AN IMPROVEMENT IN THE ARRANGEMENT AND COMBINA- TION OF CERTAIN PARTS OF STEAM ENGINES TO BE USED FOR STEAM NAVIGATION
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
MAUDSLAY, of Lambeth, Engineer, send greeting.
WHEREAS I did, by Petition, humbly represent unto Her present most
Excellent Majesty Queen Victoria that, after considerable application and
expence, I had invented "AN IMPROVEMENT IN THE ARRANGEMENT AND COMBINA-
TION OF CERTAIN PARTS OF STEAM ENGINES TO BE USED FOR STEAM NAVIGATION;"
'and Her said Majesty, being willing to give encouragement to all arts and
inventions which may be for the public good, was graciously pleased, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Sixteenth day of March,
One thousand eight hundred and forty-one, in the fourth year of Her reign,
for Herself, Her heirs and successors, to give and grant unto me, the said
Joseph Maudslay, my executors, administrators, and assigns, Her especial
licence, full power, sole privilege and authority, that I or they, by myself or
themselves, or by my or their deputies, servants, or agents, or such others as
I or they should agree with, and no others, during the term of fourteen years
from the date of the said Letters Patent, should and lawfully might make,
use, exercise, and vend my said Invention within that part of Her said
Majesty's Dominions called England, the Dominion of Wales, and Town of
Berwick-upon-Tweed, and in all Her Majesty's Colonies and Plantations
abroad, and in the Islands of Jersey, Guernsey, Alderney, Sark, and Man,
in such manner as to me, my executors, administrators, and assigns, shall seein
meet, and as that I or they shall enjoy the whole profit and advantage arising
by reason of the said Invention during the said term of fourteen years; and
for that end Her said Majesty requires and strictly commands all Her sub-

page_text: jects whatsoever within England, Wales, and Berwick-upon-Tweed, and the
Colonies and Plantations abroad, and in the Island of Jersey, Guernsey,
Aldernay, Sark, and Man aforesaid, that they shall not, neither directly nor
indirectly, make, use, or put in practice my said Invention, or any part thereof,
nor in anywise counterfeit, imitate, or resemble the same, nor make any
addition thereto or subtraction therefrom whereby to pretend himself or them-
selves to be the inventor or inventors thereof; and whereas the said Letters
Patent contain a proviso obliging me, the said Joseph Maudslay, particularly
to describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, by an instrument in writing under my hand and
seal, and to cause the same to be enrolled in Her Majesty's High Court of
Chancery within six calendar months next and immediately after the date of
the said 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
Joseph Maudslay, do hereby declare that my said Invention is described and
ascertained in manner following, and by the aid of the Shect of Drawings
hereunto annexed, that is to say :-
My said improvement relates to the arrangement and combination of certain
parts of steam engines of that kind or class whereof the centre of the steam
cylinder (wherein the piston works) is situated immediately beneath the
rotative axis of the crank or cranks, and which axis is to be turned round by
the force exerted by the said piston when it is moved alternately up and down
by action of the steam in its said cylinder, that force being transmitted to the
crank pin of the crank or cranks, by means of a crank rod or connecting rod,
which acts alternately upwards and downwards so as to urge that crank pin
round in its intended circular orbit. And as to the particular parts of steam
engines, to the arrangement and combination of which parts my said improve-
ment relates, those parts are,-the steam cylinder, with its bottom and cover;
the piston and piston rod; the cross head belonging to the piston rod, and the g
connecting rod, together with all requisite appurtenances to those said several
parts; and the said several parts above named, when the same are used as some
of the constituent parts of steam engines which are constructed according to my
said improvement, are nearly the same as (or are similar to) like parts which have
been already used (or proposed to be used), some in one kind of steam engine, 3
and others in other kinds of engines, the said parts already used or proposed to
be used as aforesaid being nearly the same as to their several forms and modes
of construction (when considered as parts detached from the different engines
to which they belong), as the like parts which are to be used in engines

page_text: constructed according to my improvement. Wherefore my Invention does
not extend to the individual forms and modes of construction (herein-after
described) of the several parts above named; but my improvement relates solely
to the arrangement and combination (herein-after described) of such parts.
