IMPROVEMENTS IN MOTIVE-POWER ENGINES
Year: 1864

page_text: LETTERS PATENT to Thomas William Miller, of The Terrace, Keyham,
Devonport, in the County of Devon, Gentleman, for the Invention of.
"IMPROVEMENTS IN MOTIVE-POWER ENGINES."
Sealed the 7th October 1864, and dated the 13th April 1864.
PROVISIONAL SPECIFICATION left by the said Thomas William Miller
at the Office of the Commissioners of Patents, with his Petition, on the
13th April 1864.
I, THOMAS WILLIAM MILLER, of The Terrace, Keyham, Devonport, in the
County of Devon, Gentleman, do hereby declare the nature of my said
Invention for "IMPROVEMENTS IN MOTIVE-POWER ENGINES," to be as follows:-
This Invention relates to a peculiar construction of combined steam and
atmospheric engines, and consists in constructing such engines with a four-
sided chamber in lieu of a cylinder, divided by a movable division plate into
two parts of equal capacities, and provided with a four-sided piston in lieu of
a circular one, and instead of cylindrical piston rods I make the. movable
division plate perform the same operations. The chamber of each engine
consists, firstly, of two planed plates for the top and bottom sides, each of
which has on its inward face so as to divide the chamber into two parts of
equal capacity a groove of the width and depth to receive the movable
division plate; secondly, of two planed plates for the right and left sides;
thirdly, of two plates for the two ends or covers, each of which has an oblong
stuffing box for the movable division plate to work through; fourthly, of the
division plate which moves in the grooves of the top and bottom plates, and;
through the stuffing boxes of the two ends, and which has a vertical slot:

page_text: through it of the vertical diameter of the chamber in length, and of the
thickness of the four-sided piston, which traverses through it in width.
To guide the piston the division plate has projecting guide pieces on each side
of it, and at one end outside of the chamber it has gudgeons for a connecting
rod to be attached to, by which the motion generated by the piston may be
transmitted to a crank.
In the chamber described above, the four-sided piston, the edges of which
fit the four-sided chamber with its packings works from end to end, and
traverses at the same time laterally through the division plate, so that it
produces on one side of the division plate a gradually increasing surface, and
on the other side of it a gradually decreasing surface by its passage during
one stroke, and vice versâ, by its passage during the reverse stroke.
The chamber above described, in addition to its being divided by the division
plate, is also again divided by the piston, so that it has four compartments or
chambers of alternately increasing or diminishing capacities, which may be
distinguished as, first, the right steam chamber; second, the right atmospheric
chamber; third, the left steam chamber; and, fourth, the left atmospheric
chamber; and both the steam chambers become alternately vacuum chambers
by the action of the condenser. Both the atmospheric chambers are left
constantly open to atmospheric pressure. The main chamber thus subdivided
is provided with the necessary slide or other valves for the admission of steam
from the boiler and for the eduction of steam into the condenser.
.
It is, intended that an engine constructed with the parts above described
shall have in combination such other parts as a condenser, air pump, hot well,
feed pump, and all other appliances of an ordinary steam engine. After
blowing through, clearing the condenser, and forming a vacuum in one of the
steam chambers when the steam is admitted by the valve through the steam port,
say, into the right steam chamber, its pressure, together with the atmospheric
pressure in the left atmospheric chamber, causes the piston to move towards
the end farthest from the port by which the steam enters, there being a
vacuum at the other side of the piston in the left steam chamber, which is at
that time in communication with the condenser, and during this stroke the
piston will expel the air from the right atmospheric chamber.
On reversing
the position of the valves the steam is admitted by another steam port into the
left steam chamber, when its pressure, together with the atmospheric pressure
in the right atmospheric chamber, causes the piston to move in a contrary
direction, there being at that time a vacuum on the other side of the piston in
the right steam chamber, at that time also in communication with the
condenser. During the last and all succeeding strokes of the piston while the

