IMPROVE- MENTS IN MOTIVE-POWER ENGINES
Year: 1864

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of "IMPROVE-
MENTS IN MOTIVE-POWER ENGINES." -A communication from abroad by
IT I
1
Eugène Desrousseaux Hubert, of Paris, in the Empire of France.
5 Middlesex, Gentleman, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN MOTIVE-POWER ENGINES," a communication to me from
abroad by Eugène Desrousseaux Hubert, of Paris, in the Empire of France,
to be as follows:-
This Invention relates to that class of motive-power engines which are
worked by compressed air in lieu of steam, the object of the present improve-
ments being economy of fuel.
According to this Invention it is proposed to work a piston or pistons in a
cylinder or cylinders by means of compressed air expanded by heat before
entering the valve box, and to employ a portion of the power so obtained in
forcing fresh air into the main receiver or compressed air vessel.
According to one mode of carrying out this Invention in practice a suitable
compressed air vessel is connected by means of a pipe with a coil or series of
heating pipes placed inside a furnace, such coil or series of heating pipes

page_text: communicating through a safety valve box with the slide or other valve box
of the working cylinder. The piston rod of the working piston is prolonged
so as to carry a second piston or plunger, which works in an air pump con-
nected by a pipe with the compressed air vessel. A second pipe is fitted to
the air pump, through which air is drawn into the pump barrel, whence it is
forced out through the pipe before referred to into the air vessel, suitable
valves being employed to direct the passage of the air. The pipe which
supplies the air pump is fitted with a throttle valve, acted upon by a self-
acting valve inside the air vessel, so that when the pressure therein diminishes
the self-acting valve will open the throttle valve, and vice versa, whereby an
This vessel is also fur-
uniform pressure is maintained inside the air vessel.
nished with two safety valves, one of which is acted upon by the governor or
regulator of the engine, so as to open and close more or less according to the
speed of working.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office
on the 8th August 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of February, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-seventh year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Henry Johnson, Her special license that I, the said
John Henry Johnson, my executors, administrators, and assigns, or such
others as I, the said John Henry Johnson, my executors, administrators, or
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 MOTIVE-POWER ENGINES," a communication
to me from abroad by Eugène Desrousseaux Hubert, Paris, in the Empire
of France, upon the condition (amongst others) that I, the said John
Henry Johnson, my executors or administrators, by an instrument in writing
under my hand and seal, or under the hand and seal of one of them, should

page_text: 5
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 John Henry Johnson, 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, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say :-
-
The said Invention relates to that class of motive-power engines which are
worked by compressed air in lieu of steam, the object of the present improve-
ments being economy of fuel.
According to this Invention it is proposed to work a piston or pistons in a
cylinder or cylinders by means of compressed air expanded by heat before
entering the valve box, and to employ a portion of the power so obtained in
forcing fresh air into the main receiver or compressed air vessel.
According to one mode of carrying out this Invention in practice a suitable
compressed air vessel is connected by means of a pipe with a coil or series of
heating pipes placed inside a furnace, such coil or series of heating pipes com-
municating through a safety valve box with the slide or other valve box of the
working cylinder. The piston end of the working piston is prolonged so as to
carry a second piston or plunger, which works in an air pump connected by a
pipe with the compressed air vessel. A second pipe is fitted to the air pump,
through which air is drawn into the pump barrel, whence it is forced out
through the pipe before referred to into the air vessel, suitable valves being
employed to direct the passage of the air. The pipe which supplies the air
pump is fitted with a throttle valve, acted upon by a self-acting valve inside
the air vessel, so that when the pressure therein diminishes the self-acting
valve will open the throttle valve, and vice versa, whereby an uniform pressure
is maintained inside the air vessel. This vessel is also furnished with two
safety valves, one of which is acted upon by the governor or regulator of the
engine, so as to open and close more or less according to the speed of
working.
And in order that the said Invention may be fully understood I shall refer
to the accompanying Drawing, which represents a partial section and
elevation of a compressed air engine constructed and worked according to this
Invention.
a is a compressed air vessel, which is kept constantly supplied with air by
the air pump b. This vessel is provided at its lower part with a pipe c. which

