IMPROVEMENTS IN ENGINES AND APPARATUS FOR PRODUCING MOTIVE POWER (RELATING CHIEFLY TO SUCH ENGINES AS ARE ACTUATED EITHER WHOLLY OR IN PART BY GASEOUS FUEL).
Year: 1880

page_text: LETTERS PATENT to William Henry Northcott, of Hatcham Ironworks,
Pomeroy Street, London, S.E., for an Invention of "IMPROVEMENTS IN
ENGINES AND APPARATUS FOR PRODUCING MOTIVE POWER (RELATING
CHIEFLY TO SUCH ENGINES AS ARE ACTUATED EITHER WHOLLY OR IN PART
BY GASEOUS FUEL)."
PROVISIONAL SPECIFICATION left by the said William Henry Northcott at
the Office of the Commissioners of Patents on the 3rd August 1880.
$6
WILLIAM HENRY NORTHCOTT, of Hatcham Ironworks, Pomeroy Street, London,
S.E. IMPROVEMENTS IN ENGINES AND APPARATUS FOR PRODUCING MOTIVE
POWER (RELATING CHIEFLY TO SUCH ENGINES AS ARE ACTUATED EITHER WHOLLY
OR IN PART BY GASEOUS FUEL)."
In one form of my improved engine I draw air and gas through a suitable valve
into a long cylinder by the movement of a piston actuated by a crank. This piston
is itself formed as a cylinder closed at the ends, except by certain passages, one near
each cover.
A second trunk piston is arranged to work in the cylindrical piston.
The trunk piston is connected to the crank pin in the usual way. The cylindrical
piston is not connected with the crank pin except through the trunk piston
connections. When a certain quantity of air and gas is admitted the admission
valve closes, and the mixture is inflamed either by a gas flame, or an electric spark,
or incandescent wire, or other means. The explosion which ensues drives the
cylindrical or free piston upwards (assuming the engine to be vertical), and the air
which was between the lower end of the cylindrical piston and the bottom of the
trunk piston is driven through a valve in the trunk piston into the upper and
annular part of the cylindrical piston. The trunk piston is practically stationary
during this explosion, and the crank is at the out end of its stroke. The weight of
the two pistons and a partial vacuum under the free piston causes the crank to make
its inward or return stroke.
When the free piston reaches the bottom of the main cylinder the air compressed
and imprisoned in the upper part of the inner cylinder is allowed to re-expand into

page_text: the lower part through a suitable passage in the main cylinder, and the upward
stroke of the crank is caused by the air pressing on the greater area of the lower
side of the trunk piston. By these means I combine a free piston with a crank
motion.
In most so called gas engines as at present constructed the motive cylinder is
kept cool by a water circulation, the heat imparted to the water being wasted. One
of my improvements consists in confining the water in the water casing until steam
is generated, which steam I convey to a separate cylinder, or to the same cylinder
as explosion is effected in, but to the opposite side of the piston, so as to aid in
producing motive power. The steam after leaving the cylinder may be sent into
the atmosphere direct, but I prefer to send it through a feedheater, and the
uncondensed remainder through a nozzle or blast pipe to induce the exhausted gases
from the cylinder, or it may be condensed altogether to produce a vacuum. The
water casing is supplied by a pump or other feeder, and is furnished with a safety
valve and other usual boiler fittings. I sometimes, but more especially in cases
where the gases are compressed by the engine, fit the generator with a
series of gas burners, whereby steam may be first got up to start the engine,
when these burners may be turned off. The same burners however also enable
the power of the engine to be increased when the engine is required to exert
an exceptional amount of power. When water is scarce or its use inconvenient,
instead of generating steam in the casing, I pass a mixture of air and water,
or moist air, through the casing, and use the hot mixture in the same way as
steam, or admit it into the explosion cylinder itself. In another form of my
improved apparatus I force air and gas by means of an air pump into a closed
chamber, where combustion is effected under pressure. By preference the air pump
is arranged to draw air and gas on the rod or smaller side of the piston, and air
only on the other side. Whether compressed in this way or separately the two
streams enter the combustion chamber in a series of jets, or in such a manner as to
cause the thorough admixture of the gases previous to combustion. The combustion
chamber proper or furnace is surrounded by a strong casing forming an annular
space, or by a coil of piping, into which water is forced by a separate pump or
otherwise, and where steam is generated under the same pressure as that subsisting
in the furnace. The products of combustion and the steam are combined by annular
streams or otherwise, and taken off by a single pipe to actuate an engine in the same
manner as steam alone. Or the products, instead of being mixed with the steam,
may be led off to one motive cylinder or to one side of a piston, and the steam led
off to another cylinder or to the other side of the same piston, and afterwards
condensed or otherwise.
