IMPROVEMENTS IN HOT AIR ENGINES AND THEIR ATTACHMENTS PROVISIONALATION
Year: 1883

page_text: LETTERS PATENT to Stephen Wilcox, of Brooklyn, in the County of Kings
and State of New York, one of the United States of America, for an Invention
of "IMPROVEMENTS IN HOT AIR ENGINES AND THEIR ATTACHMENTS
PROVISIONAL SPECIFICATION left by the said Stephen Wilcox at the
Office of the Commissioners of Patents on the 4th December 1883.
STEPHEN WILCOx, of Brooklyn, in the County of Kings and State of New
York one of the United States of America. Engineer:-IMPROVEMENTS IN "HOT
AIR ENGINES AND THEIR ATTACHMENTS,"
I employ a cooling-jacket in connection with a regenerator both arranged around
the cylinder, by which the zones of low temperature are lowered in the regene-
rator, and the water cools not only the air which moves to and from the cool end
of the cylinder but also cools the cylinder itself. I automatically regulate the
engine by means of a governor which operates by shifting a link which moves the
changing pistons. I provide peculiarly adapted packing around the piston-rods
and force air into the pipe connecting the tops of two opposite working cylinders,
to compensate for leakage. By regulating this action automatically, I maintain a
uniform pressure. I have devised means for subtracting a large portion of the
heat from the gases discharged from the furnace and for imparting it to the
incoming air to supply the fire in the furnace. A blower promotes the draft
just sufficiently to overcome the resistance due to these provisions.
I have also devised means for distributing oil in the upper portion of each
cylinder.
A working piston, reciprocating in a corresponding cylinder, is located centrally
within a larger changing cylinder enclosing an annular changing piston in the space;
between itself and the exterior of the working cylinder. The engine is preferably
worked in the upright position, and will be so described. A heater having a
suitable furnace below supplies heat to the air in the lower portion of the apparatus,
and expands it, reducing a momentary high pressure to force up. the working piston.
The operation of the changing piston then-immediately forces a large portion of
this air around through a suitable regenerator and cooler to the annular space,

page_text: above the changing cylinder, and by lowering the temperature of the air lowers its
pressure, and allows the working piston to be forced back against a reduced
pressure. The air thus worked may have a pressure considerably above that of the
atmosphere, the tension being maintained against leakage by means of a centrally
worked pump with proper regulation.
As in other Engines of this class the power is derived from the working piston
alone. The motion of the changing piston does not add to, but subtracts from the
working power. The subtraction is slight because the pressure is always
substantially equal above and below. It requires merely sufficient power from the
other working parts of the engine to overcome the friction and inertia.
In what I esteem the principal form of the invention I employ two working
beams keyed to a single stout rocking-shaft and one changing beam mounted
between them and turning loosely on the same shaft.
Each cylinder is compound, there being in each case a smaller cylinder within a
larger. These compound cylinders are coupled in twos to form one engine. Two
of these compound cylinders are united to work.together on one crank. Referring
to one of the compound cylinders and its immediate connections, the upper part is
of cast iron, made of two thicknesses. Between the outer and inner thickness is an
annular chamber, in which water is circulated. This part of the cylinder is nicely
finished both on its inner and outer face. It is finished on its inner face to form a
tight contact with the working piston, by the aid of "Dunbar" packing or other
suitable packing. It is finished on its outer face to form a tight contact by the aid
of packing, with an annular piston.
The lower portion of this cylinder is double. It is made of sheet iron or other
thin material secured to the rigid part above by rivetting or otherwise. The
interior is filled with plaster so as to form a strong and stiff support to the metal.
It serves also as a good non-conductor. There is a space below the bottom for the
free flow of air outward and inward.
The outer cylinder is formed at its upper portion also of considerable thickness,
and chambered annularly. Water also circulates through this chamber. The lower
⚫ portion is made of a single thickness of substantial material, as cast iron, with a
facing of plaster. There is thin sheet iron or other metal, to form the extreme
inner surface of the lining
The working piston is connected by a single piston rod, working through an
efficient stuffing-box, to a cross-head connected by links to a beam. The other end
of this beam is similarly connected to the working piston-rod of another similar
piston. I term these two sets of pistons, with their accompanying parts thus
connected an engine. The beam is keyed to a strong "beam centre" or rocking
shaft, on one end of which is keyed an inclined arm from a pin in the end of
which the power is communicated by a link to the crank pin of a crank, keyed on
a revolving shaft, and equipped with an efficient fly-wheel or pulley from which the
power is communicated to any machine which it is required to drive.
The annular changing piston has two small piston-rods, working through stuffing
boxes at the top, each of which is connected by a link to a beam, which turns
loosely on the beam-centre. The other end of each beam is similarly connected to
the opposite changing piston. It follows that the gravity of all the parts in the
two cylinders balance each other.
The heater is dome-shaped on its under and inner side, and cylindrical on its
outer side, with a strong and wide flange around the top by which it is bolted to
the expanded base of the outer cylinder. Between the dome like interior and the
cylindrical exterior is a limited space which performs the important function of
thoroughly heating the air to a high temperature, in its rapid transference from the
top to the bottom of the machine under the action of the changing piston. The
construction is braced, so as to effectually hold it in form in opposition to the forces
tending to warp and destroy it under the high temperature to which it is
subjected. This bracing is effected by six webs, which are cast in one therewith,
extending from near the base to a level near the top of the heater. There is a.

page_text: casting adapted to extend down in the six spaces between the under and inner side
of the heater and its outer side. This casting leaves a thin space exterior to it,
and a thin space interior to it which compels the main portion of the air to
traverse down the entire depth of the heater and up again, in its transfer between
the top and bottom of the engine.
]
The engine is in its general features, analogous to that known as the Stirling
Engine. When, by the rise of the annular changing piston, a large portion of the.
compressed air is transferred into the bottom space, it is expanded and the effect is
felt on the under face of the working piston driving it forcibly upward. When
by the descent of the annular changing piston, a large portion of the air is caused
to move into the top of the engine, its pressure is reduced by cooling and the
working piston is allowed to descend against a reduced pressure.
Eccentrics connect by eccentric-rods to a "Stevenson" link which takes hold of
a link-block, which is mounted on a pin, carried on an arm fixed on a rocking.
shaft supported in a fixed bearing in the framing. This shaft has two arms which
carry, respectively, links connecting the arms to the changing beams and by them
operate the changing pistons.
There is a regenerator composed of metallic plates set on edge and beld a little
distance apart. It is mounted in a sufficient annular space exterior to the
changing cylinder, and in communication with the hot air space below the two
pistons, and also through a cooler with the relatively cold air space above the
changing piston.
The cooler is formed with thin metallic tubes which traverse the space and allow
the air to flow up and down through them, cold water circulates in the space
around them. The cooling water enters through a pipe, and after traversing the
cooling chamber and also another which occupies an annular space within the
cylinder, is discharged through a pipe.
I have adapted my engine to drive delicate machinery by providing an automatic
regulation.
When the link holds the link block in its centre there is little or no motion of
the changing pistons. By shifting the link so that it receives and holds the block,
in one end of its curved slot, the changing pistons receive sufficient motion to cause
them to traverse to the fullest extent and shift all the air. When the link is held
in some intermediate position it induces a less amount of motion of the changing
pistons. By shifting the link further the engine may be reversed.
There is a link which connects the Stevenson link with a bell crank lever
turning on a fixed centre. This lever connects by a link and rod, to a piston in a
small cylinder equipped with passages controlled by valves which, when the valves
are held open permit the fluid, which should be oil or some analogous inelastic fluid
filling both ends of the cylinder to shift from one end to the other.
The action of the Engine communicated through the link induces a tendency of
the piston to shift alternately in one direction and the other. When these valves
are both allowed to close no such motion can occur. When however, one of the
valves is held open, the fluid in the cylinder may shift a little in one direction.
.
The governor controls the opening of these valves, through a lever, which is
raised and lowered either directly or indirectly by the action of the governor
connected by a link to a lever which rocks a spindle and a rigidly connected wheel
and by means of face cams formed on the latter forces open one or other of the.
valves on being released when the other is open.
When the lever rises the fluid may flow from above the piston around into the
space below.
But when the lever descends it liberates the upper valve and allows it to shut
thus resisting any tendency of the oil to escape from above the piston into the
space below. The same movement opens and holds open the lower valve and
allows the oil to flow away from below the piston and to come into the space above
it. This causes the piston to sink and shifts the link to the right thus decreasing
the power.

page_text: The space over the working piston is inoperative and I provide for an equal
pressure thereon at all times. As the working piston in one of the two connected
cylinders always descends when the other rises, the pressure of the condensed air on
the upper surface of the two working pistons is practically uniform in all
conditions.
The piston rods are each surrounded by a series of rings of good leather, shaped
by wetting and stretching. There are rings of vulcanized rubber of circular
section. The stuffing boxes are deep and contain a number of these leathers, each
partially enclosing its ring of rubber. The whole being gently compressed by the
gland induces a gentle contact against the piston rod.
I employ a constantly acting force pump. operated by the engine with a uniform
stroke and tending to receive and force into the spaces above the working pistons
a small uniform quantity of air at each revolution. The leakage is liable to vary
and I vary the admission of the air to this pump accordingly. There are apertures
through which the air is drawn in freely, but the passage therefrom to the pump
is controlled by a peculiarly mounted valve, having a long stem and capable of
closing tightly upon a seat. It is held open by a coiled spring. On the upper end
of the stem is a considerable button or disc; on which rests a flexible diaphragm,
above which is a chamber connected by a pipe with the large connection pipe,
between the upper parts of the working cylinders. So long as the pressure in the
latter is sufficient the valve is by the tension of the air on the diaphragm held
down to its seat. But the moment the pressure becomes reduced by leakage, the
spring lifts the valve a little and allows the pump to take in air and force it into
the pipe until the full pressure is restored.
"
The packing of the working piston is of a character known as "Dunbar
packing, which allows the air to move freely down past the piston but forbids its
return. The pumping of the air by the pump into the large pipe maintains the
pressure in all parts of the apparatus.
The air to support the combustion in the furnace is received through inverted
U shaped pipes, which being exposed to the hot gases escaping from the furnace
through the passage to the stack, warm the air within so that the fresh air
therefrom entering the furnace, by being partially heated contributes to the
efficiency of the fuel and consequently the economy of the Engine.
I employ a blower driver by a belt from the engine and forcing the air strongly
in its entrance through the U shaped pipes.
I provide peculiarly efficient means for introducing oil to lubricate the parts.
There is a single acting hand pump provided with a reservoir for receiving oil,
and communicating by a small pipe with a perforated pipe, extending around in a
recess provided in the top of the changing cylinder. Its perforations are arranged
to allow the ejection of the oil upon the annular changing piston.
I employ a thermometer the sensitive portion of which is immersed in the pipe
through which cold water enters the cooler.
There is another thermometer having its sensitive portion correspondingly
immersed in the pipe which conveys away the warm water from the cooler. When
the difference of temperature of the two thermometers is unusually great it shows,
that the water in the heater is allowed to become too much warmed and
consequently that the air is being too little cooled by the cooler.
I employ a pyrometer having its sensitive portion immersed in the hot gases.
The several furnaces have each a pyrometer.
I employ a pressure gauge subject to the influence of the pressure within the
cylinder.
When the working piston is being driven upward in its cylinder my gauge feels
the pressure at the highest. It is provided with a valve opening freely upwards to
allow the pressure of oil or other fluid acted on by the air to pass upward freely.
At every revolution of the main shaft there is a period at which the high pressure
is felt by the gauge, the same being transmitted freely past the valve. The gauge
runs down a little but only a little in the intervals.

