IMPROVE- MENTS IN FUEL AND IN ECONOMIZING FUEL USED IN THE BOILER FURNACES OF THE ENGINES OF SCREW AND OTHER STEAM SHIPS, AND OF LOCOMOTIVE OR RAILWAY OR OTHER ENGINES FOR RAISING STEAM, AND IN BOILER FURNACES." OTHER STEAM
Year: 1873

page_text: LETTERS PATENT to William Mickle, of Tynemouth, in the County
of Northumberland, Gentleman, for the Invention of "IMPROVE-
MENTS IN FUEL AND IN ECONOMIZING FUEL USED IN THE BOILER FURNACES OF
THE ENGINES OF SCREW AND OTHER STEAM SHIPS, AND OF LOCOMOTIVE OR
RAILWAY OR OTHER ENGINES FOR RAISING STEAM, AND IN
BOILER FURNACES."
OTHER STEAM
Sealed the 2nd May 1873, and dated the 13th March 1873.
COMPLETE SPECIFICATION filed by the said William Mickle at the
Office of the Commissioners of Patents, with his Petition and
Declaration, on the 13th March 1873, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MICKLE, of Tynemouth, in the County of Northumberland, Gentleman,
send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
FUEL AND IN ECONOMIZING FUEL USED IN THE BOILER FURNACES OF THE ENGINES
OF SCREW AND OTHER STEAM SHIPS, AND OF LOCOMOTIVE OR RAILWAY OR OTHER
ENGINES FOR RAISING STEAM, AND IN OTHER STEAM BOILER FURNACES," and have

page_text: petitioned Her most Excellent Majesty Queen Victoria to grant unto
me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that I am the
first and true Inventor thereof.
NOW KNOW YE, that I, the said William Mickle, do hereby declare
the nature of the said Invention to be as follows:-
In the present treatment of coal used as fuel for raising steam to
propel screw or other steam ships there is, especially in using the more
bituminous varieties of coal, enormous waste from the volatile or gaseous
combustible constituents of the coal passing off unburnt or unconsumed,
or only partly consumed or burnt; there is from this cause also very
much black dense smoke emitted; a large proportion of the solid car-
bonaceous part of the coal or carbon burnt with the oxygen of the air
into carbonic oxide, which carbonic oxide in combining with oxygen or
burned with oxygen into carbonic acid yields much heat, passes off as
carbonic oxide without being rendered further available in combustion;
there is enormous loss or waste of the heat evolved, there is much labour
in discharging the coal to be used for fuel into and storing in the vessel,
and hot, dirty, and hard labour and drudgery; and as to vessels trading
to and in hot or tropical climates the heat of such labour becomes most
oppressive in using the coal and firing or stoking, and there is great
escape of heat from the furnaces in use or the open fires of such
furnaces, and this besides being wasted diffusing through the boiler or
stoking rooms is pernicious and offensive, and in hot or tropical climates
most pernicious and offensive to the firemen or stokers; and on steam
ships being taken or proceeded with on prolonged voyages a con-
siderable portion of the vessel which would otherwise be available
for cargo is taken up or occupied by the store of coals required; the
smoke emitted as above named and which smoke consists principally of
black unburnt particles of carbon which are offensive as they fall, and are
in reality valuable; lost or wasted fuel is a nuisance to persons on board,
and a nuisance where the vessel steams or the furnace is coaled in
harbours or rivers, or comes in contiguity to other vessels, and in long
voyages a portion, of some consequence, of the coal is also used as fuel
for raising steam for the carriage of the store of coals required for fuel
on the voyage or part of the voyage.
In the use of coal also, as at present, as fuel for raising steam in
locomotive or railway engines, and also the other steam engines in use,

