AN IMPROVED ROTARY STEAM ENGINE in Rotary Steam Engine
Year: 1826

page_text: GALLOWAY'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ELIJAHI
GOLLOWAY, of the London Road, in the Parish of Saint George the Martyr,
in the County of Surrey, Engineer, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-ninth day of December, in the seventh year of His reign,
did, for Himself, His heirs and successors, give and grant unto me, the said
Elijah Galloway, His especial licence that I, the said Elijah Galloway, my
executors, administrators, and assigns, or such others as I, the said Elijah
Galloway, my executors, administrators, or assigns, should at any time agree
with, and no others, from time to time and at all times during the term of
years therein expressed, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, my said
Invention of "AN IMPROVED ROTARY STEAM ENGINE;" in which said Letters
Patent is contained a proviso obliging me, the said Elijah Galloway, by an
instrument in writing under my hand and seal, particularly to describe and
ascertain the nature of my said Invention, and in what manner the same is to
be performed, and to cause the same to be enrolled in Ilis said Majesty's High
Court of Chancery within six calendar months next and immediately after the
date of the said recited Letters Patent, as in and by the same, reference
being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Elijah Galloway, do hereby declare the nature of my said Invention to consist
in certain Improvements in Rotary Steam Engines, by which I am enabled

page_text: to make the sliders which shut off the communication of the steam from time
to time from the different sides of the piston have a better bearing than here-
tofore, and work more perfectly and with less noise than on the plans hitherto
adopted; also, in a piston with metallic and hempen packing, united in such
manner as to act more equally in resisting the escape of the steam than those
hitherto adopted for such engines; and also, in a new arrangement of valves,
and the introduction of certain sheaves on the gear, as will be hereafter more
particularly explained, and in further compliance with the said proviso, I, the
said Elijah Galloway, do hereby describe the manner in which my said
Invention is to be performed by the following description thereof, reference
being had to the Drawing annexed, and to the figures and letters marked

page_text: same breadth as the former; the dimensions of these grooves will be varied
to suit the size of the engine, and the object of them is to receive the sliders,
which will be hereafter explained. It is apparent that a section from y to z,
Figure 2, will pass through the centre of all these grooves; the sliders g, g
(Figures 3 and 4) are two plates of metal faced with a thin facing of brass or
gun metal; they are of such a thickness as to move freely in their respective
grooves, of such a length as to extend from the bottom of the grooves in each
cap, and of such a breadth as to reach from the outside of the cylinder to
nearly the bottom of the groove f,f. The purpose of these grooves is to form
a bearance for the sliders, which being made smooth and flat, and afterwards
ground into their places in the grooves, become steam-tight in every part
excepting at the space left between the bosses. Now, there is a central plate.r,
Figures 3 and 4, which is attached to and revolves with the axis e, e. This
plate is of a thickness sufficient to occupy the space between the bosses, and is
kept steam-tight by the circular rings 1, 1, and 2, 2 (placed in recesses
turned in the bosses), pressing upon each side of the plate ; underneath
each plate is introduced a quantity of hempen or cotton packing which
answers the double purpose of preventing the escape of the steam between
the ring and its recess, and the elasticity of the packing, by keeping the
ring placed upon the plate, prevents an escape in that direction. To make
the sliders and the central plate form a steam-tight union small pieces
of brass, h, h (Figure 3), are screwed to the sliders, and thereby allow them
to be brought into contact with the edge of the plate x, without permitting
any part of the sliders to touch the bottom of the grooves f. f. At opposite
points of the plate & there is a small portion the circle cut away (see F, F,
Figure 4), the purpose of which is that the sliders may be moved into their
places without noise, for that is produced by the striking of two substances
together, and these sliders are not suffered the arrangement of the cam
herein-after described to strike against the bottom of the grooves, nor yet, by
reason of the cavities (F, F), against the periphery of the plate. The boxes
or cases, i, i (1, 2, 3, and 4), are for the reception of the sliders when, they
are withdrawn from the cylinder. Stuffing boxes j, j, are placed in the middle
of the bonnets through which the rods k, k, are worked. These rods are
attached to the sliders by means of cross pieces, M, M (Figure 3), which are
dovetailed and bolted to them, and at the outer end they are keyed to the cross
heads m, m (Figures 1 and 2), similarly secured to the rods n, n, n, n, which
are forked at the ends nearest to the axis. A small spindle passes through
the ends of each fork, upon which run three friction sheaves, the larger ones, O,
Figure 1 and 2), being placed between the forks, and the smaller ones p,p, on