page_text: There is a pressure gage working under opposite conditions. The valve which
serves for this gauge is arranged to allow the oil to escape freely from the pressure
gauge at each lowering of the pressure and to rise only slightly during the period
of high pressure.
The additional gauge is of the ordinary construction and is connected to the
space above the working pistons.
I communicate power from my engine through friction gears peculiarly mounted.
The fly wheel is a large pulley having V shaped grooves turned or otherwisė
produced in its periphery adapted to transfer power by friction.
:
I employ a jack-wheel which has an iron periphery equipped with V shaped
beads corresponding to the grooves in the wheel but instead of the whole jack-
wheel being rigid and mounted fixedly upon the shaft, the force is communicated
through an annular mass of vulcanized India rubber which is mounted between
the hub and the annular rim, and which by its yielding avoids the trembling due
to ordinary friction gear. It also allows the shafts to be slightly out of their true
positions without inducing mischief.
:
The parts are insured against slipping by means of a dog, carried on the hub and
engaged in a recess in the rim. It is held by a bolt.
In some cases a less elastic material, such as wood may be employed. The
material may be inserted in blocks preferably with the grain extending radially.
I employ girders which support the mechanism resting on brick walls.
In one modification there are several changes in the structure. One of the most
important lies in the fact that instead of the regenerator being arranged annularly
around the working cylinder it is enclosed in a casing on one side. This may be
expedient under some circumstances, but I prefer generally the annular arrangement
previously described.
In the modification the top of the regenerator and cooler chamber is closed by a
removable bonnet. Two chambers in the bonnet are kept filled with cold water
divided by a continuous partition.
:
Within the upright cylinder at one side are two pieces of apparatus which
perform important functions. When the bonnet is taken off both may be taken
out and repaired or exchanged by simply raising and lowering through the
open top.
The lowermost is a regenerator, the function of which as in the previously
described engine is to alternately absorb heat from the air and give it off again.
The uppermost is a cooler for simply and solely absorbing and conveying away
heat. It is of cylindrical form, pretty closely filling the interior of the spaces
provided. All the surfaces of this cooler are made tight and strong with two pipes
connecting with the chambers, respectively in the bonnet. Small thin pipes are
provided extending from end to end through this cooler. The air in its rapid
transfer in one direction and the other moves through these tubes and is cooled by
the presence of cold water around them.
A pipe brings cold water and the arrangement compels a complete circulation of
the water in one continuous stream through the proper spaces in and around the
upper portion of the engine. The effect is to absorb and carry away the heat
which creeps up to the upper portion of the apparatus.
A radial passage, communicates from the interior of the heater through an
annular chamber to the base of a chamber at one side containing the regenerator.
This passage is entirely above the heater.
I operate the changing pistons by means of what is sometimes known as the
"Stevenson" link motion. It allows the engine to be reversed.
The link is shifted by a hand-lever connected in the ordinary manner, the
rocking shaft extending across so as to adjust the links of the connected engine
by the same movement.
ر
In this modification as also in the apparatus previously described the main
portions of the two engines are counterparts of each other. The respective beams
work in such positions that their. links engage with cranks on the same crank-

page_text: shaft. One is in position for operating on the crank with its full force while the
other is passing its dead point. By reason of this arrangement, the combination
of two complete engines works a continuous and nearly uniform action, requiring &
fly-wheel of only moderate size and weight.
A damper exercises a controlling influence on the draft of air through the furnace,
and consequently on the intensity of the heat. supplied to the heater.
It is
important to maintain the heat sufficiently high to make the engine efficient and
also to avoid burning the metal, I attain this by working the damper
automatically.
I employ a hollow casting filled with mercury or other fluid having a high
boiling point, connected by a pipe with a chamber under a flexible diaphragm,
loaded by a weight, and connected by a rod to a lever, of the damper through a
movable block, fixed in any desired position on an arm or lever, by a screw. When
from any cause the temperature of the gases in the flue rises too high, the mercury
commences to boil and the mercury vapor 'pressing on the surface drives the
mercury down and raises the diaphragm, thereby closing the damper. This damper
and the provisions for regulating it are also applicable to the other forms of the
apparatus.
In another modification the changing piston instead of being annular and
arranged to work at about the same level as the working piston, is higher and in
line with the working piston. This necessitates a greater height of the mechanism
but it may be for some purposes preferable
The working cylinder is mounted above and is of slightly greater diameter than
the thin changing cylinder. There are three lengths of the metal in line,-the
working cylinder at the top, the thin changing cylinder at the mid height, with a
thicker portion enclosing it at a little distance outside (with the regenerator and
cooler between) and the heater below.
The thin cylinder is divided in two lengths and equipped.so that while the lower
portion is left in place extending down into the heater ready when required to
again perform its useful function of compelling the air to traverse over a great
extent of heated surface in its frequent passages from the cold to the hot portions
of the apparatus, the upper portion may be easily removed and replaced.
The main working cylinder has a broad flange at its base which performs the
double function of supporting the cylinder and serving as a bonnet for the annular
cooling chamber.
The upper end of the upper section is secured by means of a stout perforated
ring which is recessed into the bottom of the main cylinder below the flange which
serves as a tight bonnet, and serves to accurately centre and support the inner
cylinder while allowing the air to move freely up and down through liberal holes
cored therein.
The annular space between is occupied at the lower portion with a series of
plates serving as a regenerator, to alternately receive and give out heat and passing
air. More space is allowed in the upper part of this annular chamber. It is
occupied by a series of tubes which extend around or partially around and convey
actively circulating currents of cold water. I term this the cooler.
The cooler does not extend around in a single piece but is adapted to be taken
off and re-applied without taking out the rod of the changing piston which
necessarily stands in the centre and would be an obstruction to the removal of a
complete ring of such tubes, and even without entirely taking out the changing
cylinder but only raising the latter.
The cooler is also made in two or more divisions horizontally. This allows it to
be removed in sections without making so large a vertical space between the
working cylinder and the case below as would be necessary to remove a cooler in
one continuous height.
In another modification of the invention the main shaft is mounted directly
over the cylinder, its axis crossing the line of the axis of the cylinder. A con-
necting rod from a crank in the mid length of the shaft connects to the working

page_text: piston. One end of the shaft carries a heavy fly-wheel The other end carries a
crank, which communicates motion by a connecting rod or link to a lever on
a rocking-shaft, which shaft has two arms connected by links to two piston rods
fixed to the annular changing piston. The single working piston rod and the two
changing piston rods, which latter may be considerably smaller than the working
piston rod, play through stuffing-boxes, all made. as tight as is conveniently
practicable.
.
A space in the upper end of the working cylinder, between the working piston
and a tight fitted cylinder head by the alternate rising and sinking of the working
piston, communicates with the external atmosphere by a self-acting valve opening
inward, and perform's important functions.
At each ascent of the working piston, the air in the space above it is compressed..
So soon as it is sufficiently compressed to have a tension above that of the air
below, the peculiar packing allows some of the air above to flow down past the
working pišton, and be retained there. At each descent of the working piston, the
air in the space above it expands. If much of the air above has been discharged
down, through the packing, the air above has been so much reduced in quantity
that it will thus be expanded to a tension below that of the external atmosphere.
When this condition obtains, fresh air is drawn in from the external atmosphere
through a self-acting valve opening inward or downward in the working cylinder
cover.
If the entire apparatus, including the stuffing-boxes, could be made absolutely.
tight, the air would soon be thus received into the working portion of the
apparatus to such tension that the rise of the working piston would compress the
air above it only to the same tension as that below, and no air would be received
down past the working piston at any time. But such tightness cannot be realized
in practice. There is always more or less leakage. In first starting the engine,
when there is only the pressure of the atmosphere in the lower portion of the
apparatus, much air is taken down past the working piston on the first revolution**
of the shaft, which must be induced by hand, or by some means external to the'
engine. At each succeeding revolution a greater pressure exists below the piston,
and consequently a greater rise of the piston is effected before the required' degree
of compression above is reached, and less air is received down. At length, a'
condition is reached under which a little air is taken down at each extreme ascent
of the working piston just sufficient to compensate for the leakage.
'
If the clearance or space remaining between the working piston and the working
cylinder cover is very small, the pressure in such space induced by the rise of the,
working piston is very great, and consequently the working pressure below will
be very great. As such clearance space is enlarged, the compression induced.
by the rise of the working-piston is less. I construct the engine with so much.
clearance or space remaining above the piston, between it and its cover when at
its extreme highest position, that the pressure induced by the rise of the piston is
moderate, say only two atmospheres. If a greater pressure is required, I remove
the cylinder cover, and insert one or more filling pieces to occupy a portion of the
space. These filling pieces are preferably in the form of rings, each made in two
or more pieces, provided with efficient fastening means. These may be inserted
and removed as required to adjust the pressure at which the engine shall work.
When it is once adjusted, the pressure induced above the piston at each stroke,
and consequently the pressure maintained in the imprisoned air below at the
moment when the working piston is at its extreme highest position, is constant.
My provision for taking in the air in this manner, to compensate for the gradual
loss of pressure in the working parts by leakage has the advantage that it is self
adjusting. When by reason of defective packing around the small piston rods of
the changing cylinder, or by reason of any other causes the air escapes rapidly.
from the working space below the pistons, that space will replenish itself the more
amply from the air compressed at each up-stroke above the working piston; and

page_text: in proportion as the air is abstracted from that space the valve opens earlier in
the down stroke and more air is drawn in.
A pipe controlled by a valve connects the space below the working piston with
the space above the working piston, so that when such valve is opened, in whole
or in part, air may flow backward. To the extent that this is permitted the
engine loses its power. I provide a governor which may be an ordinary fly-ball
governor to control this valve, and thus regulate the engine by opening this valve
more or less whenever the speed is excessive. Another valve is arranged to
discharge the air from the space below the piston into the atmosphere.
When it is desired to stop the engine with the pressure retained in the space
below the piston, the first named valve is thrown out of connection with the
governor, which is made practicable by employing a folding connection having a
rule-joint. When it is desired to subject the valve to the control of the governor
this flexible connection is by a simple movement of the hand or any other suitable
connection thrown into the straight condition, the shoulders of the rule-joint
arresting it when it is exactly straight. Thus conditioned the governor controls
the valve. When it is desired to stop the engine with the pressure on, the hand or
any suitable connection folds the rule-joint and opens the valve.
Opening the valve stops the engine with the pressure off. This latter valve may,
if desired, be opened and and let off the pressure after the engine has been stopped
with the pressure on.
In all the forms I support the engine at the mid-height so as to allow the lower
portions to expand and contract with heat and cold without inducing any
movement of the upper portion. This also relieves the lower portion largely from
strain.
The part which fails first in ordinary usage is the heater. This portion being
exposed to intense heat becomes partially oxidized or burnt, while the rest of the
engine remains in good condition. It is important to be able to replace the
heater without disturbing the main portion of the Engine. These ends are
attained by the aid of girders supported at each end by good bearings on walls of
masonry.
The compound cylinders are provided with stiffly braced flanges which are bolted
upon these girders.
The furnace is suspended in a sufficiently stout casing or box, of boiler iron or
other suitable material. This I equip at the top with means for making a tight
and strong connection to the bases of the compound cylinders above, which, the
latter being supported on the girders has the effect to suspend the box, and contents
on same. Within the box I arrange the proper fire brick lining with its arched
top and short chimney or funnel, and suitable grates, &c. The furnace and ash-
pit doors are hinged on the casing. Its front may be doubled and tripled to
protect the workmen from heat.
I completely separate the fire-room which surrounds or is adjacent to the lower
portion, from the engine room which surrounds or is adjacent to the upper portion.
I accomplish this by constructing a horizontal partition at or near the level of the
girders.
The horizontal partition serves as a floor for the engine room, which contains
the machinery above it, and as a means for protecting the machinery from the
heat, due to the fire below it. It cuts off the heat, noise, dust and ashes which are
annoyances in an engine room.
1
Instead of the webs I can use hollow stays forming an open communication
between the interior and exterior of the heater, taking care to make these passages
so small that a large portion of the gases will still be required to descend and pass
under the bottom rim of the heater.
I can make the cylinders each in one continuous length; but it is better to
make them in two or more separate lengths properly joined, and having a packing
of asbestos or other non-conducting material in the joints. This greatly retards
the conduction of heat from the hot to the cold end.