page_text: and also the boiler furnaces of manufactories and other boiler furnaces
in use, there is also as above named in reference to steam ships similar
or much waste of the carbon of the hydrocarbons or volatile part of the
coal; the nuisance of smoke; there is much labour in stoking or firing;
carbonic oxide as above named lost or wasted; enormous loss or waste of
heat, the heat being really what is required and the evolving or obtaining
of which is really the object of firing, and the agent by which the
required results or work is to be effected.
The economization or saving of coal is also of very great, and
becoming of enhancing importance, and where any of the great or staple
industries of the country can be effectually and completely served or
effected by processses in which are employed a much less weight of
carbonaceous or hydrocarbonaceous substance, the general advantage
and importance of such saving must be obvious.
It is also of much importance as to steam ships to provide or use fuel,
and by a process which where it may be needful for the safety of
the vessel, or for the evolutions or movements of the vessel, or in any way
desirable can be at once available in combustion or so as to raise steam
with rapidity.
In order to prevent or greatly diminish the above named waste of fuel,
waste of heat, nuisance from smoke, loss or waste of carbonic oxide,
labour as to steam ships in regard to the store of coal, and hot heavy and
oppressive labour in firing or stoking, escape of heat from open furnaces
and the consequent waste of such heat, and oppressiveness to the
firemen or stokers, to diminish the space or room otherwise available for
cargo taken up or required in steam ships for the store of coal used for
raising steam to propel the vessel, and to diminish the expenditure as to
steam ships of fuel used for raising steam to carry the store of coals
required for ships' use, and labour in stoking or firing, and in order to
provide or use fuel and by a process which may tend to the safety of
steam ships or which afford convenience of movement from the command
they give over instantaneous or rapid combustion, force or power of
combustion and consequent rapid evolution of steam, and in order
greatly to economise fuel I circulate the gases, products, or resulting
substances obtained on or from the combustion of the coal, coke, or
other fuel used with the oxygen of the air in the boiler furnace through
the flues, fire-tubes, or passages for such gases, products, or resulting

page_text: substances back and forward, along or through, and through the boiler
so that such gases, products, or resulting substances of combustion may
not pass off prematurely, and so that the heat from the combustion con-
tained in such gases, products, or resulting substances be utilized, and be
rendered available for passing into the water as thoroughly as possible or
as long as the heat remaining in the said gases, products, or resulting
substances may be considered to be or is sufficient for raising the steam
effectively. I also either in or through a division or distinct com-
partment of the boiler furnace, or I carry or take the said gases, products,
or resulting substances of combustion through flues or pipes to the
furnace of another boiler and in or through such furnace I supply a
further quantity of air to burn the carbonic oxide resulting from the first
combustion into carbonic acid, or the other combustibles contained in
the gases, products, or resulting substances of the first combustion as
above named so as to render available the heat from the burning of the
carbonic oxide or other combustibles for raising steam.
The air may be supplied through open grates with fire-bars, or open
furnaces as at present; but I prefer and recommend that it should be
pumped in due proportion for thorough or effective combustion as I
state below. From where the combustion is going on or the fire in the
furnace in reference to tube boilers, the inflamed or heated products of
or substances resulting from the combustion, I pass through part, or a
sufficient portion only and not the whole of the fire tubes or passages
of the boiler, and on arriving at the hinder end of the boiler I them
pass
into a fire, or smoke, or gas box, or main flue, or receiver, large enough to
cover or take in all the openings into or ends of the fire-tubes or fire-passages
of the boiler; when the said heated products or results of combustion
have passed into such main flue, or box, or receiver, and after they are
passed, or on being passed on to the entrance of a further sufficient
number of the fire-tubes or passages, I prevent them going further, in
such main flue, or box, or receiver towards the chimney or final outlet
by closures or partitions, so that such heated products or results of
combustion instead of passing out or away and the heat remaining
in them being wasted may pass into and pass or flow through
such further, and sufficient to receive them, number of the fire-tubes
or passages of the boiler from the back part or hinder end of the boiler
to the front (or furnace end) again, so as to yield the heat or part of the
heat which has not been used or absorbed in passing, and which they

