IMPROVEMENTS IN STEAM ENGINES
Year: 1855

page_text: LETTERS PATENT to John Doddridge Humphreys, of 20, Charlotte
Street, Caledonian Road, for the Invention of "IMPROVEMENTS IN STEAM
ENGINES."
Sealed the 3rd July 1855, and dated the 29th January 1855.
PROVISIONAL SPECIFICATION left by the said John Doddridge Humphreys
at the Office of the Commissioners of Patents, with his Petition, on the
29th January 1855.
I, JOHN DODDRIDGE HUMPHREYS, of 20, Charlotte Street, Caledonian Road,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN STEAM
ENGINES" to be as follows:-
This Invention has principally for its object to employ steam expansively
more advantageously when giving motion to a rotatory axis or machinery
where uniformity of power is required. For this purpose, two trunk engines
are combined in their action in such manner that high-pressure steam is first
used on the lesser area of the piston in the smaller cylinder, then on the larger
area of the same piston, then on the smaller areas of the piston in the larger

page_text: cylinder, and then on the larger areas of the last-mentioned piston; and when
giving motion to a shaft or axis by such pistons, their piston rods are attached
to two crank pins, placed on cranks which are at or about right angles to each
other; and when driving a shaft or axis by steam engines I construct a
governor in the following manner:-I form a screw on the shaft of the small
pumping engine with a nut on it, driven by the larger engine; should the
larger engine run too fast it will drive the nut and shut off steam, but whilst
both engines are going at the same speed, there will be no action on the nut;
or in place of the screw and nut, I employ gear to act mutually between
the engines, as above explained.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Doddridge Humphreys in the Great Seal Patent
Office on the 28th July 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DODDRIDGE HUMPHREYS, of 20, Charlotte Street, Caledonian Road, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing. date the Twenty-ninth day of January, in the year of our
Lord One thousand eight hundred and fifty-five, in the eighteenth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Doddridge Humphreys, Her special licence that I, the said
John Doddridge Humphreys, my executors, administrators, and assigns, or such
others as I, the said John Doddridge Humphreys, 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 Inven-
tion for "IMPROVEMENTS IN STEAM ENGINES," upon the condition (amongst
others) that I, the said John Doddridge Humphreys, by an instrument in
writing under my hand and seal, 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.

page_text: the upper end of the steam cylinder A, or so as to act on the smaller area of
the piston in that cylinder, and when the piston has arrived at the end of the
stroke, the slide valve G will be moved, so as to open.a way between the steam
passage M and the steam passage N, by which the steam will be admitted
below the piston in the cylinder A, or so as to act on the larger area thereof;
the steam will consequently overcome the lesser resistance offered on..the
smaller area of the piston, and consequently the piston will be moved to, the
other end of the cylinder A. The slide valve G will be again moved, and will
open a way N¹. between the steam passage N and the valve box O of the large
steam cylinder B, and the-steam will. by the-working of the valve H-pass into
the upper part of the larger steam cylinder B, or so as to act on; the. smaller
area of the piston therein; and when the piston has descended to. the end of its
stroke, the slide valve H is moved to admit the steam from the: lesseri area of
the piston in the steam. cylinder B, so as to act on its larger, area of that piston,
and when the steam has arrived at the end of its stroke the steam, is by the
slide valve H allowed, to pass to the atmosphere, or to a condenser through
the outlet P. By thus combining two trunk engines, so that the steam, may
be expanded three times, and by combining the pistons with a .common.shaft
or axis, as described, not only may steam be used expansively, but uniformity
of power throughout the rotation of the axis may be obtained...I would
remark that these improvements may be used in locomotives as well as in
stationary and marine engines.
a
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Figure 2 shows apparatus arranged or combined suitably for carrying out
the other part of my Invention. Qis the shaft or axis which is constantly
kept in motion by dashing or pumping engine, which by reason of its being
constantly subject to a uniform load, will maintain a considerable degree of
uniformity of action., . R is the shaft or axis of a marine or other engine,
which being subject to a varying load may require to be governed; S is. a. cog
wheel on the shaft or axis R, which gears into the cog wheel T on the axis Q.
On the axis. Q is formed a screw, and in the nave of the wheel T is formed a
female screw; hence, according as the speed of the axis Q and the speed of
the axis R may vary, so will the wheel T be moved along its axis in one, or
other direction, and will, by its .grooved nave T¹, give motion to the lever U,
and by it to a throttle valve, and thus will the passage. of steam to the chief
engine or engines be governed or regulated.
Having thus described the nature of my Invention, and the manner of per-
forming the same, I would have it understood that I make no claim to any
of the mechanical parts herein described, nor do I confine myself to the details,

page_text: so long as the peculiar character of either part of my Invention be retained;
but what I claim is, the construction of steam engines, by combining two
trunk engines as herein described, and also the combining the parts herein
described, for governing the steam supplied to steam engines.
In witness whereof, I, the said John Doddridge Humphreys, have here-
unto set my hand and seal, this Nineteenth day of June, in the year of
our Lord One thousand eight hundred and fifty-five.
Witness,
T. A. FRANKLIN, Jr.
JOHN DODDRIDGE HUMPHREYS. (L.B.)