IMPROVEMENTS IN CALORIC MOTOR ENGINES USING GAS AS FUEL."
Year: 1881

page_text: LETTERS PATENT to Henry Charles Fleeming Jenkin, of No. 3, Great Stuart
Street, in the City of Edinburgh, Professor of Engineering in Edinburgh
University, and Alexander Chalmers Jameson, residing at No. 1, Gillespie
Crescent, Edinburgh, Engineer, for an Invention of "IMPROVEMENTS IN
CALORIC MOTOR ENGINES USING GAS AS FUEL."
PROVISIONAL SPECIFICATION left by the said Henry Charles Fleeming
Jenkin and Alexander Chalmers Jameson at the Office of the Commissioners
of Patents on the 16th March 1881.
HENRY CHARLES FLEEMING JENKIN, of No. 3, Great Stuart Street, in the City
of Edinburgh, Professor of Engineering in Edinburgh University, and ALEXANDER
CHALMERS JAMESON, residing at No. 1, Gillespie Crescent, Edinburgh, Engineer.
"IMPROVEMENTS IN CALORIC MOTOR ENGINES USING GAS AS FUEL.'
The nature and object of this Invention is the production of a caloric motor engine,
substantially on the type of a hot air Stirling engine, consisting of a combination with
the usual parts or features of a Stirling engine, of the parts or features bereinafter
more particularly described or referred to as described in the Provisional Specification
of our Invention of "Improvements in Caloric Motor Engines Burning Solid Fuel,
some of which are Applicable to other Motor Engines," left by us at the office of
the Commissioners of Patents on the Twelfth day of March A.D. 1881, and
numbered 1078, or in the case of some of these of possible substitutes therefor or
modifications thereof, also hereinafter described or referred to as described in said
Provisional Specification, and with or without the omission or consolidation into
one or appropriation to the discharge of double or alternate functions of some or
all of those parts (whether belonging to the ordinary Stirling engine, or added by
us thereto) which are hereinafter or in the said Provisional Specification described
as capable of being so omitted or consolidated or made to perform double or
alternate functions, and in which engine the products of the combustion or oxidation
of inflammable or combustible or oxidisable gas are used as the working fluid
instead of air and the heat is originally supplied to the working fluid by convection
from gas and air or oxygen caused to combine in or on what we hereinafter term
the "gas grate," before entering the displacer chamber.
Our engine is in what we consider its most complete and preferable form a
combination with the usual parts of a hot air Stirling engine of the following
parts, of which however some, as mentioned hereinafter or in the parts of the said
Specification hereinafter referred to, may be substituted or modified by other
arrangements or omitted altogether, or made to perform alternate or double
functions, viz., of,—
First. What we term a "gas grate." This grate consists of a small chamber lined

page_text: with fire clay or other refractory and non-conducting material capable of retaining
and resisting a great continuous heat and of allowing continuous combustion of
fuel to be carried on therein. It is constructed in immediate proximity to and Bo
so as to be in constant communication with the hot end of the displacer chamber,
and is either filled with such materials as have the property of glowing without
being consumed (such, for example, as spongy platinum, pipe clay, or asbestos), and
of determining or promoting and facilitating combination of gas and air without
producing explosion at all in the mixture of air and gas which may be directed on
the surface, or passed through the mass thereof and within the main, no flame
accompanying the combination, the said materials being well divided or distributed
or loosely packed together, or otherwise so disposed and arranged as to present a
number of interstices and a large amount of interstitial or cellular surface, and
also so as to allow free passage for the products of combustion of the fuel through
the interstices into the hot end of the displacer chamber; or it is at least separated
from the hot end of the displacer chamber by a screen or diaphragm full of
apertures or perforations, or by a similarly perforated or permeable layer or layers
of such materials as possess the property of glowing and determining the combination
of gas and air in manner aforesaid (such as a screen of platinum wire gauze)
through which perforations or apertures the small chainber shall constantly
communicate with the displacer chamber, and through which also the products of
combustion of the fuel shall pass by expansion or current or both into the same,
that fuel being any combustible mixture of gas and of atmospheric air or other
source of free oxygen in such proportions as shall be sufficient to ensure the
complete oxidation of the gas. The fuel is intended to be wholly consumed within
the grate; that is to say, the combustion of the mixture (by which we mean
throughout this Specification the combination of the gas and oxygen from which
heat is generated, either effected with or as hereinafter mentioned without explosion
and in the main also without flame, as the case may be) is intended to be
completed within the meshes of the materials which fill the grate or on or against
what may be called the bars of it, viz., the glowing screen, diaphragm, or layers
above mentioned. The air and gas are not intended to enter the displacer chamber
in an uncombined state. The products of this combustion pass from the grate into
the hot end of the displacer chamber. The" gas grate" or chamber and the
materials which fill it or which separate it from the displacer chamber, are intended
to be kept in a permanent glow while the engine is working, and the grate is
wholly reserved for the purpose of effecting the combustion. The pressure inside
the grate should at all times be above that of the displacer chamber, so that the
products of combustion are never forced back into the grate. The form of the
grate may be varied in a great many ways, but what we mean by a grate is an
arrangement which contains the two following features :-(1.) It is wholly reserved
for effecting combustion, and should never be entered by the displacer; aud (2), it
must be suitable for carrying on continuous combustion of fuel. We do not, for
instance, call that a grate within which combustion and the production of a vacuum
alternate, or in which the space where the fuel is burnt is at times occupied by
other substances than the fuel and the air or oxygen which is to oxidize it, and no
grate can be used in our engine which could not stand or would not work if heat
were being continuously produced therein.