And my said improvement consists in disposing the connecting rod in
a space which is left vacant for its reception (together with the requisite
appurtenances herein-after enumerated of that rod) within the central part of
the steam cylinder, and within the central part of the piston which works up
and down in the said cylinder, the steam cylinder having for that purpose a
small cylinder fixed concentrically within it, and the piston being a broad ring:
or annulus, which encompasses the said small cylinder, and fits into the annular
cylindrical space which is left between the interior of the steam cylinder and
the exterior of the said small cylinder. The annular piston is moved alter-
nately up and down in the said annular cylindrical space by the force of steam
acting therein, but which steam does not enter into the interior of the small
cylinder; neither is any piston, or part of the piston, fitted therein, but the
interior of the small cylinder is left open at top, the cover of the steam cylinder
being a broad ring or annulus, covering over and closing up the said annular
cylindrical space wherein the annular piston works, but not covering over the
interior of the small cylinder, that interior being a space left open at top and
vacant within for the connecting rod and its requisite appurtenances to work
in, with liberty for that rod to move up and down therein, and likewise with
liberty when so moving to incline as much as it requires to do from a vertical
position alternately on one side of the vertical, and then on the contrary side
thereof, in consequence of the upper end of the connecting rod accompanying
the motion of the crank pin in its circular orbit (in the usual manner of con-
necting rods), whilst the lower end of the said rod moves alternately up and .
down in a vertical line, that line being at the central line or imaginary axis of
the stam cylinder, and which axis would in ordinary steam engines be
situated in the centre of the solid metal of the ordinary piston and piston rod.
But, according to my improvement in the arrangement and combination of the
various parts, the said vertical line or imaginary axis of the steam cylinder is
situated in an open space, which, as already stated, is left vacant for the
purpose of receiving the connecting rod, together with its appurtenances,
within the central part of the steam cylinder, and within the central part of the
annular piston, in consequence of the small cylinder being fixed concentrically
within the interior of the steam cylinder, and in consequence of the cylinder
cover, as well as the piston, being each a broad ring or annulus, and each being
suitably fitted to the annular cylindrical space between the two cylinders, but

page_text: without covering or occupying the interior of the small cylinder. And in order.
to communicate motion from the annular piston to the joint at the lower end.
of the connecting rod, the said annular piston is provided with two piston rods
fixed vertically to it at opposite sides of the imaginary centre of the annular
piston and of the steam cylinder, those vertical piston rods being fixed to the
annular piston nearly in the middle of its breadth, wherefore they stand,
nearly in the middle of the breadth of the annular cylindrical space.
between the interior of the steam cylinder and the exterior of the small
central cylinder. The said two vertical piston rods pass up through two
stuffing boxes which are provided for them in the aforesaid annular cover
of the cylinder, and the upper ends of the said two vertical piston rods are
firmly united to the two extremities of a strong tee-shaped cross head, resem
bling in its form the letter T, the upper part of which extends horizontally
across from the upper end of one piston rod to that of the other, and which
tee-shaped crosshead may be made double, or composed of two parallel sides
or thicknesses put together side by side, so as to be united at the two.extre-
mities aforesaid, to which the piston rods are fastened, but leaving a sufficient
opening between the two sides to admit the connecting rod between them.
