IMPROVEMENTS IN CALORIC ENGINES
Year: 1873

page_text: LETTERS PATENT to John Imray, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN CALORIC ENGINES."-A communication from abroad
by Nicolaus August Otto, of the Gas Motoren Fabrik Deutz, at
Deutz, in the German Empire.
Scaled the 22nd July 1873, and dated the 29th May 1873.
PROVISIONAL SPECIFICATION left by the said John Imray at the
Office of the Commissioners of Patents, with his Petition, on the
29th May 1873.
I, JOHN IMRAY, of No. 20, Southampton Buildings, Chancery Lane, in
the County of Middlesex, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN CALORIC ENGINES," to be as follows:-
In applying heated air, gas, or gaseous products of combustion to the
working of a piston in a cylinder for the purpose of obtaining motive
power in caloric engines, it is usual to admit the heated fluid to the
cylinder at a pressure exceeding that of the atmosphere, and to employ
this excess of pressure for the propulsion of the piston.

page_text: In the Specification of a Patent obtained on the 12th day of February
1866, No. 404, by C. D. Abel (being a communication from the said
N. A. Otto, and E. Langen, was described a caloric engine in which a
piston was propelled by the pressure of products of combustion or
gaseous explosion without doing work, the work of the engine being
performed by the return stroke of the piston subjected on the one side to
atmospheric pressure, and on the other side to the less pressure of the
fluid which had propelled it when such fluid was contracted by cooling.
In the said engine the piston during its return stroke was connected to
and worked the engine shaft while it made the other stroke freely
under the propulsive action of the fluid.
The present Invention relates to a method of and apparatus for
obtaining motive power from heated air, gas, or gaseous products of
combustion admitted to a cylinder at the pressure of the atmosphere and
cooled therein so that their pressure on one side of the piston being
reduced below that of the atmosphere, the excess of atmospheric pressure
on the other side of the piston shall effect its propulsion, the piston in
this case being always connected to the crank. For this purpose a
piston fitted to work in a cylinder is connected to a crank on a shaft
provided with a heavy fly wheel, and with an excentric or cam for
working a slide or valve whereby heated air, gas, or gaseous products of
combustion can be admitted at the proper moment and for the proper
time to one end of the cylinder, the other end of which is open. The
cylinder has a casing or jacket supplied with water for the purpose of
cooling the cylinder, and has at its closed end besides the supply port
and slide a discharge port fitted with a valve opening outwards.
The action is as follows:-When the piston is at the closed end of the
cylinder the supply port is opened by the movement of the slide, and
heated fluid is admitted at the pressure of the atmosphere.
The piston
being thus subjected to equal pressure on both sides is moved by the
momentum of the fly wheel until it has performed a certain portion of
its stroke which may be from four to seven tenths of the whole stroke.
At this point the slide is made to close the supply port, and the rest of
the stroke of the piston is effected by the momentum of the fly wheel,
the fluid within the cylinder being dilated in volume and having its
pressure reduced and temperature lowered partly by absorption of latent
heat, and partly by cooling. When the piston has reached the end of
the stroke, the fluid behind it having its pressure reduced not only by