Secondly. An air pump or pumps for supplying air and gas to the grate, and
maintaining such higher pressure inside the grate that the products of combustion
shall not be driven out of the displacer chamber back through the grate. We may
either use a separate pump or set of pumps to force air into the grate, and another
pump or set of pumps to force into it the gas to be burned; or in some cases the
same pump may be employed to throw in both gas and air, the mixture being made
before their admission to the pump; in other cases the gas and air are mixed
immediately before passing into the grate. The gas and air, either or both, from
the pumps may also be passed through a section of the regenerator, having a
suitable valve or valves in the cool end, or through a pipe or pipes led from the

page_text: cold to the hot end of the regenerator before the said air or gas or air and gas
enters the grate. We by this means obtain a warm blast and slightly cool the
regenerator. We consider it advantageous to pass the mixture through a constant
flow valve, as hereinafter mentioned.
Thirdly. An equilibrating arrangement or equilibrator. The object of this
arrangement, and the various modes in which we effect the same, and the different
forms of the equilibrator, are described under head "Thirdly" of the said Provisional
Specification of our solid fuel engine, and the whole statements and observations
contained under said heading with regard to an equilibrator as used in our said
solid fuel engine.are applicable to it as used in the gas engine to which the present
Specification relates, and are held as herein repeated in reference thereto.
Fourthly. Special arrangements by which we are enabled to use such non-
conducting and refractory materials as fire. bricks for lining or constructing the
hot end of the main displacer chamber, in order to retain the heat in the said
chamber and in the regenerator, and to resist the high temperatures attained
without introducing an injurious cushioning action which would result from the
employment of such materials without these special arrangements. The said
special arrangements are described in the said Provisional Specification of our
solid fuel engine under, head "Fifthly" thereof, and the whole statements and
observations contained under said heading are held as repeated herein in reference
to the gas engine which forms the subject of this Specification.
Fifthly. An air displacer. This device is described in the herein before mentioned
Provisional Specification of our solid fuel engine under the heading "Sixthly"
thereof, and the whole statements and observations therein contained are held as
repeated in this Specification in connection with the gas engine forming the subject
hereof, both as regards the air displacer or the devices which may be used with or
substituted for it; in short, the whole of said heading "Sixthly" is held as
repeated herein as applicable to our gas engine.
Sixthly. A special method or arrangement for obtaining the heat from the fuel
or causing the gas and oxygen to combine, and so generate heat wholly without
explosion, and in the main without flame. This we effect by taking advantage
wholly or chiefly of the physical fact (variously known as occlusion, contact action,
or catalysis) that the combination of oxygen with inflammable gases or vapours is
so greatly facilitated, promoted, or determined by contact with the surface, or
inclusion within the pores of platinum and of many other substances both metallic
and non-metallic which either in the cold, or at least when somewhat heated,
possess the same power as platinum (such as palladium, iridium, cobalt, nickel,
charcoal, pumice stone, porcelain, pipe clay, adainas, chalk, stucco, fluor spar, and
other materials), that glowing heat may be generated by the combination so
determined without the production in the main or in any very considerable
quantity of flame, and wholly without explosion of the gaseous materials employed.
With this object the materials filling the grate chamber, or forming what we have
called its bars, may consist wholly or chiefly of platinum gauze, or partly of platinum
gauze, and partly of such other substances as pipe-clay, fireclay, and asbestos which
have the said power, especially when somewhat heated, of glowing without exciting
explosion, or even to any great extent flame, when a suitable mixture of air or
oxygen and of combustible gas is blown or carried in a current along the surface or
through a mass of the same. The mixture of gas and air or oxygen is kept flowing
through the occluding materials of the grate, whereby the combination of the gas
and oxygen is determined in the main without flame and wholly without explosion,
and we thus heat the grate and its chamber to and keep them at a glowing
temperature, while we avoid the difficulties arising from explosion, and the trouble
connected with the valve or other arrangement usually employed to effect explosion
of the mixture. The combustion however may be carried on either continuously
or intermittently by keeping the flow of gas and air continuous, or intermitting it
for such short intervals as will not throw the occluding grate out of action. While
we prefer making the gas and air combine by the method of occlusion, any of the

page_text: .
ordinary arrangements, or any other arrangement for igniting, inflaming, burning,
or exploding the gaseous fuel might be substituted for our said method without
altering substantially the character of the combination in which our engine consists.
One method by which we light, ignite, or inflame the mixture of gas and air when
we do not use the said first mentioned method of combining them, is by alternately
introducing and withdrawing a piece of incandescent material such as a small bar
or strip of pipe clay or platinum, or a small roll of platinum gauze. Whenever
the piece of incandescent pipe clay or roll of incandescent platinum is immersed in
the explosive or combustible mixture, we excite a slight draft or current in the
mixture, thereby causing occlusion of the gaseous mixture to take place, the whole
arrangement resulting in a temperature high enough to cause or facilitate ignition or
produce flame and explosion. This draught or current may be maintained by having
a small plunger in the valve block in which the pipe clay or platinum is fixed, or
by any of the other familiar devices for such purpose.
"
Seventhly. The circulating valve or valves. This device is the same as that
described in the said Specification of our solid fuel engine under head "Seventhly
thereof, and we hold the whole of the statements and observations contained therein
under said heading as repeated herein with reference to our gas engine.
Eighthly. A cut-off valve interrupting the communication between the displacer
vessel and the working cylinder, as described under head "Seventhly" of our said
Specification of our solid fuel engine.
