IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR USING A LIQUEFIABLE GAS OR VAPOR AT LOW TEMPERATURES AS A MOTOR FLUID
Year: 1881

page_text: LETTERS PATENT to John Clayton Mewburn, of 169, Fleet Street, in the City
of London, Patent Agent and Consulting Engineer, for an Invention of
"IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR USING A
LIQUEFIABLE GAS OR VAPOR AT LOW TEMPERATURES AS A MOTOR FLUID."
A communication from abroad by John Gamgee, at present of Washington, in
the United States of America.
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn at
the Office of the Commissioners of Patents on the 2nd April 1881.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN THE METHOD OF AND
APPARATUS FOR USING A LIQUEFIABLE GAS OR VAPOR AT LOW TEMPERATURES
AS A MOTOR FLUID." [A communication from abroad by John Gamgee, at present
of Washington, in the United States of America.]
The Invention relates to the employment as a motor fluid of a liquefiable gas or
vapor of adequate tension, the product of a liquid which boils at or near the
temperature of surrounding objects. It is found that by working such a gas or
vapor expansively in one or more engine cylinders its heat can be converted to such
an extent into mechanical energy or motion that at the exhaust it will have returned
in great measure to its original liquid condition, from which state it may be again
caused to assume the condition of a motor vapor or gas by exposing it to the
temperature of its environment.
It is this feature, viz., the working of such a vapor or gas expansively to the
extent of more or less complete liquefaction, and then reconverting it 'from the
liquid to the vaporous or gascous condition for use again as a motor fluid, which
mainly characterizes this Invention.
The vapor having expended its energy and being mostly liquefied by the conversion
of its heat into motion is discharged from the engine cylinder into a closed exhaust
vessel protected or insulated from environing heat. The maintenance of the
exhaust at the boiling point (for atmospheric pressure or thereabouts) of the liquid
used may be ensured in various ways, for instance, by anyone of the following
methods, or by combinations of these methods.
1. By the use of an injector to free the exhaust chamber of liquid mainly.
2. By a pump to carry off whatever of vapor there may be in the exhaust
vessel, and to maintain the exhaust at any desired pressure.

page_text: By the injector or pump, or both, the cooled vapor is forced into an apparatus
for convenience sake, termed a boiler, where it is exposed to the temperature
needed to restore it to its original tension, and thence returns to the engine.
It will thus be seen that it is the object in this Invention to obtain in a motor
engine the conditions of a closed circuit with a liquid boiling at a low temperature
relatively to water transformed into vapor, the molecular energy of which is
converted into the mass or molar motion of the piston so that its initial condition
is restored.
In this way in a heat engine I extend the temperature within which heat is
utilized downwards in the direction of the absolute zero, instead of upwards above
the temperature of surrounding objects. The intense heat of boiler furnaces, the
internal work heat necessary to the formation of water steam, the abundant exhaust
waste of the steam engine, difficulties of lubrication, etc., are one and all avoided by
this Invention.
The cycle I proposed can be performed more or less satisfactorily with almost
any liquid yielding expansive vapor below the temperature at which water boils,
but in developing most power with most compact apparatus it is essential to use a
compound which has a maximum amount of latent heat.
The agent which is found in practice most available for this purpose is anhydrous
ammonia, the boiling point of which at atmospheric pressure approaches closely to
34°4 C. At 0° centigrade its vapor tension is 3183-34 millimeters, whilst at
10° it attains to 4574.03 millimeters. When the mean temperature attains
20° centigrade no less a pressure is exerted than 6387-78 millimeters, and at 30° C,
or tropical heat, it reaches over 8000 millimeters in tension. Since at blood heat
200 lbs. to the square inch is available, it is evident that the usual temperature of
ocean or river water is most desirable in practice, and best, in the opinion of the
inventor, when below 20° centigrade.
The latent heat of ammonia being about 900, as against 960 for water, it is
practicable to take advantage mostly of such latent heat in developing energy so
as to reduce the amount of rejected heat to a minimum and obtain a maximum rate
of liquefaction. Although high pressures are attainable at low temperatures it will
always be found best in practice to work below rather than over 100 lbs to the
square inch.
From the fact that heat is utilized in this system downwards to 0° centigrade,
and below towards absolute zero, it is proposed for convenience to name the
apparatus which is employed "Zeromotor.""
I will now describe an apparatus adapted to carry the Invention into effect.
