IMPROVEMENTS IN OBTAINING MOTIVE POWER
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
JOHNSTON, of Willow Park, in the County of Renfrew, Esquire, send grecting."
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Eighth day of February, in the fourth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said
James Johnston, Her especial licence, full power, sole privilege and authority,
that I, the said James Johnston, my exors, adñiors, and assigns, or such
others as I, the said James Johnston, my exors, adîiors, or assigns, should
at any time agree with, and no others, from time to time and at all times
during the term of years therein expressed, should and lawfully might make,
use, exercise, and vend, within England, Wales, and the Town of Ber-
wick-upon-Tweed, my Invention of "IMPROVEMENTS IN OBTAINING MOTIVE
POWER;" in which said Letters Patent is contained a proviso that I, the said
James Johnston, shall cause a particular description of the nature of my said
Invention, and in what manner the same is to be performed, to be inrolled in
Her said Majesty's High Court of Chancery within six calendar months next
and immediately after the date of the said in part recited Letters Patent, as in-
and by the same, reference being thereunto had, will more fully and at large
annear

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
James Johnston, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, are particularly described
and ascertained in and by the following description thereof :-
My Invention consists in the working of an engine by the explosive and
condensing properties of certain proportions of oxygen and hydrogen gases.
EXPLANATION OF THE INVENTION.
In appearance my gas engine resembles a steam engine, the only essential
point of difference between. the construction of the two engines being in the
cylinder and its valves. This difference between the cylinders of the two
engines I shall describe after I have explained how the engine works. My
engine works as follows:-Suppose the piston to be at the bottom of the
cylinder, oxygen and hydrogen gases are admitted into. the cylinder below the
piston. The valve which admitted the gases is then closed, and the gases are
exploded by any of the ordinary.methods used for exploding them. Immediately
on the explosions taking place the piston is driven to the top of the cylinder, but
as soon as the gases have ceased, expanding there is a vacuum formed below the
piston. This is caused by the two gases
gases (oxygen and hydrogen) uniting and form-
ing. water. All the space below the piston, which was formerly filled with the
expanding gases, is now a void, with the exception of a very small quantity of
water. Thus the piston is driven to the top of the cylinder by the explosion of
the gases; a vacuum is then formed below it by the condensation of the gases..
The piston is again driven down by the gases being admitted and exploded,
above the piston; a vacuum is now formed above it; and in this manner the
engine continues to work as long as the gases are admitted and exploded
alternately above and below the piston, each explosion forcing the piston into
the vacuum formed by the previous explosion. The difference between the
cylinder of my gas engine and the cylinder of a steam engine is as follows:-
In the steam engine the piston is driven up and down by the pressure of the
steam on the piston, and as the pressure, of the steam must act on the piston
during the whole length of the stroke. therefore the valve which admits the
steam to the cylinder must remain open during the whole or nearly the whole
length of the stroke. In the gas engine the whole gas that is employed for
one stroke of the piston, either up, or down, must be admitted into, the cylinder
and the valve closed, previous. to the gas being, exploded, otherwise a large
portion of the explosive force of the gas would be lost; so that in order that
the whole gas required for one stroke of the piston may be admitted into either
top or bottom of the cylinder, it is necessary that a receptacle be made for the
...

