IMPROVEMENTS IN STEAM ENGINES
Year: 1868

page_text: LETTERS PATENT to John Plews, of No. 1, Rosedale Villa, Grove
Road, Hounslow, in the County of Middlesex, Civil Engineer, for
the Invention of "IMPROVEMENTS IN STEAM ENGINES."
Sealed the 2nd October 1868, and dated the 9th April 1868.
PROVISIONAL SPECIFICATION left by the said John Plews at the
Office of the Commissioners of Patents, with his Petition, on the
9th April 1868.
I, JOHN PLEWS, of No. 1, Rosedale Villa, Grove Road, Hounslow, in
the County of Middlesex, Civil Engineer, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN STEAM ENGINES," to be as
follows:-
In order to describe the method of effecting my improvements I give
the following as the mode of working the engine. The cylinder is made
to work backwards and forwards upon a trunk pipe, which is fixed to the
sole plate, and has a piston or pistons cast upon it, which in the usual
manner fit the cylinder. The steam is let in upon one side of the piston
through orificies in the trunk pipe close to the piston, and acting against

page_text: the cylinder cover causes the cylinder itself to move forward, the trunk
pipe on the other side of the piston then becoming the exhaust. The
èngine having reversed the slide, the steam is admitted on the other side
of the piston, bringing the cylinder back again, and converting the
former inlet pipe into the eduction. Thus the cylinder is moved back-
wards and forwards upon the trunk pipes, and the connecting rods being
attached to trunnions upon it communicate the motion to the crank
shaft. I do not confine to myself the use of the piston on the trunk
pipe, but reserve the right to substitute a diaphragm cast in the centre of
the cylinder to serve as a piston, and having the ends of the trunk pipes
open, which serve as steam and exhaust pipes alternately, so that the
steam acts direct upon the diaphragm to move the cylinder on the one
:side, while the exhaust passes through the trunk pipe on the other, so
that when the cylinder has completed the stroke upon the one side the
exhaust is open, and the steam is let in on the other side to effect the
return stroke, thus acting consecutively to work the engine.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Plews in the Great Seal Patent Office on
the 9th October 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
PLEWS, of Number 1, Rosedale Villa, Grove Road, Hounslow, in the
County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of April, in the year of
our Lord One thousand eight hundred and sixty-eight, in the thirty-first
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto him, the said John Plews, Her special licence that he,
the said John Plews, his executors, administrators, and assigns,
or such others, as he, the said John Plews, his executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein ex-
pressed, 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 STEAM
ENGINES," upon the condition (amongst others) that he, the said John

page_text: Plews, 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 be filed in the
Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Plews, 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 thereof, reference being had to the accompanying
Drawings, that is to say :-
One part of my said Invention consists of a cylinder, which is made to
work backwards and forwards upon trunk pipes, which are fixed to the
sole plate, and have a hollow piston with a diaphragm cast in the
centre, which piston fits the cylinder in the usual manner. The steam is
let in upon one side of the hollow piston through orifices in one of the
trunk pipes, which is attached to the piston, and acting against the
cylinder cover causes the cylinder itself to move forward, the trunk pipe
on the other side of the piston then becoming the exhaust. The engine
having reversed the slide the steam is admitted by the trunk pipe upon
the other side of the piston, bringing the cylinder back again, and con-
verting the former inlet pipe into the eduction. Thus the cylinder is
moved backwards and forwards upon the trunk pipes, and a connecting.
rod attached to trunnions upon the cylinder communicates the motion
to the crank shaft.
Another part of my said Invention consists in substituting a diaphragm
cast in the centre of the cylinder to serve as a piston, the trunk pipes
having their ends open, and acting as steam and exhaust pipes alter-
nately, so that the steam presses directly upon the diaphragm to movo
the cylinder on the one side, while the exhaust passes through the trunk.
pipe on the other side, so that when the cylinder has completed the
stroke upon the one side the exhaust is open and the steam is let in
upon the other side to effect the return stroke, thus acting consecutively
to work the engine.
One part of my Invention consists of an improved form of steam engine,
which, is constructed as shewn in Figure 1, Sheet 1, of the accompanying
Drawings,. wherein similar parts are marked with similar letters of
reference.

page_text: A, A, is the cylinder; B, B, the piston tube, serving as a piston rod,
which is hollow up to the points C, C, to which is attached the hollow
piston, having a diaphragm in the centre, and having orifices D, D,
through which the steam passes from the hollow trunk pipe B, B, into
or out of the cylinder or cylinders A, A, as inlet and eduction pipes;
F, F, are the steam ports of the usual construction, admitting the steam
alternately to the trunk pipes B, B; at each end of the cylinder A, A;
G, G, are the trunnions cast or fixed to the moveable cylinder to com-
municate the motion direct to the crank shaft; H, H, are the guide bars.
to steady the cylinder; N, N, shew the cylinder covers upon, which the 1
steam acts upon each alternate stroke.
:
Another part of my said Invention consists in constructing the cylinder
with a diaphragm D in the centre as shewn in Figure 2, Sheet 1, and in
causing the cylinder A, A, to move upon trunk pipes B, B, passing into
the cylinder from opposite ends thereof through proper glands or
stuffing boxes E, E. The trunk pipes are hollow, and admit the steam
by the ordinary arrangement of ports F, F, alternately to each side of the
diaphragm, and so produce a reciprocating motion of the cylinder.
In order that my whole Invention may be better understood, I give in
Figure 3, Sheet 1, an elevation of the complete engine, whereof a
sectional Drawing is given in Figure 2, Sheet 1.
. 1
It is evident that modifications of" my Invention analogous to those
which I have described may readily be suggested, and also that by
slightly altering the form of cylinder A, A, it may be made to slide inside
of the trunk pipes B, B, instead of upon them. The mode of operation
and effect being identical with that above described.
One feature of my Invention is, that where great power is required, in
licu of using one trunk pipe B of large dimensions I. can combine any
number of small trunk pipes, all of which communicate with the large
cylinder, from which the motion is to be obtained.
My said. improvements are applicable to all steam engines, whether
worked as high pressure or condensing engines, and also where the
power is derived from gas or water under pressure.
. Having now fully described the nature of my said Invention, and the
manner in which the same is to be performed, I declare that I do not
intend to claim as my Invention any of the several parts of the engines
herein-before described separately or apart from the application and

page_text: combination thereof as herein-before described, but I do claim as my
Invention,-
First. The combination of parts or mode of constructing an engine
wherein a cylinder or cylinders move upon hollow trunk pipes fitted with
a piston or pistons as herein-before described.
Secondly. The combination of parts or mode of constructing an engine
wherein a cylinder provided with a diaphragm which acts as a piston is
caused to move upon hollow trunk pipes as herein-before described, or any
mere modification thereof.
In witness whereof, I, the said John Plews, have hereunto set my
hand and seal, this Ninth day of October, in the year of our Lord
One thousand eight hundred and sixty-cight.
Signed, sealed, and delivered by
the above-named John Plews,
in the presence of,
HENRY LISTER,
Clerk to Messrs. Plews & Irvine,
Solicitors,
31, Mark Lane,
London.
JOHN PLEWS. (L.S.)