page_text: yet retain to raise steam; on passing to the front part or fore end of the
boiler I pass them into a similar main flue, or box, or receiver to that
at the hinder end of the boiler with requisite partitions, or into a
separate furnace or part of furnace as after named, and so or thence let
them pass into a further adequate number of the fire-tubes or fire-
passages of the boiler from the fore end or front of the boiler to the
hinder end again, so as to yield the heat they still contain as they pass
through the said tubes to raise steam; and I continue this process so
far as may be considered desirable, or until the heat is so far abstracted
or absorbed by the boiler or water in it that there is not sufficient heat
left in such heated products or results of combustion to raise steam with
advantage before allowing such products to escape or pass away into the
chimney or waste. I further into a compartment of such flue, or box,
or receiver pass a further quantity of air either through the air spaces if
fire-bars as ordinarily be used, or which I much prefer by pumping the air
into a furnace, close as after named, sufficient to burn the carbonic oxide
or other combustibles contained in the said products or results of the
prior combustion, and then let the resulting heat and resulting
substances from the combustion or waste gases pass back and forward,
as before named, in the fire-tubes or fire-passages of the boilers until
the heat is absorbed by the water for conversion into steam
effectively exhausted in raising steam before being allowed to pass into
the waste or chimney for final exit; or where the said further quantity
of air is supplied for combustion, instead of a simple compartment of
said flue or box or receiver I have an independent furnace using
a separate small quantity of coal or other fuel, and supply sufficient air
into such furnace for the combustion of such coal or other fuel along
with the aforesaid carbonic oxide or combustibles from the prior
combustion.
or
If the air be supplied through open grates to the furnace I
recommend that the fire-bars or air openings should be at a little
interval of distance below the tubes where such carbonic oxide or other
combustibles and products from the prior combustion enter or come
into the compartment, or flue, or box, or receiver, or into the second
furnace where the said second or later combustion is.
In the case of ordinary flue boilers on the heated results or products
of combustion passing in the flue to the hinder end of the boiler I bring
them back around or along the side of the boiler through flues of fire-

page_text: .
brick or other refractory material, or, which I prefer, through large iron
pipes, and I recommend well below the level of the water again to the
front of the boiler, and over or under (but I recommend over) the
furnace along the other side of the boiler so as to save the heat, and use
it for raising steam, and this can be continued or repeated as long as
convenient or there is enough heat left; and I have a fire-box in such
flue and supply further air to consume the combustibles in the products of
the first fire or combustion similarly so far as it applies to what is named
as to tube boilers. The compartments or secondary furnace or division
of the furnace being distinct or fully partitioned off from the principal
fire or from where the first or principal combustion is going on in the
furnace. Or it may be done by any convenient and practical modi-
fication of the above to suit the form or description of boiler in use or
otherwise, so as that the heated products may be retained and made to
pass through and through the fire-tubes or fire-passages of the boiler, or
around and around the boiler, until the heat is effectively exhausted and
used in raising steam, and that the carbonic oxide or combustibles
from the products of the primary fire be burnt by second or subsequent
combustion with air, and thus the fuel effectively burnt and the waste
prevented, and the waste of heat also prevented. I further state or
explain the mode of thus retaining for use and saving and utilizing the
heat and of more thoroughly burning the fuel than as at present
hereafter in this Specification. I pump the air required in due pro-
portion for combustion by engine power through pipes into the furnace
into contact with and over the coal, coke, or other fuel used; and I
recommend that the pump or pumps for the air be doubly acting or
double acting pumps, so as to obtain regularity of blast.
I recommend that the air pipes, orifices, tuyeres, or openings at or on
reaching immediate contiguity to the furnace, and when opening into
the furnace be small enough and sufficient in number, so as to effect the
thorough mingling of air and fuel to make the combustion as complete
as possible; valves may be inserted or joined into the air pipes close to
the furnace and opening to the furnace as preventive to gas getting into
the pipes and causing any explosive mixture.
In supplying the air required by pumping open furnaces or furnaces
with grates or bars as at present may be used having moveable plates
to be closed by levers or other power so as to open for the removal of
the ash from the fire of the furnace; but I much prefer to use close