page_text: gas at both ends of the cylinder. The power of the engine will depend upon
the proportion of the e area of the cylinder to the area of the receptacles for the
gases at the ends of the cylinder. Many of the valves that are used'in steam
engines may also be used for my gas engine, but the gearing which is
commonly used for opening and shutting the valves of a steam engine will
not do for my gas engine, as the valves require to be opened to their full
extent to admit the gases, and to be immediately closed in order that the
explosion may take place. From this it is evident that each valve is only
opened for a short interval during each revolution of the fly wheel of the
engine. The gearing which I have hitherto used for opening "the valves
"differs from that which is commonly used in steam engines in this respect:
that in a steam engine the valves are usually opened by a rod worked by an
eccentric on the shaft of the 'fly wheel. Now, instead of putting 'the eccentric
upon the shaft of the fly wheel, I place it upon a shaft which lies parallel to
and within a short distance of the flywheel shaft. I shall call this the
eccentric shaft, as it is made for the purpose of putting the eccentric in motion
only at a certain period of the engine's stroke. The gearing by which the fly
wheel shaft sets the eccentric shaft in motion is by toothed wheels. On the
eccentric shaft there is place a small complete toothed wheel. On the shaft
of the fly wheel there is placed a segment of a large wheel, which has on its
circumference the same number of teeth as the small wheel on the eccentric
shaft has. These two wheels are placed on their respective shafts in such a
way as that when the fly wheel makes a revolution the teeth of the segment
wheel comes in 'contact with and causes the small wheel on the eccentric shaft
to make one revolution. From the peculiar construction of this gearing it is
evident that by 'keying the segment wheel 'on the fly wheel shaft, at a
particular point, the eccentric shaft can be set in motion' (or 'caused to make
one revolution) at any particularly required period of the revolution of the fly
wheel, and consequently that the valves can be opened and shut by the
eccentric at any required time during the stroke of the piston. The gearing
which explodes the gases is also connected' with the eccentric shaft, so that the
whole works in unison. I shall 'not go further into detail on this part of the
engine; as it is an easy matter for any mechanic to plan this or any similar
contrivance for opening the valves at the required time. I do not claim this
as a part of my Invention, as I believe an apparatus somewhat similar has
been used for working steam engines expansively. The best proportion of the
two gases for working this engine is that proportion of them which forms water
when they are exploded, without leaving a residue either of oxygen or hydrogen.
This proportion is about one part of oxygen to two parts of hydrogen. As it is

page_text: "
essential to the value of everything claimed for in a Patent that it be new and
original, I shall briefly point out wherein my Invention differs from any Inven-
tion of a similar nature that I am aware of having been discovered. Many
attempts have been made to construct engines that could be put in motion by
the explosive force of gasses; all of these engines may, I believe, be classed
into two kinds :-
First, those which work simply by the explosion of the gas;
Secondly, those that work by the joint action or force of the formation of
the gas and the explosion of it.
My Invention does not interfere with the first class of explosive engines,
because I do not claim the exclusive right of using the explosive power of
oxygen and hydrogen gases, as the explosive force of these gases has long
been known, and attempts made to apply it to the setting of machinery in
motion.
My claim does not interfere with the second class of explosive engines,
because I do not make use of or attempt to obtain any power whatever from
the formation of the gases which I use for putting my engine in motion. . *As
an engine of the second class has been lately patented, and as the Patentee
claims the exclusive use of the forces given out in the formation and explosion
of the same gases as I use; I shall now point out the difference in the working
of the two engines. The Patent which I refer to is that of William Henry
Fox Talbot, Esquire, of Laycock Abbey, Wilts; his claim is "For a Method
of Obtaining. Motive Power by the alternate Evolution and Combustion or
Explosion of (Oxhydrogen or other Inflammable) Gases, the said Evolution
being caused by the Decomposition of a Liquid by the Voltaic Current, and
the said Explosion or Combustion being also caused by a Voltaic Current."
Now, from his claim and the description which he gives of his engine, it is
plain that it works simply by the power given out by the gas or gases; in the
act of being made and exploded; he does not claim for the making use of a
vacuum, and evidently he is not aware that a vacuum is formed after an
explosion of certain proportions of oxygen and hydrogen gases, or at least he is
not aware that that vacuum can be applied to any useful purpose in the work-
ing of an engine, for, by his claim, he declares that his engine can work with
any other inflammable gases; now none of the other inflammable gases form a
vacuum after they are exploded, at least such a vacuum as could be employed
in the working of an engine.
I claim for the working condensively of "oxhydrogen gas explosive engines;"
or in other words,
I claim for the working of an engine by the joint action of the explosive
and condensive properties which certain proportions of oxygen and bydrogen

page_text: gases possess when exploded together. The best proportion of the two gases
is about one part of oxygen to two parts of hydrogen. I do not confine myself
to any particular form of engine.
In witness whereof, I, the said James Johnston, have hereunto set my
hand and seal, this Twenty-first day of July, One thousand eight
hundred and forty-one.
John Fairrie, of Clapham, in the County of Surrey, Esquire, maketh oath
and saith that he is acquainted with the handwriting of Robert Baine, Esquire,
one of Her Majesty's Justices of the Peace for the County of Renfrew; and
that the signature to the acknowledgment on James Johnston's Specification
attached hereto is, to the best of this deponent's knowledge and belief, in the
handwriting of the said Robert Baine. And this Deponent further saith that,
to the best of his belief, the said Robert Baine was, at the time of receiving such
acknowledgment, a Justice of the Peace for the said County of Renfrew.