page_text: the dilatation which it has undergone, but also by the absorption of
latent heat, and by the cooling influence of the cylinder below that of
the atmosphere, a portion of the return stroke of the piston is effected
by the excess of the atmospheric pressure on its one side above that of
the fluid on its other side, and when, by the movement of the piston
the pressure of the fluid behind it has been raised to that of the atmo-
sphere partly by compression and partly by the liberation of the heat
which had become latent it is discharged from the cylinder by the
escape valve.
In order to operate more efficiently with this apparatus it is preferred
to make the engine work quickly, also to have the one stroke, namely,
that during which heated fluid is supplied, effected more rapidly than the
return stroke during which chiefly the contraction of the fluid by cooling
should take place. This difference of speed in the two strokes may be
obtained by any known arrangements of mechanism for effecting an
alternately quick and slow reciprocating movements such as are in use
in planing and other machines. By this arrangement the heated fluid
while undergoing dilatation has little time to lose heat by conduction, but
while the piston is changing its direction and during its return stroke
a large portion of the heat is absorbed by the cooled cylinder. Thus the
power which had been absorbed in effecting the dilatation of the fluid is
regained along with the additional power obtained from the contraction
of the fluid by cooling.
It will be readily understood that the heat is more fully utilised by
admitting the heated fluid to the cylinder only during a portion of the
stroke, and causing the contents to expand therein. The effective power
thus obtained is that due to the difference between the pressure of the
fluid in the cylinder at each point of the forward stroke, and its reduced
pressure at corresponding points in the return stroke.
In order to secure greater economy and efficiency in the working of
caloric engines, such as are described above, the cylinder and its parts
may be arranged in the following manner:-The cylinder being placed
vertically with its open end downwards is made in three parts, the
highest and lowest of which are kept cool by water jackets or otherwise,
and the middle part is kept hot by a casing of non-conducting material.
The piston works in the lowest cool part, and has a fender or protecting
plunger projecting upwards from it so as to fill the middle part when

page_text: the piston is at the upper extreme of its stroke, but not to rub on the
interior surface of the cylinder. The uppermost cooled part is also filled
up by a loose displacing plunger which is held up by a latch connected
to a tappet at the lower end of the cylinder. The piston being at the
upper extreme of its stroke the slide is opened so as to admit hot fluid
at atmospheric pressure to the middle part of the cylinder. The piston
being caused to descend by the momentum of the fly wheel draws in a
supply of the hot fluid till the admission slide or valve is closed, after
which the fluid of the cylinder is dilated in the hot part of the cylinder
by the continued descent of the piston till its pressure is reduced below
that of the atmosphere. As the piston approaches the end of its down
stroke it strikes the tappet which withdraws the latch from the dis-
placing plunger and leaves it unsupported. This plunger is then caused
to descend by gravity, and in its descent it displaces the dilated fluid
above the piston fender from the hot middle part of the cylinder to the
cold upper portion, the fluid either passing annularly round the plunger
or through passages in the same, or in the sides of the cylinder. The
fluid thus transferred to the cold part of the cylinder has its pressure
still farther reduced by cooling below that of the atmosphere, and the
upstroke of the piston is effected by the excess of the atmospheric
pressure on the under side of the piston above the pressure of the dilated
and cooled fluid on its upper side, until by the ascent of the piston the
pressure of the fluid in the cylinder attains that of the atmosphere, after
which the farther ascent of the piston causes the fluid to be expelled by
an outlet valve opening outwards. The piston in its upstroke raises the
displacing plunger till it is again caught on the latch when the action is
repeated.
Instead of latching the displacing plunger as above described and
allowing it to descend by gravity and raising it by the piston, it may be
worked by a cam on the engine shaft so arranged as to time its move-
ments suitably to those of the piston, and this arrangement is applicable
when the cylinder is inverted, or in a horizontal or other position.
By the use of a displacing plunger as above described in combination
with a hot middle and cold upper compartment of the cylinder, it will
be seen that the fluid in the cylinder is kept hot while undergoing
dilatation, whereby the duty to be done by the fly wheel momentum in
effecting that dilatation is reduced; also that the fluid is cooled while
the piston is compressing it and thereby the working pressure which is

