IMPROVEMENTS IN AND CONNECTED WITH GAS MOTOR ENGINES
Year: 1882

page_text: LETTERS PATENT to John Fielding, of the Atlas Works, Gloucester, in the
County of Gloucester, for an invention of "IMPROVEMENTS IN AND CONNECTED
WITH GAS MOTOR ENGINES."
PROVISIONAL SPECIFICATION left by the said John Fielding at the Office
of the Commissioners of Patents on the 1st March 1882.
JOHN FIELDING of the Atlas Works, Gloucester, in the County of Gloucester,
"IMPROVEMENTS IN AND CONNECTED WITH GAS MOTOR ENGINES."
This invention has for object improvements in gas motor engines.
In the specification of Letters Patent granted to me and dated February 8: 1881
No. 532 there is described a gas motor engine in which the end of the cylinder
further from the crank shaft is that in which the combustion and expansion of the
gases occur, whilst that end nearer the crank shaft acts as a pump to supply
successively the fresh charges of gas and air.
These charges are slightly compressed, by the forward or acting stroke of the
piston, into a reservoir, whence they pass into the acting end of the cylinder
through ports formed in the barrel thereof which ports are uncovered for this
purpose by the main piston passing over and beyond them as it approaches the end
of its acting stroke. The exhaust valve which is situated near the rear or
outward end of the cylinder being about the same time opened permits the escape of
the waste products of combustion, the slight pressure under which the succeeding
charge enters the cylinder enabling it to assist in the expulsion of the waste
products. Provision is made whereby the actual contact between the hot
products of combustion and the combustible portion of the fresh charge is to
some extent prevented. To this end, the air inlet valve is so placed relatively to
the reservoir and the gas inlet valve that the air as it is drawn into the front end
of the cylinder is compelled to pass through the reservoir and thus clear it of
nearly all the explosive mixture which was left within it and which would
otherwise remain close to the ports formed in the cylinder barrel. Notwithstanding
this there still remains however a certain amount of the explosive compound
FD 1071

page_text: within the said ports. Now to effect more complete removal of this residual
explosive mixture according to my present invention there is connected to the front
of the piston described in the before mentioned specification another piston of
somewhat larger diameter working within an enlarged part of the same cylinder at
the end nearer the crankshaft. The front end of this large piston acts in like
manner as did the front of the piston in the before mentioned arrangement, that is
to say drawing in a supply of gas and air and forcing it at a slight pressure into a
reservoir; the air inlet valve in the present case being so situated as has been
already explained in the before mentioned specification that the portion of the
reservoir nearest to the ports in the working barrel is cleared almost completely of
explosive mixture.
The annular space representing the difference of volumes swept by the two
pistons due to the difference in their diameters is filled at each outstroke by a
quantity of atmospheric air drawn in through a port provided in the main air
valve or through a separate valve as may be most convenient. This additional air
is delivered to the reservoir through the annular ports in the cylinder barrel, the
piston uncovering them when near the end of its return or compressing stroke.
By this means the ports in the working barrel are effectually cleared of any
explosive mixture which may have remained within them and the additional
quantity of air thus pumped into the reservoir in this manner with the air already
drawn into the resesvoir by the front of the pump piston, prevents the premature
ignition of the combustible charge. The volume of gas and air drawn in at each
stroke exceeds the acting capacity of the cylinder, that is, the volume swept by the
main piston, by a volume equal to twice the annular space represented by the
difference of volumes swept by the two pistons.
I prefer to arrange the gas supply valve in such a way that the amount of
combustible mixture drawn in at each stroke is equal to the volume swept by the
main piston, the surplus volume being atinospheric air so situated that it acts as a
barrier between the hot products of combustion and the combustible charge of gas
and air, the said additional air, which is allowed to escape by the exhaust valve,
thus efficiently cleanses the combustion chamber of products of combustion.