page_text: communicates with a heating apparatus A of a spherical or other convenient
shape. The heating apparatus may consist of two cast-iron or other metal
shells covered with a refractory envelope c', over and round which is fitted a
strong wrought-iron casing made in two halves bolted together in the direc-
tion of the horizontal diameter of the sphere. The joints of the cast-iron a
shells and of the wrought-iron casing are disposed so as not to coincide with
each other, and thus prevent any exit of gas or compressed air.
The object of this arrangement of cast-iron shells and covering of refractory
material is to prevent any oxidation and undue heating of the outer or
wrought-iron casing, whilst it affords at the same time a considerable degree
of resistance to explosions. In the interior of the cast-iron sphere is placed a
coil, one end of which communicates with the fire-place or furnace C, whilst
the other end opens into the chimney. Two pipes c, f, communicate the one
with the lower portion of the sphere and the other with the upper part
thereof. The first-mentioned pipe c serves to convey the air from the com-
pressed air reservoir or vessel a to the sphere, and the second pipe f conducts
this air, after it has been heated, inside the sphere to the working cylinder i
of the engine. The inlet and outlet pipes to and from the sphere may each
be provided with a convenient stop-cock for interrupting the circulation of air
when requisite. From the heating apparatus the compressed air now in an
expanded state passes into the valve box h of the working cylinder i, and
acts upon the piston in such cylinder. The rod of this piston is con-
nected to another piston k working inside the cylinder b, which cylinder is
of the same length as the cylinder i; the function of the piston k is to draw
in air from the external atmosphere, and force it into the compressed air
reservoir or vessel a; this vessel should be provided with several valves, one
of which is intended to maintain a constant pressure of air inside the vessel a.
For this purpose the valve is so disposed as to open the air passage when the
pressure decreases inside the vessel, and to close this passage when the
pressure is sufficient. The second valve acts as an ordinary safety valve, and
is regulated according to the maximum pressure of air to be maintained in
the vessel. The third valve is acted upon by the governor or regulator, which
regulates the opening or closing of the same in accordance with the variations
in the speed of the engine.
It has been found in practice that air expanded by heat when employed
alone sometimes occasions inconvenience by causing the piston after a short
time to grip or fit too tightly inside the cylinder, and thereby injure the same.
In order to obviate this objection, the Inventor purposes to employ a small
additional boiler J containing water, and heated by the gas escaping from the

page_text: I may
heater. Steam of a very low pressure is thus produced, a jet of which is
caused to enter the working cylinder at each stroke of the piston, and by its
humidity counteracts the evil effects of the hot air above referred to.
here observe, however, that I do not claim, as forming any part of the present
5 Invention, the application and use of the boiler J above mentioned. In
order that this engine may work to the greatest advantage, the air should be
compressed to ten, fifteen, or twenty atmospheres in the vessel a, so that
when once expanded the force obtained shall exceed that expended in the
working of the air pump.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe, in conclusion, that what I consider to be novel
and original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent, is,―
First, the application and use to and in hot air engines of an air pump, a
compressed air vessel, and an air heating apparatus in combination with a
working cylinder and piston, the whole operating substantially in the
manner and for the purpose herein-before described and illustrated by the
Drawing.
Second, the application and use of compressed air expanded by heat before
entering the working cylinder for the obtainment of motive power substantially
as herein-before described.
Third, the applying of a portion of the force exerted by the working piston
of a hot air engine to the compression of air in an air vessel, such
compressed air being employed in working the engine, as herein-before
described.
In witness whereof, I, the said John Henry Johnson, have hereunto set
my hand and seal, this Eighth day of August, One thousand eight
hundred and sixty-four.