Of the eight modifications or special features hereinbefore described or referred
to, we regard the first, second, and third (viz, the gas grate, the air pump or pumps,
and the equilibrating arrangement) combined with the refrigerator, regenerator, and
working cylinder of Stirling's engine as indispensable to any of the combinations
of parts in which our gas engine consists or may consist. The omission.
from the combination of the fourth head very materially damages the efficiency
of the engine. The fourth head is capable of being introduced into, and is valuable
in any analogous form of engine, whether it contains any of our special features or
not. Similarly the sixth contrivance by which heat is produced without explosion
may be valuable in other forms of caloric engine in which gas is employed, but it
may be dispensed with in ours in favor of the other arrangements hereinbefore
mentioned. The circulating valves hereinbefore described in the seventh head or
place, and the cut-off valve described in the eighth head or place may for the sake of
simplicity be (one or both of them) omitted from our combination, in which latter case
the connection between the displacer chamber and the working cylinder is simply
that of the old Stirling engine. In small engines the radiation from the cold end
of the chamber may be a sufficient refrigerator. By keeping up the combustion
constantly or continuously we produce heat in the grate in a manner analogous to
that in which heat was supplied continuously to the hot end of Stirling's air vessel
by transmission across the iron casing, but we prefer to check the production of
heat during the period when the displacer occupies the warm end by diminishing
the supply of air and gas, and in some cases we may for a short time wholly
discontinue the supply. The fuel may be burnt in the grate as flame, and ignited
by any ordinary means or kept alight by the temperature of the grate. Our engine
may be double acting, or may by employing an air cushion or large fly. wheel for
the return stroke be made single acting. Communication may be kept open
constantly between the cool chamber and the working cylinder, or the communi-
cation may, and we prefer that it should, always be made intermittent by means of
any of the arrangements herein before mentioned or referred to as having that
.effect.
In order to start the engine when it is quite cold, the platinum grate is heated to
a temperature such that occlusion can readily take place. This may be done either
by causing the products of an actually burning mixture of air and gas to be passed
through the occluding grate, or by heating a sufficient surface of tube or other
enclosed surface to such an extent that it will either heat common air or a mixture
of gas and air to such a degree that the air or mixture will raise the temperature

page_text: of the occluding grate to the point at which occlusion begins, gas being (in the case of
common air alone having been used) then mixed with the air, so that the grate shall
then produce the requisite amount of heat to warm up the engine, the products of
combustion either before or after passing through the regenerator being discharged
into the atmosphere. This process is analogous to raising steam in the ordinary
steam engine. For stopping and starting the engine when on duty for short spaces:
of time, we arrange the gear working the main displacer or displacers so that it
can be readily thrown out of gearing, the displacer or displacers being then
worked by hand or other extraneous power, the engine then acting as an ordinary
Stirling engine would under similar circumstances; meanwhile, the equilibrator
may or may not be used by itself or in conjunction with the pump, or they may
both be thrown out of action. The engine is thus easily started after a stoppage
without extraneous power, a circumstance which renders it peculiarly suitable for
driving tramway cars and the like.
The action of the gas engine is generally speaking, and making allowance.
for the differences between it and the solid fuel engine, substantially the same
as that of the solid fuel engine, as described in our Specification thereof. It
may be described as simply that of an ordinary Stirling engine with the
following variations or modifications. (1.) The action of the circulating valves,
whose function is so to regulate the flow of fluid between the cylinder and displacer
that heat may be abstracted by the refrigerator from the cushion and working
fluid only during that portion of the cycle when the working fluid is undergoing
compression. (2.). While the ordinary cycle of operations of the Stirling engine is
going on, we introduce sufficient quantity of gas and air into the furnace to supply
the requisite amount of heat for that cycle of operations, and we abstract from the
displacer chamber by means of the equilibrator a quantity of working fluid equal
under normal conditions to the weight of air and fuel consumed during the same
cycle of operations, and we expand it down to atmospheric pressure, allowing it
then to escape into the atmosphere. The object of this abstraction of working fluid
is to make practically a balance between the power required to compress the air
and the power given out by expansion in the equilibrator. By preference we have
a small reservoir of compressed gas and air between the compressing pump and the
furnace, so that the pump does not deliver direct into the furnace, the object being
that we may admit the gas and air into the furnace at the period when in the
ordinary cycle of operations of the Stirling engine heat is required to be produced.
Or we may produce the heat continuously, thereby making it unnecessary for the
compressing pump to end its stroke at any special time during the said cycle.
We arrange the pump and equilibrator so that the combination of their turning
moments with the turning moments of the Stirling engine may be such as to
avoid as far as possible the inconvenience of negative moments in the combination
of which as a whole our engine consists, and to make these moments as constant as
may be practicable. For the purpose of effecting the last mentioned object we do
not confine ourselves to one single acting engine with its pump and equilibrator,
or to one double acting engine with pump or pumps, and equilibrator or equili-
5 brators, or to any particular number of engines, or to any particular number of
pumps and equilibrators in connection with any engine or number of engines, the
variety of possible combinations and arrangements of this nature being infinite.
In order to adapt our engine to such purposes as the driving of tramway cars, it
may be necessary or advantageous to conjoin with it a reservoir of compressed gas
to afford a supply of fuel without unduly occupying space in the car.
The displacer vessel and the working cylinder may be combined so as to form
one vessel according to a well known mode of arrangement as applied to previous
engines.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Charles Fleeming Jenkin and Alexander Chalmers Jameson
in the Great Seal Patent Office on the 16th September 1881.
HENRY CHARLES FLEEMING JENKIN, of No. 3, Great Stuart Street, in the City
of Edinburgh, Professor of Engineering in Edinburgh University, and ALEXANDER
CHALMERS JAMESON, residing at No. 1, Gillespie Crescent, Edinburgh, Engineer.
"IMPROVEMENTS IN CALORIC MOTOR ENGINES USING GAS AS FUEL."
