CERTAIN IMPROVEMENTS ON STEAM ENGINES
Year: 1817

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MOSES
POOLE, of Lincoln's Inn, in the County of Middlesex, Gentleman, send
greeting.
WHEREAS His most Excellent Majesty King George the Third, did, by
His Letters Patent under the Great Seal of the United Kingdour of Great
Britain and Ireland, bearing date at Westminster, the Fifteenth day of
December, in the fifty-eighth year of Ilis reign, give and grant unto me,
the said Moses Poole, my exors, adiñiors, and assigns, His especial licence,
full power, sole privilege and authority, that I, the said Moses Poole, any
exors, adñiors, and assigns, 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, and also in all His Majesty's Colonies
and Plantations abroad, the Invention of "CERTAIN IMPROVEMENTS ON STEAM
ENGINES," communicated to me by a certain foreigner residing abroad; in
which said Letters Patent there is contained a proviso, that if I, the said
Moses Poole, shall not particularly describe and ascertain the nature of the
said Invention, and in what manner the same is to be performed, by an
instrument in writing under my hand and seal, and cause the same to be
inrolled in His Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said Letters Patent, that
then the said Letters Patent should be void, as in and by the same (relation
being thereunto had) may more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Moses Poole, do hereby declare them to be described by the Drawing annexed
and following description (that is to say):-
These improvements on steam engines are applicable to such engines as are
usually denominated rotary engines or steam wheels, and which have a per-
manent stop placed across their steam channel. As these engines are not in
common use, it is necessary first to describe the kind of engine to which the
improvements are to be applied. The steam wheel is a hollow cylinder of cast
iron or other metal, n, n, Figures A J. and A II., with any suitable number
of arms; it is firmly fixed upon an axis with which it turns round, and the
end of the axis is connected with the machinery which the engine is intended
to move. This wheel is turned so as to stand true upon its axis. On the
external surface of the wheel, and paralel to the axis, are recesses proper
for the reception of not less than two opening leaves or valves v, v, which I
call propellers, because the steam acts upon them when they are opened or
turned outwards into the direction of radii (as is shewn by one of them), and
gives motion to the wheel and machinery connected with its axis; but when
these leaves are folded down into the recesses, they exactly fill them up, and
form a true and smooth cylindrical surface to the wheel. The propellers are
attached to the wheel by hinges or joints, on which they turn as centers of
motion. This steam wheel, with its propellers, is enclosed within a hollow
cylinder m, m, which is fixed by screws or otherwise in its required position.
Its width in the direction of the axis is the same as that of the wheel, but the
diameter of the outward cylinder is so much larger than the diameter of the
wheel as to leave an opening or circular channel between them, of a width
suitable to the height of the propellers v, v, when raised up, and they thon
fill up the whole transverse section of the channel, so that steam cannot escape
by the sides of them, although they are at liberty to move in the channel by
the force of the steam, and turn the wheel round. In one part of the circular
channel the passage of the steam must be interrupted by what I call a steam
stop, from the office it performs. It is a piece of metal which fills up the
whole section of the channel, and is fixed on the outside cylinder, and one
part of it fits close against the outside surface of the wheel. When the pro-
pellers are folled down they can pass by the steam stop. The ends of the
hollow cylinder are closed by flat plates "h, h," in Fig. A II., which are
screwed on, and they have stuffing boxes in their centers for the axis of the
wheel to pass through. These plates apply very exactly to the flat surfaces of
the wheel with packing, so that steam cannot pass between; the wheel and
its propellers are therefore completely enclosed in the cylinder. The steam to

page_text: work the wheel is admitted through the pipe a in Fig. A I., close to one end
of the steam stop, and the steam passes off through an eduction pipe y, which
inay either convey the steam to the open air, if its high-pressure steam, or to
some other engine in which it is to work as expanded steam with a low
pressure, or otherwise the said eduction pipe y may convey the steam to the
apparatus in common use for condensing. The instant that a propeller has
passed by the steam stop it is opened or raised up by a spanner or opening.