page_text: the difference between the pressure of the fluid within the cylinder and
that of the atmosphere without is increased.
By applying to the piston a fender or protecting plunger in combi-
nation with a hot middle and cold lower compartment of the cylinder,
the piston can be made to work in the latter with suitable packing and
lubrication, while the fender occupying this cold compartment during the
downstroke of the piston causes the working fluid to be retained in the
hot compartment until it is displaced by the plunger. The displacing
plunger may be hollowed out on its upper side, and the cover of the
upper compartment of the cylinder may be made with projections to
enter the hollows of the plunger so as to increase the cooling surface in
the upper compartment of the cylinder.
The construction of an engine arranged to work in the manner
last described may be simplified by dispensing with the uppermost
cooled part of the cylinder, and employing the fender or protecting
plunger of the piston in lieu of the displacing plunger in the following
manner-The cylinder being made in two parts of which one is kept
hot while the other is kept cold, the heated fluid is admitted to the
hot part while the piston make its outstroke in the cold part, the fender
or protecting plunger accompanying the piston. When the outstroke is
completed or nearly so, the piston being almost at rest, the fender or
protecting plunger is rapidly moved by a cam back from the cool part
into the hot part of the cylinder so as to transfer the hot dilated fluid
into the cold part of the cylinder, where owing to its cooling its pressure
becomes reduced as the piston is making its back stroke. In other
respects the construction and action of the engine are substantially like
those described above.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-ninth day of May, in the year
of our Lord One thousand eight hundred and seventy-three, in the Thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said John Imray, Her special license that I, the
said John Imray, my executors, administrators, and assigns, or such
others as I, the said John Imray, my executors, administrators, and
assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands
and Isle of Man, an Invention for "IMPROVEMENTS IN CALORIC ENGINES," a
communication to me from abroad by Nicolaus August Otto, of the Gas
Moteren Fabrik Deutz, at Deutz, in the German Empire, upon the con-
dition (amongst others) that I, the said John Imray, my executors or
administrators, by an instrument in writing under my or their, or one
of their hands and seals should particularly describe and ascertain the
nature of the said Invention and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said John Imray, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof, reference being had to the accompanying
Sheet of Drawings, and to the figures and letters marked thereon, that
is to say:-
In applying heated air, gas, or gaseous products of combustion to the
working of a piston in a cylinder for the purpose of obtaining motive
power in caloric engines it is usual to admit the heated fluid into the
cylinder at a pressure exceeding that of the atmosphere, and to employ
this excess of pressure for the propulsion of the piston.
In the Specification of a Patent obtained on the 12th day of February,
1866, No. 404, by C. D. Abel (being a communication from the said
N. A. Otto and E. Langen) was described a caloric engine in which a
piston was propelled by the pressure of products of combustion or gaseous
explosion without doing work, the work of the engine being performed

page_text: by the return stroke of the piston subjected on the one side to atmos-
pheric pressure, and on the other side to the less pressure of the fluid
which had propelled it when such fluid was contracted by cooling. In
the said engine the piston during its return stroke was connected to and
worked the engine shaft, while it made the other stroke freely under the
propulsive action of the fluid.
The present Invention relates to a method of, and apparatus for,
obtaining motive power from heated air, gas, or gaseous products of
combustion admitted to a cylinder at the pressure of the atmosphere,
and cooled therein, so that their pressure on one side of the piston being
reduced below that of the atmosphere, the excess of atmospheric pressure
on the other side of the piston shall effect its propulsion, the piston in
this case being always connected to the crank.
For this purpose a
piston fitted to work in a cylinder is connected to a crank on a shaft
provided with a heavy fly wheel and with an eccentric or cam for
working a slide or valve, whereby heated air, gas, or gaseous products of
combustion can be admitted at the proper moment and for the proper
time to one end of the cylinder, the other end of which is open. The
cylinder has a casing or jacket supplied with water for the purpose of
cooling the cylinder, and has at its closed end, besides the supply port
and slide, a discharge port fitted with a valve opening outwards.
The action is as follows:-When the piston is at the closed end of the
cylinder the supply port is opened by the movement of the slide, and
heated fluid is admitted at the pressure of the atmosphere. The piston
being thus subjected to equal pressure on both sides is moved by the
momentum of the fly wheel until it has performed a certain portion of
its stroke, which may be from four to seven-tenths of the whole stroke.
At this point the slide is made to close the supply port, and the rest of
the stroke of the piston is effected by the momentum of the fly wheel,
the fluid within the cylinder being dilated in volume, and having its
pressure reduced and temperature lowered partly by absorption of latent
heat, and partly by cooling. When the piston has reached the end of
the stroke, the fluid behind it having its pressure reduced, not only by
the dilatation which it has undergone, but also by the absorption of
latent heat, and by the cooling influence of the cylinder below that of
the atmosphere, a portion of the return stroke of the piston is effected
by the excess of the atmospheric pressure on its one side above that of
the fluid on its other side; and when by the movement of the piston the

