AN IMPROVEMENT OR IMPROVEMENTS UPON STEAM ENGINES
Year: 1838

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
DICKINSON, of Wood Street, Cheapside, in the City of London, Paper Manu-
facturer, send greeting.
WHEREAS Her present Majesty Queen Victoria, by Her Letters Patent
under the Great Seal of the United Kingdom of Great Britain and Ireland,
bearing date at Westminster, the Twenty-third day of August now last past,
did give and grant unto me, the said George Dickinson, Her especial licence,
full power, sole privilege and authority, that I, the said George Dickinson, my
executors, administrators, and assigns, or such others as I, the said George
Dickinson, my executors, administrators, or assigns, should at any time agree
with, and no others, from time to time and at all times thereafter 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
Invention of "AN IMPROVEMENT OR IMPROVEMENTS UPON STEAM ENGINES;" in
which said Letters Patent there is contained a proviso obliging me, the said
George Dickinson, by an instrument in writing under my hand and seal, par-
ticularly 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 inrolled
in Her 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 appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
George Dickinson, do hereby declare that my said Invention is described and
ascertained in manner following, and by the aid of the Sheets of Drawings
hereunto aunexed, that is to say:-
My said improvement or improvements upon steam engines is for the
most part applicable to steam engines of that kind which are provided
with two steam cylinders, viz', a small one and a large one, with a
moveable piston fitted into each, and in which engines the steam from the
boiler is first admitted into the small cylinder in order to impel and give
motion to the small piston therein, and then after having done so the same
steam is admitted to pass out from the small cylinder into the large one, in
order to impel and give motion to the large piston therein, during the ex-
pansion of volume which the steam must undergo by being transferred from
the small cylinder into the large one. Such steam engines are commonly
called Woolf's engines, because they were introduced into use by Mr. Arthur
Woolf, who had a Patent for them, dated the Seventh of June, One thousand
eight hundred and four; and, being well known and in common use, no further
description is requisite in order to identify them as the kind of steam engines
to which my improvement or improvements is mainly applicable; and although
Woolf's engines with two cylinders have been constructed in various ways, the
two cylinders in such engines have always been kept distinct one from the other.
Now, part of my improvements consist in disposing the small cylinder and
piston of such engines within the interior of the large cylinder thereof, and
concentrically thereto, and the piston of the large cylinder is made in the
manner of a circular ring, whereof the central interior opening fits around the
exterior surface of the small cylinder, and the exterior circumference of the
ring fits to the interior surface of the large cylinder. The said ring piston
has two piston rods affixed into it, diametrically opposite to each other,
across its centre, and the upper ends of both these rods passing up through
stuffing boxes in the cover of the cylinder are affixed to the moving cross
bar or cross head of the engine; the small cylinder which occupies the central
part of the interior capacity of the large cylinder is fitted with a small piston
as usual, and the rod of that small piston passes up through a stuffing box in
the centre of the cover, and the upper end of the said rod is affixed to. the
same moving cross head aforesaid, which therefore receives the combined effort
of both pistons to give it an up-and-down motion, and that motion is trans-
mitted to the machinery which the engine is intended to impel. All this will
be rendered more clear by a reference to the Drawing hereunto annexed, wherein
Figures 1 and 2 are vertical sections of two cylinders, one within the other;