Instead of water, air saturated with water or air alone may be pumped into the
annulus surrounding the furnace, and after cooling the products of combustion
down to an usable temperature, combine with them in driving an engine.
When the explosive compound is composed of a liquid hydrocarbon, I affect
admixture by admitting the liquid into the air pump instead of gas, which also aids
in keeping down the temperature due to compression. In this case also I prefer to
effect combustion in a chamber lined with fireclay or other refractory material, from
which the gases pass to the generator described or any ordinary form of boiler. The
fireclay lining is enclosed in an iron tube or chamber, and I prefer to surround this
chamber with another casing, through which the spray or air is forced on its way
to the furnace. Ordinarily the compressing pumps are driven by the motive power
engine, but in certain cases, such as for tramcar propulsion, the gas only, or gas and
air, or gas and part of the air, may be compressed by a separate engine and carried
.in reservoirs. When only a portion of the combustible mixture is carried in
reservoirs I compress this to a higher pressure than that under which combustion is
effected, and induce the additional air by means of the stream of compressed air or
gases issuing into the furnace through an inductor. When liquid hydrocarbon is
the fuel, I induce this in the same manner along with any additional air, or alone.
In another form of my improved apparatus I dispense with the air and gas pumps,

page_text: but produce a result much the same as described by burning the gas under a steam
generator, in Bunsen or other burners not producing smoke.
The steam is generated at a high pressure, say, about 500 lbs. per incb, but a
higher or lower pressure may be employed, and allowed to issue through an injector
orifice in connection with the smoke box, so as to induce and combine with the hot
products of combustion, the combined stream going to the engine as before. When
the products are very hot and the steam dry, I induce a few drops of water in the
same manner as the gases. Or the steam may be taken off at or near the water
line, or by two pipes, one leading from the steam space of the boiler, and the other
from the water space, each having a valve to allow of the quantities of steam and
water being separately adjusted. I prefer that the water pump work continuously, and
for it to be so proportioned and adjusted as to maintain practically a constant level
in the boiler. In some cases I allow the water and steam to escape past a loaded
valve at each stroke of the pump and then go to the injector to combine with the
hot products. For very high pressures I make the generator in the form of a coil
of piping set in the furnace, and I cause the air used for combustion to pass round
the furnace casing on its way to the furnace. With the latter arrangement, as well
as in the cases where wet steam is taken and where water is induced as described,
I place a separating vessel between the inductor and the engine. As usually
constructed this vessel consists of a vertical pipe larger in diameter than the steam
pipe, and from the higher end of which the fluid stream is taken off to the engine.
The stream from the inductor is brought into the separator also at the top, but the
inlet pipe is carried down some distance in the vessel, nearly to the bottom. When
the fluid stream contains much water, this water is separated from the air and steam
and left in the bottom of the vessel. When the stream contains much surlplus heat,
the water is evaporated and carried off to the engine. In either form of engine I
regulate the speed of the engine in the ordinary way, by a governor acting on a
throttle valve or expansion valve. But I regulate the combustion in accordance
with requirements by means of a piston valve or Bourdon tube between the
generator and the engine, so constructed as to act on the gas and water supplies.