I wish it to be understood however that I do not restrict myself to the particular
construction and combination of parts which compose the apparatus, for these may
be varied to suit special conditions so long as the apparatus as a whole is adapted
to carry out the cycle of operations hereinbefore specified.
The engine may be a double cylinder rotary engine. The gas or vapor enters
the first or high pressure cylinder through a valve and sliding division port which
runs in contact with the eccentric rotary piston in the usual way. The admission
valve is operated from the rocking valve rod in the usual way, said rod having an
arm which bears against a rotating adjustable cut off cam whose shaft is rotated
through the medium of eccentrics and connecting rods from the main shaft in the
ordinary manner. The exhaust port of the first cylinder is in communication with
the exhaust pipe which leads to the gas or vapor-admitting valve of the second or
low pressure cylinder. The latter with its accessories is similar, except in size, to
the first cylinder, the main shaft being common to both, and the two cylinders are
combined together for operation in the same way as the two cylinders of an
ordinary compound or double cylinder rotary engine.
A pipe conducts the liquefiable gas or vapor to the primary cylinder from a part
which for convenience sake will be termed the boiler, and which will be hereinafter
described.
The exhaust pipe from the second cylinder leads into a closed exhaust vessel;

page_text: this vessel receives through the exhaust pipe the liquefied vapor and gas from the
second cylinder.
From the upper part of the exhaust vessel leads a pipe to the larger cylinder
of a compound or double cylinder rotary pump driven by the rotary shaft.
The smaller or high pressure cylinder of the pump with its accessories is the
counter part of the larger, and has its induction port in communication with the
eduction port of the larger cylinder through the intermediary of a pipe. The
eduction port of the smaller cylinder communicates through a pipe with the space
in the boiler, which receives the liquid from which the motor gas or vapor is to be
generated.
The boiler is a metallic shell containing at each end an inner hollow head and a
space between that head and the outer head to receive the liquid, preferably water,
which takes the place of fuel as a heater for the liquid ammonia. Pipes lead from
one of the said spaces to the other, passing through without having communication
with the hollow inner heads. Into the space on one side enters a water induction
pipe, and from the opposite space leads a water eduction pipe. Water entering
through the induction pipe will circulate through spaces and pipes, and will pass
out through the eduction pipe. The interiors of the hollow heads are in communi-.
cation by means of pipes, each of which surrounds concentrically one of the pipes.
already described, and is sufficiently larger to leave between it and the pipe an.
annular space, through which the ammonia can pass from one hollow head to the
other. Alternating partitions are formed in the hollow heads, so that the ammonia.
vapor shall be caused to follow a tortuous path in passing through the pipes and
heads.
The eduction pipe from the pump leads into the lower part of one of the hollow
heads, and through this pipe the pump discharges into the ammonia space of the
boiler any ammonia vapor or gas that may be in the exhaust.
From the bottom of the exhaust leads a pipe which communicates with the lower
part of the other one of the hollow heads, and through this pipe is conducted from
the exhaust into the boiler the ammonia, which has liquefied by reason of the
conversion of its heat into mechanical energy. In order to force the liquid into
the boiler I make use of an injector, using a motive power therein, instead of a
steam jet; a jet of ammonia, gas, or vapor, at high pressure obtained from an
auxiliary ammonia boiler.
This boiler is supplied with ammonia by means of a small steam or other power
driven pump, which draws the supply of ammonia needed from some suitable part
of the apparatus, for instance, from the lower part of the boiler through a pipe, and
forces it into the auxiliary boiler through another pipe. The auxiliary boiler is
stayed by bolts or tie rods to resist pressure; and heat is supplied to the ammonia
it contains by means of a system of piping. Heated water supplied from any
suitable source enters a space at the bottom of the auxiliary boiler through pipes,
thence passes up the boiler through pipes, thence down through outer concentric
pipes, which are closed at their upper ends into a space, and out through a pipe.
Ammonia vapor at high pressure can be thus generated, the vapor passing from
the boiler to the injector through a pipe; in this pipe or in the upper part of the
boiler is a regulating or safety valve, which when the pressure exceeds the prescribed
limit rises. In so doing it lifts a pivoted lever attached to a connecting rod, which
at its lower end is attached to the valve that regulates the flow of the incoming
heating water. In proportion as the safety or regulating valve rises the water
regulating valve closes, and I thus regulate the supply of heat to the boiler.
The apparatus is provided at all needed points with proper valves and cocks, and
with check valves to prevent back pressure, as will be understood without further
explanation.
