IMPROVEMENTS IN STEAM ENGINES, IN PROPELLING AND IN THE CON- STRUCTION OF SHIPS AND VESSELS
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
WINSHURST, of Limehouse, in the County of Middlesex, Shipbuilder, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twelfth day of
November, One thousand eight hundred and fifty, in the fourteenth year of
the reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Henry Wimshurst, my exors, adñiors, and assigns, Her especial
licence, full power, sole privilege and authority, that I, the said Henry
Wimshurst, my exors, adññiors, and assigns, or such others as I, the said
Henry Wimshurst, my exors, adññiors, 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
Invention of "IMPROVEMENTS IN STEAM ENGINES, IN PROPELLING AND IN THE CON-
STRUCTION OF SHIPS AND VESSELS;" in which said Letters Patent is contained a
proviso that I, the said Henry Wimshurst, shall cause a particular description
of 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, to be
inrolled in Her Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters Patent,"

page_text: 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
Henry Wimshurst, do hereby declare that the nature of the said Invention,
and in what manner the same is to be performed, are fully described and
ascertained in and by the present Specification thereof, reference being had
to the Drawings hereunto annexed, that is to say :-
Firstly, my Invention has relation to rotary steam engines, and consists
in an improved plan of construction, "whereby I am enabled to obtain the
advantage of continuous direct action belonging to this class of engines, with
less friction and liability to leakage, and consequent waste of power, than
hitherto in this class of engines. An engine on this improved plan of con-
struction, with all its necessary appliances; as air pump, condenser, &c., is
represented in Sheets I. and II. of the Drawings hereunto annexed. Figure 1
(Sheet 1) is an end elevation of the engine; Figure 2, a side elevation of it;
Figure 3, another elevation on the end opposite, to, that shewn in Figure 2;
Figure 4, a transverse section; and Figure 5, à longitudinal section. Figures
6 to 12, both inclusive, are separate views of different parts of the engine,
each detached from the others. In its general structure this engine. so far
resembles others of the class that the power is obtained by means of a drum
revolving eccentrically within an external cylinder, and the pressure of steam
against a series of pistons successively protruded from the circumference of the
drum as it revolves; but it differs from others in the following among other
important particulars:-
First, the external cylinder is bored, not of a perfectly circular form as
usual, but of unequal diameters at certain points, by which a nearer corre-
spondence to the eccentric path described by the piston carried by the inner
drum is obtained;
Second, the pistons have their chief bearing points on antifriction rollers
(within the recesses of. the drum), whereby the frictional resistance to their
movements is reduced to a minimum, or as nearly so as may be;
And third, the steam is admitted (during, the forward and ordinary course
of the engine) from below into the external cylinder, and by its upward
pressure on the pistons serves in a great measure to relieve the bearings and
external cylinder from the weight and friction of the moving parts of the
engine.
In the Figures, A represents the bed or foundation plate of the engine; B,
the external cylinder, which has the peculiar form above mentioned given to it
by boring it from three centres in manner following:-Assuming the diameter