In either case to start the engines in the first place I open a direct passage from the
smoke box to the atmosphere into which the hot gases escape until sufficient steam
pressure is generated to start the engine, when the passage is closed and the engine
actuated as described. It will be understood that the motive fluid described in the
foregoing as for use in motive engines may be used to drive hammers, pumps, or
other machines usually or capable of being driven by steam.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Henry Northcott in the Great Seal Patent Office on the
29th January 1881.
"
WILLIAM HENRY NORTHCOTT, of Hatcham Ironworks, Pomeroy Street, London,
S.E. * IMPROVEMENTS IN ENGINES AND APPARATUS FOR PRODUCING MOTIVE
POWER (RELATING CHIEFLY TO SUCH ENGINES AS ARE ACTUATED EITHER WHOLLY
OR IN PART BY GASEOUS FUEL)."
In the form of my improved gas engine shewn in Figures 1, 2, & 3, air and
gas in explosive proportions are drawn through the valve a and port b into a long
or tall cylinder A by the movement of a piston B actuated from a crankpin C.
The piston B is itself formed as a cylinder, closed at the ends, but furnished with a
port or passage c at each end. A second piston D, with a trunk piston rod is
arranged to work in the cylindrical piston B, and this trunk piston is connected to
the crankpin as shewn, or in any other convenient manner. The piston B is not
itself connected to the crankpin except indirectly through the piston D.
When a suitable quantity of explosive mixture has entered the cylinder the slide
valve d is moved to cut off communication between the cylinder A and valve a,
which latter then closes, and the mixture is inflamed by an electric spark, or by
any ordinary lighting arrangement, or by one of the means shewn hereafter. An
explosion now ensues which drives the piston B upwards, and the air which was in
the space e under the piston D is forced through the valve g into the annular
space f, where it serves to retain B in its relative position with D as the valve g
closes and prevents the air returning. In Figure 1 the piston D is really the valve,
and g is the valve seat, but in Figure 3 the seat is formed in D for the valve g.
During the explosion the piston D is practically stationary, as the crank pin is
on or about its upper dead center. On passing this point the weight of the two
pistons and a partial vacuum under B cause the crank to make its downward
stroke. The two pistons travel together, or nearly so, until B reaches the bottom
of the main cylinder A, when the latter can go no further. In this position the
ports c, c, come opposite the ports of the long passage h so as to open up
communication between the top and bottom of the piston D, so that the air
compressed and imprisoned in the annulus f is now allowed to flow back into the
space e, and the upward movement of the crankpin is caused by the air pressing on
the greater area of the underside of the piston D. A water jacket i surrounds the
lower part of the cylinder A except at the passage h. A small valve k opens to
admit air into the space e, f, when the pressure there falls below that of the
atmosphere. The burnt gases are expelled through the port b and valve so soon
as they are able to overcome the atmospheric pressure, the piston slide d being
previously moved to place them in communication; m is the exhaust pipe, and n
the gas supply pipe; the air enters through the holes o, o. A camp actuates the
slide valve d, and the speed of the engine is controlled by any ordinary form of
governor, not shewn in the Drawing, but which acts on the valve d in such a
manner as to close communication between the cylinder and valve a when a lesser
or greater quantity of explosive mixture has been admitted. Or the governor may
act on a throttle valve placed between the valve a and the air and gas supply.
The engine shewn in Figures 4 and 5, and subsidiary Figure 6, is constructed to
utilise the surplus or excessive heat of explosion in the production of steam to be
employed in aiding the engine, without, however, being mixed (as in the case of
some previous engines) with the explosive mixture in such a manner as to lead to
imperfect combustion. As the piston A is moved outwards gas and air are drawn
in behind it through the throat a, gas entering by lifting the small ball valve,
shewn below, and air at the holes just above the valve. When a sufficient charge

page_text: has been admitted the slide valve b closes the gas port, and at the same time, or
just before, the slide valve c opens the port behind the piston A to the exhaust
pipe d. The gaseous mixture is now ignited, and the explosion causes the piston to
make its outward stroke. Ignition is effected in any known manner, and one
means, shown in Figure 6, consists of two gas jets, one of which, generally blown
out by the explosion, is relighted from the adjacent jet. The igniting jet is drawn
into the cylinder, past the small ball valve, at the point j.