page_text: pressure of the fluid behind it has been raised to that of the atmosphero
partly by compression, and partly by the liberation of the heat which
had become latent, it is discharged from the cylinder by the escapo
valve.
In order to operate more efficiently with this apparatus it is preferred
to make the engine work quickly, also to have the one stroke, namely,
that during which heated fluid is supplied, effected more rapidly than
the return stroke, during which chiefly the contraction of the fluid by
cooling should take place. This difference of speed in the two strokes
may be obtained by any known arrangements of mechanism for effecting
an alternately quick and slow reciprocating movement, such as are in
use in planing and other machines. By this arrangement the heated
fluid, while undergoing dilatation, has little time to lose heat by con-
duction, but while the piston is changing its direction, and during its
return stroke, a large portion of the heat is absorbed by the cooled
cylinder. Thus, the power which had been absorbed in effecting the
dilatation of the fluid is regained along with the additional power
obtained from the contraction of the fluid by cooling.
It will be readily understood that the heat is more fully utilized by
admitting the heated fluid to the cylinder only during a portion of the
stroke, and causing the contents to expand therein. The effective power
thus obtained is that due to the difference between the pressure of the
fluid in the cylinder at each point of the forward stroke, and its reduced
pressure at corresponding points in the return stroke.
In order to secure greater economy and efficiency in the working of 1
caloric engines, such as are described above, the cylinder and its parts
may be arranged in the following manner:-The cylinder being placed
vertically, with its open end downwards, is made in three parts, the
highest and lowest of which are kept cool by water jackets or otherwise,
and the middle part is kept hot by a casing of non-conducting material.
The piston works in the lowest cool part, and has a fender or protecting
plunger projecting upwards from it so as to fill the middle part when
the piston is at the upper extreme of its stroke, but not to rub on the
interior surface of the cylinder. The uppermost cooled part is also filled
up by a loose displacing plunger, which is held up by a latch connected
to a tappet at the lower end of the cylinder. The piston being at the
upper extreme of its stroke, the slide is opened so as to admit hot fluid at
atmospheric pressure to the middle part of the cylinder. The piston being

page_text: caused to descend by the momentum of the fly wheel draws in a supply of
the hot fluid till the admission slide or valve is closed, after which the fluid
of the cylinder is dilated in the hot part of the cylinder by the continued
descent of the piston till its pressure is reduced below that of the atmos-
phere. As the piston approaches the end of its down stroke it strikes
the tappet, which withdraws the latch from the displacing plunger, and
leaves it unsupported. This plunger is then caused to descend by
gravity, and in its descent it displaces the dilated fluid above the piston
fender from the hot middle part of the cylinder to the cold upper portion,
the fluid either passing annularly round the plunger or through passages
in the same or in the sides of the cylinder. The fluid thus transferred
to the cold part of the cylinder has its pressure still farther reduced by
cooling below that of the atmosphere, and the upstroke of the piston is
effected by the excess of the atmospheric pressure on the under side of
the piston above the pressure of the dilated and cooled fluid on its upper
side until by the ascent of the piston the pressure of the fluid in the
cylinder attains that of the atmosphere, after which the farther ascent of
the piston causes the fluid to be expelled by an outlet valve opening
outwards. The piston in its upstroke raises the displacing plunger till
it is again caught on the latch, when the action is repeated.
Instead of latching the displacing plunger, as above described, and
allowing it to descend by gravity, and raising it by the piston, it may
be worked by a cam on the engine shaft so arranged as to time its
movements suitably to those of the piston, and this arrangement is
applicable when the cylinder is inverted, or in a horizontal or other
position.
By the use of a displacing plunger, as above described, in combination
with a hot middle and cold upper compartment of the cylinder, it will
be seen that the fluid in the cylinder is kept hot while undergoing dila-
tation, whereby the duty to be done by the fly wheel momentum in
effecting that dilatation is reduced; also, that the fluid is cooled while
the piston is compressing it, and thereby the working pressure, which is
the difference between the pressure of the fluid within the cylinder and
that of the atmosphere without, is increased. By applying to the piston
a fender or protecting plunger in combination with a hot middle and
cold lower compartment of the cylinder the piston can be made to work
in the latter with suitable packing and lubrication, while the fender
occupying this cold compartment during the downward stroke of the