The nature and object of this Invention is the production of a caloric motor
engine substantially on the type of a hot air Stirling engine, consisting of a com-
bination with the usual parts or features of a Stirling engine of the parts or features
hereinafter more particularly described or referred to as described in the Provisional
Specification of our Invention of "Improvements in Caloric Motor Engines Burning
Solid Fuel, some of which are Applicable to other Motor Engines," left by us at the
office of the Commissioners of Patents on the twelfth day of March, A.D. 1881,
and numbered 1078, or in the Complete Specification filed or about to be filed by
us in connection therewith, or in the case of some of these of possible substitutes
therefor or modifications thereof, also hereinafter described or referred to as
described in said Provisional and Complete Specifications, and with or without the
omission or consolidation into one or appropriation to the discharge of double
or alternate functions of some or all of those parts (whether belonging to the
ordinary Stirling engine or added by us thereto) which are hereinafter or in the said
Provisional and Complete Specifications described as capable of being so omitted
or consolidated, or made to perform double or alternate functions, and in which
engine the products of the combustion or oxidation of inflammable or combustible
or oxidisable gas are used as the working fluid instead of air, and the heat is
originally supplied to the working fluid by convection from gas and air or oxygen
caused to combine in or on what we hereinafter term the "gas grate" before
entering the displacer chamber.
Our engine is in what we consider its most complete and preferable form a com-
bination with the usual parts of a hot air Stirling engine, to wit, the main displacer
vessel with its hot and cold chamber, the refrigerator and regenerator working
cylinder, and other ordinary parts of a Stirling engine exclusive of its external
furnace of the following parts (of which however some, as mentioned hereinafter, or
in the parts of the said Specifications hereinafter referred to, may be substituted or
modified by other arrangements or omitted altogether, or made to perform alternate
or double functions), viz., of,-
First. What we term a ""
gas grate." This grate consists of a small chamber
lined with fireclay or other refractory and non conducting material capable of
retaining and resisting a great continuous heat, and of allowing continuous
combustion of fuel to be carried on therein. It is constructed in immediate
proximity to and so as to be in constant communication with the hot end of the
displacer chamber, and it is either (1) filled with such materials as have the
property of glowing without being consumed (such, for example, as spongy
platinum, pipe clay, or asbestos), and of determining or promoting and facilitating
the combination of gas and air or oxygen without producing explosion at all
in the mixture of air or oxygen and gas which may be directed on the surface
or passed into a mass, or through or among masses thereof and within the main,
no flame accompanying the combination, the said materials being well divided or
distributed, or loosely packed together, or otherwise so disposed and arranged as
to present a number of interstices and a large amount of interstitial or cellular
surface, and also so as to allow free passage for the products of combustion of the

page_text: fuel through the interstices into the hot end of the displacer chamber; or it is at .
least (2) separated from the hot end of the displacer chamber by a screen or
diaphragm full of apertures or perforations, or by a similarly perforated or
permeable layer or layers of such materials as possess the property of glowing,
and determining the combination of gas and air or oxygen in manner aforesaid
(such as a screen of platinum wire gauze), through which perforations or apertures
the small chamber shall constantly communicate with the displacer chamber, and
through which also the products of combustion of the fuel shall pass by expansion
or current or both into the same, that fuel being any combustible mixture of gas
and of oxygen, or atmospheric air, or other source of free oxygen (all of which
we shall herein after include under the word "air") in such proportions as shall be
sufficient to ensure the complete oxidation or combustion of the gas. The fuel is
intended to be wholly consumed within the grate; that is to say, the combustion
of the mixture (by which we mean throughout this Specification the combination
of the gas and oxygen from which heat is generated either effected with or, as
hereinafter mentioned, without explosion, and in the main also without flame, as
the case may be) is intended to be completed within the meshes of the materials
which fill the grate, or on or against what may be called the bars of it, viz., the
glowing screen, diaphragm, or layers above mentioned. The air and gas are not
intended to enter the displacer chamber in an uncombined state. The products
of this combustion pass from the grate into the hot end of the displacer chamber..
The "gas grate" or chamber and the materials which fill it or which separate it
from the displacer chamber, are intended to be kept in a permanent glow while
the engine is working, and the grate is wholly reserved for the purpose of effecting
the combustion.
The pressure inside the grate should at all times be above that of the
displacer chamber, so that the products of combustion are never forced back into
the grate. The form of the grate may be varied in a great many ways, but
what we mean by a grate is an arrangement which contains the two following
features:(1.) It is wholly reserved for effecting combustion, and should never be
entered by the displacer; and (2), it must be suitable for carrying on continuous
combustion of fuel. We. do not, for instance, call that a grate within which
combustion and the production of a vacuum alternate, or in which the free space:
where the fuel is burnt is at times occupied by other substances than the fuel,
and the air or oxygen which is to oxidize it, or the products of their combination,
and no grate can be used in our engine which could not stand or would not work
if heat were being continuously produced therein.
Secondly. An air pump or pumps for supplying air and gas to the grate, and
maintaining such higher pressure inside the grate that the products of combustion.
shall not be driven out of the displacer chamber back through the grate. We may
either use a separate pump or set of pumps to force air into the grate, and another
pump or set of pumps to force into it the gas to be burned; or in some cases the
same pump may be employed to throw in both gas and air, the mixture being.
made before their admission to the pump; in other cases the gas and air are mixed
immediately before passing into the grate. The gas and air, either or both, from the
pumps may also be passed through a section of the regenerator, having a suitable
valve or valves in the cool end, or through a pipe or pipes led from the cold to the
hot end of the regenerator before the said air or gas or air and gas enters the grate.
