IMPROVED MEANS FOR ECONOMIZING FUEL AND PREVENTING SMOKE IN FURNACES FOR BOILERS, PANS, AND OTHER HEATING OR EVAPORATING APPARATUS
Year: 1873

page_text: LETTERS PATENT to Edward Clarke, George Clarke, and Henry
Ebenezer Harrold, all of Loughborough, in the County of Leicester,
for the Invention of "IMPROVED MEANS FOR ECONOMIZING FUEL AND
PREVENTING SMOKE IN FURNACES FOR BOILERS, PANS, AND OTHER HEATING OR
EVAPORATING APPARATUS.”
Sealed the 10th March 1874, and dated the 1st December 1873.
PROVISIONAL SPECIFICATION left by the said Edward Clarke, George
Clarke, and Henry Ebenezer Harrold at the Office of the Com-
missioners of Patents, with their Petition, on the 1st December
1873.
We, EDWARD CLARKE, GEORGE CLARKE, and HENRY EBENEZER
HARROLD, all of Loughborough, in the County of Leicester, do hereby
declare the nature of the said Invention for "IMPROVED MEANS FOR
ECONOMIZING FUEL AND PREVENTING SMOKE IN FURNACES FOR BOILERS, PANS, AND
OTHER HEATING OR EVAPORATING APPARATUS," to be as follows:-
The object of this Invention is to economize fuel and to prevent the
formation of smoke in furnaces. For this purpose we place a shield or

page_text: diaphragm, by preference of cast iron (but it may be made of or cast in
fire-clay) over the fire in the upper part of the furnace. The shield is
ormed with holes, slots, or other perforations through it which we prefer
to make tapering downwards; it may also for the sake of obtaining a
greater surface exposed to the fire be formed with a ribbed or undulating
surface underneath, and the upper part may be similarly formed. We
prefer however to form it with longitudinal ribs underneath and with
transverse ribs above.
The general shape, size, thickness, and formation of the shield depends
upon the size, arrangement, and construction of the furnace, and of the
boiler or other heating or evaporating apparatus therefor. As applied
to an ordinary Cornish boiler the shield is formed convex or more or
less following the outline of the crown of the furnace. On the other
hand as applied to an egg-ended or other underneath fired boiler the
shield would be concave, more or less following the outline of the
bottom of boiler. Or it might be made flat in all cases, but not so
advantageously as the extended heating surface is an important element
of this our Invention.
The action of the apparatus is as follows:- -When the fire in the
furnace is at a bright heat the shield takes up a portion of same, and
when the fire is in a dull or black condition the shield gives out its
surplus heat to the smoke or gases arising and passing through the
perforations of the shield, and thus smoke is prevented and fuel
economized.
SPECIFICATION in pursuance of the conditions of the Letters Patent, 25
filed by the said Edward Clarke, George Clarke, and Henry
Ebenezer Harrold in the Great Seal Patent Office on the 1st June
1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, EDWARD
CLARKE, GEORGE CLARKE, and HENRY EBENEZER HARROLD, all of 30
Loughborough, in the County of Leicester, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the First day of December, in the year
of our Lord One thousand eight hundred and seventy-three, in the

page_text: thirty-seventh year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto us, the said Edward Clarke, George Clarke,
and Henry Ebenezer Harrold, Her special licence, that wc, the said
Edward Clarke, George Clarke, and Henry Ebenezer Harrold, our
executors, administrators, and assigns, or such others as we, the said
Edward Clarke, George Clarke, and Henry Ebenezer Harrold, our
executors, administrators, and 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
"IMPROVED MEANS FOR ECONOMIZING FUEL AND PREVENTING SMOKE IN FURNACES
FOR BOILERS, PANS, AND OTHER HEATING OR EVAPORATING APPARATUS," upon the
condition (amongst others) that we, the said Edward Clarke, George
Clarke, and Henry Ebenezer Harrold, our executors or administrators,
by an instrument in writing under our, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed,
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 we, the said Edward Clarke, George Clarke, and
Henry Ebenezer Harrold, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement,
reference being had to the accompanying Drawings, and to the letters of
reference marked thereon, that is to say :-
The object of this Invention is to economize fuel and to prevent the
formation of smoke in furnaces. For this purpose we place a shield or
diaphragm, by preference of cast iron (but it may be made of or cast in
fire-clay) over the fire in the upper part of the furnace. The shield is
formed with holes, slots, or other perforations through it which we
prefer to make tapering downwards; it may also for the sake of obtaining
a greater surface exposed to the fire be formed with a ribbed or
undulating surface underneath, and the upper part may be similarly
formed. We prefer however to form it with longitudinal ribs under-
neath and with transverse ribs above. There is a space at cach side
between the outside of the shield and the inner sides of the furnace, and