In order that it may be situated in the middle of the thickness of the tee-
shaped cross head, which is so compounded of two sides fixed together; the
vertical stem of each of the said sides of the tee-shaped cross head goes down
at each side of the connecting rod into the space before mentioned within the
interior of the small cylinder, each of the said vertical stems projecting.down-
wards from the middle of the horizontal part of the cross head at right angles
thereto, and in one piece of metal therewith, in the form of the upright stem
of the letter T; and at the lowermost end of each of the said two stems, the
joint pin for the lower end of the connecting rod is fixed horizontally across
between the two stems, the joint at the lower end of the connecting rod being
fitted on the middle part of the said joint pin so as to unite the lower end of the
connecting rod to the cross head, and by means thereof to the piston rods, and
by them to the annular piston, the upper end of the connecting rod being jointed
in the usual manner of steam engines to the crank pin. The lower portion of the
connecting rod is situated in the space between the two sides, whereof the tec-
shaped cross head and its vertical stem are compounded as aforesaid, those
two sides being united together at the lowermost ends of the vertical stems by
the joint pin, which is fixed across from one stem to the other as before men-
tioned. And the said two thicknesses are also united, as already stated, at
the two extremities of the horizontal part to which the piston rods are fastened;
wherefore the two sides form as it were one compound tee-shaped cross head,

page_text: which has a sufficient opening in the middle of its thickness to admit the
connnecting rod to work within it, and to admit of that rod inclining as
much as it is required to do from a vertical position, alternately on one
side of the vertical, and then on the other side therof. And in order to
assist in retaining the joint pin at the lower end of the connecting rod in
the vertical line in which it is intended to move alternately up and down,
the lower ends of the two upright stems of the tee-shaped cross head have
sliding pieces fixed to them, which pieces are received between upright
grooved straight edges, fixed within or formed within the interior of the
small cylinder, so as to constitute a parallel guiding groove within that
interior for the lower end of the stem of the tee-shaped cross head to move
up and down in, and thereby produce the effect of a parallel motion. The
connection between the annular piston and the joint at the lower end of the
connecting rod is therefore effected by the parts above described, in the fol-
lowing manner :-The two vertical piston rods ascend from opposite sides of
the annulus, and pass up through their two stuffing boxes in the annular
cover. The ends of the horizontal part of the tee-shaped cross head are united:
with the upper ends of those piston rods, and the upright stems of the same
cross head, descending into the vacant space in the interior of the small
cylinder, sustains the joint pin for the lower end of the connecting rod, which
pin (according to the length of the upright stems of the tee-shaped cross head,)
may be nearly on a level with the annular piston, or may be somewhat higher
up or lower down than that level, as may be most convenient; but, in con-
sequence of the aforesaid mode of connection, the said pin will be moved up
and down in the open space within the interior of the small cylinder in exact
coincidence with the motion wherewith the annular piston is at the same time
moved up and down within the annular cylindrical. space between the two
cylinders. And, note, the bottom of the open space within-the interior of the
small cylinder may be left open, and a lateral passage may be left beneath the
cylinder bottom for entrance to the said open bottom of the small cylinder, for
the coveniance of getting at the joint at the lower end of the connecting rod:
And, for the more complete explanation of the arrangement and combination
of parts already described in words, I have hereunto annexed a Drawing of a
steam engine having its parts arranged and combined according to my said
improvement. The said Drawing contains all those parts, to the arrangement
and combination whereof my improvement relates; but many parts which have
no relation to that improvement are omitted in the Drawing.
Figure 1 is a longitudinal or side elevation of the said engine... Figure 2 is.
a longitudinal vertical section, corresponding to the side elevation; Figure 1.