The jacket c
surrounding the cylinder is kept filled, or nearly filled, with water by means of a
pump worked off the crankshaft and forcing into the jacket, at each stroke, a
constant but adjustable quantity of water. A portion of the heat generated by
the explosion goes to convert the water into steam, so that the jacket is really a
small steam generator. It is furnished with an escape valve f, and the generated
steam is led off by the pipe g to the valve chest h, whence it is admitted to the
cylinder by the valve c, but to one side only of the piston A. B is the crankshaft ;
Ca guide bar, and D a connecting rod; i is a can actuating the valve gear.
After leaving the cylinder the stearn may pass either direct to the atmosphere, or
to a feedheater or condenser.
Sometimes, but more especially in cases where instead of drawing the gases into
the cylinder I compress them in a separate pump, I fit the generator with a number
of gas burners, wherewith steam may be first got up to start the engine, when
these burners may be turned off. The same burners however enable the power of
the engine to be increased when the engine is required to exert an exceptional
amount of power.
When water is scarce or its use inconvenient, instead of generating steam in
the casing I pump into it a mixture of air and water spray, where it is considerably
expanded, and at the same time serves to keep the cylinder cool. The hot
expanded mixture is then admitted to the motor cylinder as described; or a
portion of this hot moist air may be admitted with the explosive charge to reduce
the rapidity of its combustion. In the case of coupled engines on this principle I
prefer to employ the forepart of one cylinder as the air and spray pump, and the
foreside of the other to use the fluid expanded by passing through both jackets.
At Figures 7 & 8 I shew a single acting form of my gas engine of the form I
prefer for small powers. On the outward motion of the piston A gas is drawn
from the pipe a and air from the holes b, b, past the valve c into the cylinder B.
When a sufficient charge has been inspired, ignition is effected by the indraught of
a gas flame placed in communication with the space above the valve c by the
movement of the lighting valve d acted upon by a cam, as shewn. Immediately
ignition is effected c is closed by excess of internal pressure, and the explosion
propels the piston forwards. The jacket may be either an ordinary water jacket,
or a free circulation of air may be permitted round the cylinder, air entering the
jacket at e and leaving it at f. I prefer however to cool the cylinder by admitting
a few drops of water with air at f, and drawing it off at e or other convenient
place by the action of the inducing nozzle, shown at Figure 9, and in which k is
the issuing pipe for the exhausted gases; 1, the pipe leading from e; and m the
discharge pipe leading to the atmosphere outside. The return stroke of this engine
is caused by the power stored up in the flywheel, and the gases are expelled
through the valves h and i to the exhaust pipe j. The valve h is opened and kept
open during the return stroke by a cam n, but the valve i is lifted by the gases.
The function of the valve i is to prevent the return of the exhausted gas when the
charge is being inspired, but the valve may be dispensed with by making the
spring o strong enough to withstand the excess of outside pressure.
In some cases I pump air and water, or water or air only, into the jacket, as in
the previous form of engine, but I admit the hot and expanded mixture into the
cylinder after explosion has taken place by the small valve g, Figure 10.
This valve is actuated by a cam, so as to admit a quantity of the hot mixture
during a portion only of the forward stroke of the piston, and the valve being
closed the combined mixture of burnt gases and hot air, or air and steam, or steam

page_text: only, is then expanded down during the remainder of the stroke to about the
pressure of the atmosphere. The water, or water and air, or air only, is pumped
into the casing by a separate pump worked off the engine in any convenient
manner; or the air mixture may be pumped into the casing by converting the
front part of the motor cylinder into a pump, as shewn in Figure 10, in which h is
the inlet valve for air from the atmosphere to the fore part of the motor cylinder
acting as a pump; is the delivery valve from the pump to casing; g has been
already described as the valve admitting hot air from the casing to the after or
motor part of the cylinder.
