IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES
Year: 1862

page_text: LETTERS PATENT to Edward Ellis Allen, of 5, Parliament Street, West-
minster, in the County of Middlesex, Engineer, and John Stewart, of
Blackwall, in the County of Middlesex, Engineer, for the Invention of
IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES.
PROVISIONAL SPECIFICATION left by the said Edward Ellis Allen.
and John Stewart at the Office of the Commissioners of Patents, with
their Petition, on the 13th February 1862.
We, EDWARD ELLIS ALLEN, of 5, Parliament Street, in the County of
Middlesex, Engineer, and, JOHN STEWART, of Blackwall, in the County of
Middlesex, Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE CONSTRUCTION OF STEAM ENGINES," to be as follows:-
We construct the cylinder of a steam engine with an annular partition at or
about the centre of its length, so as to form in reality two cylinders, and which
may be cast separately and bolted together, if preferred, the axes of these-
cylinders lying in the same line. In each of these cylinders or portions of the
same cylinder a piston works, packed in the ordinary way, the said pistons.
being united together by means of a trunk or cylinder, so as to work simul-
taneously. This trunk or cylinder connecting the two pistons is turned on
the outside, and works through the annular partition in the main cylinders
before spoken of, such annular partition being packed with metallic or wooden
rings, in the same manner as the inner circumference of an annular piston
would be. We also bore out the trunk uniting the two pistons, so that it
may serve the purpose of a cylinder, fitting to it a piston packed in the
ordinary way, or with wood, but which piston is not movable, but fixed in its

page_text: place by means of one or more rods passing through the large pistons to the
covers of the main cylinder, to which they may be attached by nuts. The
motion of the large pistons may be communicated to the crank shaft by one
or more piston rods passing through one of the covers of the main cylinder
and through ordinary stuffing boxes. The rod or rods holding the fixed piston
in place, where it or they pass through one or both of the main pistons, work
in elastic or wooden rings or other steam-tight packing. The trunk or cylinder
uniting the two main pistons may be cast double or cellular, or otherwise
have small passages traversing its thickness from end to end for the passage
of the steam. A set of such passages terminating at one end in openings
made through each of the main pistons respectively, and at the other end
opening out into the interior of the trunk at the two ends respectively forming
ordinary steam ports. When two or more piston rods are used for giving
motion to the crank shaft, the same number of these small passages may be
conveniently occupied by prolongations of the said piston rods, which in this
case may serve to secure one of the large pistons to the trunk, the other being
conveniently cast with it.
The mode of working the engine above described is as follows:-Steam
from the boiler is admitted into the annular space surrounding the trunk
alternately on each side of the central or annular partition in the main cylinder.
It is here cut off at any convenient portion of the stroke by means of the slide
valve or an ordinary expansion valve, according to the pressure of the steam,
and after (by the motion of the main pistons and trunk, which form in effect
one piece) expanding and occupying the entire annular space between the
exterior of the trunk and the interior of the main cylinder, a communication is
opened to the opposite side of the large piston, upon which the steam has been.
exerting its force, which also brings it in communication with the openings or
passages formed in the metal or thickness of the trunk, and by which it passes.
into the said trunk, pressing against the fixed piston before described, and so
forcing the second large piston in the same direction (and with a force pro-
portionate to the area of the trunk) as it does the first piston, or that upon
the whole area of which it is exerting its influence. At the same time. a
vacuum is maintained at the opposite ends of the main cylinders and trunk
respectively to those which are being filled with steam.
we utilize the entire capacity of the main cylinder; the expansion of the steam
(beyond that given in the annular space itself) being in proportion to the,
whole capacity of the cylinder minus the annular space, when compared to the.
annular space itself. The valves used for transmitting the steam from
the boiler to the annular spaces, and from these to their respective ends of the
By this
arrangement

