IMPROVEMENTS IN FURNACES FOR THE PREVENTION OF SMOKE AND ECONOMY OF FUEL
Year: 1875

page_text: LETTERS PATENT to Joseph Adam Mills, of the City of Glasgow,
in the County of Lanark, North Britain, Engineer and Boiler
Inspector, for the Invention of "IMPROVEMENTS IN FURNACES FOR THE
PREVENTION OF SMOKE AND ECONOMY OF FUEL."
Scaled the 7th March 1876, and dated the 10th September 1875.
PROVISIONAL SPECIFICATION left by the said Joseph Adam Mills.
at the Office of the Commissioners of Patents, with his Petition,
on the 10th September 1875.
I, JOSEPH ADAM MILLS, of the City of Glasgow, in the County of
Lanark, North Britain, Engineer and Boiler Inspector, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN FURNACES
FOR THE PREVENTION OF SMOKE AND ECONOMY OF FUEL," to be as follows:-
-
This said Invention, which relates to new or improved furnaces for the
prevention of smoke and economy of fuel, by burning and utilizing all
the inflammable gases evolved therein, consists as follows:-In fitting
and laying two pipes or ducts of fire-clay or other fire resisting material
within and along the whole length of the two sides of the furnace or

page_text: fire-place, close over the hearth, with their front ends passing out
through apertures in the front furnace plate or brickwork, and having
their back ends inserted into and communicating with reverse V shaped
_or_knee ducts preferably formed within fire-clay blocks at the sides of
the furnace, the front ends of which rest on or are built into the back
bridge wall, while their back or-knee-ends_are built into a-hanging
bridge wall, about nine or twelve inches behind the back bridge-wall,-
and droop some little distance below it.
The back ends of these fire-clay blocks are preferably secured by the
transverse fire-clay arch or key block which supports the hanging
bridge, and the upper reverse duct is brought forward or extends some
distance into the furnace in front of the ordinary flame bridge or wall,
where they are both entered into sockets in the back ends of a hollow
segmental fire-clay block with small holes or interstices in front, all so
that a current of fresh air entering the front open ends of the long
pipes, and controlled or regulated by a valve or other equivalent, passes
along these two side pipes up through the hollow end reversing blocks,
and return ducts, into the front distributing chamber at their upper
ends in the furnace. Thus the air in its passage becomes so heated that
on issuing from the interstices in front of the distributing chamber, it
immediately mixes with, heats, and ignites the smoke and gases rising
off the burning fuel, so that nothing but bright flame is seen to pass
the hanging bridge.
In furnaces formed in the brickwork the hollow angled or V blocks
might rest on side walls or projecting buttresses beyond the ordinary
¨bridge; which would also facilitate the supporting of the lower kcy
block carrying-the--hanging bridge; and although hollow current
reversing blocks are preferred at the back of these air-heating pipes,
it will be obvious that ordinary fire-clay knee pipes may be used with a
rose at their upper front-return ends for distributing the heated air at
the top and sides of the furnace, to mix with and burn the gases-and-
smoke all as before stated.
Hitherto it has been customary to admit cold air at the door of the
furnace, but with my improvements this will be unnecessary and
superceded by admitting the air at the back and roof of the furnace in
a heated state.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Adam Mills in the Great Seal Patent
Office on the 9th March 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
ADAM MILLS, of the City of Glasgow, in the County of Lanark, North
Britain, Engineer and Boiler Inspector, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of September, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Joseph Adam Mills, Her
special, licence that I, the said Joseph Adam Mills, my executors,
administrators, and assigns, or such others as I, the said Joseph Adam
Mills, my 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
"IMPROVEMENTS IN FURNACES FOR THE PREVENTION OF SMOKE AND ECONOMY OF
FUEL," upon the condition (amongst others) that I, the said Joseph
Adam Mills, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and scals, 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 I, the said Joseph Adam Mills, do hereby
declare the nature of my said Invention, and in what manner the
samé is to be performed, to be particularly described and ascertained
in and by the following statement in writing, reference being had to the
accompanying Sheet of Drawings and to the letters and figures marked
thereon, that is to say :-
My said Invention has reference to the construction or general
arrangement of the parts of new or improved furnaces for the pre-
vention of smoke and economy of fuel, by burning and utilizing all
the inflammable gases evolved therefrom in the said furnaces.