page_text: piston causes the working fluid to be retained in the hot compartment
until it is displaced by the plunger. The displacing plunger may be
hollowed out on its upper side, and the cover of the upper compartment
of the cylinder may be made with projections to enter the hollows of the
plunger so as to increase the cooling surface in the upper compartment
of the cylinder.
The construction of an engine arranged to work in the manner last
described may be simplified by dispensing with the uppermost cooled
part of the cylinder, and employing the fender or protecting plunger of
the piston in lieu of the displacing plunger in the following manner :—
The cylinder being made in two parts, of which one is kept hot, while
the other is kept cold, the heated fluid is admitted to the hot part while
the piston makes its outstroke in the cold part, the fender or protecting
plunger accompanying the piston. When the out stroke is completed or
nearly so, the piston being almost at rest, the fender or protecting
plunger is rapidly moved by a cam back from the cool part into the hot
part of the cylinder, so as to transfer the hot dilated fluid into the cold
part of the cylinder, where owing to its cooling its pressure becomes
reduced as the piston is making its back stroke. In other respects the
construction and action of the engine are substantially like those described
above.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 represents a vertical section of a caloric engine constructed to
operate in the manner first described above. a is the cylinder provided
with a jacket or casing, so that it can be kept cool by the circulation
therein of water or other cold fluid. The cylinder a is open at bottom
and covered at top by a cap b, having an inlet port / governed by a
slide 9, and an outlet valve i opening outwards. The cylinder a is
mounted on a framing c, on which is mounted in bearings the main
shaft e provided with a heavy fly wheel f. The piston k is connected
by a rod to one end of a lever m, which works on a fulcrum on the
framing c. In the lever m is a longitudinal slot in which works the
pin e¹ of a crank fixed on the shaft e. An eccentric o on the shaft e
works the slide 9, and the eccentric rod is provided with a right and left
screwed sleeve p by which the opening of the slide 9 can be adjusted
with respect to the port h, so as to cut off sooner or later in the stroke
of the piston.
It will be seen that the connection from the piston to the crank

page_text: through the slotted lever m is such that if the fly wheel revolve at a
uniform speed in the direction of the arrow the piston makes its down
stroke in less time than it takes to make its up stroke. The eccentric o
being properly adjusted to the crank the action of the engine is as
follows: When the piston k is at the upper extreme of its stroke the
slide opens the port for the admission of hot air, gas, or products of
combustion, and as the fly wheel revolves, causing the piston to descend,
the space above the piston becomes charged with the hot fluid until the
slide g cuts off the supply, after which the quantity already supplied
becomes dilated, losing heat partly by dilatation, and partly by the cooling
influence of the cylinder. When the piston has reached the lower
extreme of its stroke the pressure within the cylinder is thus reduced
below that of the atmosphere, and as the contents of the cylinder
continue to undergo cooling their pressure would continue to undergo
farther reduction if their volume remained constant. The excess of
atmospheric pressure acting on the under side of the piston causes it to
ascend until it has compressed the contents of the cylinder above it to
such an extent that the valve i is opened for their escape. The piston
having completed its up stroke the slide 9 again opens to admit a fresh
charge, and the action is repeated.
It will be seen that the hot fluid being admitted and also discharged
after doing its work at atmospheric pressure a large portion of the
motion of the piston is effected by the momentum of the fly wheel,
which at every up stroke of the piston receives an accession of force
from the action on the piston of the excess of atmospheric pressure over
that of the fluid within the cylinder. By cutting off the supply of fluid
so as to allow it to undergo considerable expansion in the cylinder the
efficiency of the engine is enhanced.
When the products of combustion of gas are employed, as the charging
fluid, the supply of the gas and of the air necessary for its combustion,
and the kindling of the gas at cach stroke, may be effected by arranging
the slide g and ports connected therewith in the manner shewn in
Fig. 2, which is a section of the upper part of the cylinder and its cover
with the slide g open, and Fig. 3, which is a portion of the same section,
with the slide shewn in its closed position. 9' is an opening for air;
g is the pipe supplying gas; g³ is a flame kept burning in front of the
air opening, which as well as the opening for gas is governed by the
slide g. When this slide is in the position shewn in Fig. 2 the piston