The operation is as follows:-
The ammonia gas or vapor passes from the boiler into the smaller or high
pressure cylinder, where it is worked expansively, the cut off being adjusted, for
instance, to one tenth of the stroke. In thus expanding and doing work the gas

page_text: parts with its heat. to a considerable extent; it thence exhausts into the second or
lower pressure cylinder, where it is cut off at, say, one half the stroke, and is thus
caused to do further work expansively. The result is that the vapor by the time
it passes from the second cylinder into the exhaust has been almost entirely liquefied,
only an exceedingly small proportion of the ammonia retaining vaporous form.
The engine thus may be said to act not only as a motor, but as the condenser.
From the exhaust the ammonia is by means of the compound pump and injector
forced back into the boiler to be again brought to the condition of a motor gas or
vapor.
A compound reciprocating engine and compound reciprocating pump may be
employed instead of the rotary engine and pump.
In this case the high and low pressure cylinders may be horizontal, and in each
cylinder the exhaust on each side of the reciprocating piston leads from the lowest
part or bottom of the cylinder, so that the liquefied ammonia can be conducted off
without difficulty.
In order to keep the pump cylinders cool they are preferably surrounded by a
jacket, through which a cooling liquid circulates.
In order to shield the exhaust or refrigerator from the heat of surrounding objects
I enclose it in a metallic tank.
The confined air within the tank forms a good non-conductor of heat.
It will be found desirable in many cases to have one or more vessels accessory
to the exhaust, in which a vacuum may be maintained or absorbents held for the
purpose of relieving the exhaust, or of emptying any part of the machine, as
circumstances may require. Such a vessel, which may be called an absorber, may
be placed in the same tank which contains the exhaust. It may be with advantage
constructed somewhat like a tubular boiler, the tubes being intended for the
circulation of warm water or other heating medium. A pipe leading from the
ammonia space of the boiler or exhaust or other suitable part of the apparatus
enters the vessel, and is perforated to permit ammonia to pass therefrom into the
vessel, which is to be filled with some absorbent of ammonia. This vessel is
intended to serve as a place where the ammonia can be stored temporarily when
access is to be had to any part of the interior of the apparatus.
By properly regulating the cocks and valves with which the apparatus is provided
the ammonia can be diverted into this vessel, where it will be taken up and held
by the absorbent. Whenever it is desired to withdraw the ammonia therefrom
warm water or other heating medium is caused to circulate through the tubes or
heating space of the vessel. This causes the vaporization of the ammonia, and
said vapor is carried off by the pump through a valve or cock-controlled pipe,
which communicates at one end with the upper part of the absorber, and at the
other end with another pipe.
With respect to the injector I remark that after the apparatus is started it is
feasible to use gas or vapor from the boiler, as the gas jet, instead of that from the
auxiliary high pressure boiler. For this purpose a valve or cock-controlled pipe
may lead from the dome of the boiler into the gas or vapor pipe leading from the
auxiliary boiler to the injector; and at the proper times the connection may be
closed between the said pipe and the auxiliary boiler, and opened between it and
the main boiler.
It is preferred however to make use of the auxiliary boiler as a means to work
the injector.
I remark also that in lieu of the injector. a force pump can be used to force
liquid directly from the exhaust into the boiler. In fact there are various means
by which the equilibrium may be permanently disturbed, so that the exhaust may
during the operation of the engine discharge into the boiler.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Clayton Mewburn in the Great Seal Patent Office on the
1st October 1881.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent-
Agent and Consulting Engineer. " IMPROVEMENTS IN THE METHOD OF AND
APPARATUS FOR USING A LIQUEFIABLE GAS OR VAPOR AT LOW TEMPERATURES
AS A MOTOR FLUID." (A communication from abroad by John Gamgee, at present
of Washington, in the United States of America.)
The Invention relates to the employment, as a motor fluid, of a liquefiable gas or
vapor of adequate tension, the product of a liquid which boils at or near the
temperature of surrounding objects. The inventor has found that by working such
a gas or vapor expansively in one or more engine cylinders its heat can be
converted to such an extent into mechanical energy or motion that at the exhaust
it will have returned in great measure, to its original liquid condition, from which
state it may be again caused to assume the condition of a motor vapor or gas by
exposing it to the needed temperature.
It is this feature, viz., the working of such a vapor or gas expansively to the
extent of more or less complete liquefaction, and then reconverting it from the liquid
to the vaporous or gaseous condition for use again as a motor fluid, which mainly
characterizes this Invention.