In Figure 11 the air or air and spray are merely pumped through the casing for
the main purpose of cooling it. This arrangement may be most usefully adopted
for ventilating and warming purposes, as in winter cold air from the atmosphere
drawn into the cylinder by the valve a may be expelled warm at the valve b into the
ventilating passages of the building; and in summer air may be drawn from the
ventilating passages, passed through the cylinder and casing, and dismissed into the
atmosphere.
The valves for admitting and releasing the air and gas are much the same as in
the last example, the exhaust valve is, however, in the present case shewn inverted.
The firing arrangement consists of two gas jets, one of which c is brought opposite
the air supply holes when the required quantity of gas and air has entered the
cylinder, and so that the flame is then drawn in with the last part of the explosive
charge. This flame is blown out by the explosion, and it is relighted by being
raised into proximity to the jet d, Figure 12, which also shews the air and gas
admission valves and exhaust valves in end section. The speed of the engine may
be controlled by igniting the charge when a greater or lesser quantity of mixture
has been admitted. The moment of ignition is determined by the movement of the
gas jet c, and this is effected by a cam on the main shaft of the engine. This cam
is not keyed to the shaft but is attached to the cam plate e, Figure 13, which plate
is free to move partly round on the shaft under the action of the governor balls g,
one joint of the governor arms being attached by a slot to the cam plate e, and the
other joint to the plate f keyed fast to the engine shaft. As the governor weights
fly outwards, the cam plate is moved round relatively with the fixed plate fand
crankshaft. Instead of igniting the charge by means of gas jets as shewn, in
some cases I explode it by means of the heat due to adiabatic compression in the
following manner:-I have a compressing pump large enough to take a small portion
(or it may be the whole) of the gaseous charge, which is admitted to the pump by
means of valves arranged as before described, namely, a main valve placed uext the
pump and a small valve on the gas supply orifice, with holes for admitting air
between the two valves. The admitted mixture is then compressed until its
temperature rises sufficiently to ignite it, and the moment of ignition is made to
correspond with about the beginning of the motor stroke. A loaded valve between
the pump and main cylinder prevents the escape of the gas into the cylinder until
a sufficient pressure has been reached to ensure the temperature necessary for
ignition. On starting the engine, however, may be necessary to warm the end of
the compressing pump, and this I do by means of a Bunsen gas burner placed under-
neath the pump. In another form of my improved motive power apparatus, instead
of burning the explosive mixture intermittently in the motor cylinder itself, and
generating steam or expanding air to aid the engine in the cylinder jacket, I
produce the expansive mixtures continuously in a separate vessel in the manner
following:-I force air and gas by means of a pump into a closed chamber where
combustion is effected under pressure. By preference, the pump is arranged to
draw air and gas on the rod or smaller side of the piston, and air only on the other
side. Whether compressed in this way or separately the two streams enter the
combustion chamber in such a manner as to cause the admixture of the gases
previous to combustion. The combustion chamber proper or furnace is surrounded
by a strong casing forming an annular space, or by a coil of piping, into which
water is forced by a separate pump or otherwise, and where steam is generated

page_text: under the same pressure as that subsisting in the furnace. The products of
combustion and the steam are combined and taken off by a single pipe to actuate
an engine; or the products, instead of being mixed with the steam, may be led off
to one motor cylinder, or to one side of a piston, and the steam led off to another.
Instead of water, air, saturated with water, or air alone, may be pumped into the
annulus surrounding the furnace, and after cooling the products of combustion down
to an useable temperature, combine with them to drive an engine. When the
explosive compound is formed of a liquid hydrocarbon, I effect admixture by
admitting the liquid into the air pump. which also tends to keep down the
temperature due to compression. In this case also I prefer to effect combustion in
a chamber lined with fireclay, from which chamber the gases pass to the generator.