page_text: "
Figure 3 contains a vertical section of the several principal parts corresponding
to Figure 1, but detached one from another; Figure 4 is a horizontal section,
and Figure 5 another vertical section of slide valve to explain its action. In
all the Figures the same letters of reference are used to denote the same
parts. A, A, is the large cylinder, and B, B, is the small cylinder situated
within the other. The bottom flange b, b, of the small cylinder B, B, projects
out far enough around it on all sides to serve for a bottom to the large cylinder
A, A, and the circumference of that flange b, b, being turned truly concentric
to the small cylinder B, B, and being exactly fitted to the lower flange c, c, of
the large cylinder A, A, will ensure that the small cylinder B, B, will stand up
exactly vertically and concentrically within the interior of the large cylinder
A, A. The cover D of the large cylinder A, A, serves also as a cover for
the small cylinder B, B, and to make a steam-tight junction between that
cover D and the upper edge of circular border y, y, of the small cylinder
B, B. The latter is admitted into a circular groove which is formed in the
under side of the cover D, and a ring of hemp or of lead packing is applied
around on the said top edge or border, y, y, in order to fill up the said groove
so completely as to make a close joint with the cylinder cover D, when the
same is fastened down to the upper flange d, d, of the large cylinder A, A, by
screws around its border, in the usual manner of cylinder covers for steam
engines. The cover D has three stuffing boxes in it, viz, one, e, in the usual
central position for the piston rod E of the small piston F to pass through,
and two other stuffing boxes f, f, Figures 2, 6, and 7, on each side of the
central one, for the two piston rods G, G, of the large or ring piston H, H,
to pass through. All the three piston rods G, E, G, are fastened to the
same cross bar or cross head K, K, which unites them together, and causes
them (with their two pistons F, and H, H,) to move up and down together
with equal motions in their respective cylinders. The cross bar K, K, may be
suspended, as shewn in Figure 2, by the main links L, L, of the parallel
motion, which links are themselves suspended from the end of a working beam
or great lever M, M. In case the engine is to have a great lever over
the cylinder as, is most usual for engines which are to be used on land or
otherwise, the cross head K, K, may be made, as is shewn in Figure 6, to
extend out far enough each way to receive the side rods N, N, which descend
on each side of the large cylinder A, A, to connect with two working beams or
great levers M, M, disposed one on each side of the cylinder A, A, as is the
most usual arrangement for engines which are used on board boats or vessels.
Note, the manner whereby the cross bar or cross head K, K, to which the
three piston rods G, E, G, are affixed, is caused to transmit its motion to the

page_text: further machinery of the engine, forms no parts of my improvements, and may
be performed in any manner which is most convenient, and as is well known
to competent engineers. For instance, in place of the links I, I, Figure 2,
or of the side rods N, N, Figure 6, connecting rods may by substituted, pro-
ceeding from the cross bar or cross head K, K, (in either Figure) to the
crank pin or pins of a revolving crank or revolving cranks, or a horizontal
axis, which may be situated over the cylinder or under the same. The cross
bar or cross head K, K, being in all cases guided (by parallel motions or
otherwise) so as to cause it to move up and down with a truly rectilinear
motion corresponding exactly to that of the three piston rods G, E, G. O is
the stopper or bottom for closing the lower end of the small cylinder B, B.
The steam passages for admission into and exits of the steam from the small
interior cylinder. B, B, are arranged as shewn in Figure 1 and 3, viz, one
steam passage g is formed in the metal of the bottom b, b, of the small
cylinder B, B, in order to communicate with the lower part of that cylinder
beneath its piston F, and another steam passage h is formed in the metal
of the cylinder cover D, to communicate with the upper part of the small
cylinder B, B, above its said piston F. These steam passages are con
tinued by others, i and k, which are formed through the metal of the large
cylinder A, A, at one side thereof, where that metal is made of suitable thick-
ness for the purpose, and in which metal the steam passages 7 and m are
also formed for communicating with the upper and lower parts of the large
cylinder A, A, above and below its annular or ring piston H, H; and note,
the said steam passages i and k, for the small cylinder, and 7 and m for the
large cylinder, may be connected with any suitable kind of nosels containing
any such sliding valves or moveable plugs, or turning cocks or lifting valves,
as have been or may be used for distributing the steam to the two cylinders
in a suitable manner for performing the ordinary operations of Woolf's
engine with two cylinders. And whereas those engines have been made of
two kinds, double acting and single acting, according as their valves or
other equivalent parts have been arranged for distributing the steam, either
for producing double action, that is, to cause the pistons to exert their
force in both directions, as is commonly done in such engines when they
are required to turn revolving cranks with rotative motions, or else for pro-
ducing single action, that is, to cause the pistons to exert their force when
they move in one direction only, and to be moved in the contrary direction by
the action of a counter weight, as is commonly done in such engines when
they were used for pumping water. But whether the engine is to work with
double action or with single action it makes no difference as to my Invention,