We by this means obtain a warm blast and slightly cool the regenerator. We
consider it advantageous to pass the mixture through a constant flow valve, as
hereinafter mentioned.
Thirdly. An equilibrating arrangement or equilibrator. The object of this
arrangement, and the various modes in which we effect the same, and the
different forms of the equilibrator, are described under head "Fourthly" of the
said Provisional and Complete Specifications of our solid fuel engine, and the
whole statements and observations contained in said Specifications with regard
to equilibrating arrangements or an equilibrator with all the variations on

page_text: modifications thereof, and alternative combinations therefor as used in our said solid
fuel engine are applicable to the same as used in the gas engine to which the
present Specification relates, and are held as herein repeated in reference thereto.
Fourthly. Special arrangements by which we are enabled to use such non-
conducting and refractory materials as fire bricks for lining or constructing, the
hot end of the main displacer chamber, in order to retain the heat in the said
chamber and in the regenerator, and to resist the high temperatures attained
without introducing an injurious cushioning action which would result from the
employment of such materials without these special arrangements. The said
special arrangements are described in the said, Provisional and Complete Speci-
fications of our solid fuel engine under head "Fifthly" thereof, and the whole
statements and observations contained in said Specifications as to the use of
said special arrangements in all their various forms and modifications in connection
with our said solid fuel engine are held as repeated herein in reference to the gas
engine which form the subject of this Specification.
65
Fifthly. An air displacer. This device is described in the hereinbefore mentioned
Provisional and Complete Specifications of our solid fuel engine under the heading
Sixthly" thereof, and the whole statements and observations contained in said
Specifications in reference to the air displacer of our solid fuel engine, or the
devices which may be used with or substituted for it, are held as repeated in this
Specification in reference to the gas engine forming the subject hereof.
•
Sixthly. A special method or arrangement for obtaining the heat from the fuel
or causing the gas and oxygen to combine, and so generate heat wholly without
explosion, and in the main without flame... This we effect by taking advantage
wholly or chiefly of the physical fact (variously known as occlusion, contact action,
or catalysis) that the combination of oxygen with inflammable gases or vapours is
so greatly facilitated or promoted or powerfully determined by contact with the
surface or inclusion within the pores of platinum (and of many other substances
both metallic and non metallic which, either when cold or at least when somewhat
heated, possess the same power as platinum, such as palladium, iridium, cobalt,
nickel, charcoal, pumice stone, porcelain, pipeclay, adamas, chalk, stucco, fluor spar,
and other materials), that glowing heat may be generated by the combination so
determined without the production in the main or in any very considerable
quantity of flame, and wholly without explosion of the gaseous materials employed.
With this object the materials filling the grate chamber or forming what we have
called its bars, may consist wholly or chiefly of platinum, gauze, or any other of
the substances or materials hereinbefore mentioned or indicated as possessing the
like occluding power, or partly of platinum gauze and partly of such other
substances as pipeclay fireclay and asbestos, or others aforesaid, which have the
said power, especially when somewhat heated, of glowing without exciting
explosion or even to any great extent flame when a suitable mixture of air or
oxygen and of combustible gas is blown or carried in a current along the surface
or into or through a mass or masses of the same. The mixture of gas and air or
oxygen is kept flowing through the occluding materials of the grate whereby the
combination of the gas and oxygen is determined in the main without flame and
wholly without explosion, and we thus heat the grate and its chamber to and keep
them at a glowing temperature, while we avoid the difficulties arising from
explosion and the trouble connected with the valve or other arrangement usually
employed to effect explosion of the mixture. The combustion however may be
carried on either continuously or intermittently by keeping the flow of gas and air
continuous, or intermitting it for such short intervals as will not throw the
occluding grate or materials out of action. While we prefer making the gas and
air combine by the method of occlusion, as hereinbefore described, any of the
ordinary arrangements or any other arrangement for igniting, inflaming, burning,
or exploding the gaseous fuel might be substituted for or used in combustion with
our said method without altering substantially the character of the combination in
which our engine consists. One method, for example, by which we might light,

page_text: ignite, or inflame the mixture of gas and air when we do not use the said first
mentioned method of combining them, is by alternately introducing and with-
drawing a piece of incandescent material, such as a small bar or strip of pipe clay
or platinum, or a small roll of platinum gauze. Whenever the piece of incandescent
pipeclay or roll of incandescent platinum is immersed in the explosive or
combustible mixture we excite a slight draft or current in the mixture, thereby
causing occlusion of the gaseous mixture to take place, the whole arrangement
resulting in a temperature high enough to cause or facilitate ignition or produce
flame and explosion. This draught or current may be maintained by having a
small plunger in the valve block on which the pipe clay or platinum is fixed, or by
any of the other familiar devices for such purpose. When any other method of
burning the mixture than that of occlusion, as herein before described, is employed, the
materials filling the grate and the diaphragm or layers separating it from the displacer
chamber may be omitted.
The .use of the method last described, or of any other method suggested as
capable of being used as an alternative for the said method of occlusion, herein-
before described, is subject always to such Patent rights relating thereto as may
be in force from time to time.
In all the combinations of which our engine may consist the grate and hot end
of the displacer chamber require before the engine is started to be independently
heated, as hereinafter mentioned.
"
Seventhly. The circulating valve or valves. This device is the same as that
described in the said Specifications of our solid fuel engine, under head "Seventhly
thereof, and we hold the whole of the statements and observations contained in
said Specifications regarding the said circulating valve or valves under said heading
or elsewhere therein as repeated herein with reference to our gas engine.
Eighthly. A cut off valve interrupting the communication between the displacer
vessel and the working cylinder, as described under head "Eighthly" of our said
Specifications of our solid fuel engine.
