ROV the Invention of ENGINES WORKED BY HOT GASES OR BY HOT GASES AND STEAM, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE FOR GENERATING STEAM
Year: 1875

page_text: in
LETTERS PATENT to Matthew Piers Watt Boulton, of Tew Park,
"IMPROVEMENTS IN
the County
of Oxford, for the Invention of
ENGINES WORKED BY HOT GASES OR BY HOT GASES AND STEAM, PARTS OF
WHICH IMPROVEMENTS ARE APPLICABLE FOR GENERATING STEAM."
Sealed the 5th March 1875, and dated the 11th January 1875.
FROVISIONAL SPECIFICATION left by the said Matthew Piers Watt
Boulton at the Office of the Commissioners of Patents, with his
Petition, on the 11th January 1875.
I, MATTHEW PIERS WATT BOULTON, of Tew Park, in the County of
Oxford, do hereby declare the nature of the said Invention for "Iм-
AND STEAM,
PROVEMENTS IN ENGINES WORKED BY HOT GASES OR BY HOT GASES
PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE FOR GENERATING STEAM," to be
as follows:-
This Invention relates principally to apparatus in which hot gases and
steam are emploved for the production of motive power either singly or

page_text: The principal object of the Invention is to utilise sufficiently the heat
and to reduce so far as possible bulk and weight of the engine.
In the apparatus employed the heated products of combustion of fuel,
solid, liquid, or gaseous, act on or follow a piston in a cylinder, whence
after each stroke they are discharged into the air through a regenerator
or regenerators, the heat imparted to these being utilised or partly so
by heating the working fluid for the succeeding stroke. In some cases
however, as will be hereafter described, these regenerators may be dis
pensed with.
In order to reduce bulk and weight it is important that the cylinder
should be double-acting, and in this case when regenerators are
employed they are provided in duplicate, that is, one set for each end of
the cylinder.
When the fuel employed is gaseous, then, for each end of the cylinder
I use a pair of regenerators, the one for heating the air and the other
for heating the gas. The air and gas may be drawn into the cylinder
by the movement of the piston or may be pumped in at any desired
pressure.
I make the sides of the cylinder of metal and I keep them cool by
cooling agencies applied both to their interior and exterior and in some
cases only to their interior, so that a piston can work efficiently upon
them notwithstanding that the temperature of the gaseous contents of
the cylinder is very high.
To cool the exterior of the cylinder I in many cases employ water
contained in a jacket or vessel at high pressure.
The heat passing
through the metal sides of the cylinder to this water generates steam
which passes to a suitable steam chest.
. In order to cool the sides of the cylinder on the interior, I construct
the piston and piston rod so as to act as generators of steam. For this
purpose they are made hollow and water is caused to flow through the
piston rod from a vessel at high pressure to a space or chamber in the
piston, where it comes in contact with the sides of the cylinder. Above
and below this space is a packing kept cool by the water flowing through
the piston.
As the piston moves over the heated sides of the cylinder,
steam is generated where the water in the piston comes in contact with 3
those sides, and this steam passes up the piston rod along with such

page_text: steam as may be generated in other parts of the piston and within the
piston rod, and passes to a steam chest which may also collect the steam
generated outside the cylinder.
For the purpose of effecting circulation of the water through the
hollow piston rod and piston the rod may be made to extend through
stuffing boxes at both ends of the cylinder into chambers, from the one
of which the water is supplied, and into the other of which the steam
and water are delivered. Or the hollow piston rod may extend through
only one end of the cylinder, its interior being divided annularly or other-
wise into two channels, the one for the ingress, and the other for the
egress of the circulating water. I prefer to force the circulation by
pumping, and for this purpose the piston rod may be made to act as a
plunger.
'
In order to facilitate the passage of the steam from the piston, I prefer
to slope its upper face upwards from the circumference towards the
centre, the cylinder cover being made to correspond in form thereto.
I prefer to place in the central part of the piston a vessel of thin metal
open at the bottom, forming a cavity, which is filled with air or steam
and serves to lighten the piston. The piston and its rod with the
cylinder jacket constitute a boiler or steam generator, the feed and
pressure of which may be regulated as in ordinary boilers. The cooling
agency of the piston arranged as above described may be so increased
that the exterior jacket can be dispensed with.
And so much heat may
be abstracted by the generation of steam that regenerators may be dis-
pensed with.
When it is desired to increase as much as possible the generation of
steam a number of cylinders and pistons, as above described, may be
employed. In this case I prefer to arrange several cylinders end to end
on one axis, their pistons being fixed on one tubular rod which serves to
provide circulation of the water for the whole set of pistons. Several
sets of cylinders and pistons thus arranged may be employed.
When numerous cylinders, as above described, are employed in con-
junction with regenerators they may all be made to communicate with
one set of regenerators and pumps.
It will be seen from the above that the hot air cylinder and parts
connected may be used in such a way as not to produce directly motive
power but to generate steam for the purpose of working an engine. In,