The vapor having expanded its energy and being mostly liquefied by the
conversion of its heat into motion is discharged from the engine cylinder into a
closed exhaust vessel protected or insulated from environing heat. The maintenance
of the exhaust at the boiling point (for atmospheric pressure or thereabouts) of the
liquid used may be ensured in various ways, for instance, by means of an injector
or pump.
By the injector or pump or both, the cooled vapor is forced into an apparatus,
for convenience sake termed a boiler, where it is exposed to the temperature needed
to restore it to its original tension and thence returns to the engine.
It will thus be seen that it is the object in this Invention to obtain in a motor
engine the conditions of a closed circuit with a liquid boiling at a low temperature
relatively to water transformed into vapor, the molecular energy of which is
converted into the mass or molar motion of the piston, so that its initial condition
is restored.
In this way in a heat engine I extend the temperature, within which heat is
utilized, downwards in the direction of the absolute zero, instead of upwards above
the temperature of surrounding objects. The intense heat of boiler furnaces, the
internal work heat necessary to the formation of water steam, the abundant
exhaust waste of the steam engine, difficulties of lubrication, etc., are one and all
avoided by this Invention.
The cycle I propose can be performed more or less satisfactorily with almost any
liquid yielding expansive vapor below the temperature at which water boils, but in
developing most power with most compact apparatus, it is essential to use a
compound which has a maximum amount of latent heat.
The agent which the inventor finds in practice most available for this purpose is
anhydrous ammonia, the boiling point of which at atmospheric pressure approaches
closely to 34°4 C at 0° centigrade, its vapor tension is 3183·34 millimeters, whilst
at 10° it attains to 4574.03 millimeters. When the mean temperature attains
20° centigrade no less a pressure is exerted than 6387.78 millimeters, and at 30° C.,
or tropical heat, it reaches over 8,000 millimeters in tension. Since at blood heat
200 lbs. to the square inch is available, it is evident that the usual temperature of_

page_text: avel is most desirable in practice and best in the opinion of the
inventor when below 20° centigrade.
The latent heat of ammonia is about 900 as against 960 for water; it is this
latent heat which I use in developing energy so as to reduce the amount of rejected
heat to a minimum and obtain a maximum rate of liquefaction. Although high
pressures are attainable at low temperatures, it will always be found best in
practice to work below rather than above 100 lbs to the square inch.
From the fact that heat is utilized in this system. downwards to 0° centigrade
and below towards absolute zero, it is proposed for convenience to name the
apparatus which is employed "Zeromotor."
In the accompanying Drawing is represented an apparatus adapted to carry into
effect the Invention.
I wish it to be understood, however, that I do not restrict myself to the particular
construction and combination of parts which compose the apparatus, for these may
be varied to suit special conditions, so long as the apparatus as a whole is adapted
to carry out the cycle of operations herein before specified.
Figure 1 is a side elevation partly in section.
Figure 2 is a plan of the apparatus.
Figure 3 is a section on line x, x, Figure 1.
Figure 4 is a section on line y, y, Figure 1.
Figure 5 is a view of a modification hereinafter referred to.
The engine shown in the Drawings is a double cylinder rotary engine, B being
the first or high pressure cylinder, and B¹ the second or low pressure cylinder into
which the first cylinder exhausts through pipe d. As seen in section Figure 3 the
gas or vapor enters the cylinder B through the valve a and sliding division port a¹,
which runs in contact with the eccentric rotary piston C in the usual way. The
admission valve is operated from the rocking valve rod a³ in the usual way, said
rod having an arm a² which bears against the rotating adjustable cut off cam b,
whose shaft b' is rotated through the medium of eccentrics and connecting rods
from the main shaft D in the ordinary manner. The exhaust port of the first
cylinder is shown at d¹ in communication with the exhaust pipe d, which leads
to the gas or vapor admitting valve of the second cylinder B. The latter with
its accessories is similar except in size to the first cylinder B, the shaft D being
common to both and the two cylinders are combined together for operation in
the same way as the two cylinders of an ordinary compound or double cylinder
rotary engine.
The pipe e conducts the liquefiable gas or vapor to the primary cylinder B from
the dome A* of the part A, which for convenience sake will be termed the boiler
and which will be hereinafter described.
The exhaust pipe f from the second cylinder B¹ leads into the closed exhaust
vessel E; this vessel receives through the exhaust pipe f the liquefied vapor or gas
from the second cylinder.
