IMPROVE- MENTS IN AIR AND GAS ENGINES
Year: 1863

page_text: LETTERS PATENT to Richard Archibald Brooman, of 166, Fleet Street,
in the City of London, Patent Agent, for the Invention of "IMPROVE-
MENTS IN AIR AND GAS ENGINES."-A communication from abroad by
Auguste Nicol Otto, of Cologne, Prussia.
PROVISIONAL SPECIFICATION left by the said Richard Archibald
Brooman at the Office of the Commissioners of Patents, with his
Petition, on the 24th August 1868.
I, RICHARD ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of
London, Patent Agent, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN AIR AND GAS ENGINES," to be as follows:-
This Invention consists in constructing engines in which the up stroke of
the piston is effected by the explosion within a cylinder of a mixture of air and
gas by an electric spark, while the down stroke is performed by the pressure
of the atmosphere. Inside a cylinder a piston is placed and connected to a
hollow piston rod; this piston is formed with passages through it, which are
covered by a plate or cap; inside the hollow piston rod another and solid rod
is fitted in such manner that the head thereof cannot become separated from
the bottom of the hollow rod; a solid piston is attached to the solid piston rod,
and the solid piston rod is free to work up and down in the hollow rod. The
first-named piston does not descend to the bottom of the cylinder, but only to
a point on a level with an air inlet port, while the solid piston extends to the
bottom of the cylinder where there is a port for the admission of a mixture of

page_text: gas and air; both ports are opened and closed by slides worked by excentrics
on the shaft of the engine. The first-named piston is raised to the top of its
stroke by a weighted beam, and air enters between it and the solid piston'; the
air port is closed, and a mixture of air and gas enters below the solid piston;
the air and gas passage is closed, and an electric spark explodes the gas and
air under the solid piston, and drives it up so as nearly to touch the first-named
piston, in doing so it raises the cap thereon, and allows of the atmospheric air
between the two pistons passing off through the apertures in the upper piston ;
cooling takes place almost immediately the lower piston arrives at the top.of
its stroke, a vacuum is formed, the pressure of the atmosphere closes the cap
on the upper piston and drives it to the bottom of its course, when the solid
piston falls by its own weight on the bottom of the cylinder. In order to
prevent the noise the air would make in issuing through the upper piston
directly into the atmosphere, I close the cylinder with a tight cover and con-
pect the upper part with a reservoir, into which the air rushes from the
cylinder, and from which it subsequently escapes,
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Richard Archibald Brooman in the Great Seal Patent Office
on the 24th February 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, RICHARD
ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of London, Patent
Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of August, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-seventh year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Richard Archibald Brooman, Her special licence that I, the
said Richard Archibald Brooman, my executors, administrators, and assigns,
or such others as I, the said Richard Archibald Brooman, my executors,
administrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend, within
the United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN AIR AND GAS ENGINES,"
(communicated to me from abroad by Auguste Nicol Otto, of Cologne,
Prussia,) upon the condition (amongst others) that I, the said Richard

page_text: Archibald Brooman, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Richard Archibald Brooman, 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 Drawings hereunto
annexed, that is to say :-
This Invention consists in constructing engines in which the up stroke of a
piston is effected by the explosion within a cylinder of a mixture of air and
gas by an electric spark, while the down stroke of another piston is performed
by the pressure of the atmosphere. Inside a cylinder a piston is placed and
connected to a hollow piston rod; this piston is formed with passages through
it which are covered by a plate or cap; inside the hollow piston rod another
and solid rod is fitted in such manner that the head thereof cannot become
separated from the bottom of the hollow rod; a solid piston is attached to the
solid piston rod, and the solid piston rod is free to work up and down in the
hollow rod. The first-named piston does not descend to the bottom of the
cylinder, but only to a point on a level with an air inlet port, while the solid
piston extends to the bottom of the cylinder where there is a port for the
admission of a mixture of gas and air; both ports are opened and closed by
slides worked by excentrics on the shaft of the engine. The first-named piston
is raised to the top of its stroke by a weighted beam, and air enters between
it and the solid piston; the air port is closed, and a mixture of air and gas
enters below the solid piston; the air and gas passage is closed, and an electric
spark explodes the gas and air under the solid piston, and drives it up so as
nearly to touch the first-named piston, in doing so it raises the cap thereon,
and allows of the atmospheric air between the two pistons passing off through
the apertures in the upper piston; cooling takes place almost immediately the
lower piston arrives at the top of its stroke, a vacuum is formed, the pressure
of the atmosphere closes the cap on the upper piston and drives it to the
bottom of its course, when the solid piston falls by its own weight on the bottom
of the cylinder. In order to prevent the noise the air would make in issuing
through the upper piston directly into the atmosphere, I close the cylinder
with a tight cover and connect the upper part with a reservoir, into which the
air rushes from the cylinder, and from which it subsequently escapes.