page_text: furnaces or to close the furnace, that is, I use furnaces without the fire-
bars or air openings as used at present. And the coal may be charged
through the furnace door, but I prefer that it should be charged through
a sufficient opening closed at will at the top of the furnace, so that it
may be cooler for the firemen and also check the escape and waste of
heat into the boiler room or chamber or stoker place; the bottom of the
furnace may be lined with iron, burnt fire-clay material, or other
suitable refractory material; but it may be convenient to have open
grates closed by a moveable plate as above named, so as that at the
commencement or recommencement of firing to raise steam as below
named; the air required for combustion may be supplied in the first
instance through open grates, as at present, to raise steam to obtain power
to drive or work the engines and air pump.
In commencing or recommencing to pump the air, and if liquid fuel
be used as herein-after named, to pump the liquid fuel, to raise steam
for the engine driving the air pump or pumps, and if liquid fuel be used,
the liquid fuel pump or pumps; if the paddle or screw propelling
engines of steam ships or the main engines otherwise be used for the
purpose it will be requisite either to have a separate pump worked by
hand power for the liquid fuel, if the main or regular liquid fuel pump
cannot be conveniently so worked, if such liquid fuel be used, and also
to have a separate pump worked by hand power for the air, if the main
or regular air pump cannot be conveniently so worked, to supply air to
commence or recommence the raising of steam as above described, or to
have open grates with moveable closing plates as before named to supply
air for combustion, as from the quantity of air required it might be too
onerous to work the air pump by hand power for the purpose of com-
mencing or recommencing the raising of steam as above named.
But I prefer that the liquid fuel, if liquid fuel be used, pump or
pumps and the air pump or pumps be worked by a donkey engine or
other engine and steam boiler of sufficient power, separately and
distinctly from the main propelling main factory or locomotive engine
or engines, or the principal engines of other works; and this smaller or
pumping engine may be supplied with air through open furnaces or
furnaces with grates or bars or fire-bars, and spaces for the supply of air
as at present. Or after the steam of the small pumping engine be up,
the furnace may be closed by moveable plate as before named, and the
pumping engine may pump the air required for the action of it.

page_text: I have herein-before stated mode for retaining and using the heat
contained or remaining in the products or resulting substances of
combustion, and further burning the combustibles contained in such
products, or it may be thus:-When the steam boiler is tubular
I divide the furnace into compartments or divisions, or partitions
completely divided, say by iron or cast-iron plates or fire-brick,
or other suitable material, and on the fuel and air entering
into combustion, and the resulting products or substances and heat
passing along or through the fire tubes or openings or passages, in
or which go through the boiler, and the mouths or entry to which
directly face or open into the compartment where such combustion is
going on or proceeding, I do not have nor allow the products of the
combustion and the heat after passing through such fire tubes or
passages in or passing through the boiler to escape or be discharged at
once into the chimney and thus lost; but I have at the further end of
the boiler a flue box or receiver as before named, with corelative
divisions, partitions, or compartments, and similarly divided, so that the
products of combustion and the remaining heat may go or be forced
through the fire tubes or passages in or passing through the boiler, and
these heated products thus to come back to the front part of the boiler
in the next compartment, and either into this compartment or a
succeeding one, or into the compartment of another or second boiler,
I supply or pump a further quantity of air sufficient to burn the
carbonic oxide or other combustibles which the said results or products
of the primary or first combustion may contain as completely as
possible, and the products of this second or latter combustion and the
heat still remaining from the first combustion, and the heat evolved in
such second combustion will then pass or be forced through the fire-
tubes or passages of the boiler, directly facing or opening into the
compartment of the furnace in which such second combustion takes place,
I pass the results of the said further combustion after the combustible
elements contained in the products of the said first combustion are as
completely burnt as possible back and forward from the compartments
or divisions at the hinder end of the boiler to those of the front part of
the boiler, and vice versa, through the remaining fire-tubes or passages
of the boiler and the remaining compartments of the furnace until the
remaining heat is sufficiently exhausted, and if it be not sufficiently ex-
hausted in the first boiler, or if the first boiler be not large enough to
exhaust it sufficiently it can be conveyed by or through flues or pipes to