page_text: Instead of shifting the link I can, as is often practiced in steam engineering, by
making the link with a curvature in the opposite direction, effect the required
changes by shifting the link block in the link.
For very moderate pressure I can remove entirely the head of the working
cylinder, and allow air at ordinary pressure to enter and press down on the
working piston.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Stephen Wilcox in the Patent Office on the 4th June 1884.
STEPHEN WILCOx, of Brooklyn, in the County of Kings and State of New
York, one of the United States of America. "IMPROVEMENTS IN HOT AIR
ENGINES AND THEIR ATTACHMENTS
"
I employ a cooling jacket in connection with a regenerator, both arranged around
the cylinder by which the zones of low temperature are lowered in the regenerator,
and the water cools not only the air which moves to and from the cool end of the
cylinder, but also cools the cylinder itself. I automatically regulate the engine by
means of a governor which operates by shifting a link which moves the changing
pistons. I provide peculiarly adapted packing around the piston rods and force air
into the pipe connecting the tops of two opposite working cylinders to compensate
for leakage. By regulating this action automatically, I maintain a uniform
pressure. I have devised means for subtracting a large portion of the heat from
the gases discharged from the furnace and for imparting it to the incoming air to
supply the fire in the furnace. A blower promotes the draft just sufficiently to
overcome the resistance due to these provisions. I have also devised means for
distributing oil in the upper portion of each cylinder.
A working piston reciprocating in a corresponding cylinder is located centrally
within a larger changing cylinder enclosing an annular changing piston in the
space between itself and the exterior of the working cylinder. The engine is
preferably worked in the upright position and will be so described. A heater
having a suitable furnace below supplies heat to the air in the lower portion of
the apparatus and expands it inducing a momentary high pressure to force up the
working piston. The operation of the changing piston then immediately forces a
large portion of this air around through a suitable regenerator and cooler to the
annular space above the changing cylinder and by lowering the temperature of the
air lowers its pressure, and allows the working piston to be forced back against a
reduced pressure. The air thus worked may have a pressure considerably above
that of the atmosphere, the tension being maintained against leakage by means of
a constantly worked pump with proper regulation.
The accompanying drawings form a part of this specification and represent what
I consider the best means of carrying out the invention.
Figure 1 is a central vertical section through one of the cylinders and immediately
connected parts.
Fio 1 is a horizontal section on the line 8 8. in fiơ 1.

page_text: "
Fig. 2 is on a larger scale. It is a vertical section through the regulating
chamber for the automatic link adjustment, and
Fig. 3 is an elevation at right angles to Fig. 2.
Figs. 4 to 7 represent. the construction modified in some important features.
Fig. 5 also shows several cylinders and pistons assembled to form one half of a
complete set of apparatus. The same mode of assembling is also employed with
the construction shown in Figs. 1 to 3.
Fig. 4 is an elevation of an engine constituting one half of the complete set of
apparatus and of which a side view appears in fig. 6.
Fig. 5 is a plan view corresponding to fig. 4. It shows the whole combined set.
Fig. 6 is an end elevation of a pair of compound cylinders and their directly
connected parts constituting one engine.
Fig. 7 is on a larger scale. It is a vertical section through the main portions of
one of the compound cylinders with the immediately connected parts.
Fig. 8 shows a modification in which the changing piston is in line with instead
of being annularly around the working piston. The view is a central vertical
section through one of the cylinders and connected parts.
The remaining figures represent details which may be used with either of the
forms.
Fig. 9 is a vertical section of a portion which I term a heater.
Fig 10 is a corresponding horizontal section.
Fig. 11 is a vertical section of one of the piston rod stuffing boxes on a larger scale.
Fig 12 is a vertical section through a device for automatically controlling the
action of the air pump..
Fig. 13 is an elevation of the same.
Fig. 14 is a section partly in elevation showing the provisions for-indicating the
highest pressure.
Fig 15 is an elevation of the friction provision or jack-wheel.
Fig 16 is a section of the same on the line t t, in fig 15.
Figs. 17 and 18 show a modification of the construction of this part.
Fig. 17 is a side elevation, and
Fig. 18 is a section on the line y, y, in Fig 17.
Fig. 19 is a vertical section through a modification adapted for small powers. In
it there is only one working piston and one changing piston.
Fig. 20 is a central vertical section showing a construction differing from that
in Fig. 19 in having a close top to the working cylinder and means of taking in
air and maintaining a high pressure without a separate pump.
Fig. 21 is a plan view, and
Fig. 22 is a side view of the upper portion.
Fig. 23 represents the air induction valve, and the immediately adjacent parts on
a larger scale. It is a vertical section.
Similar letters of reference indicate corresponding parts in all the figures where
they occur.
My improved engine has upright cylinders peculiarly compounded. Each has
two deep pistons fitting tightly at their upper portions only and running free in
the lower portions with a heater and furnace still lower.
As in other engines of this class, the power is derived from the working piston
alone. The motion of the changing piston does not add to, but subtracts from
the working power. The subtraction is slight because the pressure is always
substantially equal above and below. It requires merely sufficient power from the
other working parts of the Engine to overcome the friction and inertia.
A is the brickwork of the furnace A*, and A³ a fire brick funnel extending
upwards a little from an arch A in the top of the furnace and causing the hot
gases therefrom to be projected directly into the top of the dome like heater above.
Referring to Figs 1 to 3.
I employ two working beams keyed-to a stout rocking shaft; and one changing
beam mounted on each side and turning loosely-on the same shaft.

page_text: Each cylinder is compound there being in each case a smaller cylinder within a
larger. These compound cylinders are coupled in twos to form one engine. Two
of these engines or pairs of compound cylinders are united to work together on one
crank. I will first describe one of the compound cylinders and its immediate
connections.
C is the interior cylinder.. Its upper part is of cast iron made of two
thicknesses. Between the outer and inner thicknesses is an annular chamber c, in
which water is circulated as will be presently described. This part of the
cylinder C, is nicely finished both on its inner and outer face. It is finished on
its inner face to form a tight contact with the working piston D, by the aid of
"Dunbar "packing or other suitable packing. It is finished on its outer face to
form a tight contact by the aid of packing with the annular changing piston E.
The lower portion of this cylinder is also double. It is made of sheet iron or of
other thin material secured to the rigid part above by riveting or otherwise. The
interior is filled with plaster so as to form a strong and stiff support to the metal.
It serves also as a good non-conductor. There is a space below the bottom for the
free flow of air outward and inward.
C' is the outer cylinder formed at its upper portion also of considérable
thickness and chambered annularly as indicated by c¹. Water also circulates
through this chamber c¹. The lower portion is made of a single thickness of
substantial material, as cast iron with a facing of plaster. There is thin sheet iron
or other metal to form the extreme inner surface of the lining.
.
The working piston D, is connected by a single piston rod d, working through
an efficient stuffing box, to be described further on, to a cross-head connected by
links to a beam M. The other end of this beam is similarly connected to the
working piston rod of another similar piston. I term these two sets of pistons
with their accompanying parts thus connected an engine. The beam is keyed to a
strong "beam centre" or rocking shaft m on one side of which is keyed an inclined
arm M', from a pin in the end of which the power is communicated by a link M²,
to the crank pin of a crank O¹, keyed on the revolving shaft O, and equipped with
as efficient fly wheel or pulley 02, from which the power is communicated, as will
be set forth further on, to any machine which it is required to drive..
The annular changing piston E has two small piston rods e e, working through
stuffing boxes at the top, each of which is connected by a link to a beam P, which
turns loosely on a beam centre m. The other end of each beam P, is similarly
connected to the opposite changing piston. It follows that the gravity of all the
parts in the two cylinders balance each other.
The heater is designated by B, additional marks of reference as B1, B2, being
added when necessary to designate certain parts thereof.. It is substantially dome
shaped on its under and inner side B, and cylindrical on its outer side B, with a
strong and wide flange B³, around the top.by which it is bolted to the expanded
base of the outer cylinder c¹.. Between the dome like interior and the cylindrical
exterior is a limited space which performs the important function of thoroughly
heating the air to a high temperature, in the rapid transference from the top to the
bottom of the machine under the action of the changing piston. The construction.
is braced, so as to effectually hold it in form in opposition to the forces tending to:
warp and destroy it under the high temperature to which it is subjected.
This bracing is effected by six webs B, which are cast in one therewith and
firmly connect B' and B³, extending from near the base to a level near the top of
the heater.. B is a casting adapted to extend down in the six spaces between B¹
and B2, nearly to the bottom.. It is divided from the bottom nearly to the top, to
allow it to apply between the webs B'. This casting leaves a thin space exterior
to it between it and B2, and a thin space interior to it between it and B¹. It need
not fit tightly to the webs B', but it is important that it shall approximate thereto
so as to compel the main portion of the air to traverse down the entire depth of
the heater, and up again in its transfer back and forwards from top to bottom of
the engine... The engine is in its general features analogous to that known as the