page_text: Figure 1 of the accompanying Drawings is a side elevation of an engine
constructed according to this Invention. Figures 5, 6, 7, and 8, are sections
of the cylinder shewing the pistons in the several positions they occupy
successively during the working of the engine.
a is the cylinder in which is placed a piston 6 connected to a hollow piston
rod e;
the piston bis formed with passages through it, as shown, which are
covered by a plate or cap m; d is another and solid piston rod fitted inside the.
rode in such manner that the head thereof cannot become separated from the
rod e.
A solid piston c is attached to the rod d, and this rod is free to work
up and down in the hollow rod e. The piston does not descend to the bottom
of the cylinder, but only to the point at which it is represented in Figure 5, where
there is an air inlet portf; the piston c extends to the bottom of the cylinder,
as shewn in Figure 6, where there is a port g for the admission of a mixture
of gas and air. The ports ƒ and g are opened and closed by a slide k worked
by an excentric h' on the main shaft. Figure 4 is a face view of the slide k,
Figure 3 a view of that part of the cylinder à in which the ports fand g are
formed, and Figure 2 a view of the excentric. Gas is supplied to the port g
from a reservoir through a pipe n furnished with a cock o, and enters the port
through a passage r, while atmospheric air enters the port at the same time
through the passage 9; the proportion of air and gas admitted through the port g
may be regulated by the cock o. The inlet of air and gas by the passages q and r
is opened and closed by a slide 2 worked by an excentric ³.
The working of the engine is as follows:-Suppose the piston 6 to be at the
bottom of its course, as indicated in Figure 5, the piston 6 is raised by a
weighted beam, the piston c falls at the same time, or just before, to the bottom
of the cylinder, as shewn in Figure 6, air enters the cylinder between the two
pistons by the port f, the piston b continues to rise from the position shown in
Figure 6 to that shewn in Figure 7, thereby raising the piston c from off the
bottom of the cylinder and allowing a mixture of air and gas to enter the
bottom of the cylinder below the piston c by the port g. The excentric ' then
causes the slide k to rise and close the ports fand g, and at the same an
electric spark, produced as hereafter described, explodes the mixture of
gas and
air below the piston e, and drives it up so as nearly to touch the piston b, as
seen in Figure 8; in rising it lifts the cap m and allows of the atmospheric
air between the two pistons passing off through the apertures in the piston b;
cooling takes place almost immediately the piston c arrives at the top of its
stroke, a vacuum is formed, the pressure of the atmosphere closes the cap m,
and drives the piston 6 to the bottom of its course into the position indicated
in Figure 5, the excentric h' causing the slide k to descend and open the

page_text: As soon
ports fand g, the piston c falls by its own weight to the bottom of the cylinder,
the same operations are repeated as before, and so on continuously. Just before
the piston c commences its up stroke the excentric h³ lowers the slide and
allows the air and gas to enter the port 9 from the passages 7 and r.
as the slide k closes the ports f and g, the .slide should close the passages
r and g, as the gas would otherwise escape from the passage r through the
passage into the external air; or the slide k may be made to close the gas
supply at the proper moment; in this case, the gas instead of coming direct
from the reservoir to the cock o arrives by a pipe n', Figure 8, to a recess p¹ in
the side of the cylinder a, from which it passes through a slot p in the slide k
to another recess p³ in the side of the cylinder, and thence by a pipe n³ to the
cock ; thus when the slide k closes the ports f, g, it also closes the
recesses p, p, and shuts off communication between the pipes n¹ and n³. In
the position of the parts represented in Figure 5, the ports f, g, are opened by the
slide k, consequently p' is in communication with p², while the passages q, r,
are still closed by the slide 1, and another passages is.in communication with
the port g.
When the piston c falls, the air escapes from the cylinder through
the port g and passage s. In Figure 6 the passages is closed by the slide 1,
and the passages q. r, are open, so that air and gas rush into the bottom of the
cylinder inmediately the piston c begins its up stroke. In Figure 7 the slide k
has closed the ports f, g, and the recesses p', p³; the passages 9, r, are still
open, but are separated from the pipe ¹ by the slide k. In Figure 8 the
passages is represented as again opened, while 9 and 7 are closed, but this
position does not occur until the piston 6 commences its down stroke. A little
before the piston 6 reaches the bottom of its course the slide
reopens the
ports f, g, and the parts again occupy the respective positions indicated in
Figuge 5.
The explosion of the mixture of air and gas below the piston c is produced
as follows:-In the cylinder a, near the point x, Figure 1, there are two
insulated wires in connection with a galvanic battery; one of these wires is
connected to the engine and the other with an insulated spring y, Figure 1; a
projection on the main shaft of the engine comes in contact at each revolution
with the spring y, an electric spark is produced in the cylinder a, and the
mixture of air and gas is thereby exploded.
"In order to prevent the noise the air would make in issuing through the
piston directly into the atmosphere, and to increase the efficiency of the
engine, I close the cylinder a with a tight cover and connect the upper part by
means of a pipe t with a reservoir u fitted with a valve v, which is opened and
closed by a lever we connected to the rod of the excentric h³. As soon as the

page_text: piston 6 rises, the air escapes by the pipe t into the reservoir u, and thence
into the atmosphere through the valve v, which is then open. When the parts
are in the position represented in Figure 7, the ports ƒ and g and the valve v
are all closed. When the explosion takes place the air between the two pistons
is forced through the pipe t into the reservoir u. The gases. in cooling lose
the power due to their expansion, and the compressed air in the reservoir u
drives the piston 6 to the bottom of its course, when the valve vis again opened,
and so on continuously.
b
And having now described the nature of the said Invention, and in what
manner the saine is to be performed, I declare that I claim,-
First, constructing air and gas engines with two pistons in the same cylinder,
arranged and operating substantially as herein-before described and illustrated
in the accompanying Drawings.
Second, connecting the cylinder with the reservoir for air, substantially in
manner and for the purposes herein-before described and illustrated in the
accompanying Drawings.
In witness whereof, I, the said Richard Archibald Brooman, have
hereunto set my hand and seal, this Twenty-fourth day of February,
One thousand eight hundred and sixty-four.
R. A. BROOMAN. (L.D.)
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