page_text: the ends of the spindle. They are not fixed to the spindle, and therefore may
revolve separately and independently of each other. 9, 9 (Figure 4 and 6), is
the piston of the engine, and consists of four pieces of brass or gun metal,
Tr, r, r, (Figure 6), of about two inches and a half in thickness, filed or
otherwise made perfectly smooth and uniformly thick. Each piece is in the
form of the letter L, and are represented as put together in Figure 6, and the
spiral springs, 8, 8, 8, 5, &c. acting against an abutment t, t, force them out-
wards. Two plates of metal (20 is one of them), having a facing of equal
breadth to the brass, are laid on each surface of the brass pieces r, r, r, r, aud
pressed on them by means of brass bolts passing through the whole of the
piston. These plates and the brass pieces, being previously ground together,
prevent the steam from escaping between them, and, as an additional security,
there are semicircular grooves u, u, u, u (Figure 6), cast in the metal plates,
into which hemp or cotton is stuffed, and by pressing on the brass prevents the
possibility of an escape except at the points of union between the brass pieces.
In order to make these parts tight also, small overlap pieces v, v, v, are sunk
into the brass about one fourth of an inch, and as the piston wears away and
widens the openings between the pieces r,r,r,r, these still continue to cover them.
Those parts of the brass r, r, which are against the arm of the piston are let into
recesses (sec 21, Figure 4), and hemp or cotton is placed underneath them, which
prevents escape in that direction. This I call my compound compensating piston.
It possesses the property of being more tight than metallic pistons are generally
(by the using of both hempen and metallic packing), and also of being equally
free and not liable to be jammed when heated. This latter qualification arises
from making the bolts which hold the plates together of the same material as
the pieces r, r, r, r, by which means the distance between the plates when
heated is as much increased by the expansion of the bolts as the pieces
r, r, r, r, are expanded, consequently they cannot be bound or jammed in
their places under any variation of temperature. There are four valves in this
engine; two of them are placed in each cap or end of the cylinder, and are
represented on a large scale at Figure 5. They consist of circular brass
plates, the bottom ones being cemented or otherwise fastened into a recess in
the end cast for them. The upper plate then is placed above, and both being
previously ground together, the steam cannot enter the cylinder but through
the holes J, J, into the holes 6, 7 (Figure 4); that is to say, when the holes
in each plate are placed over each other, as at the lower valve, Figure 5, the
valve is open, and, when otherwise, shut. A plate L, L, Figures 3 and 5,
covers the recesses in which the valves work, and may either be cast with the
ends or afterwards bolted and cemented to them. The space between the

page_text: caps and the plate L, L, form circular chambers. The plates L, L, have each
three openings, two circular ones, large enough to get readily to the valves,
and a rectangular one, X, to which a steam pipe is attached. Bonnets, N,N,
Figure 3, cover the circular holes, which are thicker in their centres, having a
cylindric hole large enough to permit smaller bonnets, O, O, Figures 2 and 9,
to be placed thereon; spindles previously keyed to the moving plate of the
valves are brought through O, O, to the exterior of the caps. These valves
and the spindle are kept steam-tight by the screws of O, O, being turned a
little round, which presses the bonnets O, O, in the first instance, upon the
enlarged part of the spindle (shown at Figure 3); and also upon the face of
the fixed valve plate small cranks 8, 8, Figures 2 and 5, are attached to the
outer ends of the valve spindles, which are connected to the gear 9, 9. Upon
this gear are fixed two friction sheaves which, being acted upon by the cam
10 (Figure 5), at proper periods, the cranks, and consequently the valves, are
alternately moved to and fro by the revolution of the axis e, e, one of them
opening when the other is closing, and vice versa. 3, 3 (Figures 1 and 2),
are two cams, one half of which is concentric with the axis, and the other part
is the excentric or cam part by which the sliders are moved. The motion
is produced by the excentric part acting on the sheaves O, O (Figure 2), and
moving them to and from the axis. The smaller sheaves p, p, run between
the guides P, P (see the dotted lines Figure 2), which preserve a vertical motion-
to the rods n, n. The holes through which the steam escapes and is admitted
are placed as near the slider as they can be brought, and are shewn for
the purpose of illustration as being all in one cap (at Figure 4), though, as I
have previously stated, there are two in each cap. The effect, however,
would be the same were they as represented in Figure 4, and therefore
this mode of explanation will be as clearly understood. A pipe is brought
round as at A, Figure 2, into a steam chest B, Figures 1 and 2, in which
latter is a common slide valve. Into this steam chest the steam is brought
from the boiler by the pipe C, and escapes into the atmosphere or condenser
by the pipe D. This slide valve and the apparatus connected with it are for
the purpose of reversing the motion of the engine. In order to put this
engine in operation steam is admitted into the steam chest B, when the slide
valve is placed in such a position as to allow the steam to enter into the end
13, 13, and escape at the end 12, 12, or in other words, when the valves
6 and 7 (Figure 4) are the induction valves, and 14 and 15 the eduction
valves, and when the piston and sliders are in the position shewn at Figure 4.
The valve 14 is then open, and communicates with the atmosphere or con-
denser, and the valve 7 with the boiler; the steam, therefore, entering through