page_text: because such nosels and distributing valves, slides, plugs, or cocks as will render
the action double, or as will render the same single, do not constitute any part of
my Invention, and it is well known to competent engineers how to apply them
for either double or single action, hence it is not necessary to enter into a
detailed description of them; nevertheless, I have represented in the Drawings,
Figures 1, 3, 4, and 5, a kind of nosel containing one sliding valve, which will
perform the whole of the required distribution of the steam to the two cylinders
B, B, and A, A, suitably for producing a double action of their two pistons;
but note, I make no claim thereto as part of my Invention. P, P, is a steam
box or nosel joined by screws so that side of the large cylinder A, A, where the
aforesaid steam passages i, k, and l, m, are formed. The steam box P, P,
receives steam from the boiler into its interior capacity through a steam pipe Q,
which may project out at any convenient part of the steam box P, P, and
which steam pipe Q is to be provided with any such stop valves or throttle
valves, or both, as is or may be commonly used for permitting and regulating
the admission of steam from the boiler to such engines; the regulation being
effected either by the discretion of the attendant regulating the opening or
stop valve or cock from time to time as may be requisite, or by aid of what is
called a governor, which operates continually to effect the regulation, or both
means may be combined. R is the sliding valve, which is contained within
the steam box P, P, and applies with a truly vertical and flat face at each end
of it in close contact with the vertical flat surface r of that side of the large
cylinder A, A, which is covered by the steam box P, P, so as to be included
within the interior capacity thereof. The said vertical surfaces at each end
of the sliding valve R are truly fitted to the vertical surface r, so that
steam cannot pass between the surfaces which are in contact. The sliding
valve R has an upright passages, s, through nearly all its length, and by
making an elbow at each end the passage s, s, terminates at each end with
openings in the vertical surfaces at each end of the sliding valve R. t and v
are cavities in those aforesaid vertical surfaces at each end of the sliding valve
R. The middle part of the sliding valve R between those said surfaces at each
end of it does not apply to the vertical surface r, but leaves a sufficient interval
therefrom for free passage of the steam which is admitted into the steam box
P, P, so as to surround the sliding valve R at all parts of its exterior surface,
excepting at those aforesaid vertical surfaces at each end of it which apply
with such close contact to the vertical surface r that steam is excluded from
between them. u, x, are the eduction passages formed in the metal of the
large cylinder A, A, opening with apertures in the vertical surface r, and leading
to two eduction pipes z, z, Figures 4 and 7, which convey the steam away to

page_text: the condenser in case the engine is intended to work with a condenser and
air pump, as is most usual for compound engines with two cylinders. The
sliding valve R is moved up and down within its steam box P, P, by means of
a rod z, which passes through a stuffing box in the cover S, at the top of that
box P, P, and the said rod z is actuated in the usual manner commonly
practised for moving the slide valves of such engines, and which being well
known to competent engineers, and forming no part of my Invention, requires
no further description. The office of such working gear is to raise up the
sliding valve R into the position shewn in the section, Figure 1, when the
two pistons F and H, H, arrive at the lower ends of their respective cylinders
B, B, and A, A, and in that said position of the sliding valve R the steam
coming from the boiler into the steam box P, P, is admitted below the valve
or slide R, through the passage 9. into the lower end of the small cylinder
B, B, to act beneath its piston F, in order to force the same upwards; also
the steam which contained in the upper part of the small cylinder B, B, above
its piston F, is permitted to escape through the passage h, i, and down the
passages, s, within the hollow of the sliding valve R, and thence through
passage m into the lower part of the large cylinder A, A, beneath its ring
piston H, H, in order to force the same upwards; and also the steam
which was contained in the upper part of the large cylinder A, A, is permitted
to escape and pass away from the cylinder through the passage e, and through
the cavity t, in the sliding valve R, so as to be admitted therefrom into the
eduction passage w and eduction pipe z, by which the steam is carried away
from the cylinders of the engine. Under these circumstances the two pistons
F and H, H, will perform their ascending stroke, and by their three piston
rods E, G, G, will raise up the cross bar or cross head K, K, so as to give
motion to the other moving parts of the engine; and by the time that the
said two pistons G and H, H, have arrived at the upper ends of their respective
cylinders B, B, and A, A, then the sliding valve R must have become moved
downwards in its steam box P, P, by action of its working gear into the
position represented in the separate section, Figure 5, wherein it is apparent
how the distribution of the steam is reversed from what it was previously as
represented in Figure 1, and as above described, that is to say:-Steam
coming from the boiler into the steam box P, P, now obtains admission over
the top of the sliding valve R, through the passage i and k into the upper
part of the small cylinder B, B, above its piston F, in order to force the same
downwards; also at the same time the steam from the lower part of the small
cylinder B, B, beneath its piston F, is permitted to escape through the passage
g, k, and up the e passages, within the hollow of the sliding valve R, and therefrom