page_text: by its descent draws in by g¹ and 9³ a supply of air and gas, which are
mingled by their passage together through a number of narrow openings,
either short tubes, sheets of wire gauze, or interstices between bars or
plates. At the same time the flame 73 being drawn in ignites the
gaseous mixture, so that the cylinder is supplied with the hot products
of combustion. When the slide is moved to the position shewn in
Fig. 3 the supply of air and gas, and also the kindling flame are
cut off
by its descent draws in by g¹ and g³ a supply of air and gas, which are
mingled by their passage together through a number of narrow openings,
either short tubes, sheets of wire gauze, or interstices between bars or
plates. At the same time the flame ³ being drawn in ignites the
gaseous mixture, so that the cylinder is supplied with the hot products
of combustion. When the slide is moved to the position shewn in
Fig. 3 the supply of air and gas, and also the kindling flame are
cut off
It may be readily understood that instead of gas the vapour of
petroleum or other hydrocarbons may be employed as above described.
Fig. 4 is a side view partly in section of a horizontal engine arranged
to operate as set forth above. In this case the piston acts by a con-
necting rod directly on the crank without any intervening mechanism
to render the one stroke more rapid than the other, which is not essential
to the working of the engine, though it is preferable as an arrangement
conducive to economy of power, the heated fluid being thereby exposed
during a short period to the cooling action of the cylinder while it is
undergoing dilatation, and to a longer period while it is being compressed.
Although the engine is shewn as a single acting one in Fig. 4 it is
obvious that by providing the front end of the cylinder with a cover
with slide and valve arranged as at the back end the engine could be
made double acting, the cylinder receiving its charge of heated fluid at
both ends.
Figs. 5 and 6 show the modified construction of the cylinder wherein
a displacing plunger is employed to transfer the fluid from a hot to a
cold compartment. Fig. 5 being a vertical section of the cylinder
shewing the piston at the lower extreme of its stroke, and Fig. 6 shewing
it at the upper extreme. According to this modification the cylinder is
made in three parts a¹, a³, and a³, whereof the highest and lowest
parts a¹ and as are kept cool and the middle part a³ is kept hot. The
piston has attached to it a fender or plunger extending upwards
from it to protect the packing of the piston and working surface
of the cylinder from heat. A plunger or displacer n is fitted
loosely to the upper part of the cylinder, so that it can slide freely
therein. A vertical spindle p mounted in the cylinder casing has
fixed on it at top a latch arm q, and at bottom a sloping arm ↑
acted on by a spring causing the spindle to turn so as to bring