page_text: valves admit the steam into the chamber on one side of the piston, they allow
the steam to escape from the chamber on the reverse side of the piston
through the eduction passages into the condenser.
It is to be observed, that by a difference in the arrangement of the valves,
steam ports, and ends of the main chamber, the steam pressure may be made
to act, not as before described on the larger and decreasing areas of the piston,
but upon the smaller and increasing areas, and the atmospheric pressure not
on the smaller and increasing areas, but upon the larger and decreasing areas
of the piston. And to prevent cooling in the sides and ends of the steam
chambers the air to produce atmospheric pressure in the atmospheric chambers
should be heated by artificial means to a sufficient temperature before entering
the apertures in the atmospheric chambers, and the four sides and two ends of
the main chamber may be jacketted in the ordinary way.
Engines constructed with the parts included in the foregoing description are
applicable for driving or giving motion to the machinery of various mills, and.
for propelling ships, and may be constructed to work vertically or horizontally,
and engines so arranged are equally applicable for working pumps for raising,
liquids, and may be. made to act singly or during the downward or upward
strokes, or during the backward or forward strokes, and doubly, or during
both strokes; and the way in which I prefer to construct them for all the
above purposes is for the steam to act at the commencenient of the strokes
upon the larger, and then decreasing areas of the pistons, and for the atmo-.
spheric pressure to act at the commencement of the strokes upon the smaller.
and then increasing areas of the pistons. But when such engines are arranged
for working as single-acting engines, then I so construct. the valve apparatus
that the steam upon leaving the one steam chamber by the eduction passages is
made to pass into the opposite steam chamber at the other side of the piston,
so as to create an equilibrium pressure for the more ready return of the piston,
and then after the piston bas returned for the steam to pass out of this.
chamber into the condenser.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas William Miller in the Great Seal Patent Office
on the 11th October 1864.
:
TO ALL TO WHOM THESE. PRESENTS SHALL COME, I,. THOMAS.
WILLIAM MILLER, of. The Terrace, Keyham, Devonport, in the County of:
Devon, Gentleman, send. greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of April, in the year of our Lord One
thousand eight hundred and sixty-four, in the twenty-seventh year of Her reign,
did, for Herself, Her beirs and successors, give and grant unto me, the said
Thomas William Miller, Her special license that I, the said Thomas William
Miller, my executors, administrators, and assigns, or such others as 1, the said
Thomas William Miller, my executors, administrators, or assigns, should at
any time agree with, and no others, from time to time and at all times there-
after 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
MOTIVE-POWER ENGINES," upon the condition (amongst others) that I, the said
Thomas William Miller, my executors or administrators, by an instrument in
writing under my hand and seal, or under the hand and seal of one of them,
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.
NOW KNOW YE, that I, the said Thomas William Miller, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, 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 :-
My said Invention relates to a peculiar construction of combined steam and
atmospheric engines, and consists in constructing such engines with a four-
sided chamber in lieu of a cylinder, such chamber being divided by a moveable
division plate into two parts of equal capacities, and provided with a four-
sided piston in lieu of a circular one. Instead of cylindrical piston rods I
make the moveable division plate perform the same operations. The working
chamber of each engine consists, firstly, of two planed plates for the top and
bottom sides, each of which has on its inward face, so as to divide the chamber
into two parts of equal capacity, a groove of the width and depth to receive
the moveable division plate; secondly, of two planed plates for the right and
left sides; thirdly, of two plates for the two ends or covers, each of which has an
oblong stuffing box for the moveable division plate to work through; fourthly,
of the division plate, which moves in the grooves of the top and bottom
plates and through the stuffing boxes of the two ends, and which has a vertical
slot through it of a length equal to the vertical diameter of the chamber,
and of a width equal to the thickness of the four-sided piston which traverses

page_text: through it. To guide the piston the division plate has projecting guide pieces
on each side of it, and at one end outside of the chamber it has gudgeons for
a connecting rod to be attached to, by which the motion generated by the
piston may be transmitted to a crank.
In the chamber described above the four-sided piston, the edges of which
fit the four-sided chamber with its packings, works from end to end, and
traverses at the same time laterally through the division plate, so that it
próduces on one side of the division plate a gradually increasing surface, and
on the other side of it a gradually decreasing surface by its passage during one
stroke, and vice versa, by its passage during the reverse stroke. This chamber,
in addition to its being divided by the division plate, is also again divided by
the piston, so that it has four compartments or chambers of alternately
increasing or diminishing capacities, which may be distinguished as, first, the
right steam chamber; second, the right atmospheric chamber; third, the left
steam chamber; and, fourth, the left atmospheric chamber. Both the steam-
chambers become alternately vacuum chambers by the action of the condenser,
whilst the two atmospheric chambers are left constantly open to atmospheric
pressure. The main chamber thus subdivided is provided with the necessary
slide or other valves for the admission of steam from the boiler, and for the
eduction of steam from the chamber into the condenser.
It is intended that an engine constructed with the parts above described
shall have in combination a condenser, air pump, hot well, feed pump; and all'
the other well-known appliances of an ordinary steam engine. After "blowing
through," clearing the condenser, and forming a vacuum in one of the steam
chambers when the steam is admitted by the valve through the steam port,
say,
into the right steam chamber, its pressure, together with the atmospheric
pressure in the left atmospheric chamber, causes the piston to move towards
the end farthest from the port by which the steam enters, there being a
vacuum at the other side of the piston in the left steam chamber, which is at
that time in communication with the condenser, and during this stroke the
piston will expel the air from the right atmospheric chamber. On reversing
the position of the valves the steam is admitted by another steam port into the
left steam chamber, when its pressure, together with the atmospheric pressure
in the right atmospheric chamber, causes the piston to move in a contrary
direction, there being at that time a vacuum on the other side of the piston in
the right steam chamber, also in communication with the condenser. During
the last and all succeeding strokes of the piston while the valves admit the
steam into the chamber on one side of the piston, they allow the steam to