The fireclay lining is enclosed in an iron tube or chamber, and I prefer to surround
this chamber with another casing, through which the spray or air is pumped, on
its way to the furnace, or into which the water or air, or air and spray, may be
forced on their way to the generator.
Ordinarily the compressing pumps are driven by the motive power engine; but
in certain cases, such as for tram car propulsion, the gas only, or gas and air, or gas
and part of the air, may be compressed by a separate engine and carried in
reservoirs. When only a portion of the combustible mixture is carried in reservoirs,
I compress this to a higher pressure than that under which they are burnt, and
induce the additional air by means of the stream of compressed gas or gases issuing
into the furnace through an inductor, such as Figure 9. When liquid hydrocarbon
is the fuel used, it may be induced in the same manner with any additional air
or alone.
In Figure 14, A is the combustion chamber into which the gases are forced
through one or more nozzles a, b. The generator B is supplied with water, or air
and water, or air only, by the pipe c. The gases mix at the upper end of the
furnace, as shewn, and are carried away to the engine by the pipe d; f is a
safety valve held down by a spring or weight, and the removal of which allows the
combustible gases to burn under atmospheric pressure in order to get up steam, or
get the apparatus hot in the first place, additional air being, if necessary, admitted
to the furnace by the orifice e.
In Figure 15, A is the furnace lined with fireclay, and B is the steam generator,
in this case an ordinary vertical tubular boiler, the steam from which is carried off
to one side of a motor piston, or to one cylinder, whilst the hot gases are led off to
another. The gas and air are pumped through a series of nozzles a, b; or the gas
only, or gas and part of the air, is pumped into a nozzle c, whilst the supplementary
air enters through the same nozzle but is pumped first into the casing d;
Figure 16 illustrates an arrangement for use when the products of combustion are
cooled down by admixture with air or air and spray.
The combustible gases rush into the furnace A through the tuyeres a, a, and
after burning, pass upwards into the mixing chamber B through the perforated
fireclay diaphragm b. The air to dilute the hot products is forced into the casing c,
whence it passes into B through orifices d, d. In another form of my improved
apparatus I dispense with the air and gas pumps, but produce a similar result by
burning the gas under a steam generator in Bunsen's burners, or other form of gas
furnace not producing smoke, generating the steam at a much higher pressure than
that at which it is admitted to the motor cylinder, and causing the steam to issue
through an injector orifice in connection with the smoke box, so as to induce and
combine with the hot products the combined stream going to the engine as
before.
When the products are very hot and the steam dry, I induce a few drops of
water in the same manner as the gases, or the steam may be taken off at or near
the water line, or by two pipes, one leading from the steam space of the boiler and
the other from the water space, with a cock or valve on each pipe to allow of the
quantity of steam and water to be adjusted separately. I prefer that the water
pump work continuously, and for it to be so proportioned as to maintain practically

page_text: a constant water level in the generator. In some cases I allow the water and
steam to escape past a loaded valve, so that as each stroke of the pump forces
water into the generetor, an equal quantity escapes at the loaded valve and then
goes to the injector to combine with the hot products. For any high pressure I
make the generator in the form of a coil of piping set in the furnace, and I cause
the air used for combustion to pass round the furnace casing on its way to the
furnace. With the latter arrangement, as well as in the cases where wet steam is
taken, and where water is induced as described, I place a separating vessel between
the inductor and the engine; as usually constructed, this vessel consists of a vertical
pipe, larger in diameter than the steam pipe, and from the higher end of which the
fluid steam is taken off to the engine.
The stream from the inductor is brought into the separator also at the top, but
the inlet pipe is carried down some distance in the vessel, nearly to the bottom.
When the entering stream contains much water, this water is separated from the
air and steam and left in the bottom of the vessel. When the stream contains
surplus heat, the water is evaporated and carried off to the engine. In either form
of engine I regulate the speed of the engine in the ordinary way by a governor
acting on a throttle valve or an expansion valve; but I regulate the combustion
in accordance with requirements by means of a piston valve or Bourdon tube
between the generator and engine, so constructed as to act on the gas and air
supply.