page_text: 7, rushes against the side X of the piston; and the side W of the upper slider,
which thus becomes the abutment against which the steam exerts its force.
The piston recedes from the pressure in the direction of the arrow, turning
with it the central plate x, the axis e, e, the cams 3, 3, and the valve cams
10, 10; as the shaft turns therefore the cam 8 (Figure 2) revolves, and the
'cam or excentric part gradually leaves the lower rods n, n, and presents the
concentric part to the sheaves of the said rods; now, the lower cross head
being pressed upwards by the counterbalance E, gradually ascends into the
cylinder, so that when the point 4 is in contact with the sheaves of the lower
rods n, n, the slider has then reached its place in the cylinder, being nearly
in contact with the central plate at F (Figure 4), and also upon its bearing
in the grooves before described. The piston will be then at the point G of the
cylinder, and both the sliders shut, the two valves 7 and 14 only being open. Now,
as the piston continues to revolve the cams 3, 3, are gradually opening the upper
slider, and the cams 10 gradually shutting the valve 14 and opening the valve
15, so that when the piston reaches the valve 14 it is completely shut and the
latter completely open, and when the piston reaches the upper slider it is com-
pletely withdrawn from the cylinder, and thereby allows the piston to pass it; at
this point the steam is entering through 7 and escaping through 15, the lower
slider being then the abutment upon which the steam acts.
After the piston
has passed the upper slider the cam 3 allows the slider gradually to return to
its place in the cylinder, and after the piston has passed the valve 6, that
valve begins gradually to open and the valve 7 to close. Therefore when
the piston has reached the point H the upper slider is in its seat in the cylinder,
the valves 7 and 14 are quite shut, and 6 and 15 quite open. The cam 3 then
begins to give motion to the lower slider, as before described, and the cams 10
to the valves, so that a constant rotation of the axis is kept up. To reverse
the motion of this engine, the sliding valve in the steam chest is moved on its
face, so that the valve 6 and 7 become the eduction valves, and 14 and 15 the
induction valves. Supposing the piston, therefore, in the position shewn in
Figure 3, and the steam previously entering through 6 and 7, and escaping
through 14, it will be seen that if 6 and 7 become the escape valves, and 14
and 15 the induction valves, the steam from the boiler will then rush through
14, and, pressing on the piston, so drive it in a direction contrary to the arrow,
whilst the steam before actuating the engine escapes through 6 and 7, which
being shut and opened at their proper time by the cans 10, keep up the rota-
tion in the opposite direction.
Now, whereas I hereby declare that I consider my improvements to consist
of the following parts or apparatus, and notwithstanding such parts may have

page_text: been used in other machines, yet I claim their application to a rotary engine
with sliders; and I also declare that I do not claim as my Invention any parts
of the said engine which are not afterwards named.
First, I claim as my Invention the introduction of the cylindric bosses, with
their grooves f, f, by means of which the sliders may be constructed in a
rectangular form, and have a bearing upon all their four edges in the said
grooves, except at the part where they are in contact with the central plate x,
as by these bosses and grooves I am enabled to give my rectangular sliders
more bearing in the grooves than has hitherto been done.
Secondly, I claim as my Invention the cavities F, F, in the central plate, by
which means the sliders are prevented from coming forcibly in contact with
the said plate.
Thirdly, I claim the compound compensating piston, that is to say, the
uniting in one piston of hempen and metallic packing the small overlap pieces
which cover the joinings and the bolting of the piston together by bolts of the
same material as the packing.
Fourthly, I claim as my improvement the introduction of the valves already
described into circular chambers, formed or cast in the caps of the cylinder, and
the mode of tightening the valves as they become worn; and
Fitthly, I claim the friction sheaves on the gear, as here described, for
actuating the valves.
And whereas these five particulars here claimed constitute my said improve-
ments, and such improvements being, to the best of my knowledge and belief,
entirely new, and never before used within that part of His said Majesty's
United Kingdom of Great Britain and Ireland called England, His said
Dominion of Wales, or Town of Berwick-upon-Tweed, I do hereby declare
this to be my Specification of the same, and that I do verily believe that this
my said Specification doth comply in all respects, fully and without reserve or
disguise, with the proviso in the said herein-before in part recited Letters
Patent contained; wherefore I do hereby claim to maintain exclusive right
and privilege to my said Invention.
In witness whereof, I, the said Elijah Galloway, have hereunto set my
hand and seal, this Twenty-ninth day of June, in the year of our
Lord One thousand eight hundred and twenty-seven.
ELIJAH (L8.) GALLOWAY.

page_text: AND BE IT REMEMBERED, that on the same Twenty-ninth day of June,
in the year above mentioned, the aforesaid Elijah Galloway came before our Lord
the King in His Chancery, and acknowledged the Specification aforesaid,
and all and every thing therein contained, in form above written. And also
the Specification aforesaid was stamped according to the tenor of the Statute in
that case made and provided.
Inrolled the same Twenty-ninth day of June, in the year above written.