page_text: cylinder, may be of the ordinary kind, except that the exhaust port is placed at
one side instead of between the two steam ports. Both valves may be cast
together or united and worked by a single rod, or may be worked separately
either on the same or opposite or nearly opposite sides of the cylinder, as
preferred. Cylinders thus constructad may be placed vertically, horizontally,
or inclined, or may be made to oscillate like ordinary cylinders. They may
also, in place of piston rods, be fitted with small trunks for attaching the con-
necting rods to. In the case of horizontal engines for working screw propellers,
two or more piston rods may be conveniently carried past the crank shaft, and
united to a guide or tee-piece or pieces, from which the connecting rod (single
or double) may be carried back to the crank.
In some cases we do not use the trunk as a steam cylinder, in which case no
piston is fitted in it, and it is cast solid, that is, not cellular, as before described,
but in this case steam may be admitted to it, so as to assist the expansion
going on at its ends and outside it. This steam may be admitted conveniently
by one or two tubes passing through one of the pistons or both of them, care
being taken that such tubes are arranged so as to allow of the condensed water
to pass readily out. These tubes may of course form the supports for a fixed
piston, having openings into the trunk, and being packed where they pass
through the main pistons as in the following modification. In some cases,
also, we modify the arrangements above described by admitting steam from the
boiler to the inside of the trunk, allowing it to expand in the annular space.
In this case the piston rods retaining the fixed piston in place are made hollow
or in the form of tubes, so as to form steam passages. In the arrangements
above described it is not essential, although in most cases preferable, that the
two ends of the main cylinder should be of the same diameter. In the case
of vertical or inclined engines a difference can be made in the areas, so as to
allow of a difference in the working pressure of the steam equivalent to the
weight of the large pistons, trunk, and piston rods, or part of them. The
packing for the trunks and piston rods we sometimes make of perforated bands
of tin or white metal, and work the valves by means of a trunk in the valve
asing
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edward Ellis Allen and John Stewart in the Great Seal
Patent Office on the 13th August 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, EDWARD
ELLIS ALLEN, of 5, Parliament Street, Westminster, in the County of Middlesex,

page_text: Engineer, and JoHN STEWART, of Blackwall, in the County of Middlesex,
Engineer, send grecting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
.Patent, bearing date the Thirteenth day of February, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-sixth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the
said Edward Ellis Allen and John Stewart, Her special licence that we, the
said Edward Ellis Allen and John Stewart, our executors, administrators, and
assigns, or such others as we, the said Edward Ellis Allen and John Stewart,
our 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 THE CON-
STRUCTION OF STEAM ENGINES," upon the condition (amongst others) that we, the
said Edward Ellis Allen and John Stewart, or one of us, our, or one of our
executors or administrators, by an instrument in writing under our, 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 Scal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Edward Ellis Allen, on behalf of myself
and the said John Stewart, do hereby declare the nature of our said Invention,
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement, reference being had to the
accompanying Drawings, and to the letters and figures marked thereon, that
is to say:-
We construct the cylinders of steam engines with an annular partition A,
Figure 1, at or about the centre of its length, so as to form in reality two
cylinders B, C, and which may be cast separately and bolted together, if pre-
ferred, their axes lying in the same line. In each of these cylinders or portions
of the same cylinder, two pistons D, E, work, packed in the ordinary way, the
said pistons being united together by means of a trunk or cylinder F, so as to
work' simultaneously. This trunk or cylinder connecting the two pistons D
and E is turned on the outside, and works through the annular partition in
the main cylinder before spoken of, such annular partition being packed with
metallic or wooden rings in the same manner as the inner circumference of
an annular piston would be. We also bore out the trunk uniting the two

page_text: pistons, so that it may serve the purpose of a cylinder, fitting to it a piston G,.
packed in the ordinary way, or with wood, but which piston is not moveable,
but fixed in its place by means of one or more rods H, passing through the
large pistons D, E, to the covers of the main cylinder, to which they may be
attached by nuts. The motion of the large pistons may be communicated to
the crank shaft by one or more piston rods I, I, passing through one of the
covers of the main cylinder and through ordinary stuffing boxes. The rod
or rods holding the fixed piston in place where it or they pass through one or
both of the main pistons work in elastic, metallic, or wooden rings, or other
steam-tight packing. The trunk or cylinder uniting the two main pistons
may be cast double or cellular, Figure 2, or otherwise have small openings or
passages traversing its thickness from end to end for the passage of the steam,
a set of such passages terminating at one end in openings made through each
of the main pistons respectively, and at the other end opening out into the
interior of the trunk at the two ends respectively, forming ordinary steam
ports, as seen at J, J, Figure 2. When two or more piston rods as used for
giving motion to the crank shaft the same number of these small passages
may be conveniently occupied by prolongations of the said piston rods, as shewn
at K, K, Figures 1 and 2, which in this case may serve to secure one of the
large pistons to the trunk, the other being conveniently cast with it. When
one piston rod only is used, as in ordinary oscillating or direct acting engines,
the piston inside the trunk is held by a rod attached to one of the covers of
the cylinder only, videlicet, the one opposite to that through which the piston
rod I passes from the main piston to the connecting rod. The Drawing, Figure 1,
shews the arrangement suited to a horizontal engine for driving the screw
propeller, but cylinders as described may be placed vertically, or inclined or
be made to oscillate, as required. In arranging engines worked with side
levers we place guides on the upper part of the cylinders, the cross head on
top of piston rod being bent down so as to form a bow for attachment to guide
blocks and side rods.
The mode of working the engine above described is as follows:-Steam-
power from the boilers is admitted into the annular space surrounding the trunk
alternately on each side of the central or annular partition in the main cylinder.
It is here cut off at any convenient portion of the stroke by means of the
slide valve or an ordinary expansion valve, according to the pressure of the
steam, (and after by the motion of the main pistons, and trunk, which form
in effect one piece) expanding and occupying the entire annular space between
the exterior of the trunk and the interior of the main cylinder, a communi-
cation is opened to the opposite side of the large piston, which the steam has

