thus they act upon a larger area of metal than is, perhaps, con-
veniently attainable in the actual grate. Under these circumstances
the metal or cast iron mantel-piece acts as a continuation of the fire-
place in exposing an extended metallic surface to the heating action.
Instead of making the grates' or fire-places and mantel-pieces wholly
of metal they may be made partially of fire clay or other suitable
material. It is also to be understood that, in addition to the advantage
of using this system of heating, there is also an advantage gained as
regards the chimney draught; with the new arrangement the smoke is
effectually carried off, so as to remove the very common difficulty of a
smoky chimney.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used
or carried into effect, I may observe, in conclusion, that I do not
confine or restrict myself to the precise details or arrangements which
I have had occasion to describe or refer to, as many variations may be
made therefrom without deviating from the principles or main features
of my Invention; but what I consider to be novel and original, and
therefore claim as the Invention secured to me by the herein-before in
part recited Letters Patent, is,-
First, the general arrangement and construction of fire-places, grates,
or furnaces for the purpose of obtaining a superior extent of heating
surface, as herein-before described.
Second, the system or mode of arranging and constructing domestic
fire-places, wherein the heated currents are directed behind the front
plate or portion of the grate for the obtainment of an enlarged heating
area.
Third, the system or mode of arranging fire-places wherein the
heated currents may either pass directly upwards from the fuel to the
chimney, or be directed behind the main body of the grate, more or
less, at pleasure.
Fourth, the application and use in fire-places of an adjustable cover
or plate over the fuel to divert the heated currents behind the grate.
Fifth, the application and use of chimney or mantel pieces of metal

page_text: or other material for the obtainment of an extended heating surface by
passing the heated currents behind the chimney or mantel pieces.
In witness whereof, I, the said Malcolm Malcolm Maclaren, have
hereunto set my hand and seal, this
day of April, in
the year of our Lord One thousand eight hundred and fifty-four.
MALCOLM MACLAREN. (L.S.)"