page_text: a second boiler with similar compartments, and there the remaining heat
can be similarly utilized and used for the purpose of raising steam. The
partitions of the compartments in the front or fore end of the boiler will
necessarily alternate with those of the back part or end or hinder end of
the boiler. When the boiler is an ordinary flue boiler the flues may go
about and about or along and along or round and round the boiler, and
further air supplied as above mentioned for second combustion in any
convenient way so as to burn the fuel as above named and also to use
and utilize the heat evolved in burning as completely as possible.
In the use of tube boilers or ordinary flue boilers or other boilers,
the above modes of causing the heat to traverse back and forward and
be diffused and utilized or used, and also burning the residue of the fuel
can be varied in any convenient way so as to fulfil the purpose.
In the furnace where the fuel is charged I recommend that it should
be in two adjacent compartments or divisions passing into one flue at
the hinder end of the boiler, so that when the ash requires to be drawn
the air may be turned off that compartment, the fire being kept up in
the other compartment of the furnace, thus rendering it cooler for the
firemen when the furnace door is open and tending to keep the fire
regularly up.
I pass the steam tubes of the boiler or water for raising steam in pipes
or part of the boiler, or I pass the air pipes as after named, to heat the
air round or about the boiler furnace to economize the heat there, and
use it for raising steam and also to prevent its diffusion, that is, of heat in
the boiler room or chamber so as to keep it cooler for the firemen.
The pipes leading from the pumps of air and liquid fuel (if liquid fuel
be used) to and contiguously to the furnace can have taps in them so as
to regulate the supply of air and liquid fuel (if liquid fuel be used).
To further economize the heat I heat the air required for combustion
in the furnace either before it enters the air pump or after it quits the
air pump for the furnace, by passing the pipes containing the air
through or down the inside of the chimney of the furnace, and this may
be done in coils or spirally so as to heat it more, and by passing it round
and round or along and along the outside of the boiler, and one coil may
surround another or there may be inner and outer coils, and I recommend,

page_text: to save heat or also to cause coolness in the boiler room or stoke hole,
that the inner or innermost coil be that of the hotter or hottest, or more
or most heated air, and if the boiler or part, or feeder of the boiler do not
go round the furnace the pipes of air may pass or be coiled round and
round, or a receiver of air from the air pipes, and yielding the air to the
pipes may pass or go round the furnace to heat the air required. If
the air be heated before entering the air pump and be partly heated in
the chimney, the air pipe may pass by a hole in the chimney to the
outside to the atmosphere, so as to get supplied with air as free as
possible from the gases or results of combustion which leave the 1
chimney.
Any convenient modification of the above for heating the air may
be adopted, so that it answers the purpose effectually. The heating
of the air round the boiler and also round the furnace will also, besides
the saving of heat, tend to make the boiler or stoker room or chamber ]
cooler and more comfortable for the firemen.
I also use naphtha, liquid paraffin, or other liquid combustible spirits,
or oils rectified so as not to clog the pumps, pipes, orifices, or other
parts of the apparatus, and of the varieties or qualities not too volatile
nor inflammable, and of those used safely in ordinary consumption, or 2
of those which may be used or made to use without danger as fuel in
the boiler furnace to raise steam, instead of or partly instead of coal or
other solid carbonaceous fuel, and although from the relatively high cost
of such liquid fuel it may not be found expedient nor profitable to use
it commonly, or ordinarily, or altogether as a substitute for coal or 2
coke, yet weight for weight it will give out a greater amount of heat;
it will also require smaller furnaces, and I use it when convenient or
expedient for these considerations, and also because in combustion it
gives out or affords instantaneously strong white heat, and pumped,
gives so much command and power over combustion and heat, and as a
to steam ships in case of storm, or when it is required to avoid pirate
ships, or in time of war to avoid hostile vessels, it will enable steam to
be raised with great rapidity, and thus give power and facility to make
movement or evolution very quickly and may tend greatly to the safety
of the vessel and the persons on board. In long voyages too the weight 3
of store of coals required will also be less. And in steaming in hot or
tropical climes where the temperature is high, it will be a sensible relief
to the firemen to use it partially or occasionally, as it will prevent the