Of the eight modifications or special features hereinbefore described or referred
to we regard the first, second, and third (viz., the gas grate, the air pump or pumps,
and the equilibrating arrangement), combined with the refrigerator, regenerator,
and working cylinder of Stirling's engine as indispensable to any of the com-
binations of parts in which our gas engine consists or may consist. The omission
from the combination of the fourth head very materially damages the efficiency of
the engine. The fourth head is capable of being introduced into and is valuable
in any analogous form of engine, whether it contains any of our special features or
not. Similarly the sixth contrivance, by which heat is produced without explosion,
may be valuable in other forms of caloric engine in which gas is employed, but it
may be dispensed with in ours in favor of the other arrangements herein before
mentioned.
The circulating valves hereinbefore described in the seventh head or place, and
the cut off valve described in the eighth head or place may for the sake of
simplicity be (one or both of them) omitted from our combination, in which latter
case the connection between the displacer chamber and the working cylinder is
simply that of the old Stirling engine. In small engines the radiation from the
cold end of the chamber may be a sufficient refrigerator. By keeping up the
combustion constantly or continuously we produce heat in the grate in a manner
analogous to that in which heat was supplied continuously to the hot end of
Stirling's air vessel by transmission across the iron casing, but we prefer to check
the production of heat during the period when the displacer occupies the warm end
by diminishing the supply of air and gas, and in some cases we may for a short
time wholly discontinue the supply. The fuel may be burnt in the grate as flame,
and ignited by any ordinary means or kept alight by the temperature of the
grate. Our engine may be double acting, or may by employing an air cushion or
large fly wheel for the return stroke be made single acting. Communication may
be kept open constantly between the cool chamber and the working cylinder, or

page_text: the communication may, and we prefer that it should, always be made intermittent
by means of any of the arrangements hereinbefore mentioned or referred to as
having that effect.
In order to start the engine when it is quite cold, the grate is heated to a
temperature such that occlusion can readily take place. This may be done either
by causing the products of an actually burning mixture of air and gas to be passed
through the occluding grate, or by heating a sufficient surface of tube or other
enclosed surface to such an extent that it will either heat common air or a mixture
of gas and air to such a degree that the air or mixture will raise the temperature
of the occluding grate to the point at which occlusion begins, gas being (in the
case of common air alone having been used) then mixed with the air, so that the
grate shall then produce the requisite amount of heat to warm up the engine,
the products of combustion either before or after passing through the regenerator
being discharged into the atmosphere. Or for the same purpose of raising the
temperature of the grate to the point of ready occlusion we may actually burn the
mixture of gas and air on the grate, either by passing the gas and air already
mixed up through the grate and igniting the mixture there or by passing the gas
and air up through separate channels, which meet in or on the grate and igniting
the gas and air when they so mix in or on the grate. In.all these arrangements the
chimney is connected to the main displacer vessel so as to cause a draught through
the grate. We may for the purpose of kindling or starting the ignition of the
mixture of gas and air, and so starting the occluding action of the grate, should
the grate by reason of a long stoppage have fallen to such a temperature that the
occlusion does not readily take place, use the method of ignition specially herein-
before described at the end of head Sixthly, or any other suitable arrangement. This
process is analogous to raising steam in the ordinary steam engine. For stopping
and starting the engine when on duty for short spaces of time, we arrange the
gear working the main displacer or displacers so that it can be readily tbrown out
of gearing, the displacer or displacers being then worked by hand or other
extraneous power, the engine then acting as an ordinary Stirling engine would
under similar circumstances; and the gearing may be so connected with the engine
that the motion of the plungers may be readily adapted for driving the engine,
either forwards or backwards as by eccentrics and a link, or by a shifting eccentric
or by any of the well known means at present used for slide valves. Meanwhile
the equilibrator may or may not be used by itself or in conjunction with the pump,
or they may both be thrown out of action. The engine is thus easily started after
a stoppage without extraneous power, a circumstance which renders it peculiarly
suitable for driving tramway cars and the like.
The action of the gas engine is generally speaking, and making allowance for the
difference between it and the solid fuel engine, substantially the same as that of the
solid fuel engine, as described in our Specification thereof. It may be described
when the engine is in its most complete or perfect form as simply that of an
ordinary Stirling engine, with the following variations or modifications, but the
description will require modification, such as will be obvious to engineers when
applied to less complete forms of the engine:-
-
(1.) The action of the circulating valves (when these are used). Their function is
so to regulate the flow of fluid between the cylinder and displacer that heat may
be abstracted by the refrigerator from the cushion and working fluid only during
that portion of the cycle when the working fluid is undergoing compression.
(2.) While the ordinary cycle of operations of the Stirling engine is going on we
introduce a sufficient quantity of gas and air into the furnace to supply the requisite
amount of heat for that cycle of operations, and we abstract from the displacer
chamber by means of the equilibrator a quantity of working fluid equal under
normal conditions to the weight of air and fuel consumed during the same cycle of
operations, and we expand it down to atmospheric pressure, allowing it then to
escape into the atmosphere. The object of this abstraction of working fluid is to
make practically a balance between the power required to compress the air and the

page_text: ·
power given out by expansion in the equilibrator. By preference we have a small
reservoir of compressed gas and air between the compressing pump and the furnace,
so that the pump does not deliver direct into the furnace, the object being that we
may admit the gas and air into the furnace at the period when in the ordinary
cycle of operations of the Stirling engine heat is required to be produced. Or we
may produce the heat continuously, thereby making it unnecessary for the
compressing pump to end its stroke at any special time during the said cycle.