page_text: And in order that the full nature, novelty, and mode of performing
my said Invention may be properly understood I will now proceed to
describe the several Figures on the accompanying Sheet of Drawings
which I have hereunto appended for the purpose of showing-the best.
modes and means I am at present aware of for performing it, the-same-{
reference letters indicating the same or like parts in all the Figures
where shown.
-
-
Figures 1 and 2 are a sectional elevation and a plan respectively taken
on the lines 1 1 and 2
2 in Figure 4, and Figures 3 and 4 are
respectively a front end view and a transverse section, the latter taken 1
on the lines 3 3 and 4 4 in Figure 1, all of the front furnace,
part A, A, of two-flue and internal furnace, Cornish steam boiler, as
fitted with and illustrative of one modification or arrangement of my
Invention or improvements as applied thereto, and sufficient to show the
mode of carrying the same into effect or practice, although many of the 1
ordinary fittings and mountings are not shown, as these are all made in
a usual manner, and form no part of my Invention.
Referring to these Figures 1 to 4 inclusive, my said Invention and
mode of carrying it out consist in fitting and laying two inlet air pipes
or ducts a of fire-clay or other fire-resisting material within and along 2
the whole length of the two sides of the furnace or fire-place A, close
over the hearth (or it might be level with or rather under the furnace
bars), with their front ends a¹ passing or opening out through apertures
in the front furnace plate A¹as at a¹ (or in some cases it might be brick-
-work),-and-having-their_back_ends a" entering or opening into and com- 2
municating with the lower part of a receiving, reversing, and distributing
channel or duct b, preferably formed within fire-clay blocks, B, ạt
the sides of the back flame wall or bridge C, C¹, of each furnace A, and
formed into a hollow arch or segment B' above, with the reverse current-
distributing holes or openings 6' in each brick in front (or it might be a 3
narrow channel), built close to the upper side of the furnace tube or
flue A", over or rather in front of the bridge wall C, the top of which
is preferred to be nearly level with the back of the furnace bars A", and
continued back some distance at C' in a rising inclined plane (or con-
tinuation of the furnace hearth from the bars A"), on which the 8
charcoal or hot solid carbon rests and burns, and on which the flames
and ignited gases impinge, so as to burn any unconsumed gases or
light floating carbon which may not have been consumed in the

page_text: DORIC passing or the now bridge D In some cases LO
assist this a hanging bridge D may be placed some little distance behind
the back end of the continued part C' of the bridge C, as indicated in
red lines at D, the back end of the bridge C¹ when desired being
supported on a back wall at O".
The inlet air-heating pipes a are preferably formed of thin iron pipes
covered with short lengths of the fire-clay heating and protecting
pipes a, and a current of fresh air enters at the front open ends a¹ of
these long pipes, controlled or regulated by a valve or other equivalent
when desired, and is heated on its passage through these two side pipes
by the fire or fuel burning between and over them before it passes up,
into, and through the hollow current reversing ducts b, b¹, in the blocks
and front of the distributing arched chamber B', and finally out through
the holes ¹ in its upper front face right into the furnace, as indicated
by the black darts, over and in the opposite direction to the current of
gases from the coal or fuel, passing under the hollow arch B to the
chimney, and indicated by red arrows. Thus the air is so thoroughly
heated in its passage through these pipes and ducts a, b, that on issuing
from the distributing interstices ¹ in front of the arch chamber B¹,
that it immediately heats, mixes, and ignites with the gases rising off
the burning fuel, consuming all the inflammable gases before they form
smoke, so that nothing but bright flame is seen to pass the continuation
or back end C¹³ of the flame bridge, or the hanging bridge D beyond it,
when that is used.
In some cases the hollow or arch bricks B' may be continued down
round the lower part of the tubes or flues A", A", as seen at .6*, in the
right-hand furnace of Figure 4, or instead of this the ends a" of the
pipes a could enter long hollow blocks at B forming the sides of the back
rising or inclined fire-part C³, and supported by the key blocks thereof,
or by the back wall C", having the heated air returned by a hollow
rising angled knee piece B to the front distributing segment B¹, as
indicated in red lines in Figure 1.
.
.
In furnaces formed in the brickwork or for furnaces formed below the
boilers,. the hollow arch B, B', b, b', or the return angled or V blocks B*
might rest on side walls or projecting buttresses in front of or behind
the ordinary bridge or wall C, and which might be made to assist in

page_text: supporting the lower key block carrying the hanging bridge C¹ or D and
hollow arch B', which in this case would be built close up to the bottom
of the boiler, or the top of the pans used in the salt trade. And although
_hollow_current_reversing blocks B, B', B³, are preferred at the back¨¯of
the air heating pipes a, it will be obvious that ordinary fire-clay knee
pipes may be used, with a rose at their upper return front ends, instead
of the perforated hollow arch B', 6', for distributing and forcing the
heated air forward at the top and sides of the furnace to mix with and
burn all the inflammable gases as before stated.
Hitherto it has been customary to admit cold air at the door of the
furnace, but by my improvements this will be unnecessary and super-
ceded by admitting the air in the new or improved manner at the upper
back part or roof of the furnace, and projected in a heated state forward
in direct opposition to and against the current of gases to be burned,
and entering a certain distance into the furnace before the force of the
draught of the chimney carries it back under the above-mentioned
hollow arch B¹ as a mixture of gas and air.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is to be performed,
I have to state that I do not restrict myself to the precise details herein
described, neither on the other hand do I desire to claim the whole of
the parts by themselves of furnaces and boilers except in combination
with my said improvements; but what I consider 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 construction and arrangement of the parts of
fürnaces with air heating and conducting pipes and ducts for the
consuming of all the inflammable gases, and preventing the production
and emission of smoke from such furnaces, all substantially as herein
described in reference to and shown in the accompanying Drawings, or
any mere modification thereof.
Second. The heating and conducting of air so as to be introduced and
distributed from a chamber or hollow arch B', 6 at the top part of the
furnace in a current against or contrary to that of the gases from the
fuel, so as to mix and burn with these over the fire before or as they are
passing under the hollow arch, all substantially as herein described in

page_text: reference to and shown in the accompanying Drawings, or any mere
modification thereof.
In witness whereof, I, the said Joseph Adam Mills, have hereunto
set my hand and seal, this Seventh day of March, in the year
of our Lord One thousand eight hundred and seventy-six.