page_text: this case the piston of the hot cylinder and parts connected are worked
by the steam engine. But it is evident that the hot-air cylinder and
parts connected may act as an air engine which may be used in con-
junction with the steam engine, or separately, and that the power of the
air engine can be varied at pleasure within certain limits principally by
varying the pressure employed.
When it is not desired to generate a large quantity of steam portions
of the piston and of the cylinder ends may be shielded.
When the apparatus works both as an air engine and a steam engine
the steam generated may be used in the same cylinder as the hot air,
but I prefer generally to employ the steam in a separate cylinder,
working the air engine at a moderate pressure and the steam engine at a
higher pressure. When separate cylinders are thus employed I prefer
so to arrange them that the action of each piston aids the other in
passing the dead points.
In some cases steam may be made to work at the one end of the
cylinder, the hot gases working at the other end.
When it is desired to employ the steam along with the hot air in the
same cylinder I prefer to provide a separate regenerator at each end of
the cylinder for heating the steam and to introduce the steam unmixed
with the other fluid through this regenerator into the cylinder. I pro-
vide valves or slides suitably timed for governing the passage of the
steam through the regenerators and the discharge through it from the
cylinder. I prefer generally to introduce the steam next to the interior
surface of the cylinder.
In cases in which it is desired to dispense as much as possible with
the use of water I shield some parts as previously explained. I reduce
the quantity of water brought into contact inside the piston with the
sides of the cylinder, and I cool the exterior sides of the cylinder by
means of air caused to flow in contact with them. For this purpose I
by preference provide a helical passage winding round the sides of the
cylinder, through which passage the air is forced into the regenerator
and thence to the cylinder. When gaseous fuel is employed it may be
treated in a similar way.
Having thus previously explained the construction of the piston and
the parts connected with the generation of steam, and having above
explained the general nature of the operations to be performed, I

page_text: proceed now to describe a construction of engine for carrying those
operations into effect. In this description I shall suppose that the
engine acts both as an air engine and a steam engine, and I shall
suppose that gas or inflammable vapour is the fuel employed. In this
case there are three cylinders, one for pumping the air supply, one for
pumping the gas supply, and one for receiving the heated products of
combustion, which I shall call the main or hot cylinder;
I shall suppose
this cylinder to be double acting, it being important to secure this.
Between each end of the main cylinder and the air pump is a regene-
rator. In one stroke heated gases which have acted in the main
cylinder are discharged into the atmosphere through this regenerator,
imparting heat to it, while in the succeeding stroke air passes from the
air pump into the main cylinder through this regenerator, receiving heat
from it. Similarly between each end of the gas pump and the main
cylinder is a regenerator of smaller dimensions which in one stroke
receives heat from the hot fluid discharged through it from the main
cylinder into the atmosphere, and in the succeeding stroke heats the gas
passing from the gas pump into the main cylinder. The communications
between the pumps and the regenerators are opened and closed at the
proper times by valves in the cool portions of the passages.
The engine operates in the following manner-I will suppose that, at
starting the pistons of the air and gas pumps are at the bottom of their
respective cylinders ready to start for their up stroke. The valves in
front of these pistons are closed, those behind them are open. The
pistons ascend, each compressing its charge of air or gas in front of it,
and each followed by air and gas, respectively entering the cylinder
behind it. When the pistons have advanced so far in their strokes that
the air and gas are compressed to the extent desired, the valves between
the upper ends of the pumps and the regenerators are opened. The
piston in the main cylinder is timed so that simultaneously it is at the
top of its cylinder ready to make its down stroke. The charges of air
and gas flow through their respective regenerators into the main cylinder,
becoming heated in the passage. On issuing from the regenerators they
are mixed and ignited, and the heated mixture acts on the piston of the
main cylinder, following it and performing work. The pistons in the air
and gas pumps continue to advance, supplying the main cylinder with
combustible material until they reach the ends of their strokes. When
they bave reached the ends of their strokes the communications