page_text: Figure 3 is a horizontal plan of the upper part of the engine; and Figure 4 a
horizontal section of the cylinders thereof. Figure 5 is a transverse vertical
elevation and section representing two such engines, disposed side by side for
combined action, in the manner engines usually are combined on board steam
vessels, one of the two engines in Figure 5 being represented in section, to
shew the interior parts, the other being represented in elevation, to shew the
exterior parts. The same letters of reference denote the same parts in all the
Figures. a, a, is the steam cylinder, its interior surface being bored truly
cylindrical, as usual for steam cylinders; and b, b, is the small cylinder, which
is fixed concentrically within the steam cylinder a, a. The external cylindrical
surface of the small cylinder is turned true in a lathe, but the interior of the
small cylinder does not require boring. n, n, is the bottom of the steam
cylinder, to which the flange around the lower power of the steam cylinder a, a,
is fitted, as usual with a close joint; and the cylinder b, b, is also fitted to the
same bottom, with an internal flange at the lower end of the small cylinder b, b,
so as to be truly concentric with the interior of the cylinder a, a, in order that
an annular cylindrical space may be left between the two cylinders of exactly
equal breadth all round. m, m, is the cylinder cover, which is also annular,
and adapted to cover over and close up the said annular cylindrical space,
without covering over the interior of the small cylinder b, b. The cylinder
cover m, m, is fastened down (as cylinder covers usually are) by bolts to the
exterior flange around the top of the cylinder a, a; and the cover enters into
the upper part of the cylinder, in the usual manner of cylinder covers. The
annular cover may be also fastened down by screw bolts to an internal flange
around the top of the small cylinder b, b;. and the annular cover drops also
over around the top of that small cylinder, so that, in fact, the cylinder
cover m, m, drops into and fits into the annular. cylindrical space between the
two cylinders a, a, and b, b, and is fastened down by bolts to the exterior flange
at the top of the. steam cylinder a, a, and may also be fastened down to the
interior flange at the top of the cylinder b, b. c, c, is the annular piston,
which is fitted into the annular. cylindrical space between the two cylinders.
The exterior circumference of the annular piston c, c, is fitted to the. in
terior of-the. steam cylinder a, a, with packing, either of hemp or metallic
packing, of any such kind as is commonly used for ordinary pistons. Also: the
interior circumference of the same annular piston is fitted to the exterior
cylindrical surface of the interior cylinder b, b, with like packing, either of hemp
or metallic packing. d, d, are the two piston rods, which are fixed (by any
of the usual modes of fixing piston rod to its-piston,) to the annular piston at
two points therein, diametrically opposite one to the other across the centre of

page_text: the annulus c, c, as is shewn in Figures 2 and 4; and the rods d, d, pass up
through two stuffing boxes in the annular cover m, m, as shewn in Figure 2,
those stuffing boxes being constructed to retain packing around the rods in the
same manner as stuffing boxes usually do. The upper ends of the two piston
rods d, d, are securely fastened to the two extremities of the upper horizontal
part of the tee-shaped cross head e, e, e, e, f, f, which, as already mentioned,
is compounded of two parallel sides, united together at the two extremities of
the
upper horizontal part, to which extremities the two piston rods d, d, are
fastened; and the said sides are also united at the lower extremity of the
upright stem ff, by the joint pins, for the lower end of the connecting rod g,
the said two parallel sides whereof the tee-shaped cross head is compounded
being so far apart one from the other as will leave between them a space suffi-
cient for the connecting rod g to work in, as is clearly shewn in Figures 8, 4,
and 5. The lower end of the connecting rod 9 is fitted with a joint upon the pin
s, which is fixed across between the lower extremities of the upright stems f,f,
and serves to unite those extremities together, as already mentioned, and as is
shown in Figure 4; and the upper end of the connecting rod g is fitted with a
similar joint upon the crank pin of the crank h, in the usual manner of the
connecting rods and cranks of ordinary marine steam engines. p, p, Figures 2
and 4, are the two sliding pieces, which are fixed at the. lower ends of the
uprights stems f, f, of the tee-shaped cross head. Those sliding pieces p, p,
are fastened to both the stems f. f, as is shewn in Figure 4, and form,
as it were, a sort of box, within which the joint at the lower end of the
connecting rod g is inclosed, but without touching the interior of such box.