We arrange the pump and equilibrator so that the combination of their turning
moments with the turning moments of the Stirling engine may be such as to avoid,
as far as possible, the inconvenience of negative moments, in the combination of
which as a whole our engine consists, and to make these moments as constant as
may be practicable. For the purpose of effecting the last mentioned object we do
not confine ourselves to one single acting engine with its pump and equilibrator,
or to one double acting engine with pump or pumps and equilibrator or equilibrators,
or to any particular number of engines, or to any particular number of pumps and
equilibrators in connection with any engine or number of engines, the variety of
possible combinations and arrangements of this nature being infinite.
In order to adapt our engine to such purposes as the driving of tramway cars it
may be necessary or advantageous to conjoin with it a reservoir of compressed gas
to afford a supply of fuel without unduly occupying space in the car.
·
The displacer vessel and the working cylinder may be combined so as to form
one vessel, according to a well known mode of arrangement as applied to previous
engines.
Figures 1º, 2º, 3º, 4°, show one complete form of our engine.
In Figure 1°, A is the grate or furnace surrounded by refractory non conducting
material a, a, a; B, B, is the inner metallic casing, cutting off from the bulk b, b, b,
of the non conducting material a thin layer a, a, a, sufficient for the protection of
the said inner metallic casing against oxidation and burning, the exterior non-
conducting material b, b, b, being enclosed in another metallic casing C, which may
be so constructed that it is capable of retaining and withstanding pressure from
within; or it may be made with a direct communication between b, b, b, and the
atmosphere. The grate A is filled with any suitable substance or substances which
have the property of facilitating the combustion of gases in their pores when
somewhat heated, such as platinum, porcelain, pipeclay, firebrick, &c., which
substances are so arranged as to present a large surface to the action of the gases,
and on which surface the gas and air may combine entirely or in the main without
flame.
E is a passage from which the plug shown as occupying it in the Drawing may
be withdrawn and a chimney attached thereto for the purpose of heating up the
hot end of the displacer vessel preparatory to starting the engine.
F is a similar passage which is opened for the admission of gas and air for this
purpose; D, is the tube through which the mixture of gas and air enters the grate
when the engine is working, and is lined with glass or other suitable material to
prevent the occluding action running back from the grate.
Figure 7° shows another arrangement of grate in which the grate may be
removed from the engine for examination if desired. The whole plug 8, 8, carrying
the grate A along with it may be screwed back by means of the nut and handle t
till there is an annular open space round the plug 8, 8, up which the air flows to
the grate A. Gas is admitted by the pipe u, which is lighted on the grate, and
allowed to burn till the hot end of the displacer vessel has attained a sufficient
temperature, the products of combustion being carried off by the chimney E,
Figure 1. After the engine is started the gas and air mixture flows up the tube w,
entering it by the branch v, and the pure gas supply at u is turned off by a suitable
valve.
D², Figure 5º, is a second passage through which the mixture supplied to the
grate may be ignited and the occluding action thereby started in cases where the
temperature of the grate has fallen so low in consequence of a long stoppage or

page_text: from any other cause that its temperature is not sufficient to start the occluding
action though the hot end of the displacer vessel may be at a sufficient temperature
for working purposes. G is the displacer, H the regenerator, I the refrigerator,
J the hot chamber, and K the cool chamber.
The plungers are worked by the eccentric and gear marked L, L, in the
Drawings; M is the working cylinder communicating with the main displacer
vessels by the passages O, O, and N, N, are the pumps and equilibrators worked
off the crank pin of the engine by a slot P.
QQ, are the circulating valves, of which there may be any number; one to each
displacer vessel is shown in the Drawings. Cut off valves may be placed on the
pipes O, O, so as totally to interrupt the communication between the main displacer
vessels and the working cylinder, but they are not necessary unless the engine is
intended to work at varying speed or with a varying load. For the sake of
simplicity they are not shown in the Drawing.
R is the reservoir for gas and air; S, S, are the constant flow valves.
Figures 5° and 6° show an arrangement by which the gas and air may be ignited
on the grate; o is a small gas jet which burns passing through a hole in the slide p.
If the slide p is rapidly pushed in between the cover and seat q, q, it shears off the
top of the gas jet o and coming opposite the passage D' ignites the mixture of gas
and air, thereby starting the occluding action on the grate, the small pipe r commu-
nicating with the gas and air reservoir ensures the tube D, being full of a mixture
of gas and air, so that the flame may run along the tube D, to the grate; x is an
eyepiece through which the state of the occluding grate may be examined. This
valve is not shown in the other views of the engine.
The action of the engine is as follows:-
The plugs enclosed in the passages F and E are removed and E are placed in commu-
nication with a chimney. The gas jet is introduced and kindled in the openings F, F,
. and allowed to burn there, or it is pushed so close up to the grate that the com-
bustion is effected either in the grate itself or on its surface inside the hot chamber.
The draft in the chimney may be maintained either by heating the chimney
directly or by any other suitable means. The hot end having attained a sufficient
temperature, the plugs are screwed into E and F, the whole apparatus is then
closed up and working fluid is then admitted into the displacer vessels either from
a receiver previously stored or it may be pumped up by a small supplementary
pump, which may supply a mixture of gas and air so as to keep the grate glowing,
or it may supply fresh air or burnt air.