lever s, which is fixed to the propeller, and as the wheel turns it comes against
a fixed pin p. The propeller continues open, and fills up the channel until it
comes to the steam stop, and then it folds down into the recess in the edge of
the wheel, so as to pass beneath the stop. The steam, which enters at x, being
prevented by the steam stop from passing at once from the eduction pipe, will
press on the propeller, which is open, and tend forwards in the circular channel,
because the steam on the other side of the propeller is drawn off or escapes
through the eduction pipe y. When the propeller in its course round the
steam channel has passed the opening of the eduction pipe y, the steam, which
pressed it forwards escapes, and the propeller being no longer acted upon falls
by its own gravity, and folds up by its action against the sloping end of the
steam stop which it may have, or a roller or rollers at D; this closes the
propeller into its seat, so that it may pass under the stop without suffering
any steam to pass by at the same time. The propeller having passed the stop
is opened again in its rotation, and fills the steam channel so as to receive the
action of the steam. As there are two propellers a constant action is kept up
upon the steam wheel and its attached machinery. Steam wheels of this or
a similar construction have been repeatedly tried, but they have not been
brought into general use, chiefly from the difficulty of preventing a great waste
and escape of steam between the sides of the steam wheel and the flat end
plates of the hollow cylinder which inclose it, also between the edges of the
propellers and the circular channel on which they work, likewise between the
wheel and the steam stop. To all these parts a packing of hemp, cotton, &c:
is usually applied, or of yarn, or of plaites of yarn, and when at work the
whole must be properly lubricated with tallow or other substance.
manner of packing produces great friction and loss of power, particularly
when the compressure of the substances used for packing is sufficiently great
to make the fittings perfectly steam-tight; this is more particularly experienced
at the square angles of the propellers and steam channel.
This
These improvements consist in the following methods of forming the steam
channel, and applying the packing:-The outer angles of the propellers must
be rounded off with curves, and the circular steam channel, which is the space

page_text: between the wheel and its enclosing cylinder, must be made of a corresponding
figure to the propellers, by means of inward projection on each of the said
plates h, h, in B II. or otherwise, by a similar projection from the inside of
the outer cylinder m, m, so as to form curves, as shewn in B II., in place of
sharp angles. The packing or stuffing, which may consist of caskets or plaited
yarns, is instorted into a groove formed all round the edge of each propeller,
and projects rather beyond the edge of the propeller, so as to bear against the
inside of the channel. By this improvement of rounding the angles of the
channel, the packing round the two sides and the top of each propeller forms
an unbroken line. Its termination over each end of the hinge or joint of the
propellers may be pinned into one or more holes, or secured in any proper
manner. This packing must be lubricated with tallow and black lead, or any
other substances usually employed in steam engines for that purpose.
Another of these improvements is a method of applying metalic packing to
the propellers.
The sharp right angles of the propellers may be cut off, as shewn in B III.,
or they may be rectangular, as in A II., and B IV., which last shews only the
propeller and a part of the hollow cylinder. The metalic packing consists of
a plate or plates of brass or other suitable substance, disposed around the
edges of the propeller or falling leaf, provided with springs to press them out-
wards towards the internal surface of the hollow cylinder, as at g in B III.
and B IV. The motion of the plates is restrained by stops within proper
limits, to avoid derangement, when the contact of the propeller with the
external cylinder ceases from the closing of the propellers, and the said stops
are so made as to regulate the utmost motion of these metalic plates from
time to time as their outward extremities wear away, the form and arrange-
ment of the plates being such that they will always continue to occupy the
section of the steam channel, and press close to its sides and the internal
surface of the outer cylinder, notwithstanding their progressive diminution by
wear.