page_text: previously opened in front of them with the regenerators are closed, and
the supply for further combustion in the main cylinder is cut off. The
piston in that cylinder is urged forward during the remainder of its
stroke by the expansion of the heated elastic fluid within it. While
making its stroke it drives out into the air through the regenerators
connected with the lower end of its cylinder the heated fluid which had
previously acted on that side in its up stroke. For this purpose the
valves connecting those regenerators with the outer air are opened, and
those connecting them with the air and gas pumps are closed. The
operations on each side are similar. Thus, at each stroke of the piston
in the main cylinder it discharges hot products of combustion through
a pair of regenerators, and in the succeeding stroke compressed air and
gas are forced through these regenerators and heated in them previously
to entering the main cylinder and undergoing combustion therein. The
degree of compression given to the air and gas is regulated by the 1
timing of the pistons and valves.
The air and gas cylinders may be kept cool by water; in some cases
this cooling may be done by air.
When it is desired to use great compression of the air and gas
successive cylinders or pumps may be employed. When it is not ?
desired to compress the air and gas supplied to the main cylinder the
operations are similar but somewhat simpler. In this case the air pump
and gas pump can be dispensed with, the entrance of the air and gas
being caused by the motion of the piston of the main cylinder which
causes reduction of pressure inside. In this case the piston is moved by 2
the steam engine worked by the steam generated as previously described.
The air and gas employed should be mixed thoroughly in order that
their combustion may be complete. This may be effected by any of the
known means adopted for that purpose, as for example, by arranging
the jets so as to impinge upon one another, or by causing the air and the
gas to flow through passages alternating or arranged as in a Bunsen's
burner.
The ignition of the gas and air may be effected by the heat imparted
to them by the regenerators (when such are employed), after the
operation has continued some time, or by the heat of refractory bodies a
placed in the main cylinder and exposed to the heat of the combustion
therein. At the commencement of the operation such bodies raised to a
high heat may be placed within the cylinder near its entrance or in

page_text: passages connected with it, so as to ignite the gaseous mixture as it
comes in contact with them. Otherwise a constant flame may be
maintained in a chamber communicating with the cylinder, by means of
air and combustible matter supplied by a pump. A small gas flame
may be conveniently used for this purpose. In this case the gas like the
air continually flows from a receptacle supplied at suitable pressure by
pumping, the pressure of the entering jets being regulated so as to
exceed somewhat that of the working fluid in the main cylinder during
the one stroke, and to be reduced by wire drawing duing the return
stroke..
When liquid fuel is used it may be injected on to a hot body in the
cylinder, and there turned into gas or vapour with which the entering
air mixes so as to effect combustion. Or it may be converted into
vapour in a separate vessel, this vapour being treated in the manner
previously explained for gas; when this plan is adopted a certain portion
of the heated products of combustion are discharged from the cylinder
through the flues or passages of a boiler containing the liquid, heating
it and converting it into vapour. Or the liquid fuel may be introduced
along with the air into the cylinder so as to form spray.
When solid fuel is used it may be burned in a chamber communicating
with the cylinder, heated air being forced upon it from the regenerators.
Or it may be burned in the form of dust injected with the air into the
cylinder or into combustion chambers communicating therewith.
For starting the engine the main cylinder may be temporarily con-
nected to a chimney, so that combustion may be for a time maintained
in it by draught, the piston remaining stationary till sufficient steam is
thus generated in the piston and jacket for putting the engine in motion.
Otherwise steam may be generated by heat applied externally to the
parts containing water or steam, or heated water may be supplied to
those parts from a separate boiler.
Several engines, such as I have described may be made to work in
connection on one shaft, and they may be regulated by a governor