The two sliding pieces p, p, are each formed with a salient angle, which angles
are fitted to move up and down in angular grooves formed in the two upright
straight edges r, r, Figures 2 and 4, which are fixed withinside of the interior
of the small cylinder b, b, at opposite sides of the circumference of that interior;
so as to constitute a parallel vertical guiding groove r, r, within that interior;
into which groove the lower ends of the stems of the tee-shaped cross head are
fitted by means of the sliding pieces p, p, so as to move freely up and down,
in accordance with the motion of the annular piston c, c, but without liberty.
of lateral deviation from a vertical motion. The two ends of the joint pin s,
for the lower end of the connecting rod, are reduced to small joint pins, which
project out on each side beyond the sides f, of the tee-shaped cross head; and
on those pins are fitted the lower ends of two links 9, 9, for working the air
pump, the upper ends of those links being jointed to the long ends of two
levers k, k, situated one on each side of the tee-shaped cross head c, e; and from
the opposite or short ends of those two levers the rod 7 of the air pump is

page_text: suspended by two suitable links, both of which are jointed to the said rod 7.
The fulcrum or centre of motion t of the two levers k, k, is common to both
levers, and is sustained by suitable framing. The two levers k, k, act as one,
and may be considered as one lever compounded of two parallel sides, with
sufficient space left between those sides to admit the tee-shaped cross head to
work in that space. The remaining parts represented in the Drawing, having
no relation to my improvement, do not require much description, and those
parts may be constructed in any manner which is preferred. The horizontal
axes i, i, i, of the cranks h are the same as usual in marine steam engines.
The several bearings for the said axes are sustained in one horizontal line in a
framing of iron, which is affixed between two parallel wooden beams, extending
horizontally across the vessel from side to side thereof, and the iron framing is
upheld by four upright props of wrought iron, which are erected on and firmly
affixed to the base whereon the cylinder a, a, stands, those props passing up
through holes in four ears, which project outwards from the exterior flange
around the top of the cylinder a, a, the props being by that means firmly re-
tained in place in respect to each other and to the steam cylinder a, a; and
they retain the said framing, which carries the bearings for the axes of the
cranks at an invariable position in respect of the steam cylinder a, a. The
base whereon the steam cylinder a, a, stands, is made to serve for the con-
denser being prolonged out one way from beneath the cylinder, as shewn in
Fig. 4, also Figs. 1 and 2, in order to admit the air pump to be placed in it.
That air pump, with its bucket and valves, and the hot well, also the hot water
pump or pumps, may be constructed in any mode used in steam engines.
The said base or condenser also has a lateral branch projecting out from
beneath the cylinder to receive the lower end of the sliding valve, by
which the same is distributed to the cylinder, and the said branch serves as
the eduction passage for exhausting the steam from the cylinder, and con-
veying it down into the condenser. The upper surface of the said base or
condenser serves as the bottom n, n, of the steam cylinder a, a, and a lateral
passage y may be formed within the said base or condenser, to lead beneath
the open space within the small cylinder b, b, and give access to the to
the joint at the lower end of the connecting rod, as already mentioned.
The sliding valve for distributing the steam to the cylinder, as represented in
the Drawing, is what is called a dec-sliding pipe valve, of the same kind as is
most commonly used in marine steam engines; but any other kind of distri-
buting valve or valves may be used, either one, or two, or four sliding valves
or four lifting valves, as may be preferred, those parts having no reference to
my improvements. And as to the parts commonly called working gear, for

page_text: giving the requisite motion to the sliding valve from an excentric on the axis i
of the cranks, those parts are not represented in the Drawing, because the
manner of applying suitable working gear is familiar to competent engineers,
and may be arranged in various ways, and must be adapted to suit the kind of.
distributing valve or valves which is used, and has no relation to my improve-
ment. And as to dimensions of engines which are constructed according to my
improvement, the steam cylinder a, a, must be larger than the usual size for
the steam cylinder of an engine of like power on the ordinary construction, in
order to compensate for the space taken up by the small cylinder b, b, within
the steam cylinder a, a. The horizontal area of the annular space between the
two cylinders (or of the annular piston c) must be fully equal to the horizontal.