page_text: "
Stirling Engine." When by the rise of the annular changing piston a large
portion of the compressed air is transferred into the bottom space, it is expanded
and the effect is felt on the under face of the working piston D, driving it forcibly
upward. When by the descent of the annular changing piston a large portion of
the air is caused to move into the top of the engine, its pressure is reduced by
cooling and the working piston D, is allowed, to descend against a reduced
pressure.
Eccentrics 0, 0%, connect by eccentric-rods W¹ W³, to a "Stevenson " link W,
which takes hold of a link-block V2, which is mounted on a pin V₁, carried on an
arm fixed on a rocking shaft V supported in a fixed bearing in the framing. This
shaft V, has two arms V³, only one of which is shown, which carry respectively
links V4, connecting the arms to the changing beams P, and by them operate the
changing pistons E. The two changing pistons connected to the opposite ends of
the changing beam by the rods e and links e¹, (see figs 3 and 4) balance each other.
The link W has only to overcome the inertia and slight friction of the changing
pistons and the slight resistance, due to the friction and inertia of the air which
the changing pistons cause to be transferred, rapidly between the hot and cold
portions of the apparatus. The power is produced by the changes of temperature
and consequently of pressure due to such transference, as will be readily
understood.
I, is a regenerator composed of metallic plates set on edge and held a little
distance apart. It is mounted in a sufficient annular space exterior to the changing
cylinder and in communication with the hot air space z, below the two pistons and
also through a cooler with the relatively cold air space y, above the changing piston.
The space above the working piston is subject to a constant pressure from air
pumped in as will be fully explained further on.
The cooler is formed with thin metallic tubes k, which traverse the space c¹, and
allow the air to flow up and down through them. Cold water circulates in the
space around them. The cooling water enters through a pipe k, and after
traversing the cooling chamber c³, and also another c, which occupies an annular
space within the cylinder C, is discharged through a pipe k².
The air tubes K, of the cooler communicate through passages at the top with the
annular space over the changing piston.
The traversing of the air between the top and the bottom of the apparatus in a
thin annular space around the working cylinder is of advantage in allowing the
passage to shut and the amount of space in the passage to be small.
The presence of the cooler insures that the upper edge of the regenerator which
is below it shall be at a low temperature. The regenerator with its several zones
of temperature varying fron the hottest at the bottom to the coolest at the top is
a well known adjunct of hot air engines. It absorbs heat from the air as the hot
air rises and becomes heated thereby, its lower edge being heated the most. It
imparts heat to the descending air and is itself cooled thereby, the upper edge
being cooled the most. All the zones of heat are carried low on the cylinder
by reason of the cooler above them. The ultimate effect is the confining of the.
heat in the cylinders and in all the parts to a limited domain at the base of the
apparatus.
By shifting the annular piston to the fullest possible extent, theoretically all the air
is transferred alternately from the top to the bottom of the apparatus. This is the
condition for the most effective working. I have adapted my engine to drive
delicate machinery by providing an automatic regulation. It acts by reducing the
extent of motion of the changing pistons and consequently the extent to which
the air is transferred between the cool and hot portions.
When the link W, holds the link block V2, in its centre as indicated in the
drawing there is little or no motion of the changing pistons. By shifting the
link W, so that it receives and holds the block V2, in one end of its curved slot, E
the changing pistons E, receive sufficient motion to cause them to traverse to the
fullest extent and shift all the air. When the link W is held in some intermediate

page_text: :
position it induces a less amount of motion of the changing pistons. Under these
conditions less air is transferred alternately between the cool and hot ends of the
apparatus, less changes of pressure are induced and less power is developed by
the action of the air, on the working pistons. By shifting the link further the
engine may be reversed.
R¹ is a link which connects the "Stevenson" link W with a bell-crank lever R,
turning on a fixed centre r. This lever R connects by a link R2 and rod R³, to a
piston R, in a small cylinder Q. This latter is equipped with passages arranged
as shown, controlled by valves T1, T2, which when the valves are held open permit
the fluid, which should be oil or some analogous inelastic fluid filling both ends
of the cylinder, to shift from one end to the other.
The action of the engine communicated through the link W induces by well
known laws a tendency of the piston R, to shift alternately in one direction and
the other. This tends to raise that piston during one portion and to lower it
during another portion of each revolution of the mainshaft. This tendency is
resisted by the fluid; the fluid can under certain limitations shift past the
valves T T. When these valves are both allowed to close no such motion can
occur. The piston K' and consequently the link W is held against any shifting.
It vibrates by the action of the eccentrics 0, 0%, but does not shift to one side or
the other. When however one of the valves T₁ T', is held open the fluid in the
cylinder Qmay shift a little in one direction. The governor controls the opening
of these valves.
This control by the governor is effected through a lever G₁, which is raised and
lowered either directly or indirectly by the action of the governor G. It is con-
nected by the link G2, to the lever G³. This lever rocks the spindle g, and the
rigidly connected wheel G4, and by means of face cams formed on the latter, forces
open one or the other of the valves T¹ T², one being released when the other is
open.
That is to say when the lever G¹ rises it turns the wheel G, into such position
that the uppermost valve T', is held open. Under these conditions the fluid may
flow from above the piston R*, around into the space below said piston, the lower-
most valve T, opening automatically against the force of its gentle spring. Under
these conditions the piston R, rises and acting through the connections shifts the
link W to the left and increases the power of the engine.
But when the lever G¹ descends it liberates the upper valve T', and allows it to
shut, thus resisting any tendency of the oil to escape from above the piston into
the space below. The same movement opens and holds open the lower valve T³,
and allows the oil to flow away from below the piston and to come into the
space above it. This causes the piston R*, to sink and shifts the link W to the
right, thus decreasing the power.
The space over the working piston D, is inoperative, and I provide for an
equal pressure therein at all times. It is well that the pressure in such space shall
be about equal to the lowest pressure below the piston. That is to say, if the
pressure below the working piston varies between 60 and 90 pounds with a mean
pressure of 75 per square inch, the air in the space above the working piston
should be always 60 pounds. The idle space over the working piston is marked x.
I extend it upward in a small annular chamber around the stuffing-box which
encloses the piston-rod d, and unite these portions of the two connected engines
by a pipe X.
As the working piston in one of the two connected cylinders always descends
when the other rises the pressure of the compressed air on the upper surface to
the two working pistons is practically uniform in all conditions. Its pressure
contributes to depress each against the considerable pressure which remains on
the under face of the working piston during the down stroke. It equally resists
the pressure of the working piston during the up stroke. The existence of a
considerable pressure in the chamber and pipe X, tends to reduce the slight leakage
which is perhaps unavoidable past the packing of the working piston.

page_text: I take care to provide a very efficient stuffing box around the several piston
rods, so as to hold the compressed air efficiently with a minimum friction. The
piston rods d, e, are each surrounded by a series of rings i of good leather, shaped
by wetting and stretching to the form shown in Fig. 1 and Fig 11. These must
be carefully kiln-dried at a moderate heat after which they will endure the
temperature without difficulty. The rings are of vulcanized India rubber of
circular section. The stuffing boxes are deep and contain a number of these
leathers, each partially enclosing its ring of rubber. The whole being gently
compressed by the gland induces a gentle contact against the piston rod and
becoming highly polished by friction reduces the leakage around the piston rods to
a very small amount even if the pressure in the engine be as high as a hundred
and fifty pounds per square inch. One hundred pounds per square inch I esteem
about the best pressure to maintain above the working piston.
✗ is a constantly acting force pump (See Fig 12) operated by the engine with a
uniform stroke and tending to receive and force into the spaces above the working
pistons a small uniform quantity of air at each revolution: The leakage is liable
to vary and I vary the admission of the air to this pump accordingly. ✗* is a
casing having a nozzle bolted on the induction aperture of the pump. There are
apertures a through which the air is drawn in freely but the passage therefrom to
the pump is controlled by a peculiarly mounted valve X², having a long stem and
capable of closing tightly upon a seat x². It is held up and consequently open by
a coiled spring X³, acting between the collars ³, and an adjustable abutment x,
controlled by a screw 5. On the upper end of the stem is a considerable button
or disc x, on which rests a flexible diaphragm X', above which is a chamber
connected by a pipe x', with the large connection pipe X, between the upper parts
of the working cylinder. So long as the pressure in the latter is sufficient the
valve X2, is by the tension of the air on the diaphragm X, held down to its seat.
But the moment the pressure becomes reduced by leakage the spring Xs lifts the
valve X2, a little and allows the pump X, to take in air and force it into the
pipe X, until the full pressure is restored when it is again stopped by the refusal
of the valve to rise. In practice the valve X³, rises a little and the pump takes a
little air at each stroke. Changing the screw ³, determines the amount of
pressure to be maintained in X.
The packing of the working piston D, is of a character known as "Dunbar"
packing, which allows the air to move freely down past the piston but forbids its
return. The pumping of air by the pump X', into the large pipe X maintains the
pressure in all parts of the apparatus.
The air to support the combustion in the furnace is received through inverted
U shaped pipes S. These pipes being exposed to the hot gases escaping from the
furnace through the passages a a¹ a² a³ a³, to stack as, warm the air within so that
the fresh air therefrom entering the furnace by being partially heated contributes
to the efficiency of the fuel and consequently the economy of the engine. But the
passage of the air through these U shaped pipes is resisted by friction. So also is
the passage of the escaping gases from the furnace resisted by the effort required
to flow through the passage obstructed by these pipes. The consequence is a
tendency to a retarded draft.
S' is a blower driven by a belt from the engine and forcing the air strongly in
its entrance through the pipes S. The effect of this blower should be sufficient to
overcome the resistance of the fresh air in moving through the interior of the
pipes S, and also to overcome the resistance of the hot gases in escaping from the
furnace through the obstructed flue or chamber in which the pipes S, are mounted.
The combination of the blower with the pipes secures both economy and efficiency.
The changing piston E, although it need not be packed and need not rub with
much tightness against the surfaces on the exterior and interior respectively has
large surfaces subject to friction and parts are liable to rise to a high temperature
under some conditions which cannot be conveniently insured against. I provide
peculiarly efficient means for introducing oil to lubricate the parts.

page_text: His a single-acting hand-pump provided with a reservoir H1, receiving oil. It
communicates by a small pipe h¹, with a perforated pipe h, extending around in a
recess provided in the top of the working cylinders. Its perforations are arranged.
to allow the ejection of the oil upon the annular changing piston. It spreads
thereon and lubricates both the outer and inner edges.
L', (see fig 3) is a thermometer the sensitive portion of which is immersed in the
pipe, through which cold water enters the cooler.
L² is another thermometer having its sensitive portion correspondingly immersed
in the pipe k, which conveys away the warm water from the cooler. An inspection
of these two thermometers shows by direct comparison the changes of temperature
induced in the water of the heater. When the change of temperature is too small
it indicates that too much water is admitted to the cooler and I partially close a
controlling cock, not shown, which lessens the quantity of water allowed to traverse
the cooler. This is important when as is frequently the case the supply of cooling
water is small. When the difference of temperature of the two thermometers is
unusually great it shows that the water in the heater is allowed to become too
much warmed and consequently that the air is being too little cooled. When this
is observed the attendant opens further the cock, not shown, and allows the water
to circulate through the cooler more freely.
L is a pyrometer having its sensitive portion immersed in the hot gases filling
the flue or chamber a. It has a dial mounted in position to be easily observed by
the attendant. When he sees that the heat in the flue is too low he opens the
damper, and quickens the blower or otherwise encourages the fire in the furnace.
When he observes that the temperature of the pyrometer is too high he closes the
damper or decreases the action of the blower or both and consequently allows the
fire to become less active. The several furnaces have each a separate pyrometer.
N is a pressure gauge. Its interior is subject to the influence of the pressure
within the cylinder. This pressure varies widely between its greatest and its least
during any given revolution. It also varies considerably in its absolute pressure
at the period of greatest heat. When the working piston is being driven upward
in its cylinder my gauge feels the pressure at the highest. It is provided with a
valve n¹, opening freely upwards to allow the pressure of of oil or other fluid acted
on by the air to pass upwards freely. When during another portion of the
revolution the pressure in the working cylinder is greatly reduced, this pressure
gauge does not show the corresponding diminution of pressure, the pressure does
not diminish in the gauge except by a very small amount, that due to a slow
movement of the oil or other fluid past a stop cock N¹, which communicates
through small passages with the gauge and with the source of pressure. At.every
revolution of the main shaft there is a period at which the high pressure is felt by
the gauge the same being transmitted freely past the valve n¹. The gauge runs
down a little but only a little, in the intervals. It vibrates between indicating the
highest pressure which obtains in the cylinder, and a pressure only a pound per
square inch or thereabouts below such highest pressure.
N° is a pressure gauge working under opposite conditions. The valve, not
represented, which serves for this gauge is arranged to allow the oil to escape freely
from the pressure gauge N³, at each lowering of the pressure and to rise only
slightly during the period of high pressure..
. An additional gauge N³, is of the ordinary construction and is connected to the
space above the working pistons. It is subject to a nearly uniform pressure of air.
The air in the upper end of one working cylinder is transferred from the pipe X to
the top of the opposite working cylinder, as the working beam. M vibrates, and the
two working pistous alternately ascend and descend.
I communicate power from my engine through friction gears peculiarly mounted.
The fly-wheel O3, (See fig 3) is a large pulley having V shaped grooves turned or
otherwise produced in its periphery adapted to transfer power by friction in the
well known manner.
F is a jack-wheel certain portions being designated when necessary by additional