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Matthew Piers Watt Boulton in the Great Seal
Patent Office on the 9th July 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, MATTHEW
PIERS WATT BOULTON, of Tew-Park, in the County of Oxford, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of January, in the
year of our Lord One thousand eight hundred and seventy-five, in
the thirty-eighth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Matthew Piers Watt
Boulton, Her special license that I, the said Matthew Piers Watt
Boulton, my executors, administrators, and assigns, or such others as
1, the said Matthew Piers Watt Boulton, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
"IMPROVEMENTS IN ENGINES WORKED BY
and Isle of Man, an Invention for
HOT GASES OR BY HOT GASES AND STEAM, PARTS OF WHICH IMPROVEMENTS ARE
APPLICABLE. FOR GENERATING STEAM," upon the condition (amongst others)
that I, the said Matthew Piers Watt Boulton, my executors or admini-
strators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be per-
formed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said Matthew Piers Watt Boulton, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement thereof, reference being had to the
accompanying Sheet of Drawings and to the figures and letters marked
thereon, that is to say:-
- This Invention relates principally to apparatus in which hot gases and
steam are employed for the production of motive power either singly or
in combination.

page_text: The principal object of the Invention is to utilise sufficiently the heat
and to reduce so far as possible bulk and weight of the engine.
In the apparatus employed the heated products of combustion of fuel,
solid, liquid, or gaseous, act on or follow a piston in a cylinder, whence
after each stroke they are discharged into the air througn a regenerator
or regenerators, the heat imparted to these being utilised, or partly so, by
heating the working fluid for the succeeding stroke. In some cases
however, as will be hereafter described, these regenerators may be
dispensed with.
In order to reduce bulk and weight it is important that the cylinder
should be double acting, and in this case when regenerators are employed
they are provided in duplicate, that is, one set for each end of the
cylinder.
When the fuel employed is gaseous, then, for each end of the cylinder
1 use a pair of regenerators, the one for heating the air and the other for
heating the gas. The air and gas may be drawn into the cylinder
by the movement of the piston or may be pumped in at any desired
-pressure.
I make the sides of the cylinder of metal, and I keep them cool by
cooling agencies applied both to their interior and exterior, and in some
cases only to their interior, so that a piston can work efficiently upon
them notwithstanding that the temperature of the gaseous contents of
the cylinder is very high.
To cool the exterior of the cylinder I in many cases employ water
contained in a jacket or vessel at high pressure.
The heat passing
through the metal sides of this cylinder to this water generates steam,
which passes to a suitable steam chest.
In order to cool the sides of the cylinder on the interior I construct
For this
the piston and piston rod so as to act as generators of steam.
purpose they are made hollow, and water is caused to flow through the
piston rod from a vessel at high pressure to a space or chamber in the
piston, where it comes in contact with the sides of the cylinder. Above
and below this space is a packing, kept cool by the water flowing through
the piston. As the piston moves over the heated sides of the cylinder
steam is generated where the water in the piston comes in contact with

page_text: those sides, and this steam passes up the piston rod along with such
steam as may be generated in other parts of the piston and within the
piston rod, and passes to a steam chest, which may also collect the steam
generated outside the cylinder.
For the purpose of effecting circulation of the water through the
hollow piston rod and piston the rod may be made to extend through
stuffing boxes at each end of the cylinder. into.chambers, from the one
of which the water is supplied, and into the other of which the steam
and water are delivered; or the hollow piston rod may extend through
only one end of the cylinder, its interior being divided annularly or
otherwise into two channels, the one for the ingress and the other for the
egress of the circulating water. I prefer to force the circulation by
pumping, and for this purpose the piston rod may be made to act as a
plunger.
In order to facilitate the passage of the steam from the piston I prefer
to slope its upper face upwards from the circumference towards the
centre, the cylinder cover being made to correspond in form thereto. I
-prefer to place in the central part of the piston a vessel of thin metal open
at the bottom, forming a cavity which is filled with air or steam, and
serves to lighten the piston. The piston and its rod with the cylinder
jacket constitute a boiler or steam generator, the feed and pressure of
which may be regulated as in an ordinary boiler. The cooling agency of
the piston arranged as above described may be so increased that the
exterior jacket can be dispensed with, and so much heat may be
abstracted by the generation of steam that regenerators may be dispensed
with.
C
When it is desired to increase as much as possible the generation of
steam a number of cylinders and pistons as above described may be
employed. In this case I prefer to arrange several cylinders end to end
on one axis, their pistons being fixed on one tubular rod, which serves to
provide circulation of the water for the whole set of pistons. Several
sets of cylinders and pistons thus arranged may be employed.
When numerous cylinders as above described are employed in con-
junction with regenerators they may all be made to communicate with
one set of regenerators and pumps.
It will be seen from the above that the hot-air cylinder and parts con-
nected may be used in such a way as not to produce directly motive
power, but to generate steam for the purpose of working an engine. In