area of the cylinder (or of the piston) of an engine of like power on the
common construction. If a straight line, such as the dotted line v, x, Fig. 4,
is drawn in the manner of a tangent to the circle of the exterior of the small
cylinder b, b, the said line will also form a chord within the circle of the interior.
of the steam cylinder a, a, and the length v, x, of that chord will give the dia-
meter of a cylinder, (see the dotted circle, Figure 6,) which, having a piston of
the ordinary construction, would have the same horizontal area as the annular
cylindrical space and annular piston c, c, will have. And as to the dimensions
of all other parts, they should be proportioned to the power of the engine
(which is constructed acccording to my improvement,) in the same manner as
in ordinary steam engines, all which is well understood by competent
engineers, has no reference to my improvement. The Drawing is drawn to a
scale of half an inch to a foot, or one twenty-fourth of the real size, and repre-
sents an engine of one hundred horse power. And note, although the tee-
shaped cross head e, f, has been described and represented as being.compounded
of two parallel sides united together, leaving a space between them to receive
the connecting rod, nevertheless, the said cross head may be made in one piece,
the connecting rod being in that case double, or composed of two parallel rods,
disposed one on each side of the tee-shaped cross head. Those two parallel
rods may unite together into one at the upper end, above the upper horizontal
part e, e, of the tee-shaped cross head, so that the joint at the upper end of the
connecting rod will be the same as already described and represented; but at a
short distance below that joint the connecting rod will divide into two in the
manner of a fork, to go down at each side of the upright stem of the tee-
shaped cross head, and the lower joint pins being fixed across the two parts of
the rod from one to the other, will unite them together, the joint which is
fitted on the pins being at the lower end of the upright stem of the tee-shaped
cross head. In this way the cranks h, h; on the rotative axes may require to

page_text: have somewhat more space left between them, in order to admit the forked
part of the connecting rod to go up between the cranks when the rod is near
to the top of the stroke. And note, although the steam cylinder has been
described and represented as standing in a vertical position, that circumstance
has no reference to my improvement, and if preferred, the cylinder may be
placed in any other position. For instance, the steam cylinder may be inclined
at an angle of forty-five degrees to the vertical, and two engines having their
cylinders so inclined (but inclining in contrary directions one to the other)
may be combined with the joints at the upper ends of their respective con-
necting rods, jointed side by side on the same crank pin, which will in that
case serve for both engines, because the direction in which the pistons of the
two engines act on that crank pin will be at right angles one to the other.
This is a well known mode of combining two engines; and each of the engines
which are so combined, may be according to my improvement. In that case the
connecting rods of the two engines which are so combined may, if requisite,
be made longer in proportion to the length of the stroke made by the piston
than is the case in the engine represented in the Drawing; and, consequently,
the cylinders will be farther distant from the axes of the cranks. The inclining
position of the cylinders will permit of such increase in the length of the con-
necting rod being made without the axes of the cranks being at any higher
level than represented in the Drawing; and such increased length may be
given, if it is requisite, in order that the ends of the tee-shaped cross heads of
the two engines may not interfere one with the other in working (by the said
mode of combination) on one crank pin.-
Having now described my said improvement in the arrangement and com-
bination of certain parts of steam engines to be used for steam navigation, I,
the said Joseph Maudslay, do hereby declare that I make no claim to the
exclusive use of a piston constructed in an annular form with two piston rods,
as herein-before described, nor to the exclusive use of one steam cylinder
within anotlier, leaving an annular cylindrical space between them within the
steam cylinder for the said annular piston to work in, nor of a cylinder cover
in an annular form, with two stuffing boxes therein for the two piston rods, as
herein-before described, all those parts having been already proposed to be
used nearly in the same forms as herein-before described for that particular
kind of steam engine which is commonly known as Woolf's compound engine,
with two steam cylinders and pistons, vizt., a small steam cylinder and piston