page_text: -
letters of reference as F¹ F³, (See figs 3, 15, and 16.) It has an iron périphery F¹,
equipped with V shaped beads f corresponding to the grooves in the wheel 02, but
instead of the whole jack-wheel being rigid and mounted fixedly upon the shaft F4,
the force is communicated through an annular mass F2, of vulcanized India rubber
which is mounted between the hub F³, and the annular rim F, and which by its
yielding avoids the trembling due to ordinary friction gear. It also allows the
shafts to be slightly out of their true positions without inducing mischief. A false
position is accommodated by the yielding of the rubber F3.
The parts are insured against slipping by means of a dog F³, carried on the hub
and engaged in a recess in the rim F. It is held by a bolt as shown.
Figs. 17 and 18 show a construction in which a less elastic material, as wood
is employed. The wood is inserted in blocks preferably with the grain extending
radially.
In this form the rim F¹, is strongly held against slipping around on the contained
· parts by means of a metal key F.
I have shown in the drawings Figs 2 and 3, a flexible pipe of India rubber or
analogous material having a contracted nozzle at one end, and connected at the
other end to an iron pipe which connects with the top of the working cylinder C.
On opening a cock a strong blast of air is ejected from the nozzle which on opening
one of the slides represented, and directing the current into the aperture thus
exposed, clears the ashes and soot from around the base of the heater.
Y are the girders which support the mechanism, resting on brick walls Z.
I will now describe some important modifications.
Figs 4, 5, 6 and 7 represent one modification in which there are several changes
in the structure. One of the most important lies in the fact that instead of the
regenerator being arranged annularly around the working. cylinder it is enclosed in
a casing on one side. This may be expedient under some circumstances but I prefer
generally the annular arrangement previously described.
The top of the regenerator and cooler chamber is closed by a removable bonnet I¹.
This also is chambered as indicated by ¹². The two chambers in the bonnet are
kept filled with cold water and are divided by a continuous partition.
Within the upright cylinder at one side are two pieces of apparatus which
perform important functions. When the. bonnet I', is taken off both may be
taken out and repaired or exchanged by simply raising and lowering through the
open top.
The lowermost is a regenerator the function of which as in the previously
described engine is to alternately absorb heat from the air and give it off again.
The uppermost is a cooler for simply and solely absorbing and conveying away
heat. It is of cylindrical form pretty closely fitting the interior of the spaces
provided. All the surfaces of the cooler are made tight and strong with two
pipes K K², connecting with the chambers i¹, i, respectively in the bonnet. Small
thin pipes are provided extending from end to end through this cooler. The air
in its rapid transfer in one direction and the other between the spaces y z, moves
through these tubes k, and is cooled by the pressure of cold water around them.
A pipe brings cold water from a pump or other supply source into one of the
chambers, in the bonnet. A passage 23, leads the water away from the chamber i³,
into the space which surrounds the cooler.. This latter space is in free communication
with the chamber, which extends around near the upper portion of the changing
cylinder C¹. A passage seen at the top of the cylinder leads the water into
the chamber c. After circulating around the working cylinder the water escapes
through a passage c³, into the discharge pipe k².
The passage c³, receives water through a pipe which extends down nearly to the
base of the annular chamber c. This and the arrangement generally compels a
complete circulation of the water in one continuous stream through the proper
spaces in and around the upper portion of the engine. The effect is to absorb and
carry away the heat which creeps up to the upper portion of the apparatus.
: A radial passage g², communicates from the interior of the heater B through

page_text: an annular chamber g¹, to the base of a chamber at one side containing the
regenerator I as shown. This passage g³ is entirely above the heater.
W is the "Stevenson" link worked by two eccentric rods W', W, connected to
straps which enclose eccentrics 0', '0'.
The link is shifted by a hand-lever W³, connected in the ordinary manner, the
rocking shaft extending across so as to adjust the links of the connected engine by
the same movement.
In this modification as also in the apparatus previously described the main
portions of the two engines are counterparts of each other. The arms M¹ of the
respective beam centres m, work in such positions that their respective links N,
engage with cranks on the same crank-shaft. One is the position for operating on
the crank with its full force while the other is passing the dead point. By reason
of this arrangement the combination of two complete engines works with a
continuous and nearly uniform action requiring a fly-wheel O2 of only moderate
size and weight.
The damper turns on an axis land is actuated by an arm or lever . This
damper exercises a controlling influence on the draft of air through the furnace,
and consequently on the intensity of the heat supplied to the heaters. It is
important to maintain the heat sufficiently high to make the engine efficient and
also to avoid burning the metal. In other words it is important to keep the
temperature of the gases discharged through the flue a nearly uniform. I attain
this by working the damper automatically.
T is a hollow spheroidal casting filled with mercury or other fluid having a bigh
boiling point, connected by a pipe t, with a chamber U, under a flexible diaphragm.
This diaphragm is loaded by the weight U¹, and connected by the rod 13, to the
lever of the damper through the movable block , fixed in any desired
position on the arm or lever by a screw. When from any cause the temperature
of the gases in the flue a rises too high, the mercury in T, commences to boil and
the mercury vapor pressing on the surface drives the mercury down and raises the
diaphragm, thereby closing the damper 7. When the temperature falls sufficiently
all the mercury vapor condenses again and the diaphragm sinks, opening the
damper. When the apparatus works properly it keeps the damper always
partially shut closing it tighter or opening it further by the action of the mercury
as required, so that the temperature of the gases in the flue a is kept nearly
uniform. This damper and the provisions for regulating it are also applicable to
the preferable form of the apparatus just described, and to those to be hereafter
:described.
"
In the modification shown in fig: 8, the changing piston instead of being
annular and arranged to work at about the same level as the working piston, is
higher and in line with the working piston. This necessitates a greater lightness
of the mechanism but it may be for some purposes preferable.
I employ a cylinder of boiler iron or analogous thin material to form a cylinder
within which the changing piston works with approximate tightness there being
another cylinder or casing of cast iron or other strong and rigid material outside of
the thin cylinder and at such a distance therefrom as allows room for the
regenerator and for efficient cooling tubes in which cold water is circulated.
The working cylinder.is mounted above and is of slightly greater diameter than
the thin changing cylinder.. The heater is mounted below. Thus there are three
lengths of the metal in line, the working cylinder at the top, the thin changing
cylinder at the mid-height with a thicker portion enclosing it at a little distance
outside (with the regenerator and cooler between) and the heater below.
The thin cylinder is divided in two lengths and equipped so that while the
lower portion is left in place extending down into the heater ready when required
to again perform its useful function of compelling the air to traverse over a great
extent of heated surface in its frequent passages from the cold to the hot portions
.of the apparatus the upper portion may be easily removed and replaced...

page_text: The main working cylinder has a broad flange at its base which performs the
double function of supporting the cylinder and serving as a bonnet for the annular
cooling chamber.
:
The upper end of the upper section is secured, by means of a stout perforated
ring which is recessed into the bottom of the main cylinder below the flange which
serves as a tight bonnet, and serves to accurately centre and support the inner
cylinder while allowing the air to move freely up and down through liberal holes
cored therein.
This annular space between is occupied at the lower portion with a series of
plates serving as a regenerator to alternately receive and give out heat and passing
air. More space is allowed in the upper part of this annular chamber. It is
occupied by a series of tubes which extend around or partially around and convey
actively circulating currents of cold water. I term this the cooler.
The cooler does not extend around in a single piece but is adapted to be taken
off, and reapplied without taking out the rod of the changing piston which
necessarily stands in the centre and would be an obstruction to the removal of a
complete ring of such tubes and even without entirely taking out the changing
cylinder but only raising the latter.
The cooler is also made in two or more divisions horizontally. This allows it to
be removed in sections without making so large a vertical space between the
working cylinder and the case below as would be necessary to remove a cooler
in one continuous height.
In any form of the parts I employ a thick mass of ashes or other good non-
conducting material around the bases of the several parts of the apparatus above
the brick-work A and held by an exterior case of metal or other suitable material.
If the regenerator is removed and the air allowed to flow from the cooler
directly into the heater, the escaping products of combustion can be reduced some
300° F or 400° F. But if the regenerator is in use the air is delivered into the
heater at about 500° F, and as there must be a difference of temperature of
some 200°, between the air inside the heater and the gases outside in order to
effect a rapid transfer of heat, the gases will pass away at some 700° F, involving
a loss of one third of the efficiency of the fuel. Under these circumstances the
efficiency of the economizer pipes becomes apparent, as by them at least one half
the escaping heat is returned to the furnace and a high degree of efficiency
secured.
The
In the form of the invention shown in Figs 20 and 21, the main shaft is
mounted directly over the cylinder, its axis crossing the line of the axis of the
cylinders. A connecting rod from a crank in the mid length of the shaft connects
to the working piston. One end of the shaft carries a heavy fly-wheel.
other end carries a crank which communicates motion by a connecting rod or link
to a lever on a rocking-shaft, which shaft has two arms connected by links to two
piston rods fixed to the annular changing piston. The single working piston rod
and the two changing piston rods which latter may be considerably smaller than
the working piston rod play through stuffing boxes all made as tight as is
conveniently practicable.
A space in the upper end of the working cylinder between the working piston
and a tight fitted cylinder head by the alternate rising and sinking of the working
piston communicates with the external atmosphere by a self acting valve opening
inward and performs important functions.
At each ascent of the working piston the air in the space above it is compressed.
So soon as it is sufficiently compressed to have a tension above that of the air
below, the peculiar packing allows some of the air above to flow down past the
working piston and be retained there. At each descent of the working piston the
air in the space above it expands. If much of the air above has been discharged
down through the packing the air above has been so much reduced in quantity
that it will be thus expanded to a tension below that of the external atmosphere.