According to one arrangement I close the front end of the cylinder by a sliding
cover fitted with a stuffing box or gland bush constructed in such a manner that
whilst air tight it allows of the reciprocating and vibrating motions of the
connecting rod which is coupled directly to the pump piston and works through the
aforesaid stuffing box. The sliding cover acts also as a valve controlling the flow
of the combustible mixture between the pump cylinder and the reservoir. By this
arrangement I am enabled to dispense with the usual crosshead, guide bars and
piston rod and to reduce the space occupied by the engine.
Instead of utilizing the front part of the acting cylinder as a pump as described
in my before mentioned patent specification No 532/81, or instead of [placing a
pump of larger diameter in front of the acting cylinder and piston as above
described I sometimes provide a pump driven by a separate crank and which may
conveniently be placed side by side with the acting cylinder. This pump I prefer
to make of somewhat larger capacity than that represented by the volume swept
by the main piston. A space equal to the difference between these two volumes is
filled at each stroke by atmospheric air only so that the pump supplies a quantity
of combustible mixture equal to the volume of the main piston stroke and also a
surplus of pure air acting as a barrier as aforesaid. The annular port in the
working barrel of the cylinder as above described is, by suitably proportioning the
length of acting piston, arranged to be uncovered at both ends of the stroke. When
uncovered near the end of the forward or acting stroke the new charge is delivered
by the pump through the port into the cylinder, and when uncovered near the
end of the main piston's return or compressing stroke the pump draws in air through
the port the latter thus acting as both inlet and delivery port,-the main piston
acting as a slide valve in connection with the port. The pump crank can
conveniently be placed at one third to three eighths of a revolution in advance of

page_text: the main crank. In this modification no air inlet valve is required, a gas supply
valve is provided in connection with the pump, the arrangement being such that
the pump piston will first draw in the desired quantity of air, and when that has
been accomplished will open the port to admit gas or combustible mixture which
will be drawn in next to the piston so as to be situated between it and the air
previously drawn in. The supply of air being drawn into the pump as described
through the annular port in the main cylinder barrel, any combustible mixture
that may remain in the said port is effectually cleared out and drawn into the
pump cylinder with the air.
I consider it advantageous to arrange the pump cylinder in such a position with
regard to the main cylinder and annular port that the clearance spaces are kept as
small as possible.
In a modification of such an engine two acting cylinders can be used driving
cranks placed at opposite centres, so that two efforts may be exerted at every
revolution of the crank shaft. One double acting charging pump may in such an
engine be used to supply the charges to both acting cylinders such pump being
preferably placed between the two cylinders one end of pump cylinder com-
municating with the annular port of one cylinder and the other end with that of
the other cylinder.
According to another arrangement of engine with separate pump I make the
pump piston an annular one fitting internally upon a portion of the cylinder liner,
and externally within an enlargement of the cylinder jacket the open end of the
annulus within which the pump piston works being towards the crank shaft and
the back or closed end being in direct communication with the annular port in the
cylinder barrel. The pump piston in this case may be worked by a suitable crank
or eccentric on the crank shaft or the motion may be taken by suitable levers and
a link from the connecting rod of the main piston.
For igniting the combustible mixtures in the above described and other gas and
hydro carbon engines by electricity I provide means whereby the spark for
effecting ignition is produced by a sudden break in the electric circuit, this break
taking place within the combustion chamber of the cylinder. In carrying out this
part of my invention I use suitable levers and a cam operated by the engine for
causing the break in the circuit within the combustion chamber. In one arrange-
ment a fixed electrode is placed within the combustion chamber, and in connection
with it another electrode capable of receiving motion from outside the cylinder
through the agency of the aforesaid cam and levers. During the greater part of
each revolution of the engine these electrodes are kept in contact, the dynamo
electric machine or other electrical generator employed being during that period
short circuited, at the moment that the spark is required the movable electrode is
very quickly and automatically moved away from the fixed one and a spark is
thus produced which, providing the generator is sufficiently powerful, causes the
ignition of the combustible charge. The contact can, according to another
arrangement, be broken by means of the piston itself striking one of the
electrodes.
In order to produce a supply of electricity to enable the engine to be started
in the case of large engines provide means for driving the dynamo machine at
two different speeds.