page_text: been exerting its influence, which also brings it in communication with the
:openings or passages formed in the metal or thickness of the trunk, and by
which it passes into the said trunk, pressing against the fixed piston before
described, and so forcing the second large piston in the same direction, (and
with a force proportionate to the area of the trunk,) as it does the first piston
or that upon the whole area of which it is exerting its influence. At the same
time a vacuum is maintained at the opposite ends of the main cylinder and
trunk respectively to those which are being filled with steam. By this arrange-
ment we utilize the entire capacity of the main cylinder, the expansion of the
steam (beyond that given in the annular space itself) being in proportion
to the whole capacity of the cylinder minus the annular space, when compared
with the annular space itself. The valves used for transmitting the steam
from the boiler to the annular spaces, and from these to their respective ends
of the cylinder, may be of the ordinary kind, except that the exhaust port is
placed at one side instead of between the two steam ports, or the exhaust
port may be placed in the centre of the cylinder or between the several steam
ports. Both valves may be cast together or united and worked by a single
rod, or may be worked separately, either on the same or opposite or nearly
opposite sides of the cylinder, as preferred.
Instead of piston rods, these engines may be fitted with trunks for attaching
the connecting rods to in the usual manner, such trunks being attached to one
of the main pistons, and passing through stuffing boxes in one of the corners of
the cylinder. The connecting rod trunk may be the same or of less diameter
than the trunk connecting the two pistons, and may in some cases form a
single trunk. In this case the trunk connecting the pistons is not necessarily
used as a cylinder, but steam may be admitted to it so as to prevent con-
densation at its ends and outside it, which steam may be admitted by one or
two tubes passing through one of the pistons or both of them, care being
taken that such tubes are arranged so as to allow the condensed water to pass
readily out.
In some cases we modify the arrangement by admitting steam from the
boiler to the inside of the trunk, allowing it to expand in the annular space.
In this case the rods retaining the fixed piston in place are made hollow, so as
to form steam passages opening out into the trunk, such rods passing through
the main piston or pistons and being packed in the ordinary way.
In the arrangements above described, it is not essential, although in such
cases preferable, that the two ends of the main cylinder should be of the same
In the case of vertical and inclined cylinders a difference can be
in the areas so to allow of a difference in the working pressure of the steam
diameter.

page_text: equivalent to the weight of the large pistons, trunk, and piston rods, or part of
them. The packing of the trunks and piston rods we sometimes make of
perforated bands of tin, or white or other metal, lapped round the same with
ordinary hemp packing at the back. The valves we sometimes work with
small trunks instead of the ordinary guides, and if the two ends of the cylinder
are not of the same diameter, we sometimes place the valves as close to the
cylindrical part at each end as possible, so as to shorten the steam passages
connecting such valves externally, in order to work them. Instead of attaching
the second main piston to the trunk, as shewn in Figure 1, a series of small
bolts may be used, passing through the metal of the trunk, or having nuts
inserted therein. In this case the piston rods are attached to one of the main
pistons only.
Having now described our Invention, and the manner in which the same
is to be performed, we do not confine ourselves to the precise arrangements or
details described and illustrated, as many variations may obviously be made
therefrom without departing from the nature and objects of the Invention, but
what we believe to be new, and therefore claim as the Invention secured to
us by the herein-before in part recited Letters Patent, according with and
having reference to the descriptions herein-before contained, and the illus-
trative Drawings therein referred to and annexed, is as follows:-
First, the construction of compound cylinder engines with double pistons, as
described and illustrated with reference to Figures 1 and 2, with the various
modifications described.
Second, the peculiar mode of packing by means of bands of perforated
metal, as described.
Third, the arrangement of the valves close to the circumferences of the
respective ends of the cylinder or cylinders when of different diameters.
In witness whereof, I, the said Edward Ellis Allen, on behalf of myself
and the said John Stewart, have hereunto set my hand and seal, this
Thirteenth day of August, in the year of our Lord One thousand eight
bundred and sixty-two.
EDW. E. ALLEN. (L.S.)