Iм- PROVEMENTS IN MOTIVE-POWER ENGINES WORKED BY EXPLOSIVE MIXTURES OF OR VAPOUR
Year: 1864

page_text: LETTERS PATENT to Francis Herbert Wenham, of 1, Union Road
Clapham, in the County of Surrey, Engineer, for the Invention of "Iм-
PROVEMENTS IN MOTIVE-POWER ENGINES WORKED BY EXPLOSIVE MIXTURES OF
OR VAPOUR"
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Scaled the 28th October 1864, and dated the 9th May 1864.
PROVISIONAL SPECIFICATION left by the said Francis Herbert Wenham
at the Office of the Commissioners of Patents, with his Petition, on the
9th May 1864.
I, FRANCIS HERBERT WENHAM, of 1, Union Road, Clapliam, in the
County of Surrey, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN MOTIVE-POWER ENGINES WORKED BY EXPLOSIVE
MIXTURES OF GAS OR VAPOUR," to be as follows:-
This Invention consists of two pistons contained in a cylinder with open
ends. The first piston works a crank by means of a connecting rod; the
second is disconnected. During the revolution of the crank the second
piston follows close to the first by atmospheric pressure till near the termination
of the up stroke, they then separate for a short distance, at which time a
mixture of gas and air or explosive vapour is drawn in between them. When
the first piston arrives at the end of the stroke, it uncovers a small firing
aperture or touch-hole, through the side of the cylinder a flame is drawn in,
the gases take fire, and by explosion drive the second piston to the opposite
open end of the cylinder; here is fixed a cross bar, through which the flat rod

page_text: of the second piston passes, this is now instantly held fast by means of two
wedges driven into the cross bar against the flat sides of the rod; this, and
the wedges may be grooved to increase the grip. A vacuum is formed
between the pistons and the one connected with the crank,in approaching, the
other, by atmospheric pressure, causes the revolution of the shaft. The
pistons before again coming into contact drive the products of combustion
from between them through an outlet valve in the side of the cylinder. The
loose piston is again released by withdrawing the wedges, and follows after
the other for the succeeding stroke.
The next improvement is for a means of igniting the gaseous mixtures. A
gas jet points directly into the above-mentioned touch-hole in the side of the
cylinder. Surrounding the flame of the jet is a cage or coil of wire of
platinum or other metal, or a perforated cylinder of any substance capable of
retaining heat may be used. A similar arrangement, but of larger diameter,
is also fixed round the touch-hole; both these remain in a red-hot state during
the working of the engine, and prevent the flame of the jet from being blown
out by the force of the explosion through the touch-hole. I also increase the
force of the igniting jet by means of a small pump, or hydraulic or other
bellows, for giving greater pressure to the gas and intensity to the flame of
the igniting jet.
A further improvement consists in passing the gas or air, either separately
or together before entering the working cylinder, through a receptacle
containing naptha, petroleum oil, or other volatile liquids capable of affording
imflammable vapour, which receptacle may be heated to assist the
vaporization.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed.
by the said Francis Herbert Wenham in the Great Seal Patent Office
on the 8th November 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FRANCIS
HERBERT WENHAM, of 1, Union Road, Clapham, in the County of Surrey,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of May, 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 Francis Herbert Wenham, Her special licence that I, the said