page_text: charging of coal and the opening of fire-doors for the removal of ashes,
so far as it is used, and so avoid this heat and labour to the firemen,
and keep the boiler or stoking room or chamber cooler for them.
The liquid fuel as above named may be stored in casks or receivers or
tanks, but I think it being stored in strong iron receivers or tanks
preferable to it being used from the casks, or what it is supplied in; I
pump it thence by steam power through pipes into the furnace of the
boiler; and I recommend that the pump or pumps for liquid fuel be
doubly acting or double acting pumps so as to have regularity of flow
or supply of the liquid without alternation.
I recommend that the pipes, orifices, tuyeres, or openings, where these
are in immediate contiguity to the furnace and open into the furnace, be
small enough and sufficient in number and sufficiently apart or open to
allow the oil or spirit, or liquid fuel to mingle well with the air to make
the combustion as complete or thorough as possible.
I recommend that there be valves inserted or joined into the pipes of
liquid fuel close to the furnace, or at or contiguously to the furnace, and
these valves opening to the furnace as preventive to air getting into the
pipes and causing explosive mixture.
In using peat, wood, or other fuel instead of coal or coke in boiler
furnaces as fuel to raise steam as before named, I treat and use such
peat, wood, or other fuel in the same way that I do coal or coke, and
economize the combustibles contained in such peat, wood, or other fuel
and the heat from the combustion with the oxygen of the air similarly
and as before expressed in reference to coal or coke.
There is I believe on the average from fifteen to twenty per cent. of
volatile carbon or hydrocarbons and hydrogen in the coal of this country,
and this although the finest and purest part of the fuel in the coal is all
lost and wasted in coking, and in using the raw coal as at present done
in boiler furnaces, especially the furnaces of steamships, it is mostly
lost and wasted, and is dissipated in black particles of carbon or
smoke which are and are found to be a thorough nuisance, and I con-
sider, taken as a fair average, that though in parting from the hydrogen,
from vapour of carbon insensible heat may be disengaged in passing into
the solid form there is fully ten per cent. of the coal used as raw coal
wasted, and when the coal is converted into coke the hydrogen by far

page_text: the most powerful and effective part of the fuel taken weight for weight
as compared with the carbon, and in instantaneous ignition and action
is also altogether wasted, besides about twenty per cent. of the solid
carbon burnt or consumed in coking wasted. There is from the boiler
furnaces, as the fuel is at present used, also a considerable portion of the
fuel burnt with the oxygen of the air into carbonic oxide passes away as
carbonic oxide and further combustion, and the heat from such com-
bustion are thus quite lost. I believe that taking the insensible heat of
the carbonic oxide into account, from fifteen to twenty per cent. of the
practical heating value of the fuel is thus lost.
To one ton of fuel thoroughly burnt there will be required for com-
bustion about eight tons of air of which about three-fourth parts or six
tons are nitrogen, a gas not only noncombustible but which absorbs the
heat in the furnace to raise it to the furnace heat, and I consider that to
raise the nitrogen which necessarily passes in with the oxygen of the air
to 212° or the boiling point of water it will require about fifteen per
cent. of the fuel, as to the heat also resulting from combustion if the
results of combustion containing heat be not allowed prematurely to
escape, but be made to traverse through and through, or along and
along, or round and round the boiler so long as they contain heat
sufficiently or adequately available; I believe that such heat will alone
economize the fuel to a very great extent.
And I consider that the foregoing mode of using fuel or process fully
carried out will in all probability diminish the quantity of fuel used for
raising steam to one-fourth or one-fifth of the present quantity.
In the case for instance of a screw steamer going on an Indian voyage
and requiring on such voyage six hundred tons of coal for fuel, I believe
that about one hundred and fifty tons or perhaps less will be sufficient ;
such vessel now consuming as named six hundred tons coal to India
would require say from six to eight firemen, at a cost of say five hundred
pounds to seven hundred pounds per year for wages, rations, and grog;
and with such reduction of consumption as above named the item of cost
of firemen would be very materially reduced.
I do not bind myself to this extent of saving or to the above estimate
or statistics, but I believe that it will be approximately found correct.
As to steamships when steaming in very hot tropic temperatures, as
for instance in the Red Sea or Indian Ocean, I understand that the

