IMPROVEMENTS IN OBTAINING MOTIVE POWER
Year: 1860

page_text: LETTERS PATENT to Henry Francois Cohade, late of Gravelle, Saint
near Charenton, (Seine,) France, for the Invention of
Maurice,
"IMPROVEMENTS IN OBTAINING MOTIVE POWER."
Sealed the 24th August 1860, and dated the 30th June 1860.
PROVISIONAL SPECIFICATION left by the said Henry Francois Cohade at
the Office of the Commissioners of Patents, with his Petition, on the
30th June 1860.
I, HENRY FRANCOIS COHADE, of Gravelle, Saint Maurice, near Charenton,
(Seine,) France, do hereby declare the nature of the Invention for "IMPROVE-
MENTS IN OBTAINING MOTIVE POWER," to be as follows: -
This Invention has for its object improvements in obtaining motive power.
Heretofore in machines which have been constructed for obtaining motive
power by means of explosive mixtures of gases and compounds, it has been
usual to cause the force of the explosion to act directly on a piston or other
instrument, which, by rods or other more or less rigid connections is linked
with the shaft or machinery to be actuated by it. Now, according to this
Invention, I cause the explosive mixture of gases or other explosive compound
to be exploded or burnt in a close vessel furnished with a valve, opening from
the explosion chamber into a close vessel. With each charge of explosive
gas or compound a quantity of air is admitted to the explosion chamber, and
[Price 8d.]

page_text: when the charge is burnt, the air with the gaseous products of the combustion
(if any) are forced by the valve on the combustion chamber into the close
vessel before mentioned, and with this compressed air any engine suitable to be
worked by the pressure of gas may be actuated. The explosive compound 1
commonly employ is a mixture of coal gas and air, and I employ two pumps
of different diameters, but working in unison, one of which throws gas, and
the other air into the explosion chamber; this chamber is separated by a valve
from the pumps, and after each stroke of the pumps, when this valve has
closed, the explosion is produced. The heated gas and air as it leaves the air
engine I cause to pass over surfaces which absorb its heat (causing it to pass
through metal tubes is a convenient arrangement), and the explosive mixture
before it enters the explosion chamber I cause to pass in contact with the
same surfaces; by this means the heat of the waste gases is utilized.
In some cases I place a piston in the explosion chamber, which is then
made cylindrical. The explosive mixture is introduced on one side of the
piston, and air by a suitable valve on the other. When the piston is moved
by the explosion of the gas on one side of it, the air on the other is forced
out through a valve into a close vessel as before, and from the pressure so
generated an air engine may be worked. The same air in this case may con-
veniently be worked through and through the engine by receiving it into a
reservoir after it passes the air engine, and connecting the said reservoir with
the valve before mentioned for admitting air to the combustion chamber. A
partial vacuum will be produced in the combustion chamber after each
explosion, which, in the arrangement above described, will tend to exhaust
the reservoir mentioned above. In this arrangement the piston in the
explosion chamber is perfectly free, and this chamber is made of such a length
that (with the charge employed) that the piston may not be thrown violently
against the end of the chamber. The working length of this chamber may be
made adjustable, and a slide valve is employed, which opens to allow the
products of combustion to escape; the same valve may also be used to admit
explosive gases to the chamber. In some cases, in place of leaving the piston
perfectly free in the explosion chamber, I connect it so as to cause it to work
a valve to admit the explosive mixture to the chamber to cut it off therefrom,
and also to regulate the escape of the products of combustion.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, nied
by the said Marie Josephine Cohade, of Gravelle, Saint Maurice, near
Charenton, (Seine,) France, (Widow and Executrix of the said Henry
Francois Cohade, who departed this life on or about the Fifteenth day
of October, One thousand eight hundred and sixty,) in the Great Seal
Patent Office on the 29th December 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME. 1, MARIE
JOSEPHINE COMIADE, of Gravelle, Saint Maurice, near Charenton, (Seine,)
France, Widow and Executrix of Henry Francois Colade, late of Gravelle,
Saint Maurice, near Charenton, (Seine,) France, aforesaid, who departed this
life on or about. the Fifteenth day of October, One thousand eight hundred
and sixty, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of June, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto him,
the said Henry Francois Cohade, Her special licence that he, the said Henry
Francois Cohade, his executors, administrators, and assigns, or such others as
he, the said Henry Francois Cohade, his 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 "In-
PROVEMENTS IN OBTAINING MOTIVE POWER," upon the condition (amongst others)
that he, the said Henry Francois Cohade, his executors, or administrators, by
an instrument in writing under his, 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 bo
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 Marie Josephine Cohade, as such,
widow and executrix, as aforesaid, do hereby declare the nature of the said
Invention, and in what manner the same is to be performed, to be par
ticularly described and ascertained in and by the following statement thereof,
that is to say-
This Invention has for its object improvements in obtaining motive power.
Heretofore in machines which have been constructed for obtaining motive
power by means of explosive mixtures of gases and compounds, it has been