By providing two pairs of wheels or their equivalents for driving the dynamo
the latter can be caused to revolve say ten times for each turn of the engine shaft
whilst being started, and after the engine has attained a sufficient speed the second
pair of wheels may be substituted for the first and the dynamo caused to revolve
only say five times for each turn of the engine shaft. According to another
modification I use an electrical storage battery or accumulator for the purpose of
igniting the mixture when starting, the accumulator being kept constantly
charged by the dynamo driven by the engine. I may further cause the dynamo to
revolve very quickly by means of a spring, the latter being coiled or compressed
by suitable means actuated by the engine in turning the crank shaft round by

page_text: hand the spring being released and the dynamo thus caused to revolve just before
the spark is required. The dynamo would thus receive an intermittent rapid
motion at such part of the engine's revolution as required.
To facilitate the starting of large gas engines I propose to use an electrical
accumulator in conjunction with a dynamo electric machine such machine being
used as a motor to set the engine in motion until it has drawn in a sufficient
supply of the combustible mixture to enable the engine to run without its aid.
The ignition of the combustible mixture might in such an arrangement be effected
by means of electricity supplied from the electrical accumulator aforesaid. The
engine once being started the dynamo machine may be used as generator to supply
the electricity for the purpose of igniting the combustible mixture and also for
recharging the electrical accumulator.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Fielding in the Great Seal Patent Office on the 31st August
1882.
JOHN FIELDING of the Atlas Works Gloucester in the County of Gloucester
"IMPROVEMENTS IN AND CONNECTED WITH GAS MOTOR ENGINES,'
"
In the
This invention has for object improvements in gas motor engines.
specification of Letters Patent granted to me and dated February 8, 1881 No. 532
there is described a gas motor engine in which the end of the cylinder further
from the crank shaft is that in which the combustion and expansion of the gases
occur, whilst that end nearer the crank shaft acts as a pump to supply successively
the fresh charges of gas and air.
These charges are slightly compressed, by the forward or acting stroke of the
piston, into a reservoir, whence they pass into the acting end of the cylinder
through ports formed in the barrel thereof, which ports are uncovered for this
purpose by the main piston passing over and beyond them as it approaches the
end of its acting stroke. The exhaust valve which is situated near the rear or
outward end of the cylinder being about the same time opened permits the escape
of the waste products of combustion, the slight pressure under which the succeeding
charge enters the cylinder enabling it to assist in the expulsion of the waste
products. Provision is made whereby the actual contact between the hot products
of combustion, and the combustible portion of the fresh charge is to some extent
prevented. To this end, the air inlet valve is so placed relatively to the reservoir
and the gas inlet valve that the air as it is drawn into the front end of the
cylinder is compelled to pass through the reservoir and thus clear it of nearly all
the explosive mixture which was left within it and which would otherwise remain
close to the ports formed in the cylinder barrel. Notwithstanding this there still
remains however a certain amount of the explosive compound within the said
ports. Now to effect more complete removal of this residual explosive mixture
according to my present invention there is connected to the front of the piston
described in the before mentioned specification another piston of somewhat larger
diameter working within an enlarged part of the same cylinder at the end nearer
the crank shaft. The front end of this large piston acts in like manner as did the
front of the piston in the before mentioned arrangement, that is to say drawing in
a supply of gas and air and forcing it at a slight pressure into a reservoir; the air
inlet valve in the present case being so situated as has been already explained in
the before mentioned specification that the portion of the reservoir nearest to the
ports in the working barrel is cleared almost completely of explosive mixture.