page_text: this case the piston of the hot cylinder and parts connected are worked
by the steam engine; and it is evident that the hot-air cylinder and parts
connected may act as an air engine, which may be used in conjunction
with the steam engine or separately, and that the power of the air engine
can be varied at pleasure within certain limits, principally by varying the
pressure employed.
When it is not desired to generate a large quantity of steam, portions
of the piston and of the cylinder ends may be shielded.
When the apparatus works both as an air engine and a steam engine
the steam generated may be used in the same cylinder as the hot air, but
I prefer generally to employ the steam in a separate cylinder, working
the air engine at a higher pressure. When separate cylinders are thus
employed I prefer so to arrange them that the action of each piston aids
the other in passing the dead points.
In some cases steam may be made to work at the one end of the
cylinder, the hot gases working at the other end.
When it is desired to employ the steam along with the hot air in the
same cylinder, I prefer to provide a separate regenerator at each end of
the cylinder for heating the steam and to introduce the steam unmixed
with the other fluid through this regenerator into the cylinder. I provide
valves or slides suitably timed for governing the passage of the steam
through the regenerators and the discharge through it from the cylinder..
I prefer generally to introduce the steam next to the interior surface of
the cylinder.
In cases in which it is desired to dispense as much as possible with
the use of water I shield some parts, as previously explained, I reduce
the quantity of water brought into contact inside the piston with the
sides of the cylinder, and I cool the exterior sides of the cylinder by
means of air caused to flow in contact with them. For this purpose I,
by preference, provide a helical passage winding round the sides of the
cylinder, through which passage the air is forced into the regenerator
and thence to the cylinder. When gaseous fuel is employed it may be
treated in a similar way.
Having thus previously explained the construction of the piston and
the parts connected with the generation of steam, and having above
explained the general nature of the operations to be performed, I procced
now to describe a construction of engine for carrying those operations.

page_text: explained into effect. In this description I shall suppose that the engine
acts both as an air engine and a steam engine, and I shall suppose that
gas or inflammable vapour is the fuel employed. In this case there are
three cylinders, one for pumping the air supply, one for pumping the
gas supply, and one for receiving the heated products of combustion.
which I shall call the main or hot cylinder. I shall suppose this cylinder
to be double acting, it being important to secure this. Between each end
of the main cylinder and the air pump is a regenerator. In one stroke
heated gases which have acted in the main cylinder are discharged into
the atmosphere through this regenerator, imparting heat to it, while in
the succeeding stroke air passes from the air pump into the main cylinder
through this regenerator, receiving heat from it. Similarly between each
end of the gas pump and the main cylinder is a regenerator of smaller
dimensions which in one stroke receives heat from the hot fluid dis-
charged through it from the main cylinder into the atmosphere, and in
the succeeding stroke heats the gas passing from the gas pump into the
main cylinder. The communications between the pumps and the
regenerators are opened and closed at the proper times by valves in
the cool portions of the passages.
The engine operates in the following manner-I will suppose that at
starting the pistons of the air and gas pumps are at the bottom of their
respective cylinders ready to start for their up stroke. The valves in front
of these pistons are closed, those behind them are open. The pistons
ascend, each compressing its charge of air or gas in front of it, and each
followed by air and gas respectively entering the cylinder behind it.
When the pistons have advanced so far in their strokes that the air and
gas are compressed to the extent desired, the valves between the upper
ends of the pumps and the regenerators are opened. The piston in the
main cylinder is timed so that simultaneously it is at the top of its
cylinder ready to make its down stroke. The charges of air and gas flow
through their respective regenerators into the main cylinder, becoming
heated in the passage. On issuing from the regenerators they are mixed
and ignited, and the heated mixture acts on the piston of the main
cylinder following it and performing work. The pistons in the air and gas
pumps continue to advance, supplying the main cylinder with combus-
tible material until they reach the ends of their strokes. When they have
reached the ends of their strokes the communications previously opened
in front of them with the regenerators are closed, and the supply for