page_text: usual to cause the force of the explosion to act directly on a piston or other
instrument, which, by rods or other more or less rigid connections, is linked with
the shaft or machinery to be actuated by it. Now, according to this Invention,
I cause the explosive mixture of gases or other explosive compound to be
exploded or burnt in a close vessel furnished with a valve opening from the
explosion chamber into a close vessel. With each charge of explosive gas or
compound a quantity of air is admitted to the explosion chamber, and when the
charge is burnt, the air with the gaseous products of the combustion (if any)
are forced by the valve on the combustion chamber into the close vessel before
mentioned, and with this compressed air any engine suitable to be worked by
the pressure of gas may be actuated. The explosive compound I commonly
employ is a mixture of coal gas and air, and I employ two pumps of different
diameters, but working in unison, one of which throws gas, and the other air
into the explosion chamber; this chamber is separated by a valve from the
pumps, and after each stroke of the pumps when this valve has closed the
explosion is produced. The heated gas and air as it leaves the air engine 1
cause to pass over surfaces which absorb its heat (causing it to pass through
metal tubes is a convenient arrangement), and the explosive mixture before it
enters the explosion chamber I cause to pass in contact with the same
surfaces; by this means the heat of the waste gases is utilized.
Figure is a vertical section of an apparatus so arranged; Figure 2 is a
plan of the same.
a and b are two pump cylinders, the smaller cylinder a is supplied, by
preference, with coal gas by the pipe c; d, d, are valves admitting the gas to
the cylinder; and e, e, are other valves to prevent its return after it has been
forced from the cylinder by the piston f; this piston is mounted on a rod g,
which may be worked to and fro by a crank on the axis of the air engine, or
in other convenient manner; is a piston also fixed on the rod g, and working
in the cylinder b, to which air is admitted by valves i, i, and the cylinder is
also provided with other valves j. j, to prevent the return of the air after it has
been forced from the cylinder by the piston. The air passes from the cylinder
b by the pipe k, and is led by it into the heater 1, which is, as the Drawing
shows, a vessel traversed by a number of pipes of small diameter, through
which the air which works the air engine (and which is highly heated) is
caused to pass before it escapes into the atmosphere; by passing amongst
these pipes the air becomes heated before it enters the explosion chamber,
and the air which has passed through the machine is deprived of the greater
part of its heat, which would otherwise be wasted. In place of passing the
incoming air only through the heater, the explosive
mixture of gas and air

page_text: may be so heated; the arrangement shown is, however, more convenient.
The air from the heater, and the gas from the cylinder a pass by pipes m
and to the explosion chamber o, which they enter through a valve p. When
the pumps come to the end of their strokes the valve p closes, and immediately
by suitable electric apparatus, a spark is caused to pass over the short space
between the ends of the wires q, q, which are carefully insulated the one from
the other, and explosion immediately ensues, by which the air in the explosion
chamber which was in excess of the quantity necessary to consume the com-
bustible gas, together with a portion of the residual gases is forced through
the valve r at the top of the explosion chamber into the reservoir s, immedi-
ately the pumps force another charge of gas and air into the explosion
chamber, and this is in turn fired, and the action thus continues, the air to
work the air engine being drawn from the reservoir s by the pipe t. The
Drawing shows two explosion chambers o working together.
A
In some cases I place a piston in the explosion chamber, which is then
made cylindrical. The explosive mixture is introduced on one side of the
piston, and air by a suitable valve on the other. When the piston is moved
by the explosion of the gas on one side of it, the air on the other is forced out
through a valve into a close vessel as before, and from the pressure so gene-
rated an air engine may be worked. The same air in this case may con-
veniently be worked through and through the engine by receiving it into a
reservoir after it passes the air engine, and connecting the said reservoir with
the valve before mentioned for admitting air to the combustion chamber.
partial vacuum will be produced in the combustion chamber after each explo-
sion, which in the arrangement above described will tend to exhaust the
reservoir mentioned above. In this arrangement the piston in the explosion
chamber is perfectly free, and this chamber is made of such a length that
(with the charge employed) the piston may not be thrown violently against
the end of the chamber. The working length of this chamber may be made
adjustable, and a slide valve is employed which opens to allow the products
of combustion to escape; the same valve may also be used to admit explosive
gases to the chamber.
A vertical section of apparatus arranged in the manner above described is
shewn at Figure 3.
a is the explosion chamber of a cylindrical form, in which the piston bis
placed; it is properly packed and fits the cylinder accurately; c is a pipe for
admitting the explosive mixture to the explosion chamber; it is forced into the
same by pumps as already described, or in other convenient manner; d is a
slide which is removed from the orifice of the pipe c, when the explosive com-