The annular space representing the difference of volumes swept by the two pistons
due to the difference in their diameters is filled at each outstroke by a quantity of
atmospheric air drawn in through a port provided in the main air valve or through
a separate valve as may be most convenient. This additional air is delivered to
the reservoir through the annular ports in the cylinder barrel, the piston uncovering
them when near the end of its return or compressing stroke. By this means the
ports in the working barrel are effectually cleared of any explosive mixture which
may have remained within them and the additional quantity of air thus pumped
into the reservoir in this manner with the air already drawn into the reservoir by
the front of the pump piston, prevents the premature ignition of the combustible
charge. The volume of gas and air drawn in at each stroke exceeds the acting
capacity of the cylinder, that is, the volume swept by the main piston, by a
volume equal to twice the annular space represented by the difference of volumes
swept by the two pistons. I prefer to arrange the gas supply valve in such a way

page_text: that the amount of combustible mixture drawn in at each stroke is equal to the
volume swept by the main piston, the surplus volume being atmospheric air so
situated that it acts as a barrier between the hot products of combustion and the
combustible charge of gas and air, the said additional air which is allowed to
escape by the exhaust valve thus efficiently cleanses the combustion chamber of
products of combustion According to one arrangement I close the front end of
the cylinder by a sliding cover fitted with a stuffing box or gland bush constructed
in such a manner that whilst air tight it allows of the reciprocating and vibrating
motions of the connecting rod which is coupled directly to the pump piston and
works through the aforesaid stuffing box. The sliding cover acts also as a valve
controlling the flow of the combustible mixture between the pump cylinder and
the reservoir. By this arrangement I am enabled to dispense with the usual
crosshead, guide bars and piston rod and to reduce the space occupied by the engine.
Referring to the accompanying three sheets of drawings, Figure 1 represents a gas
motor engine constructed according to the first part of my invention.
Figure 2 is a transverse section on line A' B¹ Figure 1.
Figure 3 is a transverse section on line C¹ D'. Figure 1.
Figure 4 is a part front elevation of the charging pump cover, and a part section
through the sliding cover.
Figure 5 is a horizontal section of the charging pump cover and sliding cover.
A is the working cylinder, in which is formed an annular port B; C is the
working piston; D the charging pump; E the pump piston which is connected
directly to crank shaft by the connecting rod; F is a cover having an oblong orifice
formed in it to allow of the angular vibration of the connecting rod; the outerface
of the cover F is of convex form, the centre from which the curved face is described
being about coincident with that of the gudgeon G, when the piston is at half
stroke as shown on drawing. His a sliding cover, having a concave inner surface
corresponding with the convex outer surface of F, and scraped to form an airtight
sliding joint with it. The surfaces are held in contact by means of suitable bolts
and stripes I, I, I, II, and J. J¹ In the centre of the sliding cover H is formed a
spherical socket fitted with a cover within the socket fits a spherical boss formed
on a stuffing box K which is fitted with gland L for the purpose of receiving
suitable packing. Ports M M are formed in the cover F, corresponding with other
ports N. N. in the sliding cover H and forming a communication between the
charging pump D and a reservoir O. P Figures 2 and 3 is a rotating air valve,
having two passages QR formed in it corresponding respectively with passages or
ports Q and S and R¹ and S of which S communicates with the external air, R' with
the reservoir O, and Q¹ with the cylinder. R¹ & S control the admission of air to
the reservoir O and front of charging pump D. Q&S similarly control the
admission of air to the space between the two pistons C & E. T is a gas supply
valve fitted with perforated pipe T¹ to ensure the perfect mixing of the gas and air.
The gas valve may be worked by any suitable means, such as an eccentric cam, or
tappett, by the engine itself. U Figure 1 is a valve to allow of the escape of the
products of combustion, from the acting cylinder, and may be worked automatically
by any suitable mechanism, preferably by a cam and levers. The operation of the
engine is as follows, assuming that one or more complete revolutions have been
performed during inward stroke of the pistons C & E. i. e. that in which they
recede from the crank shaft, air is drawn through the valve P, passages R¹ & S, and
reservoir O into the charging cylinder D, the air, however on reaching the
perforated pipe T₁ becomes thoroughly impregnated with gas which enters
through valve T. Thus when the pistons reach the end of the inward stroke, that
part of the reservoir O which is situate between the air valve P and the
perforated pipe T¹ contains pure air only, whilst the remaining portion of the
reservoir and the pump cylinder are filled with a mixture of gas and air. Slightly
before the pistons reached the end of the stroke, the piston C uncovered the
annular port B thus permitting the escape into the reservoir O of air which had
been drawn into the space between the pistons C & E during the previous outward

page_text: stroke, through the air valve P and passages Q¹ & S. By this means the annular
port B is cleared of such explosive mixture as may have remained in it from the
previous stroke; the air delivered from the space between the pistons C and E also
adds to the amount in that portion of the reservoir containing pure air, and thus
increases the immunity from premature ignitions. The action of this engine as
regards compression, ignition, and exhaustion is exactly similar to that described
in the specification of Letters Patent granted to me and numbered 532 of 1881.