page_text: through the passage l into the upper part of the large cylinder A, A, above
its piston H, H, in order to press the same downwards; also at the same
the steam contained in the lower part of the large cylinder A, A, beneath its
piston H, H, is permitted to escape through the passage m, and through the
hollow of the sliding valve R, into the eduction passage a, which leads to the
eduction pipez, by which the steam is carried away from the cylinders. Under
these circumstances the two pistons will perform their descending stroke, and
by their three piston rods E, G, G, will raise up the cross bar or cross
head K, K, so as to give motion to the other moving parts of the engine.
Before stating the advantages derivable from its arrangement, and the appli-
cation of a ring piston to make use of the expanding steam, one thing which
at first strikes as objectionable may here be noticed, which is, the increased
extent of steam-tight surface to be maintained by using a ring instead of a com-.
mon piston, and which conveys the idea of a corresponding increase of friction.
That a badly constructed engine and ring piston would produce such a result is
undeniable, but if due regard be paid to the fitting up the cylinders and pistons.
of these engines, and the best methods of making pistons are resorted to, it is
presumed no sensible increase of friction will in practice occur, as in all
mechanical movements, where friction either takes place or is apprehended,
guides of a suitable nature have generally been resorted to with good effect.
Inasmuch, therefore, as the friction against the internal cylinder acts as a
guide to the movement of the ring piston, so would the friction on the outer
circle be reduced and admit of a diminished degree of tightness on its springs
or packing, as well as a diminished width of the surface usually brought into
contact in low-pressure pistons of the ordinary construction. This method of
arranging the two cylinders possesses several advantages over compound
engines now in use, both in the developement of the powers of the steam and
of those of the engine itself; for,-
First. The high-pressure cylinder being contained within the low-pressure
cylinder, the usual appendage of a steam case to the former is rendered un-
necessary, and whatever radiation of heat which takes place from it is trans-
mitted into the chamber of the low steam, and is thereby preserved in use till
the second operation of the steam is performed.
Secondly. The interior cylinder, being constantly charged with steam of a
high temperature in the centre of the chamber of expanding steam, operates
like the heater in an urn, and will keep up the elasticity of that expanding
steam to its fullest calculable extent, and thus will the double working of the
steam be effected,, corresponding, or very nearly corresponding, to the theory
of its expansibility, for there cannot happen any radiation of heat except from

page_text: the exterior surface of the low-pressure cylinder, which may be prevented.
almost wholly by an exterior coating of any non-conducting substance upon
that cylinder.
Thirdly. The steam case of the high-pressure cylinder being no longer used,
the steam will be transmitted more directly from the boiler into that cylinder,
and consequently its force more rigidly preserved, and by the juxta-position of
the two cylinders the use of pipes and joints are rendered unnecessary in
transmitting the steam from the one to the other, as this important process
is carried on in the hot aperture contained within the slide itself, and all
radiation in this passage is prevented by the slide being surrounded by the
steam on the outside being of a higher temperature.
Fourthly. A simple arrangement is attainable in the structure, as in the
opening and shutting the slide, whereby a simplicity equal to that of a common
high-pressure engine is attained, together with a perfect unison in the timing
of those valvular operations which the nature of the compound engine requires
should concur with exactitude, and upon which unison a perfect developement
of the powers of steam in its compound use does mainly depend.
Fifthly. By this combination of the two cylinders all capability is afforded of
applying the twofold power to one cross head, and thereby avoiding the detri-
ment arising from the double leverage by which those powers are communi-
cated to the beam in the compound engines now in use, and by the same com-
bination one slide applied to the surface of the outer cylinder is made to effect
by a single motion all the objects of the different valves or slides commonly
used in the two cylinders and the condenser in the compound engines now in
use, by which application of the power to the beam and the perfect unison of
the valves the compound powers of the steam appear to be carried by this
engine to the point of absolute truth, beyond which they cannot exceed in
point of effect and substantiality, and which conclusion involves also as a
consequence a reduction of fuel to the lowest possible standard.
Sixthly. Another advantage peculiar to this Invention is, the greater com-
pactness and portability of the engine, and the greater security arising from the
simplifying the valvular process by which it appears peculiarly adapted to the
purposes of marine engines. Since an engine so constructed would occupy
much less space than a common condensing engine such as are usually applied
to marine purposes, a boiler generating steam at thirty pounds on the square
inch, would do as much work with this compound engine as a boiler gene-
rating steam at sixty pounds on the square inch would do with a common high-
pressure engine, hence it follows the superiority of this engine over a simple
high-pressure engine is very great, both in point of safety and economy, as the