page_text: pound is to be allowed to pass into the chamber a. When the slide is thus
drawn back, the explosive mixture enters the chamber a until the piston b is
raised to the position b', the slide d is then again caused to close the inlet pipe,
end the mixture is fired by a spark passing between the ends of the wires e;
the explosion throws the piston a greater or less distance up the explosion
chamber according to the quantity of inflammable gas or material in the mix-
ture admitted. The air contained in the vessel a over the piston before the
explosion is forced out through the valves /, /, into the reservoir g, from whence
it is drawn by a pipe h to supply the air engine. The valves /, /, are fitted in
a moveable end or cover of the chamber a, which can slide therein as a piston;
it is attached to the end of the pipe i, and when the apparatus is at work it
should be set at such a height that the piston bat each explosion just comes
up to it without striking it. To allow of its being so set a screw thread is
formed on the exterior of the pipe i, and a nut i works thereon, this nut can
be turned by a worm k on the axis of the crank handle 1, gearing with teeth
on the periphery of the nut, the pipe i is prevented from turning by being
made at its upper end to fit the exterior tube m, which is made square, or of
other convenient form. Immediately after the explosion, the piston b begins
to fall by its own weight, and also in consequence of there then being a partial
vacuum beneath it, and air then passes from the reservoir n, which receives
the air after it has passed through the air engine by the pipes m and i into the
space over the piston in the chamber a. The return of the piston to the
bottom of the chamber is ensured by the slide o opening to allow the escape
of the residual gases; another charge of explosive compound is then admitted
to the explosion chamber a, and so the action goes on.
In some cases in place of leaving the piston perfectly free in the explosion
chamber, I connect it so as to cause it to work a valve to admit the explosive
mixture to the chamber to cut it off therefrom, and also to regulate the escape
of the products of combustion.
Figure 4 shews a vertical section of an apparatus in which the piston is
caused in its motion to open and close the valves. This apparatus differs also
in some other respects from that shewn at Figure 3. a and bare two pipes
conducting the one gas, and the other air from the pumps to the apparatus;
c is a slide valve which regulates the admission of the gas and air to the explo-
sion chamber d, and also the escape of the residual gases therefrom; e is a
piston working gastight in the explosion chamber, and having a rod con-
nected to it; g is a double incline or cam surface fixed at the end of the
rod f; h, h, are rollers carried by the arms of the lever i, which turns on a
fixed centre, and is connected with the valve c by a link ; the incline or cam

page_text: surface comes in contact with the rollers h, h, and so moves them as to
work the valve. When the piston is in the position in which it is shewn in
the Drawing the first operation is to admit the explosive mixture until it is
raised to about the position e', when the valve is closed, and an explosion pro-
duced by an electric spark passing between the ends of the wires as before.
The air in the explosion chamber over the piston is forced past the valve !
into the reservoir m, from which it is drawn to work the air engine n; it passes
to the said engine by the pipe o, and returns therefrom by another pipe p into
another reservoir q, to pass again through the apparatus as soon as the
piston e has arrived at the point e' or thereabouts; the slide valve c is so
placed as to allow of the escape of the residual gases from under it, and it
then again descends towards the bottom of the explosion chamber, the space
over it being supplied with air from the reservoir q, the air in passing from
the reservoir raising the valve r, which prevents its return to the reservoir q
when an explosion takes place. When the piston gets to the bottom of the
explosion chamber a fresh charge of explosive mixture is admitted, and in
this manner the apparatus continues to work; s is a jacket to prevent loss of
heat from the chamber d.
Figure 5 is a horizontal section of an apparatus differing somewhat from
those before described, but similar in its principle of action; Figure 6 is a
vertical section, and Figure 7 a transverse section of the same apparatus.
a is a cylindrical explosion chambor in which a piston b works; it is fixed to
a piston rod c, and is worked to and fro by preference by a crank on the axis of
the air engine which the apparatus is employed to work; d is a pipe supplying
combustible gas to the apparatus, this pipe is fitted with a valve e to regulate
the amount of gas supplied, this valve is actuated by the governor on the air
engine;,, are slide valves, they are linked together, and are by preference
worked by a cam on the axis of the air engine; g, g', are passages for admit-
ting gas to the explosion chamber; and h, h', are passages to admit air to,
As soon as the
and to allow the residual gases to escape from the same.
piston b gets to the position in which it is shewn at one end of its stroke, the
slide valve is so placed as to admit gas and air to the chamber a as the
piston returns, and the valve fis at the same time so placed as to allow
the escape of the residual gases which pass away in the passage i.
When the piston gets nearly to the other extremity of its course, the slide
valves close all the orifices, and an explosion is produced by the wires i, i; this
forces the excess of air and some of the residual gases through the valve k into
the reservoir which supplies the air engine. Immediately the slide valve f¹
is set to admit the gas and air behind the piston and the valve f, to allow the

page_text: escape of the residual gases by the passage i', and when the chamber a is full,
the wires, fire the mixture, and air and residual gas is driven through the
valve into the reservoir l, and thus the operation continues. The chamber a
being surrounded by the reservoir will keep the air in this reservoir highly
heated; m, m, are stops to prevent the valves k, k', being thrown off their
seats; n is a safety valve; o is an instrument for indicating the temperature
of the air in the reservoir l.
In witness whereof, I, the said Marie Josephine Cohade, have hereunto
set my hand and seal, this Twenty-seventh day of December, in the
year of our Lord One thousand eight hundred and sixty.
Witness,
T. BASSET.
VVE. COHADE. (I..S.)