page_text: of the cylinder to be sixty inches, it is in the first instance bored out of a true
circle from (a) as the centre in the Diagram. Figure 1", the centre or axial
line of the boring tool, is then shifted in a vertical line from a towards b,
about one inch and one eighth of an inch, or about one fifty-third part of the
cylinder's diameter, which, being done, it is again shifted in a horizontal
direction towards d, about three eighths of an inch, or about one hundred and
sixtieth part of the diameter, which will bring the axial line of the cutter bar
to the point f. The tool is then pláced at such a distance from the last
centre that it shall first touch the circumferential point g, about two inches
above d, and while it is in this position a cut is made through the cylinder
from end to end, whereby a lune-shaped piece is cut away, as indicated by the
dotted lines. To make the lower side of the cylinder of a corresponding shape
a similar series of operations are gone through (that is to say), the cutter bar
is first shifted from the centre a towards c one iuch and one eighth of an inch,
and next horizontally towards d about three eighths of an inch, when a third
cut is made through the cylinder from end to end as before (beginning at the
point h, about two inches from the under side of d). The slight ridges left by
boring from different centres are to be then worked off, and the internal
surface of the cylinder to be rendered quite smooth. The result of the peculiar
form thus given to the interior of the external cylinder is, that although the
inner drum is revolving eccentrically to the outer cylinder, yet the pistons,
which are of one continuous length, passing through the inner drum, are kept
nearly in constant contact with the inner surface of the external cylinder, and
with as little movement of the necessary packings as may be. C is the inner
drum, which may be cast wholly solid or partially hollow, as shewn in Figure 4,
and is divided by six slots or recesses (for as many pistons to work in) into six
segments c, c', c, c', c', c'. C¹, C, are bosses, which are affixed to the ends
of the drum (revolving with it) for the double purpose of strengthening the
drum and affording a ready means of packing it at the ends. D, D, are two
shafts that are keyed on one line with the two bosses, and carried by suitable
standards F, F, (or they may be supported by bearings affixed to the ends
E, E, of the outer cylinder). These two shafts form the main shaft of the
engine, which may be coupled to any other machinery. The details of the
mode of packing the drum at the end are shewn in Figure 5, and in Figures 9,
10, '11, and 12. A metallic hoop H, Figures 10, 11, and 12, is shipped
loosely over each of the bosses C, C; connected with the hoop there is a
metallic ring. y², y³, y, are segmental pieces of metal, between which and
the ring y and the bosses there are inserted packings (of cork or any other
suitable yielding material). y', y, are pinching screws, by which the pressure

page_text: given to the cork or other yielding packing is regulated. For regulating the
pressure of the ring y² against the cylinder cover there are pinching screws
passed through the hoop H.
The segments, packing-rings, and hoops are secured to the boss by screw
bolts y', y', so that they all revolve along with the inner drum. When the
drum revolves the inner edge of the metallic ring packings runs against the
inner edge of the cylinder cover (rendering that part steam-tight), but to
prevent them or the bearings from being injured by the heat the whole are
enclosed in cases S, S, which may be filled with water or other liquid, and
made also steam-tight round the shafts D, D, by means of packings, such as
represented in the plan Figure 6. T, T, are the packings, which are formed
of cork or some other like yielding material; T, T¹, are gaskins; and T², T³,
metallic blocks, by which the packings are pressed against the shaft by means
of the pinching screws T3, T3. U, U, are the pistons, which are of a rectangular
form, and connected together in pairs by means of bars V, V, which are passed
through the pistons and secured at the ends by cotters, for which screws or nuts
might be substituted. Each pair of pistons works to and fro through the
drum in the recesses made for them, and bear at the sides against antifriction
rollers X, X, placed at different distances but near to the extremities of these
recesses when the pistons are fully protruded from the drum. To keep these
antifriction rollers true in every change of position they have at their ends
small pinion guides m, m, (see Figure 7,) which gear into fixed racks n, n,
within the recesses in the body of the drum. The pistons are rendered steami-
tight by means of packings, which are inserted at y, y, in grooves running
parallel to the recesses, and pressed by springs against the sides of the pistons,
by which means the steam is prevented from passing through into the eduction
side. W, W, are caps or head-pieces, which are affixed on the outer ends of
the pistons, and made on their rubbing surfaces of a convex form; and 2,,
are metallic packings, which are inserted into these caps at the extreme points
where they come in contact with the exterior cylinder. To keep these packings
pressed out against the inner face of the external cylinder they are acted on
by spiral or other suitable springs inserted in recesses made in the pistons and
caps. The springs are each covered by a plate, between which and the metallic
packing a gaskin is inserted, if required, or any other suitable packings. a¹, a³,
are the induction or steam ports (supposing the engine to be revolving in the
direction indicated by the arrows), aud b', b, the eduction steam ports; c is a
reversing slide, which is worked when necessary by means of the hand-wheel O
and the pinion O2 and rack O³, the last of which is affixed to the spindle of
the reversing slide. d is the exhaust port. The steam ports and passages a¹, a²,