From the upper part of the exhaust vessel leads a pipe g to the larger cylinder F
of a compound or double cylinder rotary pump F, F, driven by the rotary
shaft D.
The larger of these pump cylinders is shown in section in Figure 4; the smaller
or high pressure cylinder F1 with its accessories is the counterpart of the other and
has its induction port in communication with the eduction port of the larger
cylinder through the intermediary of pipe h. The eduction port of the smaller
cylinder F communicates through pipe h¹ with the space in boiler A, which
receives the liquid from which the motor gas or vapor is to be generated. The
pump being of known description, and the arrows in Figure 4 indicating plainly
the direction of motion and the induction and eduction, further description of this
instrumentality is unnecessary.
Boiler A is a metallic shell containing at each end an inner hollow head A¹,
and a space i between that head and the outer head A to receive the liquid
preferably water, which takes the place of fuel as a heater for the liquid ammonia

page_text: Pipes lead from one space i to the other, passing through without having com-
munication with the hollow inner heads A¹. Into the space i on one side enters
the water induction pipe 2, and from the opposite space i leads a water eduction
pipe Water entering through pipe will circulate through the spaces i and
pipes j, and will pass out through 2. The interiors k of the hollow heads A' are
in communication by means of pipes 1, each of which surrounds concentrically one
of the pipes j, and is sufficiently larger to leave between it and the pipe j an
annular space through which the ammonia can pass from one space k to the other.
The water is permitted by proper means to circulate not only through pipes j but
also around the exterior of the ammonia pipés z. Alternating partitions m are formed
in the spaces k, so that the ammonia vapor shall be caused to follow a tortuous
path in passing through the pipes / and spaces k.
The eduction pipe h¹ from the pump leads into the lower part of one of the
spaces, and through this pipe the pump discharges into the ammonia space of the
boiler A any ammonia vapor or gas that may be in the exhaust E.
From the bottom of the exhaust leads a pipe n, which communicates with the
lower part of the other one of the spaces kc, and through this pipe is conducted
from the exhaust into the boiler, the ammonia which has liquefied by reason of
the conversion of its heat into mechanical energy. In order to force the liquid into
the boiler I make use of an injector, indicated at G, using as motive power therein
a jet of ammonia gas or vapor at high pressure, obtained from an auxiliary
ammonia boiler H.
This boiler is supplied with ammonia by means of a small steam or other power
driven pump I, which draws the supply of ammonia needed from some suitable
part of the apparatus, in this case from the lower part of boiler A through a
pipe o and forces it into the auxiliary boiler through pipe o¹. The boiler H is
stayed by bolts or tie rods p to resist pressure, and heat is supplied to the ammonia it
contains by means of a system of piping r, 8. Heated water supplied from any
suitable source enters the space r¹ through pipes 23, thence passes up through the
pipe r, thence down through the outer concentric pipes 8, which are closed at their
upper ends into spaces s¹ and out through pipe s². Ammonia vapor at high
pressure can thus be generated, the vapor passing from the boiler to the injector
through a pipe t; in the pipe t or upper part of the boiler is a regulating or safety
valve t', which when the pressure exceeds the prescribed limit rises. In so doing
it lifts a pivoted lever t² attached to a connecting rod 3, which at its lower end is
attached to the valve v that regulates the flow of the incoming heating water. In
proportion as the safety or regulating valve t¹ rises the valve v closes, and I thus
regulate the supply of heat to the boiler.
The apparatus is provided at all needed points with proper valves and cocks and
with check valves to prevent back pressure, as will be understood without further
explanation.
The operation is as follows:-
The ammonia gas or vapor passes from the boiler into the smaller or high
pressure cylinder, where it is worked expansively, the cut off being adjusted, for
instance, to one tenth of the stroke. In thus expanding and doing work the gas
parts with its heat to a considerable extent. It thence exhausts into the second or
lower pressure cylinder, where it is cut off at, say, one half the stroke, and is thus
caused to do further work expansively. The result is that the vapor by the time
it passes from the second cylinder into the exhaust has been almost entirely
liquefied, only an exceedingly small proportion of the ammonia retaining vaporous
form. The engine thus may be said to act not only as a motor but as the
condenser.
From the exhaust the ammonia is by means of the compound pump and
injector forced back into the boiler to be again brought to the condition of a
motor gas or vapor.
In Figure 5 is represented in further illustration of the Invention a plan of the

page_text: apparatus, in which a compound reciprocating engine and compound reciprocating
pump are employed instead of the rotary engine and pump.