Instead of utilizing the front part of the acting cylinder as a pump as described in
my before mentioned Patent specification No. 532/81 or instead of placing a pump
of larger diameter in front of the acting cylinder and piston as above described I
sometimes provide a pump driven by a separate crank and which may conveniently
be placed side by side with the acting cylinder. This pump I prefer to make of
somewhat larger capacity than that represented by the volume swept by the main
piston. A space equal to the difference between these two volumes is filled at each
stroke by atmospheric air only, so that the pump supplies a quantity of combustible
mixture equal to the volume of the main piston stroke and also a surplus of pure
air acting as a barrier as aforesaid. The annular port in the working barrel of
the cylinder as above described is, by suitably proportioning the length of the
acting piston, arranged to be uncovered at both ends of the stroke.
When uncovered near the end of the forward or acting stroke the new charge is
delivered by the pump through the port into the cylinder; and when uncovered
near the end of the main pistons return or compressing stroke the pump draws in
air through the port the latter thus acting as both inlet and delivery port, the
main piston acting as a slide valve in connection with the port. The pump crank
can conveniently be placed at one third to three eighths of a revolution in advance
of the main crank.
In this modification no air inlet valve is required, a gas supply valve is provided
in connection with the pump. This valve may be operated in such a manner that
when the desired quantity of explosive mixture has been drawn in, it is closed, the
pump during the rest of the stroke, drawing in air only, which entering by the
annular port is so situated that it enters the acting cylinder in advance of the
explosive mixture thus preventing premature ignition.
The same end may be attained by increasing somewhat the length of the passage
between the annular port and the pump cylinder and so placing the gas valve that
whilst remaining open during the whole of the pump's drawing in stroke, the charge is
divided into two portions viz:-that lying between the annular port in the acting
cylinder, and the gas valve consisting of pure air only, whilst the space between
the gas valve and pump piston is filled with explosive mixture, this arrangement
is essentially the same as that shewn in Sheet No. 1. The supply of air being
drawn into the pump as described through the annular port in the main cylinder
barrel, any combustible mixture that may remain in the said port is effectually
cleared out and drawn into the pump cylinder with the air. In a modification of
such an engine two acting cylinders can be used driving cranks placed at opposite
centres so that two efforts may be exerted at every revolution of the crank shaft.
One double acting charging pump may in such an engine be used to supply the
charges to both acting cylinders such pump being preferably placed between the
two cylinders one end of pump cylinder communicating with the annular port of
one cylinder and the other end with that of the other cylinder.
Figure 6 represents in elevation a gas motor engine constructed according to this
part of my Invention.
Figure 7 is a sectional plan of the same, the section following line A¹ B'
Figure 6.
Figure 8 is a transverse section in line C¹ D', Figure 7.
A is the working cylinder. B the piston and crosshead (formed together
preferably) connected by means of rod C to crank D. E is the air and gas supply
pump, F its piston connected by rod G to a second crank H. The crank H, is
placed at about an angle of 120° in advance of the crank D in the direction of the

page_text: crank shafts rotation. At about the centre of the working cylinder's length is
formed a port I, by preference annular which is in free communication, with the
cylinder of the supply pump by means of a passage J, at the rear end of supply
pump. The main piston B passes to and fro over the annular port I and is made
of such a length that it uncovers the port at both ends of the stroke, the period
during which the port remains uncovered. corresponding with about one third of
the crank shaft's revolution at each end of the main pistons stroke Projecting
into the passage J is provided a gas supply pipe K preferably perforated, this pipe
being connected to a gas inlet valve actuated by means of suitable gear by the
engine itself. The gas inlet valve may be opened during the whole or a portion
of the drawing in stroke of the supply piston and closed during its delivering or
compressing stroke and may be controlled by a suitable governor so as to reduce
or cut off entirely the supply of the combustible gas for the purpose of regulating
the speed of the engine. An outlet or exhaust valve L is shown connected to the
outer or rear end of the acting cylinder to permit of the escape of the spent
products of combustion; this valve being operated by suitable means such as a
cam or crank and levers by the engine itself. Any suitable method of igniting the
combustible charge may be employed such as are in common use in gas motor
engines. Figures 9, 10, 11, 12, 13 and 14 illustrate the action of the engine during
one complete revolution of the crank shaft, and constitute a complete cycle of
operations as regards the supply and compression of the combustible charge.