page_text: shield.
The general shape, size, thickness, and formation of the shield depends
upon the size, arrangement, and construction of the furnace and of the
boiler or other heating or evaporating apparatus therefor.
And in order that this our Invention may be more fully ascertained
we will now describe the same with reference to the accompanying
Drawings which illustrate same modes of applying it.
Figure 1 is a longitudinal section through the furnace part of an
ordinary one-flued Cornish boiler; Figure 2 is a cross section of the
same, and Figure 3 is an outside elevation of the shield alone.
A is the shield which is formed convex or more or less following the
outline of the crown of the furnace in which it is applied; b, b, arc
taper holes through the shield for the admission of air to the furnace;
the air enters at each side of the grate from beneath the same and gets
heated during its passage between the shield and the furnace crown;
c, c, are ribs on the outside of the shield, and d, d, ribs on the inside of
the shield for the sake of obtaining a larger heat absorbing and heat
diffusing surface, both for the hot products of combustion and for the
air in contact with the shield. When the fire in the furnace is at a
bright heat the shield takes up a portion of the heat so as to attain a
high temperature, and when the fire is in a dull or black condition the
shield gives out its surplus heat to the gases arising and passing through
or against the perforations of the shield, there mixing intimately with
the subdivided streams of air which as aforesaid is heated in its passage
between the shield and the furnace crown; we thus prevent the
formation of smoke and effect a saving in fuel. The shield might in
this and all other cases be made flat instead of following the outline of
the boiler more or less, and it might also be made plain or unribbed on
one or both sides, but not so advantageously.
A collateral advantage arising from the use of this Invention is that
the cold air which enters in bulk when the furnace door is opened by
reason of the shield is prevented from coming in direct contact with the
furnace crown plates, whereby the sudden and detrimental contraction
of the said plates is avoided.
.
Figure 4 is a cross section shewing the Invention applied to an egg-ended
or other underneath fired boiler. The shield A is concave to suit the

page_text: shape of the boiler and rests at each end on brick projections, but this
part of the shield may be formed in many other ways without departing
from the nature of this Invention. There is here shown a pocket at each
side to which the air may be admitted through holes in the furnace front,
or a pipe e with an opening, or openings in the side may be placed in
each pocket as here shown for the purpose of conveying air to the space
between the shield and the bottom of the boiler.
Figure 4 shews a modified arrangement of shield suitable for Cornish
or for underneath fired boilers. The shield is here formed with sides g
between which and the brickwork the air may be admitted to the
perforated part of the shield. It is here shewn applied to an underneath
fired boiler.
Figure 5 is a cross section, and Figure 6 a longitudinal section through
the furnace or firing hole of a baker's oven, or similar apparatus and
with our Invention applied thereto.
Figure 7 is a plan of the shield A, and Figure 8 a plan of the under side
of the shield. Air is admitted to the upper part of the shield by means
of pipes or pockets e formed one on each side of the shield and having
perforations, holes, or slots as shewn. For these and other purposes we
sometimes extend or close up the shield behind in the form of chamber f
which may be in one with the shield casting or not, and which is
supplied with air from the open ends of the pipes or pockets e, and is
formed with small holes or slots for admitting air at this part of the
oven. The shield may be built into the brickwork as shewn or be made
to rest on projecting parts of the same, or it might be formed with
sides g and otherwise be arranged similarly to the plan described with
reference to Figure 4*.
And having now particularly described and ascertained the nature of
this our Invention we declare that we claim,―
Firstly. The construction and application of a shield with perforations
through which air is admitted, all substantially as and for the purposes
set forth.
Secondly. The construction and application of a shield with per-
forations through which air is admitted, the said shield being formed so
as to more or less follow the outline of the furnace crown, and formed

page_text: with ribs or not on one or both sides, all substantially as and for the
purposes set forth.
And Thirdly. The modes and means here described and shewn for
admitting air to the space between the perforated shield, and the furnace
crown or boiler bottom to which said shield is applied, all substantially
as set forth.
In witness whereof, we, the said Edward Clarke, George Clarke,
and Henry Ebenezer Harrold, have hereunto set our hands and
seals, this Twenty-ninth day of May, in the year of our Lord
One thousand eight hundred and seventy-four.
EDWARD CLARKE. (L.S.)
GEORGE CLARKE.
(L.S.)
H. E. HARROLD.
(L.S.)