page_text: steam, when generated at a pressure of sixty pounds above the atmosphere,
becomes not only dangerous, but consumes much more fuel to raise and main-
tain it at that point, as an increased loss at the joints, as well by radiation, takes
place. Thus, safety and economy, both of fuel and room, increased power,
simplicity of action, and portability, are all combined together in this engine;
advantages like these thus brought into the focus of one machine which have
hitherto been held to be incompatible with one another appears to open &
still wider field to the energies of steam navigation, to which purpose it is
peculiarly applicable. The small piston F, with its rod E, is exactly the
same as usual, and it may be made either to be packed with hemp, or else it
may be made for metallic packing, all which, being well known, requires no
particular description. The large or ring piston H, H, has packing around its
exterior circumference in the same manner as a common piston, but it has a
large circular aperture through its centre which reduces it to a ring, and that
aperture is fitted exactly to the exterior surface of the small cylinder B, B,
which exterior surface is made truly cylindrical and smooth. The interior of
the circular aperture of the ring piston must be provided with suit-
able means of receiving and retaining packing, which may be either of
hemp or else metallic packing, and which packing is to apply to the
exterior surface of the small cylinder B, B, so as to make a steam-
tight fitting thereto, and yet allow the ring piston to move freely up and
down within the large cylinder A, A, and round about the small one B, B.
The two piston rods G, G, are fixed into the ring piston at opposite sides of
its centre, as is clearly shewn in the Drawings. The exterior circumference of
the ring piston is provided with the usual means for receiving and retaining
packing to apply to the interior surface of the large cylinder A, A. In Figures
2 and 4.the ring piston is represented with metallic packings around its inte-
rior aperture, and also around its exterior circumference, each of those pack-
ings being formed of metallic segments disposed in two circles, one within the
other, and in two heights one above the other, and the segments are continu-
ally pressed towards the surfaces, against which they are to fit respectively by
means of suitable springs, which may be applied as shewn in Figure 4; the
springs for the packing around the exterior circumference and those for the
packing around the central aperture being applied back to back, so that the
two sets of springs react one against the other; and as the dimensions and
proportions of the parts of steam engines which are constructed according to
my said improvement or improvements, they may be the same as usually
practised, that is to say, the small cylinder, considered in reference to the
area of its piston and the length of stroke made by that. piston, may have

page_text: the same capacity as would, according to the usual practice, be allowed for the
small cylinder of a double cylinder engine of the ordinary construction, and
the ring piston should have the same superficial area in the ring, and the
same length of stroke, as would usually be given to the large circular piston of
such an engine; and in like manner the several steam passages for conveying
the steam into and out of each cylinder may be of the same size as would,
according to the usual practice, be given to the corresponding passages of a
double cylinder engine.
And another part of my said improvement or improvements is appli-
cable to steam engines which operate with only one steam cylinder and
piston, and consists in fixing a strong cylindrical central rod within the
cylinder, to pass with exact fitting through a central 'hole in the piston, in
order to form a right-lined guide thereto for keeping it steady as it moves up
and down, or else backwards and forwards within the cylinder, and, instead of
one central piston rod affixing two piston rods to the piston at opposite sides of
its centre, those two piston rods passing through two stuffing boxes in the
cover of the cylinder, and being both fixed to one cross bar in the same
manner as already described respecting Figures 2, 6, and 7, the only difference
therefrom being that, instead of the small cylinder B, B, occuping the central
part of the large cylinder A, A, a solid cylindrical rod, somewhat larger than
an ordinary piston rod, is fixed fast in the centre of the cylinder A, A, by being
received at its lower end in a hole at the centre of the bottom of the cylinder,
and its upper end being received in a like hole in the centre of the cover of
the cylinder, whereby the rod will be securely retained and fixed in the centre
of the cylinder, in order to serve as a central right-line guide for the piston
during its motion; and the central hole, which fits closely around the said rod,
is provided with packing of hemp, or else metallic packing, to apply closely to
the cylindrical surface of the fixed central rod, and prevent any passage of
steam by the same, in like manner as the central aperture of the ring piston
H, H, has packing to apply to the exterior surface of the small cylinder
B, B, as already described. And note, this mode is applicable to cylinders
which lie in a horizontal position as well as those which stand in a vertical
position.
Having now described my said improvement or improvements upon steam
engines, I, the said George Dickinson, do hereby declare, that the new
Invention whereof the exclusive use is granted to me by the said Letters Patent,
consists in the manner herein-before described of disposing the small cylinder
of a double cylinder engine within the centre, of the large cylinder for such an
engine, the piston of that large cylinder being made in the manner of a ring

page_text: Inrolled the same Twenty-third day of February, in the year above written.