page_text: When this condition obtains; fresh air is drawn in from the external atmosphere
through a self acting valve opening inward or downward in the working cylinder
cover.
If the entire apparatus including the stuffing boxes could be made absolutely
tight the air would soon be thus received into the working portion of the apparatus
to such tension that the rise of the working piston would compress the air above
it only to the same tension as that below, and no air would be received down past
the working piston at any time. But such tightness cannot be realized in practice.
There is always more or less leakage. In first starting the engine when there is
only the pressure of the atmosphere in the lower portion of the apparatus, much
air is taken down past the working piston on the first revolution of the shaft,
which must be induced by hand or by some means external to the engine. At
each succeeding revolution a greater pressure exists below the piston and
consequently a greater rise of the piston is effected before the required degree of
compression above is reached, and less air is received down. At length a condition
is reached under which a little air is taken down at each extreme ascent of the
working piston just sufficient to compensate for the leakage..
If the clearance or space remaining between the working piston and the working
cylinder cover is very small the pressure in such space induced by the rise of the
working piston is very great, and consequently the working pressure below will be
very great. As such clearance space is enlarged the compression induced by the
rise of the working piston is less. I construct the engine with so much clearance
or space remaining above the piston between it and its cover when at its extreme
highest position, that the pressure induced by the rise of the piston is moderate,.
say, only two atmospheres. If a greater pressure is required, I remove the
cylinder cover, and insert one or more filling pieces to occupy a portion of. the
space. These filling pieces are preferably in the form of rings each made in two or
more pieces provided with efficient fastening means. These may be inserted and
removed as required to adjust the pressure at which the engine shall work. When
it is once adjusted the pressure induced above the piston at each stroke and
consequently the pressure maintained in the imprisoned air below at the moment
when the working piston is at its extreme highest position is constant.
In figs 20 to 23 the inner cylinder is the working cylinder, and is marked C.
This cylinder C, is made of considerable thickness. The upper portion is of cast
iron and chambered, and receives water which aids to keep the upper portion of
the apparatus cool. The lower portion of the cylinder is of sheet metal, in two
thicknesses filled with ashes or other non-conducting material.
Concentric to this is a larger changing cylinder C¹. This is of cast iron, the
upper portion thick and chambered and containing water. The inner face of the
lowest portion is a separate casting C³, reaching down nearly to the bottom
casting B which is the heater and performs the usual functions of that important
portion of a hot air engine.
In the space between the casting and the exterior of the cylinder C¹, I mount
thin plates of metal not represented, serving the well understood functions of a
regenerator to absorb the heat from the air as it rises and impart it again to the
air in its descent. The working piston is marked D. The packing is near the
top. The lower portion is of sheet metal filled with ashes or other good non-
conductor. The working, piston D, is deeply chambered at the top as shown. The
chamber thus provided adds to the space sometimes called "clearance' which
remains filled with compressed air when the piston is at its highest point.
12
In the cover C³, of the working cylinder C, is a sufficient aperture controlled
by a self acting valve opening downward. It is closed by a gentle spring, see
fig 23.
The working piston rod d steadied by what is sometimes called a "slipper-
guide" d, which serves in lieu of the ordinary cross-head, communicates by the
connecting rod d², with the crank q' on the main shaft q. This shaft carries a

page_text: fly-wheel q which should be of considerable weight, so as to accumulate more
momentum than is required in a double-acting engine.
The changing piston E, has two piston rods each of which is connected by a
link w³, to an arm w. This shaft is rocked by means of an arm w¹ (see Fig 22)
which is operated by a link q', from a crank 9³ on one end of the main shaft
Զ.
The throw of the crank q³, is constant. Instead of connecting the other end of
the link to a fixed point on the arm w¹, the link q is connected to a block q
which is capable of being moved in a long curved slot in the arm w¹. When the
block is at one end of the slot the rocking shaft w receives so much motion that
the changing piston is shifted to its fullest extent and the engine develops its
.greatest power. But when in order to drive delicate machinery or for any other
reason it becomes desirable to reduce the power, the block q may be shifted
partially or entirely to the other end of the slot. In this position it rocks the
shaft w to a less extent, and consequently moves the changing piston up and
down to a less extent. The effect of this is to make the engine develop less power.
I provide a screw 8, supported between collars in a swivelling block, in the line
of the shaft w and operated by a hand wheel s'. This screw is tapped through
the block q³, or through a swivelling piece attached thereto, and by turning it in
one direction or the other the block may be adjusted at will in different positions
in the slot. By this means the effective working force of the air in the engine
and consequently the speed of the engine may be regulated by turning the hand-
wheel 8 one way or the other as required.
The cooler or cooling jacket K is traversed by a series of pipes k, through which
the air moves, surrounded by the cold water in its passage alternately upward and
'downward between the hot and cold ends of the apparatus. I use the letter K,
to indicate the entire belt of cold water surrounding the principal portion of the
changing cylinder. I use the letter I, to indicate the series of metal plates which
serve as the regenerator.
My provision for taking in the air in the manner to compensate for the gradual
loss of pressure in the working parts by leakage has the advantage that it is self a
adjusting. When by reason of defective packing around the small piston rods of
the changing cylinder or by reason of any other causes the air escapes rapidly
from the working space below the pistons that space will replenish itself the more
amply from the air compressed at each upstroke above the working piston; and
in proportion as the air is abstracted from that space the valve c*, opens earlier on 3
the down stroke and more air is drawn in.
J is a pipe leading from the space above the working piston to a channel
connecting with the space below said piston. It is provided with a valve or cock J¹,
'having a lever J' which is controlled by a joint connection J3 J4, leading to a
governor J. So long as the speed of the engine is at or below the proper limit 4
this cock J', remains closed. But whenever the speed becomes excessive this
governor Jo, by elevating the lever J2, opens the cock J, and at each stroke of the
piston allows some of the compressed air below the piston to blow back into the
space above the piston thus reducing the power and consequently the speed of the
engine the proper limit of speed is again reached when the valve or cock J¹ will be 4
closed, and the engine will work again as before.
The rod Ja, is provided with a rule joint J. When it is desired to stop the
engine the attendant by the direct application of the hand or by any suitable
connection, not shown, folds the rod J³, at this joint J, and thus lifts the lever J*
so as to allow a free motion of the air back and forward through the pipe J which 5
immediately equalizes the pressure above and below the piston.
Je is a valve which when opened by hand or otherwise discharges air into the
atmosphere. Opening this valve instantly stops the engine and leaves it with no
compressed air within it, thus allowing the engine to be more easily turned around
by hand, when it is desired to start again. This valve may be opened to let off 5
the pressure after the engine has been already stopped by the other means if
desired.

page_text: In all the forms I support the engine at the mid-height so as to allow the lower
portions to expand and contract with heat and cold without inducing any
movement of the upper portion. This also relieves the lower portion largely from
strain.
The part which fails first in ordinary usage is the heater B. This portion being
exposed to intense heat becomes partially oxidized or burnt while the rest of the
engine remains in good condition. It is important to be able to replace the heater
without disturbing the main portion of the engine. These ends are obtained by
the aid of girders.
Y Y are stiff girders of cast iron or other suitable material supported at each
end by good bearings on walls Z of masonry: The compound cylinders are
provided with stiffly braced flanges which are bolted upon these girders.
.
The furnace is suspended in a sufficiently stout casing or box of boiler iron or
other suitable material as indicated by Y¹, (See Figs. 1 & 7). This I equip at the
top with means for making a tight and strong connection to the bases of the
compound cylinders above, which, the latter being supported on the girders Y, has
the effect to suspend the box and contents on the same. Within the box Y¹, I
arrange the proper fire brick lining A, with its arched top A), and short chimney or
funnel A2, and suitable grates &c. The furnace and the ash-pit doors, are hinged
on the casing Y¹. Its front may be doubled and tripled to protect the workmen
from heat.
The grate bars are represented as separate bars of hard iron or steel to be turned
over from time to time.
The furnace casing Y' is just large enough to to hold the heater and the necessary
brickwork without regard to the size of the foundation, except that it must have
room between the walls Z. The heater is secured to the top of the furnace casing,
and to apply it in place the whole is slid under the compound cylinder C O¹, and
the beater bolts are screwed up. The entire furnace with its enclosing case is thus
suspended in its place.
I completely separate the fire-room which surrounds or is adjacent to the lower
portion from the engine room which surrounds or is adjacent to the upper portion.
I accomplish this by constructing a horizontal partition y¹, (see fig. 7) at or near
the level of the girders-Y. All the hottest portions are below this.
The horizontal partition y, serves as a floor for the engine room, which contains
the machinery above it and as a means for protecting the machinery from the heat,
due to the fire below. It cuts off the heat, noise, dust and ashes which are
annoyances in an engine room.
All the parts not fully represented or described may be of any ordinary or
suitable description.
Further modifications may be made in the forms and proportions of the details.
I can vary the proportion of the diameter of the stroke. I can increase the length
of the arm M², correspondingly increasing the throw of the crank O¹. This will
have an effect on the relations of the two engines to each other. It is well to so
proportion the parts as to bring the effect of the respective links M², of the two
engines about quartering to each other.
+
I can extend the cooling bath of water farther down on the respective cylinders.
I can extend the non-conducting envelope further up.
:
Instead of the solid webs B₁, I can use hollow stays forming an open
communi-
cation between the interior and exterior of the heater, taking care to make these
passages so small that a large portion of the gases will still be required to descend
and pass under the bottom rim of the heater. Such would increase the heating
surfaces and may be desirable in some instances in large engines. Such flues
should be of much greater vertical than horizontal dimensions. They should be
narrow gaps extending up and down at certain points along the periphery of the
heater. I can make such gaps extend quite down to the bottom rim of the heater
so as to forin the lower portion of the heater in. a number of separate sections or
flattened pipes, always taking care to form the base casting B, with corresponding

page_text: divisions a little narrower than the space in which they are to fit, so that they can
be easily inserted and removed. Series of cylindrical or nearly cylindrical pipes
may be provided instead of flat sections, taking care to always provide a proper
division in each pipe extending nearly to the bottom. Such pipes may be screwed
or secured by any ordinary or suitable means in a continuous ring above, but I
prefer the continuous dome with webs as shown.
I can make the cylinders C C¹, each in one continuous length, but it is better to
make them in two or more separate lengths properly joined and having a packing
of asbestos or other non-conducting material in the joints. This greatly retards the
conduction of heat from the hot to the cold end.
I can increase or diminish the width of the friction gear wheels O³, F. I can
make the annular mass of rubber "F" of greater or less diameter and thickness.
In the packing instead of rubber any other elastic material as twisted wool or
hair may be employed as the part j, to distend the formed leathers i, when the
gland is pressed down.
Instead of shifting the link I can as is often practiced in steam engineering by
making the link with a curvature in the opposite direction effect the required
changes by shifting the link block in the link."
In the form shown in Figs 20 to 23 the central recess in the top of the working
piston, and the annular recess on the under side of the corresponding cylinder
cover, may be omitted, and the necessary space in which the air inhales through
the valve c, is compressed by the rise of the working piston, may be preserved by
simply making the working cylinder as much larger as is required.
I can employ more than one of the valves c'. Such might be of a little
advantage in starting by allowing the air to be taken in more freely to be a
compressed in the apparatus. But so soon as the proper working conditions are
attained one small valve as shown is amply sufficient.
The mounting of the mainshaft q directly over and transverse to the axis of the
cylinder allows the simplest possible connections.
For very moderate pressures I can remove entirely the head of the working
cylinder, and allow air at ordinary pressure to enter and press down on the
working piston. Such a construction is shown in Fig. 19.
Some of the advantages due to certain features of the invention may be
separately enumerated as follows:
First: By reason of the webs B4, connecting the inner and outer shells of the
heater, combined with a base casting B', formed in corresponding divisions, I am
able by means easily removable and accessible to stiffly support and increase the
durability of the heater, and also compel the air to traverse in the thin space along
the whole inner surface of the heater.
Second: By reason of the short chimney 'A², extending upward from the aperture
in the arch A¹, over the furnace, arranged as shown relatively to the heater B, I
am able to distribute the draft over the heating surface and also to protect the
bottom rim of the heater from the direct radiation of the fire.
Third By reason of the radial passage g² being above the heater B, I am able
to maintain the continuity of the metal and allow all required amounts of
expansion and contraction of the heater below without injury.
Fourth By reason of the mercury vessel T, in the discharge flue a, from the
furnace, and of the diaphragm U, operated by the expansion or boiling of the fluid
in such vessel, and of the mechanical connection from the diaphragm to the
damper, I am able to automatically keep the temperature of the flue, and
consequently of the heater approximately equal under all conditions of working.
Fifth By reason of the adjustments 13, 14, 15 in combination with the damper
of the diaphragm U, and mercury vessel T, I am able to conveniently change the
conditions for working with more or less power.
Sixth: By reason of the fact that the working parts are supported on the cross
girders Y, above the heaters, and that the heaters are suspended therefrom, with