The main displacers are then disconnected from the engine by means of the
gear L. The pumps are temporarily thrown out of action but the equilibrators are
allowed to work. The plungers are then worked up and down by hand or other
power, thereby causing a difference of pressure on opposite sides of the piston,
which, assisted by the action of the equilibrators, starts the engine. As soon as it
is running at sufficient speed the displacers are put in gear by the rod and levers L,
the pumps are thrown into action, and the engine is at work. The cycle of
operations in the working cylinder and displacer vessel is similar to that of the old
Stirling engine, which has been hereinbefore described, except in so far as the
circulating valves modify its action. The circulating valves Q, Q, are actuated by
a bell crauk c which is worked by an eccentric d on the rocking shaft which works
the main displacers. This eccentric is set so that the circulating valves guide
the air on its way up to the cool end of the main displacer vessels past the
refrigerator by the passages T, T, and on its return cause it to pass through the
refrigerator L
While the ordinary cycle of operations of a Stirling engine is going on in the
working cylinder the following operations are taking place in the pumps and
equilibrators:The pumping and equilibrating arrangements are carried on in two
cylinders N, N. The ends of these cylinders through which the piston rods pass
are those in which the equilibrating action takes place. The other ends through
which the rods do not pass are those in which the pumping action is carried on,

page_text: During each stroke of the engine four distinct operations take place in these
cylinders, one operation in each end of each cylinder. These are, 1°, draw in air'
and gas by the valve e; 2°, compress and deliver it through the valve f into the
receiver R; 3°, receive a charge of high pressure working fluid by the valve g and
expand it down to atmospheric pressure; 4°, deliver this charge into the atmosphere
by the valve h. These valves g and h are driven by the eccentrics i, i, on the main
shaft of the engine and the rocking shafts k, k. In the arrangement shown in the
Drawings the compression of the charge of air and gas is always carried out in
the same ends of the same cylinders, and the equilibrating action is carried on
in the other ends of the same cylinders. These cylinders may be surrounded by a
water casing.
The pipes, l, convey the charge of air and gas into the receiver R, from which
it flows by the pipes m, m, to the constant flow valves S, S, and is delivered by
the tube D, Figure 5°, into the grate A. The pipes n, n, supply the equilibrators
with working fluid, and are connected to the main displacer vessels at a point near
the middle of the regenerator. Any of the other arrangements of pumps and
equilibrators mentioned in our Patent, No. 1078, 1881, or analogous arrangements
may be used, but the method shown is that in which the gas and air are raised to
the highest pressure, and afterwards allowed to flow into the grate through a
constant flow valve.
The main displacers may be driven by other means than that shown, so that they
may more nearly accord with their exact theoretic motion.
Having now described the nature of our Invention, and the best methods we are
acquainted with of performing the same, we wish to say that we do not confine "
ourselves to the precise details set forth, and we do not claim as our Invention
several of the arrangements described if taken separately. We do not claim the
internal combustion of gaseous fuel in a Stirling engine, neither do we claim any
combination in which the grate or combustion chamber do not require to be heated
before the engine can be started in the manner hereinbefore described. But what
we do claim as novel, and as secured to us by the hereinbefore in part recited
Letters Patent is,―
First. The caloric motor-engine hereinbefore described, being an engine the
cycle of whose operations is in the main that of the Stirling engine, but which
differs from the Stirling engine primarily in the internal combustion under pressure
of gaseous fuel, and which engine is a combination of the regenerator, refrigerator,
working cylinder and ordinary parts of a Stirling engine other than its external
furnace with the previously heated occluding grate and its adjuncts, all herein
before described under heads first and sixth, and with the further parts, arrange-
ments, or details herein before described or referred to in the first place under
heads Secondly, Thirdly, Fourthly, Fifthly, Seventhly, and Eighthly, or (2) in each
of the cases wherein for any such part, arrangement, or detail herein before described
or referred to one or more alternative or alternatives is or are hereinbefore or in the
said Complete Specification described, then either with the said part, arrangement,
or detail itself, or the said alternative, or one or other of the said alternatives
therefor, and that whether such engine be double acting or single acting, and whether
it have or have not all or any of its parts duplicated or otherwise multiplied or
repeated, all as hereinbefore described.
Second. The said caloric motor engine in any of its forms falling under the
preceding claim, but with the omission therefrom of any one or more of its con-
stituent parts, arrangements, or details which it is herein before or in our said
Complete Specification stated may be omitted.
Third. A caloric motor engine with its cycle of operations in the main, that of
the Stirling engine, but which differs from the Stirling engine primarily in the
matter of internal combustion under pressure of gaseous fuel by means and in
manner mentioned in claims first or second, and which engine consists of a com-
bination with the parts of a Stirling engine specified in claim first of a previously
heated glowing grate, in which continuous combustion may be effected, and of the

page_text: parts, arrangements, or details herein before under the several respective heads,
Secondly, Thirdly, and Fourthly, or in the several and respective places of our said
Complete Specification therein referred to first described; or instead of the part,
arrangement, or detail so first described, then of any other part, arrangement, or
detail herein before or in said Complete Specification described as an alternative
therefor, and that whether such engine be double acting or single acting, and
whether it have or have not all or any of its parts duplicated or otherwise
multiplied or repeated, all as hereinbefore described.
Fourth. A caloric motor engine consisting of the engine in any of its forms
claimed under claim three, with the addition thereto of any one or more of the
parts, arrangements, or details herein before under the several and respective heads,
Fifthly, Seventhly, and Eighthly, or in the several and respective places of our said
Complete Specification therein referred to first described, or instead of any part,
arrangement, or detail so first described, then of any other part, arrangement, or
detail herein before or in said Complete Specification described as an alternative
therefor, and that whether such engine be double acting or single acting, and
whether it have or have not all or any of its parts duplicated or otherwise
multiplied or repeated, all as hereinbefore described.
"
In witness whereof, I, the said Alexander Chalmers Jameson, have hereunto
set my hand and seal, this Seventh day of September, in the year of our
Lord One thousand eight hundred and eighty one.