In this apparatus the high and low pressure cylinders are horizontal, and in
each cylinder the exhaust on each side of the reciprocating piston leads from the
lowest part or bottom of the cylinder, so that the liquefied ammonia can be
conducted off without difficulty. The lettered parts in this Figure indicate
parts which correspond in function to like lettered parts in the preceding
Figures.
The compound engine and pump require no detail description, being constructed
and arranged in a manner similar to compound reciprocating steam engines and
pumps which have heretofore been used.
In order to keep the pump cylinders cool they are preferably surrounded by a
water jacket, as indicated at F2, Figure 4. The cooling liquid enters at w and is
discharged at one or the other of the openings w¹.
In order to shield the exhaust from the heat of surrounding objects I enclose it
in a metallic tank J.
The confined air within vessel J-forms a good non-conductor of heat.
It will be found desirable in many cases to have one or more vessels accessory
to the exhaust in which a vacuum may be maintained or absorbents held for the
purpose of relieving the exhaust or of emptying any part of the machine as
circumstances may require. Such a vessel, which may be called an absorber, is
shown in Figure 1 at K placed in the same tank J, which contains the exhaust. It
is constructed for the most part like a tubular boiler, the tubes y being intended for
the circulation of warm water or other heating medium.
A pipe leading from the ammonia space of the boiler or exhaust or other
suitable part of the apparatus enters the vessel and is perforated, as shown at z¹,
to permit ammonia to pass therefrom into the vessel which is to be filled with
some absorbent of ammonia. This vessel is intended to serve as a place where
the ammonia can be stored temporarily when access is to be had to any part of the
interior of the apparatus.
By properly regulating the cocks and valves with which the apparatus is
provided the ammonia can be diverted into this vessel, where it will be taken up
and held by the absorbent. Whenever it is desired to withdraw the ammonia
therefrom warm water or other heating medium is caused to circulate through the
tubes or heating space of the vessel. This causes the vaporization of the
ammonia, and said vapor is carried off by the pump through the valve or cock
controlled pipe 22, which communicates at one end with the upper part of the
vessel K and at the other end with the pipe g.
I may remark that in lieu of the injector a force pump, such as pump I, can be
used to force liquid directly from the exhaust into the boiler; in fact, there are
various means by which the equilibrium may be permanently disturbed, so that
the exhaust may during the operation of the engine discharge into the boiler.
Having now described the nature of the said Invention as communicated to me,
and in what manner the same is to be performed, I declare that I claim,-
First. The method of condensing a liquefiable gas or vapor, the product of a
liquid of low boiling point used as a motor fluid in a thermo-dynamic engine,
which consists in working the gas or vapor expansively to the extent of more or
less complete liquefaction in giving motion to the engine, substantially as herein-
before set forth.
Second. The method herein described of using a liquefieable gas or vapor, the
product of a liquid of low boiling point, as a motor fluid for engines, which consists
in working the vapor or gas in the engine expansively to the extent of more or less
complete liquefaction; then exhausting the vapor thus liquefied into a suitable
receiver, thence conveying it to a boiler where it is subjected to the low degree of
heat needed to bring it again to the condition of a motor gas or vapor, and thence
returning it to the engine to again go through the same cycle of operations,
substantially as herein before set forth.

page_text: Third. The combination of an engine proper in which a liquefiable gas or vapor
is worked expansively to the extent of liquefaction, so that the engine shall serve
not only as motor but as condenser; a closed exhaust vessel which receives the
liquefied gas or vapor from the engine cylinder; a boiler and means substantially
as described for forcing the contents of the exhaust directly to the boiler, the
combination being and acting substantially as hereinbefore set forth.
Fourth. In a thermo-dynamic engine, in which a liquefiable gas is used as the
motor fluid substantially as specified; the combination with the engine cylinder of
a closed liquefied gas receiver or exhaust protected by a non-conducting covering
from the heat of the environment, substantially as set forth.
Fifth. In a thermo-dynamic engine, vessels accessory to the exhaust in which a
vacuum may be maintained or absorbents held for the purpose of relieving the
exhaust at any moment or emptying any part of the machine as circumstances may
demand, substantially as set forth.
In witness whereof, I, the said John Clayton Mewburn, have hereunto set
my hand and seal, this Twenty ninth day of September, One thousand eight
hundred and eighty one.
J. C. MEWBURN. (L.S.)