page_text: Francis Herbert Wenham, my executors, administrators, and assigns, or such
others as I, the said Francis Herbert Wenham, 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 MOTIVE-POWER ENGINES WORKED
BY EXPLOSIVE MIXTURES OF GAS OR VAPOUR," upon the condition (amongst
others) that I, the said Francis Herbert Wenham, my executors or adminis⚫
trators, 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 Francis Herbert Wenham, do hereby
declare the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement and accompanying Drawings, that is to say :-
The first part of this Invention consists of two pistons, a and b, Figs...
1 and 2, contained in a cylinder c, with open ends. The first piston a works
a crank d by means of a connecting rod e. The second piston is disconnected.
During the revolution of the crank the second piston follows close to the
first by atmospheric pressure, till near the termination of the up stroke, a
stop fon the second piston rod causes them to separate for a short distance,
at which time a mixture of gas and air or explosive vapour is drawn in
through the slide valve g worked by the rod and cam h, the air entering
through passages drilled in the end of the valve, and the gas supply being
regulated by a cock. When the first piston arrives at the end of the stroke,
passes and uncovers a small firing aperture or touch-hole i. Through the
side of the cylinder a flame is drawn in, the gases take fire, and by explosion
drive the second piston b to the opposite open end of the cylinder; here there
is a cross bar through which the flat rod of the second piston passes. This
is now instantly held fast by means of two wedges),j, driven into the cross-
bar against the sides of the rod. This and the wedges may be.grooved to
increase the grip. A vacuum is formed between the pistons and the one
connected with the crank in approaching, the other, by atmospheric pressure,
causes the revolution of the shaft. The pistons before coming into contact
drive the products of combustion from between them through an outlet
it

page_text: valve in the side of the cylinder. On the return stroke the loose piston is
again released by the cam / withdrawing the wedges, and follows the other
for the succeeding stroke.
The next improvement, shown full size by Fig. 3, is for a means of
igniting the gaseous mixture. A gas jet a points directly to the above-
mentioned touch-hole in the side of the cylinder. Surrounding the flame of
the jet is a cage or coil of wire b, of platinum or other metal, or a perforated
casing of any substance capable of retaining and enduring heat may be used.
A similar arrangement c, but of larger diameter is also fixed round the touch-
hole. Both these heat retainers remain ignited during the working of the
engine, and prevent the flame of the jet from being extinguished by the force
of the explosion through the touch-hole. In cases where the gas supply is
delivered at a low pressure, I increase the force of the jet flame by means of
a small pump or hydraulic or other bellows worked by the engine. In order
to increase the power of the engine, the gas or air may be passed either
separately or together beforeentering theworkingcylinder, through a receptacle
containing naptha, petroleum, oil, or other volatile liquid capable of affording
inflammable vapour, which receptacle may be heated to assist the vaporization..
The engine just described is single acting; when much power is required, two
of them may work on cranks set in opposite directions, but the following
arrangement will give double action, with only one cylinder in Figs.
4 and 5; a, a, is the working cylinder containing a piston b, the rod of which
passes through a stuffing box, and works the crank by a connecting rod.
When the piston is at either end of the stroke, the air and gas valve c is
opened by the cam d, after the pistou has travelled a short distance the valve
is closed, the touch-hole e is then uncovered, and quickly closed again by a
cam motion. The mixture fires and exerts a pressure on the piston till near
the termination of the stroke, by which time this pressure is exhausted, and is
succeeded by a vacuum which acts on the piston during the return stroke, at
the end of which the products of combustion are discharged through an outlet
valve f, which valve is kept closed by the catch g, while the piston is receeding
and during the explosion. The action described is for one end of the stroke,
but it will be seen that the touch-hole and valves are the same at each end of
the cylinder, so that this action repeated causes the engine to give an equal
force at the up and down stroke, and makes it double acting.
Having described the nature and action of my Invention, what I claim is
first, the arrangement of engine and mode of holding the loose piston during
the acting stroke by wedges substantially as described in Figs. 1 and 2.
I also claim the mode of firing described in Fig. 3, by surrounding the
gas

page_text: jet and touch-hole by a wire cage or perforated case of suitable fire enduring
material kept in au ignited state.
I also claim increasing the pressure of the gas for igniting and thereby
adding to the intensity of the flame, by forcing it through the jet by a pump
or bellows.
I also claim the engine described in Figs. 4 and 5, and the peculiar
action relating to the exploded mixtures of gas exerting a pressure on the
piston during the forward stroke, and the subsequent vacuum acting on the
piston during the return stroke.
In witness whereof, I, the said Francis Herbert Wenham, have hereunto
set my band and seal, this Eighth day of November, in the year of
our Lord One thousand eight hundred and sixty-four.
FRANCIS HERBERT WENHAM. (L.S.)