page_text: and 6, 6, open into the cylinder at different parts of its circumference, which
enables the steam to work more or less expansively at pleasure without the
necessity of having a separate expansion valve for the purpose. If it is desired
to work the steam expansively, then the reversing slide valve is so placed over
the ports that it admits the steam only into the lower one (a¹), in which case
the quantity of steam admitted behind the piston during one sixth of a revolu-
tion after passing the port has to expand in the compartment contained between
that and the next succeeding piston till after having traversed over about one
balf the entire circumference of the cylinder it ultimately escapes through the
exhaust port, the compartment having progressively increased in capacity
during nearly the whole time, whereby the full expansive force of the steam
is brought into action upon the piston, and transmitted to the main or driving
shaft of the engine. If the steam employed in giving motion to the engine is
not to be so much expanded, then the reversing slide is pushed further up, so
as to open both the ports a¹ and a² for the supply of steam; and when this is
the case the steam entering by the port a', after acting through one fourth of
a revolution, is further augmented by steam through the port a², so as again to
fill the compartment with steam at the same pressure as that in the steam
pipes. After producing its useful effect, or impelling the pistons and shaft, the
steam escapes by the passages b', 62, and so on continuously. Sometimes, instead
of opening the ports a¹ and b' to their full extent for supplying the steam to
the engine, I only partially open them, so that the pressure of steam admitted
behind the piston in the first instance may be less than that contained in the
boiler. When such is the case a separate set of passages (either cast along with
the cylinder or pipes may be substituted for these passages) and valves are
employed for admitting the full pressure of steam behind the pistons after they
have advanced a portion of their course under the influence of the low-pressure
steam; these passages are indicated by dotted lines in Fig. 4, Sheet 2. The
reversing of the engine is effected by simply moving down the slide c, so that
it may admit the steam to the ports b', 63, and put the ports a', a², in communi-
cation with the exhaust port d. In large engines it will be further necessary
to shut off the steam by the throttle valve previous to moving the reversing
slide valve. G is the condenser, which I have placed over the engine, con-
sidering that the nearer the condenser is to the level of the water line of the
vessel (when the engine is used for marine propelling) the less will be the
back pressure upon the air-pump piston. The condenser is enclosed in an
outer casing G2, the intervening space being kept constantly filled with the
injection water, which is allowed to flow through it into the condenser, whereby
the temperature of the condenser is kept at a comparatively low state.
His

page_text: 65
a double-acting air pump, the plunger of which is directly connected-to-the
piston of an auxiliary donkey engine" J, which in most cases. I prefer to
having the air pump worked by the rotary engine itself, as that would be
revolving at too high a velocity for conveniently connecting the air pump
directly to it. When, however, the rotary engine is of great power; and the
cylinder of considerable length, then an auxiliary shaft may be employed to
give strength or prevent any risk of fracture from torsion; the auxiliary shaft
in such case would be placed parallel to the main shaft, and be connected to
it by wheel gearing placed at both ends of the cylinder. By adopting an
arrangement of this sort the auxiliary shaft may be made to revolve with
much less velocity than the main shaft, and under such circumstances
might be employed for working the air pump. K is a steam cylinder, the
piston rod of which forms the slide valve spindle of the cylinder J; the slide
valve of the cylinder K is worked by tappets affixed to the piston rod of the
air pump.
The various Figures in Sheet 2 are representations of a rotary engine fitted
for either land, marine, or locomotive purposes, which is similar in its general
construction to that just described, but differs in some of the details. It is
shewn without an air pump or condenser, but is equally applicable for being
worked thereby as well as by high-pressure steam. The packings at the ends
of the drum and those in the outer edges of the piston, as also those around
the bosses, are constructed as follows:-The piston, packings a³ have interposed
between them and the plate a² a gaskin, as in the engine first described; but
on the back of the plate a there are formed a number of projecting pieces
which take into holes formed in the bottom of the recesses for the packings,
and beneath those pins or projecting pieces, there are placed helical springs,
which keep the packings up against the periphery of the outer case of the
engine. The helical springs a may be inserted into their places previous to
the packings being put in, or they may be inserted through openings in the
sides of the piston after the packings are in their places.
Fig. 7 is a cross section of a piston packed in this way, in which the plate a²
is made sufficiently deep to allow, of the gaskin and plate as being altogether
dispensed with. a, a, are the helical springs. a, a, another set of helical
springs, which keep the surface of the metallic packing a in contact with the
surface of the centre piece of the cap or head of the piston. 7, I, are the packings
around the bosses, which are formed of segments of cork or other soft yielding
substance. m, m, is a ring of metal which goes round the packings 1, 1, and
serves to keep them in their places while the edges of the ring itself work up
in contact with the cylinder cover of the engine.. n, n, are a set of segmental