In Fig. B III., q, q, are two packing plates of brass, the lower end of
which entering into slits in the hinge of the propeller, as shewn in the side
view of BV; the remaining parts are received in recesses at the back of the
propeller, which recesses are equal in depth to the thickness of the packing
plates. The recesses should extend a little further inwards than the breadth
of the plates so as to leave an interval behind the plates capable of being filled
with cotton or hemp, or any other elastic substance capable of withstanding the
heat of steam, which substance may be renewed or increased from time to
time, to keep the edges of the plates always pressed outwards against the.

page_text: inside plates of the hollow cylinder, and also to prevent any escape of steam
under the ends of the plates g, which lies flat against the back of the propeller
on the part between the recesses, which part is level with the side plates q, q,
and the ends of the plate 9 lie across the ends of the plates 9, 9. The plate g
is constantly pressed outwards against the inside of the hollow cylinder by a
spring, as shewed in B III., and the extent of that motion is limited by means
of steady pins, as at i, i, inserted in openings for that purpose from time. As
the metalic plate 7 wears, so much as is necessary must be filed away from
the lower side of the openings thro' or in which the steady pins project. The
same method may be used in steam channels of square section, but when the
plates wear, some leakage will arise in the angles, to prevent which recourse
may be had to five metalic plates, all disposed in one plane at the back of the
propeller, and acting upon each other by inclined planes or wedge joints, as in
B IV., the ends of the plates 7, 9, are cut off obliquely, and the plate 9 is
fitted in between them. In like manner the lower ends of the plates q, 7,
are cut off obliquely, and two wedge pieces w, w, are fitted beneath them;
these pieces pass into a slit through each end of the axis of the propellers,
and are forced outwards by springs. This action is transmitted by the inclined
or wedge joints to all the other plates, which are thereby forced outwards to
fill the steam channel. Metalic plates should not be of homogeneous metal,
because when the outward plate 9 which applies to the outward cylinder is
worn away any given quantity, and side wedges 9, 9, are equally worn away
against the side plates of the cylinder, the action of the springs upon the
wedges w, w, cannot bring the wedges 2, 1, into contact with the wedge g,
unless the ends of q, q, next to the outer cylinder be worn down much more
than their sides, which apply to the sides of the cylinder. For this reason
about 1/3 or 2/5 of the length of the plates 9, 9, along the sides of the pro-
pellers should be made of a softer metallic composition, which will wear faster
than the remainder. The two parts of each plate q, should be pinned or
soldered together. The plates 7, 9, will also recede towards the outer cylinder
much faster than the points of the wedges w, w, will wear away, unless the
said wedges w are formed of a softer composition than the outward plate "g,"
for this reason the narrow ends of the wedges w, w, should be of a
softer composition, which is more subject to wear away.
The propellers
have no gudgeons at their joints, but that end of each propeller which is
the joint is formed round to and as an axis of motion, which axis is fitted
into a socket in the edge of the steam wheel; to keep the axis of the
propellers from falling out of their sockets, small returning bars of iron are
pinned into each axis, and pass thro' grooves or slits made through the rini of

page_text: the wheel in the bottom of the socket beneath the axis, which grooves are
sufficiently long in the direction of the bar's motion to admit the propeller to
open and shut; the inside of the rim of the wheel where the slits come through
should be circular and concentric to the axis, so that by a side projection
from the retaining bar, the axis and propeller may be kept in its socket; a
prolongation of this bar if there be a single onc, or from one of then if there
be two, may form the spanner or lever by which the propeller is opened, and
for that purpose the said bar should project so far. The metalic packing
plates must necessarily be ground to each other, and to the form of the
channel they are to move in; they, as also the plates B III., may be kept from
falling off the back of the propeller by a flat plate fixed behind them, so as
nearly to touch them, but not to prevent their movement as to come against
the fixed pin p,.A I., A II., and B I., which is inserted through one of the side
plates of the outer cylinder. The steam stop may be formed in different ways,
one method is to form it of two separate plates set at a sufficient distance from
each other to include the length of one of the propellers when closed, or so
much thereof as may be requisite to prevent the escape of the steam; these
plates being stationary are close fitted to the external cylinder and its side
plates, so as to prevent the passage of steam by their sides, but those edges
which are oposite to the circumference of the steam wheel do not quite touch
it or its propellers when closed, but some moveable or elastic packing is requi-
site, which may either be of metal or of any compressible substance suitable for
the purpose. If metalic packing is used, the stop plates should radiate from
the centre of the wheel or nearly so, as shewn in B VI., and on that face of the
plate which is nearest the steam pipe either a single plate is placed at "t,"
in that Figure, or three metalic wedges of sufficient thickness to prevent them
from entering into the vacancies left at each end of the closed propellers, as
shewn at "A & C," BI. This plate or plates may he pressed towards the
rotary wheel by a spring acting on them.