page_text: escape from the chamber on the reverse side of the piston through the eduction
passages into the condenser.
It is to be observed that by a difference in the arrangement of the valves,
steam ports, and ends of the main chamber, the steam pressure may be made
to act not as before described on the larger and decreasing areas of the
piston but upon the smaller and increasing areas; and the atmospheric
pressure not on the smaller and increasing areas but upon the larger and
decreasing areas of the piston. And to prevent cooling in the sides and ends
of the steam chambers, the air to produce atmospheric pressure in the atmo-
pheric chambers should be heated by artificial means to a sufficient tempe-
rature before entering the apertures in the atmospheric chambers. And the
four sides and two ends of the main chamber may be jacketted if desired in
the ordinary way.
The way in which I prefer to construct these engines is for the steam to
act at the commencement of the strokes upon the larger and then decreasing
areas of the pistons, and for the atmospheric pressure to act at the commence-
ment of the strokes upon the smaller and then increasing areas of the pistons.
But when such engines are arranged for working as single-acting engines,
then I so construct the valve apparatus that the steam upon leaving the one
steam chamber by the eduction passage is made to pass into the opposite
steam chamber at the other side of the piston, so as to create an equilibrium
pressure for the more ready return of the piston, and then after the piston has
returned for the steam to pass out of this chamber into the condenser.
And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose. I shall
refer to the several Figures on the two Sheets of Drawings hereunto annexed,
the same letters of reference indicating corresponding parts throughout all
the Figures.
Fig. 1 (Sheet 1) of my Drawings, is a longitudinal vertical section of my
improved motive-power engine, taken along the line 1-2 in Fig. 4; Fig. 2
is a longitudinal section, taken along the line 3-4 in Fig. 4; Fig. 3 is a
transverse vertical section of the engine, taken along the line 5-6 in Fig. 1;
Fig. 4 is a horizontal section, taken along the line 7-8 in Fig. 1; Fig. 5 is
an elevational and partial sectional plan of the engine corresponding to Fig. 2,
the section being taken along the line 9-10 in Fig. 2; Figs. 6 and 7 repre-
sent respectively a detail side elevation and corresponding plan of the
moveable division plate, the piston being removed; Fig. 8 (Sheet 2) of the
Drawings represents an end elevation of the engine corresponding to one end

page_text: of Fig. 9; Fig. 9 represents a complete, side elevation of the same; and
Fig. 10 is a corresponding elevation of the opposite end thereof; Fig. 11 is a
sectional plan of the chamber, taken along the line 7-8 in Fig. 1, the
moveable division plate and piston being removed; Fig. 12 is a plan of the
engine with the cover of the slide valve box removed; and Fig. 13 is a
transverse vertical section of the chamber and valve chest, taken along the
line 5-6 in Fig. 1, the moveable division plate, piston, and slide valves being
removed.
In these Figures; A reprepresents the planed plate for the bottom side of
the chamber, formed with its groove B for the moveable division plate to slide
in; C is the planed plate for the top side of the chamber, formed with its
groove D for the moveable division plate to slide in, and with slide valve
box E, slide faces and ports, and with its steam and eduction passages together
with the nozzles for the steam pipe from the boiler. and the exhaust pipes to
the condenser, all herein-after referred to. F, the slide valves for regulating
the admission and egress of steam; G, the slide valve rods, which are to be
continued and attached to proper weight shafts or other well known or suitable
means for giving motion to the slide valves; these rods work; through the
stuffing boxes H; I is the cover to the slide valve box; J, the steam pipe,
nozzle, and pipe from the boiler; and K, the exhaust pipes, nozzles, and pipes
to the condenser. The steam ports and passages. are shewn at L, and the
exhaust ports and passages at M; N, N, are the two planed plates for the
right and left sides of the chamber, formed hollow, so as receive and heat the
air employed to produce atmospheric pressure in the atmospheric compart-
ments of the main working chamber, such air being also heated by artificial
means, well known to engineers, to a sufficient temperature before entering
the apertures in the atmospheric compartments of the main chamber. 0, 0, are
the nozzles and pipes which convey the artificially heated air from the heating
apparatus, which may be of any kind so long as the air is raised by it to a
sufficient temperature. The two ends or covers of the main chamber consist
of two plates P, P, each of which has an oblong stuffing box Q formed therein
for the moveable division plate R to work through, and is formed with a
passage through which the artificially heated air will enter the atmospheric
compartment of the main chamber during one stroke of the piston, and be
expelled from it by the reverse stroke. The moveable, division plate R slides
along the two guiding grooves of the top and bottom plates and through the
stuffing boxes of the two end covers, and has a vertical slot T made through
it, and two projecting guide pieces S formed on each side of it, and is provided
at one end outside of the chamber with gudgeons U, U, to which is attached