page_text: liberty to expand and contract freely, the highly heated, parts are relieved from.
strain, and the machinery above works in more fixed positions.
Seventh By reason of the rigid support of the cross girders Y, on parallel
walls Z with a clear passage between, I am able to more conveniently remove and
replace a heater when necessary.
Eighth By reason of the casing Y, enclosing the entire furnace with its brick
work grates &c, I am able, by simply removing the heater bolts and lowering the
casing from its connections with the girder Y, to remove the entire furnace for
repairs or exchange and to replace it with little labor or skill. The heater is with
all the precautions, shorter lived than the other parts. This facilitates the repairs.
and changes required.
:
Ninth By reason of the tight horizontal partition or flooring yl, I defend the
working parts of the engine from the heat and dust due to the fire below.
Tenth By reason of the fact that the cooler or water jacket K-surrounds the
cylinder as shown, with the regenerator I below it, the zones of low temperature are
carried lower in the regenerator and the upper end of the cylinder is maintained
cooler than would otherwise be possible..
Eleventh By reason of the fact that the cylinder C¹ forms one side of the
water jacket K, and also that the cooler is traversed by the pipes through which
the air moves in its passage upward in coming to such cylinder and downward in
flowing from it, the water performs the double functions of cooling the air in its
passage and also of bathing and cooling the cylinder:
Twelfth By reason of the inner cylinder C being finished on both its outer and
inner surfaces and equipped with a water tight chamber extending around in its
upper portion with suitable connections for circulating water, I provide a cylindrical
surface for the exterior of the inner piston D, and for the interior of the outer
annular piston E, both under favorable conditions for stability and coolness.
Thirteenth By reason of the connections between the baths of water in the
upper portions of the outer cylinder C³, and inner cylinder C, a single current of
water is made efficient to cool the upper portion of the entire apparatus, as herein
Specified.
Fourteenth By reason of the construction of the double inner cylinder C, with
its upper portion of cast metal filled with water and its lower portion of sheet
metal filled with, a non-conducting material, the structure conducts upward little
heat and is adapted to serve for a bearing for packing on the outer and inner sides
so far as the packings of the two pistons move, and to serve merely as a wall
approximately fitting the pistons.in the lower portion.
:
Fifteenth By reason of the fact that the outer cylinder C', is of thick cast metal
at the upper portion with water circulating in an ample chamber therein and that
the lower portion is made thinner, the thickness being filled out with plaster as
shown, I am able to strongly support the parts and to maintain a suitable surface
and to avoid the transmission of much heat upward through the material.
Sixteenth By reason of the beams P P, and M, engaged by links to the
respective piston rods d and e, with their proper cross-heads, as shown, I am able
to communicate the power efficiently from the working piston D, to the continuously
revolving shaft O, and the annular: changing pistons E, and to guide the several
cross-heads by few slides.
Seventeenth: By reason of the two sets of duplicate working pistons and their
connections forming two complete engines operating on a single shaft as shown in
fig 5, I avoid dead points.
Eighteenth: By reason of the fact that the heater B, which requires to be very
hot and necessitates the discharge of the gases at a high temperature, is combined
with pipes (S, conducting fresh air to the ash-pit, through the escaping gaseous
products of combustion, I am able to return a large portion of the heat of such
gases to the furnace and to discharge the gases into the stack at an economical
temperature.
Nineteenth Ry reason of the arrangement of the regenerator I. in a passage
ג
:

page_text: outside of both pistons D and E, I am able to make the passage large and deep' and
to employ a regenerator of any desired Size and weight.
Twentieth By reason of the annular form of the regenerator and its location
in a corresponding space concentric to the cylinders and between the changing
cylinder and a casing exterior thereto, I am able to economize space and to make
the action of the air more equable on all sides of the heater and of the working
parts above.
Twenty-first: By reason of the combination in an air engine of the economizer
tubes S, for restoring to the furnace the heat in the escaping gases with the
regenerator I, for restoring to the compressed air on its return a portion of the
heat with which it left the heater, I realize the economy due to both these
provisions and am able to produce a highly efficient compact and reliable engine.
Twenty-second: By reason of the blower S¹, forcing air through the pipes S
into the ash pit and thence through the furnace and escape-passage a, I am able to
overcome the considerable, frictional resistance due to the passage of the air through
the pipes and to the passage of the escaping gases from the fire past such pipes and
maintain an active combustion and consequent efficiency of a given size of
apparatus, combined with provisions for high economy.
:
Twenty-third: By reason of the removable bonnet I over the regenerator
passage and the arrangement of the cooler K and regenerator I, so as to provide
for easy removal and insertion, I am able to greatly facilitate examination, cleaning
and repairs.
Twenty-fourth: By reason of the connection ✗, between the upper portion of
the two working cylinders above the top of the changing cylinders, I am able to
allow a free transmission of the compressed air between the tops of the working
cylinders respectively without interfering with the action of the changing
pistons.
Twenty-fifth: By reason of the continuously acting pump X¹, valve X², and
diaphragm X, the latter influenced as shown by the pressure obtaining on the
upper faces of the working pistons, I am able to automatically open the valve and
allow air taken by the pump when the pressure is below a given point, and to
automatically close the valve and prevent air from being taken when the pressure
has reached and is maintained at the required standard.
Twenty-Sixth By reason. of the "Stevenson" link W, with its rods W', W³,
operated as shown, and of the block V2 and V, rock-shaft V, arm V³, links V', and
two beams P P, operating the rods e e, of the annular changing piston E, and its
connections for operating the changing pistons, I am able to vary the extent of
motion of the changing pistons so as to make them perform their full strokes or
various lesser strokes, and thus to vary the power and regulate the action so as to
maintain uniform speed, and am able also to conveniently change the relations of
their motions to those of the working piston so as to reverse the engine when
desired.
Twenty Seventh: By reason of the combination of the governor G, and its
connections to the hydraulic cylinder Q, with its piston R, and connections to the
link R¹ controlling the "Stevenson" link W, I am able to automatically regulate
the extent of motion of 'the changing piston and consequently the power of the
engine, so as to maintain uniform speed.
Twenty-eighth: By reason of the fact that the changing beams P, turn loosely
on the rocking shaft or beam centre m of the working beam M, I attain a high
degree of simplicity strength and compactness in the structure.
:
Twenty-ninth: By reason of the perforated pipe h, and connection h¹ to the
pump H, with its oil reservoir H¹, I am able to conveniently introduce lubricating
fluid, and to distribute it effectively in the space y, in the changing cylinder C',
above the annular changing piston Ę.
Thirtieth-By reason of the pressure gauges N and N2, each having a valye n¹,
and a contracted passage adapted to indicate the greatest and the least pressure

page_text: I am able to conveniently determine the exact conditions under which the engines
are working with regard to pressures.
Thirty-first; By reason of the friction gear wheel rim F¹, and the rubber, wood
or analogous elastic material F, interposed between itself and the: central hub F,
and of the fly-wheel Os, I am able to allow for the rapid rolling action of the parts
and the movements or tremors due thereto, without noise or objectionable vibration
of the other parts and also to allow the wheel F, to change its position axially on
the hub and its plane of rotation within certain limits to compensate for defective
workmanship.
Thirty-Second: By reason of the trough like or U section form of each ring i, of
the packing adapted to be partially flattened by pressure from any source applied
on the interior, and the fact of these rings being leather or analogous material
which wears smoothly, and the fact of each ring j being cylindrical and of rubber
or analogous elastic material adapted to spread laterally under pressure, and of the
combination and arrangement as shown, of a ring i with a ring ), whereby the
ring i is expanded by the fluid pressure on its inner surface, and also the rubber
ring being compressed by the gland, gently flattens and dilates the leather, I obtain
a smooth wearing packing, peculiarly adapted for the dry hot fluid and bigh
temperatures employed in hot air engines.
Thirty-third By reason of the series of two or more U sectioned leather rings i,
and two or more cylindrical rubber rings j combined with each other and with the
compressing gland a', as shown, I provide a succession of smooth surfaces closely
fitting against the piston rod and against the inner face of the stuffing-box, each
subject to the pressure of such fluid on its inner surface as shall have been able to
pass the preceding leathers and all being positively distended gently by the
adjustment of a single gland.
Thirty-fourth By reason of the working piston and changing piston being
mounted in line as shown in fig 8. I simplify the construction and reduce the
amount of friction between the pistons and their respective cylinders.
Thirty-fifth By reason of the additional fact that the changing piston is smaller
than the working piston, as shown in fig. 8, I provide a passage around the changing
piston in which the air may flow to and from the space between the pistons when
both are up in the working cylinder.
Thirty-sixth: By reason of the thick exterior cylinder, firmly supporting the
parts as shown in fig. 8, and the thin inner cylinder serving as the cylinder proper,
I simplify and cheapen the construction and secure ample space for the cooler and
regenerator with a small exterior diameter of the apparatus.
Thirty-seventh: By reason of the semi-circular construction of the cooler as
described referring to fig. 8, I am able to employ efficient cooler tubes with facility
for applying and removing.
Thirty-eighth: By reason of the fact that the cooler is in two separate and
independent layers or series of sections, as shown in fig. 8, I am able to remove the
sections of the cooler, one ring or layer at a time, without hoisting the interior
cylinder so high as would be otherwise necessary.
Thirty-ninth: By reason of the construction of the cylinder in three separate
lengths, as shown in fig. 8, I am able to more conveniently bore the working
cylinder, introduce and remove the regenerator and cooler, and remove and replace
the heater.
.
Fortieth: By reason of the detachable or loose openwork ring below the
regenerator as shown in Fig. 8, I form a mechanically continuous but perforated
base to the outer and rigid portion of the cylinder, extending inward to steady the
thin inner cylinder and to support the regenerator plates, with facility for removing
it and the several other parts when required:
Forty-first: By reason of the flange at the top of the thin inner cylinder, which
encloses the the changing piston; as shown in fig 8, serving also as a bonnet to cover
the cooler chamber, I am able to conveniently and reliably support the inner
cylinder
:
'