page_text: heat from the boiler fires in the boiler or stoking room or chamber
together with the heat of the atmosphere is so severely felt by the
firemen, and becomes so intolerable that they have sometimes to be
withdrawn thoroughly exhausted and prostrate for the time being, and
that it sometimes causes death to them.
In steam ships when liquid fuel as above named is used, and it and
the air are pumped, instantaneous combustion and consequent power for
raising steam and for motion can be increased as may be desirable by
accelerating the action of the pumps of air and liquid fuel.
I claim, firstly, and as a distinct and separate claim the retention or
keeping of the heated resulting substances or products of the com-
bustion of fuel with air or oxygen of the air in the furnaces of boilers
as before named, and the continued circumfusion or circulation of such
resulting substances or products of combustion through or around or at
the boiler so long as they contain or retain available or sufficient heat
or are at sufficiently high temperature to raise steam in the boiler with
advantage for the purpose of raising steam; and this effected or done
in mode as herein-before named, so as to economize heat and con-
sequently fuel. Also the supplying of further air in or into another
division or part of the furnace or furnace, to or than that where the coal
or other fuel is being burnt or consumed with air or oxygen of the air
and yield the said resulting substances or products of combustion,
so as to burn the carbonic oxide or other combustibles contained in
such resulting substances or products of combustion, and use the heat
so obtained for raising steam, in mode as herein-before named, and
thus more thoroughly or effectively burn the fuel and so economize fuel
used in boiler furnaces for raising steam; and also besides the great
saving of fuel, for preventing or greatly diminishing smoke and other
purposes or considerations relating to this claim of this Patent as herein-
before named.
I claim, secondly, so as more completely or thoroughly to burn the
coal or other fuel, or to effectuate the retention and circulation of the
said heated products of combustion to obtain the available heat, as
above named, and also the burning of the combustibles contained in the
said products of combustion or furnace waste gases, and also to obtain
more power quickly, and command over the raising of steam than as at
present, in case of requirement or it being desirable, and also for comfort

page_text: to firemen, that I pump the air required for combustion with the fuel
from the atmosphere into the boiler furnace to obtain the heat required
to raise the steam, and this done as herein-before named.
I claim, thirdly, so as further to economize heat, and not let it be
wasted, and consequently to economize fuel, and for the other objects
or considerations bearing on this claim (such as the requirement of less
stoking or firing labour, from less fuel being required) of this Patent
as before named, the heating of the air required for combustion in the
boiler furnace for raising steam, in mode as herein-before named.
And I claim, fourthly, so as to have more command than as at present
and have very great command over instantaneous abundant combustion,
and consequently rapid raising of steam in case of emergency, or where
it may be desirable or advantageous, and for the other objects or
considerations bearing on this claim of this Patent, as before named,
the pumping, and use of naphtha, liquid paraffin, or other liquid
combustible oils or spirits, rectified to prevent the clogging of the pumps
or other apparatus through which they pass, as before named as fuel
instead of or partly instead of coal or other fuel in the boiler furnace
for raising steam, and this done in mode herein-before named.
In witness whereof, I, the said William Mickle, have hereunto set
my band and seal, this Tenth day of March, in the year of our
Lord One thousand eight hundred and seventy-three.