to receive high pressure steam from the boiler, and a large steam cylinder and
piston to receive the same steam after it has been discharged from the sinall
steam cylinder, in order that tho steam may art over again in the large steam

page_text: cylinder, with an expansive action of the steam. It has been proposed to
place such small steam cylinder and piston within the large steam cylinder and
piston, the latter being of an annular form, and having two piston rods, the
cylinder cover being also of an annular form, with two stuffing boxes in it for
those two piston rods; but in steam engines constructed according to my
improvement, as herein-before described, no piston works in the small cylinder,
or can be applied therein, neither is there any cover to that small cylinder,
and in fact it is not a steam cylinder, for no steam is ever admitted into it; the
interior thereof is a mere open space which receives the connecting rod with
its appurtenances, as herein-before discribed, viz, the upright stems of the tee-
shaped cross head, and the joint pin for the connecting rod and the sliding
pieces at the lower ends of those stems, along the upright straight edges,
forming the grooves wherein those sliding pieces move up and down, so as to
produce the effect of a parallel motion; also the links for working the air-
pump, all which parts are received within the interior of the small cylinder, as
herein-before described; and the only object of using a small cylinder (in
engines constructed according to my improvement) is to obtain a central open
space for those parts to work in.
Neither do I claim, by virtue of the aforesaid Letters Patent of the
Sixteenth of March, One thousand eight hundred and forty-one, the exclusive
use of the tec-shaped cross head herein-before described, and which has a
piston rod united to each extremity of the upper horizontal part of such
tee-shaped cross head, and the lower end of the connecting rod or rods being
jointed to the lower end of the upright stem or stems of such tee-shaped cross
head, and the said lower ends being also guided to move up and down with
sliders, in parallel grooves, so as to answer the purpose of a parallel motion;
because such tee-shaped cross head, with the aforesaid appurtenances thereto,
and nearly (although not quite) in the same form as herein-before described,
constituted a part of improvemonts in the construction of marine steam engines,
for which former Letters Patent were granted by Her present Majesty to me,
the said Joseph Maudslay, conjointly with Joshua Field, on the Seventh day
of May, One thousand eight hundred and thirty-nine. But in that case the
said two piston rods, which were united to the two ends of the horizontal part
of the tee-shaped cross head, belonged to two distinct pistons, working with
simultaneous motion in two distinct steam cylinders, each of those pistons and
steam cylinders by itself being nearly of the ordinary kind, and the upright
stems of the tee-shaped cross head, and the connecting rod worked up and
down in a space left for that purpose between the said two steam cylinders,
wherefore neither of the said steam cylinders was situated with its centre imme-

page_text: diately beneath the axes of the cranks; but according to my present improve-
ment, the same or a similar tee-shaped cross head and two piston rods with
the connecting rod and other parts or appurtenances aforesaid, are arranged
and combined so that the connecting rod, with its said appurtenances, will be
received in the open space which is left for that purpose within the interior of
the small cylinder, and the two piston rods aforesaid are affixed to the opposite
sides of the annular piston which surround the said small cylinder.
Wherefore I claim as the new Invention, whereof the exclusive use is
granted to me by the aforesaid Letters Patent of the Sixteenth day of March,
One thousand eight hundred and forty-one, the improvement herein-before
described in the arrangement and combination of the parts (herein-before
mentioned) of steam engines to be used for steam navigation, the dis-
tinguishing character of that improvement being, that the connecting rod, with
the requisite appurtenances of that rod, as herein-before enumerated, is
situated and works within a space which is left vacant for the reception of
those said parts within the interior of the small open top cylinder, which is
fixed in the central part of the steam cylinder, and within the central part of
the annular piston, which works up and down in the annular cylindrical space
that is left between the interior of the steam cylinder and the exterior of the
said small cylinder, as herein-before fully described.
In witness whereof, I, the said Joseph Maudslay, have hereunto set my
hand and seal, this Sixteenth day of September, One thousand eight
hundred ..