page_text: : Forty-Second: By reason of the two working piston rods and one changing piston
rod, as shown in fig. 8, I am able to conveniently communicate power between the
respective pistons and corresponding beams suitably arranged above.
Forty-third: By reason of the working shaft mounted over a compound cylinder,
as shown in fig. 19, I am able to produce an effective and very simple construction.
Forty-fourth: By reason of the end crank and long rock shaft with its two arms,
as shown in fig, 19, I am able to conveniently communicate the proper motion to
the annular working piston and to obtain a very simple form of engine.
Forty-fifth: By reason of the open top cylinder, as shown in fig. 19, I am able
to extend the connecting rod down to the piston, avoid the stuffing-box and allow
the height of the engine to be greatly contracted.
:
Forty-sixth By reason of the provisions for inducting air through the valve C*,
in the cylinder cover C³, in combination with the working cylinder C, and its
piston D, (figures 20 and 23) I am able to obtain the required pressure of the air
and to automatically maintain it without a separate pump.
Forty-seventh: By reason of the long rock-shaft w with its two arms w³ w³,
connecting to the piston rods e of the annular changing piston E operated by the
crank q³ on the end of the shaft q, I obtain the required motion of the changing
cylinder by very simple mechanism.
Forty-eighth By reason of the pipe J, connecting the space above the working- 2
piston with the space below it, and of the valve J¹ operated by the governor J³,
am able to reduce the power of the engine temporarily by letting the air flow
back to the space above the piston, and to recover the compressed air again during
the next stroke without the absolute loss of the compressed air which would result
from its discharge.
Forty-ninth By reason of the rule-joint J', in the connecting rod J³, I am able
to fold it and thus to open the valve wide by hand when it is desired to stop the
engine without letting off the compressed. air, and to instantly straighten the
connection again when required and set the engine in full operation as before.
2
Fiftieth By reason of the combination of the valve Jo, discharging the 3
compressed air into the atmosphere with the other parts as shown, I am able to
choose at will between stopping with the pressure on or with pressure off, or to let
the air off in whole or in part after the engine has been stopped with the pressure
on whenever it is found too difficult to start otherwise.
I claim as my invention:
:
3
1st In a hot air engine working by the alternate heating and cooling of the
same compressed air the working piston D, working cylinder C, induction valve C4,
and means substantially as specified for delivering air from above to below the
cylinder and preventing its return, combined and arranged substantially as shown
so as to automatically take in just enough air to compensate for leakages, as herein 4
specified.
:
2nd In a hot air engine the arched top A¹ of the furnace and short chimney or
funnel A, in combination with the dome shaped heater B, and arranged to serve
therewith as and for the purposes herein specified.
3rd: In a hot air engine the outer cylinder C', having a passage g³, extending 4
radially above the heater and aiding to form a connection through the thin space
in the heater between the bottom z and the upper space y, as herein specified.
4th In a hot-air engine the flue damper 7, with its controlling arm 13, and rod 13,
in combination with the vessel T, pipe t and diaphragm U, charged with a fluid
having a high boiling point arranged to serve as herein specified.
5th: In a hot-air engine the adjusting means 13, 14, 1, in combination with the
arm, operating the damper l, and the diaphragm U, and mercury vessel T, as
herein specified.
6th A hot-air engine supported above the heater or heaters substantially as and
for the purposes herein specified.
50
5

page_text: and their several attachments, and with the supporting walls Z, arranged to
present a clear passage between the latter, substantially as herein specified.
:
8th In a hot-air engine the casing Y¹, enclosing the furnace and making the
whole conveniently portable, in combination with means Y, for supporting the
engine by its upper portion, substantially as herein specified.
9th: The partition y¹, arranged relatively to the furnace and to the working
parts of the engine, substantially as herein specified.
10th: The annular cooler or water jacket K, arranged relatively to the cylinder C¹,
and to the annular regenerator I, substantially as herein specified.
:
11th The water jacket K, with its pipes k, arranged as shown and with suitable
water connections k² k², arranged as shown adapted to perform the double functions
of cooling the cylinder C', and of cooling the air in its passage to and from it, as
herein specified.
- 12th In a hot-air engine the inner cylinder C, finished on both its inner and
outer surfaces with provisions for circulating a current of water in the upper portion
thereof in combination with the inner piston D, and annular outer piston E, as
berein specified.
18th: In a hot-air engine the inner cylinder C, and outer cylinder C, having
provisions for circulating a single current of water through both, in combination
with each other and with the inner piston D, and annular piston E, as herein
specified.
14th In a hot-air engine the construction of the inner cylinder C, between the
working piston and the changing piston with double cast metal enclosing water
between, in the upper part, and of double sheet metal enclosing a non-conductor
between in the lower part, substantially as herein specified.
15th In a hot-air engine the outer cylinder C, having its upper portion of cast
metal in two thicknesses, with water flowing between, and its lower portion of less
thickness faced with a rigid non-conducting material, as herein specified.
16th In a hot-air engine the inner cylinder C, and outer cylinder C¹ inner
piston D, with its rod d, and annular piston E with its rods e e, in combination
with each other and with slides and suitable cross-heads, and with mechanism
connecting these cross-heads to a crank mounted on the shaft O, as herein
specified.
17th In a hot-air engine the combination of two pairs of working pistons with
their respective working means M M², connecting rods or connecting links M² M²,
arranged to act on the same shaft O, as herein specified.
18th In combination with the heater B, of a hot-air engine the air heating
pipes S, conducting through the escaping gases the air to support the combustion
in the furnace, substantially as herein specified.
19th: In a hot-air engine the regenerator I, in combination with the working
piston D, and annular piston E, and mounted in a passage outside of both,
substantially as herein specified.
20th: In a hot-air engine the arrangement of an annular regenerator in a space
exterior and concentric to the changing cylinder, substantially as specified.
21st: The economizer S, for returning to the furnace a portion of the heat in the
gases escaping therefrom, and the regenerator I for the alternately absorbing and
giving out of heat in the compressed air, in combination with each other and
with the working parts of an air engine, arranged for joint operation, as herein
specified.
22: In a hot-air engine the blower S¹, heating pipes S, furnace A* and escape
flue a, combined and arranged for joint operation, as herein Specified.
23rd: In a hot-air engine the regenerator I, and cooler K, in combination with
each other and with a passage and removable bonnet I', adapted to allow their
ready removal, and with a suitable working piston D and annular piston E, mounted
in suitable cylinders, as herein specified.
24: In a hot-air engine the two working pistons D D, connected to the same

page_text: beam M in combination with the cylinders C, therefor, and the two annular changing
pistons E, E, with the enclosing cylinders C¹ concentric to C, and having a con-
necting passage X between the upper portion of the working cylinders for the rapid
and easy transfer of the air above the piston, as herein Specified.
.
25th In a hot-air engine the case X*, pipe x, and diaphragm X, in combination 5
with a valve X2, controlling the admission of the air to the air pump X', so as to
automatically maintain a uniform pressure, as herein specified.
:
24
26th In a hot-air engine the Stevenson" link W and its connections for
operating the changing pistons arranged to serve as herein specified.
27th The "Stevenson" link W, and suitable connections for receiving motion
from the shaft and imparting it to the changing pistons in combination with such
pistons and with the governor G, and with means for automatically shifting the
link, substantially as herein specified.
28th The working beam M fixed on its centre or rocking shaft m, in combina-
tion with the two changing beams P, mounted loosely on the same centre all
arranged to serve with their respective pistons and connections, as herein specified.
29th In a hot-air engine the oil reservoir H³, pump H, connection pipe h¹,
and oil distributing pipe h, in combination with each other and the concentric
cylinders C, C¹ and annular changing piston E, as herein specified.
30th In a hot-air engine the gauge or gauges N, each having a self acting
valve n¹, and a contracted passage adapted to show the highest or the lowest
pressure or both, in combination with suitable cylinders and pistons, as herein
specified.
31 In a hot-air engine the rim F¹, elastic material F, and hub F³, in combina-
tion with each other and with a friction gear wheel O2, engaged with the rim F',
substantially as herein specified.
:
32nd A packing ring i of leather or analogous material having a U shaped
section as shown, in combination with a packing ring j, of rubber or analogous
elastic material, of cylindrical section, and with compressing means a arranged to
serve, as herein specified.
33rd A series of two or more U sectioned rings i i, and two or more elastic
rings jj, in a series alternating one with the other and with compressing means a¹,
arranged to serve as herein specified.
34th In a hot air engine the working piston and changing piston reciprocating
in line with each other, in combination with a suitable regenerator and cooler, as
shown in fig. 8.
35th In a hot-air engine a changing cylinder smaller than the working cylinder
arranged in a line with the working cylinder as shown in fig. 8.
36th In a hot-air engine the thin inner-cylinder and the thick outer cylinder in
combination with each other and with a suitable regenerator and cooler enclosed
between, and with the working piston and changing piston and their connections,
as shown in fig. 8.
C37th: In a hot-air engine a cooler composed of tubes in sections each extending
only partially around to allow of easy removal as described referring to fig. 8.
38th In a hot-air engine, a cooler in two or more separable layers one above the
other as shown in fig. 8.
39th: In a hot-air engine the construction of the cylinders in three separate
lengths, the lower portion being the heater; the middle portion being a case
enclosing the changing piston and also the regenerator and cooler; and the upper
portion enclosing the working piston, as shown in fig. 8.
:
40th In a hot-air engine having a regenerator and cooler in an annular space
between an inner cylinder and an outer cylinder, a detachable perforated ring
forming the bottom of the regenerator as shown in fig. 8.
41st: In a hot-air engine a flange at the upper end of the inner cylinder, serving
the double function of a flange for the cylinder by which it may be supported and
firmly held in place, and of a bonnet or cover for an annular chamber between that

page_text: cylinder and an exterior one which contains a cooler and regenerator, as shown
in fig. 8.
42nd In a hot-air engine having a working piston and changing piston in line
with each other, a single piston rod for the changing piston traversing through the
centre of the working piston, and two piston rods for the working piston arranged
on opposite sides of the centre, adapted to transmit the power as described, referring
to fig. 8.
43rd: In a hot-air engine a compound cylinder enclosing a working and a
changing piston with a main shaft, mounted transversely thereto crossing the
line of the axis of the cylinder and suitably connected, as described referring to
Fig. 19.
44th In a hot-air, engine a compound cylinder with the main shaft crossing the
line of the axis of the cylinder, a rocking shaft operated by an overbung crank at
one end of the main shaft and having two arms with connections to two piston
rods for the annular changing piston, as described referring to fig. 19.
45th: In a hot-air engine a working piston traversing in an open topped working
cylinder in combination with an annular changing piston, working in a closed
changing cylinder, and with a heater, regenerator and cooler, as described referring
to fig. 19.
46th In a hot-air engine the valve C' opening inward to admit air freely to the
space above the working piston, and closing to prevent its return, in combination
with a piston D having packing which allows the air to move downward past it,
but forbids its return, and with a changing piston E, heater B, regenerator I, and
cooler K, all arranged for joint operation, substantially as shown in figs. 20 to 23
47th: In a hot-air engine having a shaft q extending across the line of the axis
of the cylinder, the end crank q³, link g, and rock-shaft w, with its armıs w² w³ and
links w³, connecting the latter to the rods e, of the changing piston E, all combined
and arranged to serve substantially as shown in figs 20 to 23.
48th: In a hot-air engine the pipe J, and valve J¹, in combination with the
governor J, adapted to serve as herein Specified.
49th In a hot air engine the flexible connection J3 J4, between the governor J5
and the cock J adapted to allow the valve or cock to be opened wide at will as
berein specified.
50th: In a hot air engine the valve Jo, for discharging the compressed air into
the atmosphere, in combination with the pipe J and valve J¹ for discharging the
air into the space above the working piston; arranged for joint operation as herein
specified.
In Witness whereof I have hereunto my hand and seal this 5th day of March,
100A
AD100A
40331
Witnesses:-
THOMAS DREW STETSON
Patent Solicitor New York.
CHARLES ROBINSON SEARLE.
STEPHEN WILCOX (L.S.)