IMPROVEMENTS IN THE PRODUCTION OF MOTIVE POWER
Year: 1853

page_text: LETTERS PATENT to LAURENCE HILL junior, of Port Glasgow,
in the County of Renfrew, Ship Builder, for the Invention of
"IMPROVEMENTS IN THE PRODUCTION OF MOTIVE POWER."- A commu-
nication.
--
Sealed the 23d August 1853, and dated the 2d March 1858.
PROVISIONAL SPECIFICATION left by the said Laurence Hill junior,
at the Office of the Commissioners of Patents, with his Petition, on
the 2d March 1853.
I, LAURENCE HILL junior, of Port Glasgow, in the County of
Renfrew, Ship Builder, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN THE PRODUCTION OF MOTIVE POWER" to be as
follows, viz. To move or actuate engines (such as are at present usually
driven by steam) or any other convenient form by means of air heated
and expanded by admixture therewith of steam or heated vapour. Th
heat is thus more economically imparted to the air than when done

page_text: through the intervention of metallic substances, as has hitherto been
the case. To do this, one or more force-pumps to compress the air
(and it may be an air reservoir), and valves to admit the air so com-
pressed into the working cylinder, require to be added to an engine,
such as presently driven by steam. In the experiments made, the air
has been admitted for a part of the stroke; say, for example, 1-7th; and
the steam for about a similar length; and the rest of the stroke is
finished by the united expansion of the air and steam.
Steam at
various pressures up to 75lbs. pressure per inch was used, and the air
was compressed to nearly the same density; but I do not limit myself
to this pressure; and, as a good effect may be obtained by mixing the
steam and air previous to admission to the working cylinder, I do not
confine myself to the above manner of carrying out the Invention. A
more complete description will be given in the "Complete Specification,"
and I wish to patent the heating and expansion of air in a closed
vessel, by direct contact or admixture with steam, for the purpose of
producing motive power.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Laurence Hill junior, in the Great Seal Patent
Office, on the 30th August 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
LAURENCE HILL junior, of Port Glasgow, in the County of Renfrew,
Ship Builder, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of March, in the year of our
Lord One thousand eight hundred and fifty-three, in the sixteenth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Laurence Hill junior, Her special licence that I,
the said Laurence Hill junior, my executors, administrators, and
assigns, or such others as I, the said Laurence Elill junior, my executors,
-administrators, and assigns, should at any time agree with, and no

page_text: 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 THE PRODUCTION OF MOTIVE POWER," being a communication from
abroad, upon the condition (amongst others) that I, the said Laurence
Hill junior, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said In-
vention, 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 Laurence Hill junior, 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 (that is to say):
The Invention consists in moving or actuating engines, such as are
usually driven by steam (or of any other convenient form), by means of
air heated and expanded by admixture therewith of steam or hicated
vapour. The heat is thus more economically imparted to the air than
when done through the intervention of metallic substances, as has
hitherto been the case. To do this, one or more force-pumps to com-
press the air, and a strong air-vessel to act as a receiver and reservoir
for the air when compressed, and a set of cocks or valves to admit the
compressed air into the working cylinder, require to be added to an
engine similar to those presently driven by steam. The steam cylinder
must be fitted with expansion valves, or valves constructed and worked
so as to admit the steam from the boiler or generator for a portion of
the stroke, as is well known to engineers; and the additional set of valves.
attached to the working or steam cylinder to admit the compressed
air from the receiver into the cylinder, must also be constructed and
worked so as to admit the air for only a part of the stroke, and then to
close to prevent further admission of air. The steam-valve is then
opened, and steam admitted for another portion of the stroke, and then
also closed. The air being thus admitted for a certain part of the

page_text: stroke, and the steam for another part, the whole stroke (or movement
of the piston from one end of the cylinder to the other) is accomplished
by the united effect produced by the expansion of the air, the expansion
of the steam, and also by the further expansion of the air due to the
heat imparted to it by the steam.
From the foregoing description it will be seen that the various ap-
paratus and parts required in the construction of an engine to carry out
this Invention are well known, and can be varied in arrangement and
form as much as the common steam-engine; and a mechanic, skilled in
making steam-engines, will have no difficulty in adapting my improve-
ments thereto; either adding them to an old engine, or making a new
one, with an arrangement of parts to suit circumstances. Care must
be taken, however, that the pump for compressing the air is able to
supply the required quantity at the required density into the air-receiver,
or into the cylinder (as it may be forced into the cylinder at once, but
I prefer to use a reservoir); and also that the valves and apparatus for
working them are constructed so as to admit and cut off the air and
steam at the proper times, and as quickly as possible; and that they
are fitted or packed so that they cannot be lifted ofl' their seats when
the pressure in the cylinder is increased by the admixture of the steam
with the air. The pressure of the steam must exceed the pressure of
the air, to prevent its being forced back by the increased pressure
caused by said admixture. The quantities of air and steam, and the
pressure of cach, may be varied; but it is found that air at a pressure
of from forty to fifty pounds per square inch, and steam at a pressure
of from seventy to eighty pounds per square inch, or about that pro-
portion, and the air let into the cylinder for about one eighteenth or
one twentieth part of the stroke, and the steam for as much, have been
productive of good results. The air, up to the time of its entrance into
the cylinder (which should be at the dead points), should be as cold as
possible, and the steam should be let in suddenly, and at the instant the
air is cut off, and not till then.
Having thus described the nature of the said Invention, and how the
same may be carried into effect, I wish it understood that I do not

page_text: claim any particular arrangement; but I do claim the heating and ex-
panding of air in closed vessels by direct contact or admixture with
steam or heated vapour, for the purpose of producing motive power.
In witness whereof, I, the said Laurence Hill junior, have here-
unto set my hand and seal, this Twenty-seventh day of August,
in the year of our Lord One thousand eight hundred and fifty-
three.
LAUR. (L.B.) HILL, JR.