It will be understood that the motive fluid described in the foregoing as for
use in a motive power engine may be used to work a hammer, pump, or other
machine usually or capable of being driven by steam. In Figure 17, the air and
gas are admitted to the furnace through nozzles, similar to Figure 14, but they are
withdrawn from the furnace and mixed with the steam by the action of the injector
apparatus shewn at the side. Steam and water under a very high pressure in the
generator are taken off at the orifices a and b in quantities adjustable by the screw
valves c and d. This mixture issuing at the orifice e induces a stream of hot gases
from the furnace at the throat f, and the combined stream is taken off to the
engine at g. Figure 18 shews an ordinary Bunsen burner a under a vertical
boiler B. The induction apparatus is the same as in Figure 17, both in construction
and action. Figure 19 shews a large Bunsen gas burner a placed under a coil of
piping forming the generator, and into which water is continuously pumped at b,
where there is a check valve to prevent its return to the pump, and a pressure
gauge c.
A portion of the air required for combustion is drawn in with the gas
in the ordinary way, but the supplementary quantity is admitted at the orifices d, d,
which are adjustable by the circular shutter e. This air passes down between the
two casings, and being warmed by contact with the inner casing is admitted to
the flame by the series of holes f,f. As each stroke of the pump forces cold water
into the coil the same quantity escapes at the loaded valve g and out at the inducing
nozzle h, where it induces the hot products of combustion, combined with which
it enters the chamber i on its way to the engine; j is a valve, the removal of which
enables the gas to burn during the getting up of steam in the coil. The separating
vessel previously referred to is shewn at Figure 20. The steam, water, and gases
enter at a; the water is left at the bottom of the vessel, whilst the gases and
vapour are led off at b to the engine. Any residual water may be drawn off as
required at c and returned again to the generator; a gauge glass of usual make is
attached at d, d, to enable the water level to be seen.
Having now described the nature and purpose of my improvements in engines
and apparatus for producing motive power, and several forms in which the same
may be embodied, I have to state that I do not restrict myself to the precise
details herein described or illustrated, but that what I believe to be novel and
claim as the special features of the Invention are,―
1st. The explosive fluid engine, combining a free piston with a crank motion,
substantially as described.
2nd. In a gas engine, preventing the overheating of the cylinder by enveloping

page_text: it in a water casing serving as a steam generator, the steam generated being used
in aid of the engine on the opposite side of the motor piston, or in a separate
cylinder, substantially as described.
3rd. The means of starting or increasing the power of an engine using steam
in conjunction with gaseous explosives by steam generated with gas heat, as
described.
4th. Preventing the overheating of a gas engine cylinder by enveloping it in a
casing and pumping into this casing air only, or air with spray, which when
expanded by the heat necessarily abstracted is used in aid of the engine on the
opposite side of the gas motor piston or in a separate cylinder, as described.
5th. Cooling a gas motor cylinder by air, or air and spray, drawn through the
cylinder casing by an inducing nozzle, substantially as described.
6th. In a gas engine, the cylinder of which is kept cool by air, or air and spray,
pumped into its casing, admitting the expanded fluid to the gas side of the motor
piston in aid of the engine, substantially as described.
7th. Cooling a gas motor cylinder by pumping air, or air and spray, into the
forepart of the cylinder and through the casing, substantially as described.
8th. The arrangement of admission and exhaust valves, shown in Figures 7, 8, 11,
and 12.
9th. The method of igniting the explosive gases by rapid adiabatic compression,
as described.
10th. The apparatus for producing motive power from the combustible gases
and steam, combined or separate, or the combustible gases and hot air, or air and
spray, substantially as described.
11th. The combination of parts or constructive form of the motive power
apparatus and engines embodying the above novel features, substantially as
described.
In witness whereof, I, the said William Henry Northcott, have hereunto set
hand and seal, this Twenty eighth day of January, in the year of our
Lord 1881.
WILLIAM HENRY NORTHCOTT. (L.S.)