page_text: further combustion in the main cylinder is cut off. The piston in that
cylinder is urged forward during the remainder of its stroke by the expan-
sion of the heated elastic fluid within it. While making this stroke it
drives out into the air through the regenerators connected with the lower
end of its cylinder the heated fluid, which had previously acted on that
side in its up stroke. For this purpose the valves connecting those re-
generators with the outer air are opened, and those connecting them with
the air and gas pumps are closed; the operations on each side are similar.
Thus at each stroke of the piston in the main cylinder it discharges hot
products of combustion through a pair of regenerators, and in the
succeeding stroke compressed air and gas are forced through these
regenerators and heated in them previously to entering the main cylinder
and undergoing combustion therein. The degree of compression given
to the air and gas is regulated by the timing of the pistons and
valves.
The air and gas cylinders may be kept cool by water; in some cases
this cooling may be done by air.
When it is desired to use great compression of the air and gas, suc-
cessive cylinders or pumps may be employed. When it is not desired
to compress the air and gas supplied to the main cylinder, the operations
are similar but somewhat simpler. In this case the air pump and gas
pump can be dispensed with, the entrance of the air and gas being
caused by the motion of the piston of the main cylinder which causes
reduction of pressure inside. In this case the piston is moved by the
steam engine worked by the steam generated as previously described.
The air and gas employed should be mixed thoroughly in order that their
combustion may be complete. This may be effected by any of the known.
means adopted for that purpose, as for example, by arranging the jets so
as to impinge upon one another, or by causing the air and the gas
to flow through passages alternating or arranged as in a Bunsen's
burner.
The ignition of the gas and air may be effected by the heat imparted
to them by the regenerators (when such are employed) after the opera-
tion has continued some time; or by the heat of the refractory
bodies placed in the main cylinder and exposed to the heat of the com-
bustion therein. At the commencement of the operation such bodies
raised to a high heat may be placed within the cylinder near its

page_text: entrance, or in passages connected with it, so as to ignite the gaseous
mixtures as it comes in contact with them. Otherwise a constant flame
may be maintained in a chamber communicating with the cylinder by
means of air and combustible matter supplied by a pump. A small gas
flame may be conveniently used for this purpose.
In this case the gas
like the air continually flows from a receptacle supplied at suitable
pressure by pumping, the pressure of the entering jets being regulated
so as to exceed somewhat that of the working fluid in the main cylinder
during the one stroke, and to be reduced by wire drawing during the
return stroke.
When liquid fuel is used it may be injected on to a hot body in the
cylinder, and there turned into gas or vapour, with which the entering
air mixes so as to effect combustion. Or it may be converted into vapour
in a separate vessel, this vapour being treated in the manner previously
explained for gas. When this plan is adopted a certain portion of the
heated products of combustion are discharged from the cylinder through
the flues or passages of a boiler containing the liquid, heating it and
converting it into vapour. Or the liquid fuel may be introduced along
with the air into the cylinder so as to form spray.
When solid fuel is used it may be burned in a chamber communicating
with the cylinder, heated air being forced upon it from the regenerators.
Or it may be burned in the form of dust injected with the air into the
cylinder, or into combustion chambers communicating therewith.
For starting the engine the main cylinder may be temporarily con-
nected to a chimney, so that combustion may be for a time maintained
in it by draught, the piston remaining stationary till sufficient steam is
thus generated in the piston and jacket for putting the engine in motion.
Otherwise steam may be generated by heat applied externally to the
parts containing water, or steam or heated water may be supplied to
those parts from a separate boiler.
Several engines, such as I have described, may be made to work in
connection on one shaft, and they may be regulated by a governor
arranged so as to control the supply of air and fuel.