page_text: g
the latch q into the position shewn in Fig. 6, where the latch entering a
notch in the displacer n holds it up. The piston k has projecting from
it a horn 8 so that as the piston approaches the lower extremity of its
stroke, this horn acting on the sloping arm causes the spindle p to
turn partly round, withdrawing the latch q and leaving the displacer n
free to descend. This engine operates in the following manner :-The
piston k with its fender k¹ ascends and raises with it the displacer n
until the latch 9 engages therewith, the piston being then at the upper
extreme of its stroke. The slide 9 being then opened the piston descends
and a supply of hot air, gas, or products of combustion is admitted to
the middle compartment of the cylinder, the displacer n remaining
above, supported by the latch q. As the piston approaches the lower
extreme of its stroke, its horn 8 acting on the arm r turns the spindle p,
and thus withdraws the latch q from from under the displacer n. The
displacer thereupon descends, transferring the hot fluid from the middle
compartment of the cylinder to the cold upper compartment, where it is
cooled and has its pressure reduced. The piston again ascends and the
action is repeated. The fluid in passing from the middle to the upper
compartment flows past the displacer by the annular passage left between
its periphery and the interior of the cylinder. Or tubular passages may be
provided for it through the displacer or outside the cylinder. To keep
the upper compartment of the cylinder cool it is provided with a water
jacket, and the cooling surface may be increased by forming the
displacer and cylinder cover as shewn in Fig. 7, the cylinder cover being
made with one or more closed tubes or hollow conical projections
extending down into corresponding cavities in the displacer. Instead of
raising the displacer by the motion of the piston latching it and allowing
it to descend by gravity as described above, it may be moved by a cam
on the engine shaft properly timed to the movement of the piston.
For this purpose the piston and displacer may be arranged as shewn in
Fig. 8, where the displacer n is worked by two rods n¹, n¹, passing
through stuffing boxes in the piston k, the rods n¹, n¹, being connected
in any convenient manner to a cam on the engine shaft so formed that
the displacer is held up during the down stroke of the piston that it is
made to descend rapidly while the piston is at or near the lower extreme
of its stroke and to ascend with the piston.

page_text: /
the displacer, the upper portion of which n³ is made to fit like a piston
the cold part of the cylinder, the lower part acting as a fender and
loosely fitting the lower part of the cylinder which is kept hot. is the
supply port with its slide g; t is a pipe with a valve opening upwards,
connecting the bottom of the cylinder with a side port in the upper
portion, and i is the discharge pipe with valve opening outwards when
the piston and displacer are at the lower extreme of the stroke, as shewn
in Fig. 9, the slide g is opened and the hot fluid is thereby admitted to
the cylinder, the piston and displacer rising until the former passes the
port t¹, as shewn in Figure 10; the hot dilated fluid thereupon flows by
the pipe from the lower to the upper portion of the cylinder, the
displacer descending by gravity to the bottom, as shewn in Fig. 11.
The fluid thus transferred to the cold upper part of the cylinder is
reduced in pressure, and the piston descends, compressing the fluid till it
has sufficient pressure to issue by the pipe i. The piston having again
reached the lower extreme of its stroke the action is repeated.
Having thus described the nature of this Invention and in what
manner the same is to be performed, as communicated to me by my
foreign correspondent, I claim,—
First. The use of a caloric engine wherein a piston working in a
cylinder is connected to a crank, and heated air or gas or gaseous
products of combustion at atmospheric pressure are drawn into the
cylinder during a portion of the stroke of the piston, and the supply
being cut off, they are therein dilated and are cooled, so that the piston
in making its return stroke is subjected to an excess of atmospheric
pressure which is utilized as working force, substantially as herein
described.
Second. In a caloric engine operating in the manner referred to,
above, connecting the piston to the crank in such a manner that the one
stroke during which the gaseous charge of the cylinder undergoes
dilatation is effected more rapidly than the return stroke, substantially
in the manner and for the purpose herein set forth.
Third. In a caloric engine operating in the manner above referred to,
forming the working cylinder, with hot and cold compartments and
providing and working a displacing plunger, which, after the gaseous
charge of the cylinder has been dilated in the hot compartment, transfers

page_text: it to the cold compartment, substantially in the manner and for the
purpose herein described.
In witness whereof, I, the said John Imray, have hereunto set my
hand and seal, this Twenty-fifth day of November, in the year
of our Lord One thousand eight hundred and seventy-three.
JOHN IMRAY. (L.S.)