Air enters by the front or mouth of the acting cylinder and passes by way of the
annular port I and passage J. into the cylinder of supply pump.
As it passes
through the passage J it mixes intimately with the gas which enters by the
perforated pipe K, and forms an explosive compound. An examination of the
Figures 9, 10, 11, 12, 13, and 14 will shew that the acting piston B, operates as a
slide valve passing to and fro over the annular port I controlling the flow of air
into the supply pump and of air or air and gas from the supply pump into the
working cylinder A.
Figures 9, 10, 11*, 12ª, 13, and 14*, shew respectively the positions of the
cranks corresponding to the positions of the pistons in Figures 9, 10, 11, 12, 13,
and 14. In Figure 9 the acting piston B is at the commencement of its forward
stroke, the annular port I being open to allow of the air to pass into the supply
pump E the piston F. of which is advancing on its outward or drawing in stroke.
In Figure 10 the main piston B is advancing whilst the pump piston F has reached
the end of its drawing in stroke, the annular port I. is just closed by the advance
of main piston B.
Figure 11 shows the main piston B still advancing and about to open the annular
port I to allow the charge from supply pump to enter the working cylinder A
which it does under slight compression as the pump piston has now commenced its
return or compressing stroke. The outlet valve L has been opened slightly before
this point has been reached so that the spent products of combustion have to a
great extent escaped from the working cylinder, their expulsion being completed
by the admission of the fresh charge which as aforesaid enters under a slight
amount of compression. In Figure 12 the main piston B has arrived at the end of
its outward or acting stroke, the annular port I being still open and the pump
piston F continues its inward or delivering stroke forcing the new charge into the
working cylinder A.
Figure 13 shows the main piston B on its return or compressing stroke having
just closed the annular port I, at the same moment that the pump piston F has
reached the end of its inward or delivering stroke.
Figure 14 shows the main piston continuing its compressing stroke and about to
uncover the annular port I to permit the inlet of air to the pump cylinder E the
piston F of which has commenced its outward or drawing in stroke.
Figure 14 shows a double cylinder gas motor engine according to this invention.
The pistons B and B' are coupled to cranks D and D¹ which are diametrically
opposite each other.

page_text: One supply pump E serves for both cylinders, the pump being double acting.
The front end of the pump acts in conjunction with the cylinder A¹ and the rear
end with cylinder A
Figure 15 shews the relative positions of the cranks D and D¹ with the supply
pump crank H. For igniting the combustible mixtures in the above described and
other gas and hydro-carbon engines by electricity I provide means whereby the
spark for effecting ignition is produced by a sudden break in the electric circuit,
this break taking place within the combustion chamber of the cylinder. In carrying
out this part of my invention I use suitable levers and a cam operated by the
engine for causing the break in the circuit within the combustion chamber. In
one arrangement a fixed electrode is placed within the combustion chamber, and in
connection with it another electrode capable of receiving motion from outside the
cylinder through the agency of the aforesaid cam and levers. During the greater
part of each revolution of the engine, these electrodes are kept in contact, the
dynamo electric machine or other electrical generator employed being. during that
period short circuited. At the moment that the spark is required the movable
electrode is very quickly and automatically moved away from the fixed one and a
spark is thus produced, which, providing the generator is sufficiently powerful,
causes the ignition of the combustible charge. The contact can according to
another arrangement be broken by means of the piston itself striking one of the
electrodes.