wedges being displaced by any accident, they may be secured by applying a
fixed plate before them, the same as the propellers; the space or interval
between the two plates forming the steam stops should be filled up with any
suitable substance, but not placed so low as to touch the surface of the wheel,
otherwise the steam which escapes by the edges of the closed propellers when
they pass under that stop which is next to the steam pipe, would fill the
vacancy between the two stops, and would subsequently be wasted when the
propeller passed beneath the stop next the eduction pipe. When compressible
packing is used for the steam stop, the two permanent stop plates should be
placed parallel to each other, as in BI., at a suitable distance assunder, and a
To prevent these plates or metalic

page_text: moveable inetal plate is fitted between then, which fills up the space between
the side plates of the external cylinder and the two stop plates; in or near the
center of the moveable plate is a hole for the reception of the end of a screw
pin a, which passes through the outer cylinder in a radiating direction; between
this moveable plate and the circumference of the wheel a packing is placed,
composed of folds of matting made of hempen or other yarn, or folds of course
hempen cotton, or other suitable cloth, or any compressible substance not
distructible by steam. This package must be supplied with tallow and black-
lead or other suitable substances. By means of the screw through the cylinder
it should be compressed against the circumference of the wheel sufficiently to
prevent leakage of steam, but without causing unnecessary friction. The
packing between the flat sides of the steam wheel and the side plates of the
hollow cylinder is disposed in a groove, which is cut in a waving or serpentine
line round the edge of the wheel, as shewn in B I.; the waves of the groove
proceed quite to the circumference of the wheel, leaving openings at intervals
where the packing will shew itself on the circumference of the wheel at both
edges, and will touch the steam stop in a sufficient number of places to prevent
escape of steam. When the steam stop is made in two separate stops, each
with metalic packing plates, as first described, if the packing plates are not of
sufficient thickness to cover the solid metal intervening between the spaces c, c,
where the packing is exposed, then the said intervals of solid metal must be so
arranged that one of the packed spaces c, c, shall pass beneath one of the
packing plates, whilst the intervals between the packed spaces c, c, of the wheel
shall be beneath the other packing plate. The plaited yarns or other substance
driven into this groove to form the packing may be taken out when they
become slack, and one or more thicknesses of canvas, as circumstances may
require, may be placed under it. The same may be done if elastic packing be
used round the edges of the propellers; the substance in both instances being
properly lubricated.
And, lastly, I do declare that I do not claim any other improvement on
steam engines, except on those rotary engines or steam wheels that have falling
leaves or propellers, which folds down upon the steam wheel so as to pass
under a fixed steam stop. My improvements on this species of steam wheel
are herein-before described, and the manner of carrying them into effect is
pointed out, but to distinguish my improvements from what is old, I hereby
confine my claims to, viz, the rounding-off the corners of the outer part of the
propellers, and making of the surrounding steam channel correspondent with
that form; the making of a serpentine groove in the flat side of the rotary
wheel, so near the onter edge of the wheel as to admit the packing at certain