page_text: in the usual manner a connecting rod lending to a crank shaft. The vertical
slot T and guide pieces S are for the piston X to traverse through and between
whilst moving from end to end of the chamber. V, V, are long bolts and nuts
for connecting the two parts in which the moveable division plate R is made.
These two parts are joined together near to the vertical slot, through which
the piston traverses. Spring packing W is provided in the moveable division
plate for the purpose of rendering the vertical slot through which the piston
traverses steam and air tight. This packing may be metallic, and forced
outwards by the ordinary means of springs at the back of the plate, as shewn,
or otherwise. The piston traverses laterally through the vertical slot in the
moveable division plate, and, with the exception of being made four-sided, may
be constructed and packed similar to the ordinary pistons of steam engines.
The packing of this piston is shown at Y; it may consist of metallic packing
pieces in two tiers, one above the other, each tier to be composed of two
L-shaped pieces in plan, the two sides or arms of each L piece corresponding
with two of the four sides of the piston. These pieces are so placed that each
L-shaped piece in one tier may break joint with that of the other in the other
tier at opposite corners of the piston, and they may be forced outwards by the
ordinary means of springs placed behind them, as shewn in the Drawings.
Z, Z, are the junk pieces for retaining the packing pieces and the springs
in their positions, and for rendering these parts of the piston air and steam
tight.
Engines constructed with the parts included in the foregoing description
are applicable for driving or giving motion to the machinery of various mills,
and for propelling ships, and may be constructed so as to work either vertically,
horizontally, or obliquely, and they are equally applicable for working pumps
for raising liquids, and may be made to act singly or during the downward or
upward strokes, or during the backward or forward strokes, and doubly or
during both strokes.
The black arrows represent the induction, and the blue arrows the eduction
steam, whilst the red arrows shew the incoming atmospheric air, and the
yellow arrows the outgoing air.
The mode in which I prefer to work these engines for all the above
purposes is for the steam to enter the compartments 1-2 alternately of the
main chamber, so as to act at the commencement of the strokes upon the
larger and then decreasing areas of the pistons, and for the air to enter
alternately the compartments 3-4 of the main chamber, so that the atmo-
spheric pressure may act at the commencement of the strokes upon the
smaller and then increasing areas of the pistons. But when such engines are

page_text: arranged for working as single-acting engines, then I so construct the valve
apparatus that the steam upon leaving the one steam chamber (1) by the
eduction passages is made to pass into the opposite steam chamber (2) at the
other side of the piston, so as to create an equilibrium pressure for the more
ready return of the piston, and then after the piston has returned for the
steam to pass out of this chamber (2) into the condenser.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and
original, and therefore claim as the Invention secured to me by the herein-before
in part recited Letters Patent, is―
First, the general construction and arrangement of combined steam and
atmospheric engines, substantially as herein-before described.
Second, the constructing of motive-power engines so that the power is
obtained from the combined pressure of the steam in the generator above the
atmospheric pressure, and the pressure of the atmosphere in conjunction with
a vacuum exerted conjointly upon the surfaces of a piston working simul-
taneously in the steam and atmospheric compartments of a main chamber,
whether such engine be double or single-acting, substantially as herein-before
described.
Third, the combination in motive-power engines of a four-sided chamber
with a rectangular piston made to slide laterally through a moveable division
plate whilst traversing from end to end of the chamber, and working steam
and air-tight in the chamber and moveable division plate, substantially in the
manner and for the purpose herein-before described and illustrated by my
Drawings.
In witness whereof, I, the said Thomas William Miller, have hereunto
set my hand and seal, this Eighth day of October, One thousand
eight hundred and sixty-four.
THOMAS WILLIAM MILLER. (L.S.)