Figures 16 and 17 sheet 3 represent the form of electrical igniting gear according
to my invention. It consists of two platinum or other electrodes, forming part of
an electric circuit. The contact between these electrodes is alternately completed,
and rapidly broken thus causing a spark, which ignites the explosive charge in the
cylinder of the gas motor engine. A is the fixed electrode, secured in the holder B
which is preferably made so that it can be readily removed together with the
moving electrode C. The latter is secured in a vibrating lever D both the holder B
& the lever D project some distance into the explosion chamber of the cylinder,
to ensure their being perfectly surrounded with explosive mixture.
The fixed electrode A is thoroughly insulated from the holder B so that unless
the electrodes are in contact no current exists. The lever D is carried upon a short
shaft E working through a bearing formed in the holder B, the shaft projecting
outside and carrying a second lever F which is actuated by means of a cam G
driven by the engine. The action of the cam causes the levers F and D and the
shaft E to oscillate, the cam being shaped so that the electrodes are brought
smoothly into contact, but the contact between them is suddenly broken by the
pressure of the spring H acting on the lever F in the contrary sense to the action
of the cam. This action takes place at about the end of the inward or compressing
stroke of the gas motor piston. One terminal of the electrical generator is attached
to the holder B as at J, and the other to the fixed electrode A as at I the moving
electrode c being in electrical contact with the holder B.
To generate the electricity required for the production of the igniting spark, I
prefer to use a small dynamo-electric machine, such as is generally used for the
purpose of electric lighting. This dynamo I drive by belt or gearing from the
engine itself. In order to prevent damage to the lever F should the engine be
turned in the wrong direction, a small lever K is fitted at the end of lever F, so
arranged that should the engine turn in the wrong direction, the lever K yields
and permits the cam to pass it without damage. In my provisional specification I
referred to a modification with a separate annular pump piston fitting upon a
portion of the cylinder liner within an enlargement of the cylinder jacket, and
worked from the crank shaft, but I do not consider such an arrangement so advan-
tageous as those hereinabove described. Also I referred to the use of a dynamo
machine driven at various speeds for igniting the charge, and to the use in com-
bination of an electrical accumulator and a dynamo machine for starting a gas
engine, but as I do not now consider such arrangements advantageous in practice I
lay no claim thereto.

page_text: Having thus described the nature of the said Invention and the manner in which
it is to be performed I would have it understood that what I consider to be novel
and original and therefore claim as secured to me by the Letters Patent herein-
before first in part recited is :-
(1) In a gas motor engine wherein the combustible mixture is admitted to the
cylinder through an annular port uncovered by the working piston itself, the use
of a charging pump in the sam axial line as the cylinder, so arranged that it
delivers a quantity of pure air into the said annular port to clear it from com-
bustible mixture and interpose a body of air between the combustible charge and
the products of the following explosion substantially as described.
(2) In a gas motor engine wherein the charging pump is arranged in front of
and in the same axial line as the working cylinder, the use of a sliding cover and
stuffing box arranged to permit angular motion of the piston rod, and to maintain
an efficient joint substantially as described with reference to Figures 1, 4 and 5 of
the drawings.
(3) The improved gas motor engine constructed, arranged and operating
substantially as described with reference to Figures 1, 2 and 3 of the drawings.
(4) In a gas motor engine wherein a charging pump is used in conjunction with
the working cylinder of the engine controlling the admission of air to the pump
cylinder and also the delivery therefrom of combustible mixture to the working
cylinder by the use of the engine piston as a valve substantially as described.
(5) The improved gas motor engine, constructed, arranged and operating sub-
stantially as described with reference to Figures 6 to 14 inclusive of the
drawings.
(6) In a gas motor engine the use in combination of two working cylinders
and one double acting pump for charging them, the arrangement being such that
admission of air from each such working cylinder to the pump cylinder and
delivery from the latter of combustible mixture to each such working cylinder is
controlled by the piston of the respective working cylinder acting as a valve
substantially as described.
(7) The use of electric igniting apparatus substantially as described.
In witness whereof I the said John Fielding have hereunto set my hand and
seal this thirtieth day of August in the year of our Lord, One thousand
eight hundred and eighty two.
JOHN FIELDING. (L.S.)