page_text: to my Invention. A is the air pump with suction valves a¹, a³, and
discharge ports b', b², governed by a slide B, so constructed as either to
close the port, as shewn at b', or to form a communication from it to one
of the two regenerators R', R, as shewn at b. The slide B also, when
it closes one of the ports 6', forms a communication from the
regenerator R' to an outlet passage r, and similarly when it closes the
other port it opens a passage from the regenerator R. Passages r¹, 3,
lead from the regenerators to the combustion cylinder C, and combustible
gas or vapour is admitted to these passages by ports g', g², which are
controlled by a slide similar to B. The gas or vapour may be generated
at sufficient pressure to enter by either of the ports g', g², when the slide
opens it, or when it is not generated at sufficient pressure a pump similar
to A can be employed to force it in at pressure corresponding to that
of the air forced in by A. There may also be a pair of regenerators similar
to R', R, placed between the ports g', g², and the slide of the pump with
which they communicate. Nozzles of known kinds can be provided in
the passages, 7₁³, and g¹, g³, to effect the mixture of the air and the
combustible gas or vapour as they enter the cylinder C, and the mixture
may be ignited by any known means, as, for example, an electric spark
or a jet of flame as in gas engines. The cylinder C is fitted with a
hollow piston P with a tubular rod p', p², extending upwards and down-
wards, and passing through packings c', c², at each end of the cylinder.
Below the cylinder C is a water space W²; above it is a water and steam
space W₁; and around it is a water jacket W; the two spaces W' and W
communicating with each other, and the jacket W by a number of
holes w. The lower part 2 of the tubular piston rod forms a hollow
pump plunger, and a delivery and suction valve v', v³, are provided, so
that at every up stroke of the piston P water is drawn from W2, and at
every down stroke it is discharged through the hollow piston, and the
upper tubular rod p' into the space W'. In passing through the cavity of
the piston P the water comes in contact at the periphery of the piston
with the interior surface of the cylinder C, the annular space h by which
the water has access to the cylinder surface having packings h¹, h³, above
and below it. A portion of the cavity of the piston P may be occupied
by a vessel V of thin metal containing air or steam, so as to lighten the
piston, this vessel having small orifices at its lower side, and having
through it a small pipe 3 for the passage of steam that may be generated
below it. The steam generated from the water in the spaces W', W³,
jacket W, and in the cavities of the piston and its rods is collected in the

page_text: upper part of the space W', whence it is conducted by a pipe s to work a
steam engine S in the usual way. It is to be understood that the piston
rod of this steam engine, that of the pump A, and that of the cylinder C
are all connected to cranks on one rotating shaft, the cranks for the
pump A and the piston P being set opposite to each other, so that the
latter ascends when the pump piston descends, and conversely. In like-
manner when a pump is employed for forcing the combustible gas or
vapour its piston works in accord with that of the
The slide B
pump A.
is worked by a cam or eccentric from the rotating shaft, as well as the
similar slide for the gas pump when such a pump is employed.
•
Fig. 2 represents a construction of the combustion cylinder C in a
multiple form, three such cylinders being arranged on one axis with
their pistons attached to the same line of rod. The same letters of
reference indicate the same parts as in Figure 1.
Having thus described the nature of my Invention, and in what
manner the same is to be performed, I claim,-
First. The use in a cylinder in which combustion is effected, or to
which hot products of combustion are admitted, of a hollow piston
through which water is caused to circulate, portions of the water being
by the movement of the piston brought successively into direct contact
with the heated surface of the cylinder, substantially in the manner
and for the purposes herein set forth.
Second. The combination of a cylinder and piston, such as are referred
to above, with regenerators and an air pump with or without a gas pump
and with a steam engine, the whole constituting a combined hot gas and
steam engine, substantially as herein described.
In witness whereof, I, the said Matthew Piers Watt Boulton, have
hereunto set my hand and seal, this Nineteenth day of June, in
the year of our Lord One thousand eight hundred and seventy-
I
M. P. W. BOULTON. (L.S.)