page_text: pieces, which are secured to the bosses by the bolts or screws o, o; these
segments carry other bolts or pinching screws p, p, by which the segments of
the packings may be screwed up to their proper degree of tightness. r, r,
are another set of cork packings which are superimposed around the main
shaft of the engine at the outer ends of the water cases which surround the
bosses; each of the pieces r, r, is held in its place, and has the requisite degree
of pressure given to it by means of the segmental pieces of metal ; 2, and the
pinching screws ³, 23.
Figure 2 is an
Secondly, my Invention has relation to the propelling of vessels, more
particularly to such as are propelled by screws, and consists:-First, in so
disposing the propeller that the propeller may be conveniently raised up out of
the water when required, and retained there at pleasure; this arrangement is
more especially applicable to auxiliary steam propelled vessels, for when the
vessel is under sail, and the steam power not required, the vessel will be free
from the obstruction which would otherwise result from the propeller being
dragged through the water. Figure 1, Sheet III., is a side elevation of the
stern of a vessel fitted with this part of my improvements;
elevation of the stern; Figure 3 is another elevation of the stern partly in
section; and Figure 4 is a half plan viewed from below. A, is the propeller
shaft, which may run parallel with the keel of the vessel, but is laid out at
such an angle with it that the point where the shaft passes through the hull
shall be, situated in the run of the vessel. By this angular position the
propeller shaft is enabled to be extended so far as to admit of the propeller
being placed abaft the rudder, and at the same time of the rudder being
brought sufficiently round towards that sile on which the propeller shaft is
placed as is requisite for the steering of the vessel. B is a joint in the main
shaft A. C, the lower half of the outer bearing of the shaft, which is securely
fixed to the stern post D. E is the outer bearing, which loosely encircles the
shaft, but fits accurately to the upper side of it when the propeller is lowered
down into its place. The inner end of the bearing E is of a T form, and is free
to slide up and down in a groove of the same shape formed in a metal plate
affixed to the side of the, stern post, and by which the stern post is greatly
strengthened. F is a long screwed rod, the upper end of which turns in a
bearing and the lower end is in a socket. The rod is free to turn within the
socket, but cannot move either up or down; the lower part of the rod is
screwed, and takes into a corresponding screwed recess or hole through the.
bearing E, by which means, when the propeller is desired to be raised out.of
the water into the position indicated by dotted lines in Figure 1, it is only
necessary to turn the screwed rod F, by means of a crank or handle mounted

page_text: on its upper end, and which will raise the bearing E, and along with it the
outer end of the propeller shaft and the propeller. By turning the screwed
rod in the reverse direction the propeller is again lowered into its place when
required. Figures 5, 6, 7, and 8, are respectively separate plans of the under
bearing, the T shaped groove, and of the upper bearing; the groove may be
of any other form capable of retaining the end of the sliding bearing E.
In some cases, where the propeller is of great weight, I suspend the
outer end of the propeller shaft by an outrigger attached to the stern
of the vessel, in which case a much smaller bearing would be formed on
the outrigger than is required upon the stern post to carry the main shaft.
Secondly, a further improvement in relation to propulsion consists in the
construction of a bow steering apparatus of one or more blades, so attached to
the shaft that the angle at which they are placed with the axial line of the
shaft may be readily changed, so as to stand in the most effective position.
Figure 1, Sheet IV., is a cross section, and Figure 2, a longitudinal section of
a propeller, constructed according to this part of my said improvements.
a, a, a, a, are the blades, which may either be cast in. one piece with their
arms b, b, b, b, or may be made separate from them, and then secured together
by bolts or rivets. The inner ends d, d, of the arms are fitted into bearings or
sockets formed in the central boss c, and in which they are at liberty to revolve.
9, 9, are glands, which bear against collars formed on the arms, and so as to
securely retain them in their proper places. e, e, e, e, are cranks, one keyed to
each blade arm; the outer ends of the cranks are joined by connecting bars
with a travelling plate. f, the junctions of the connecting bars, with both the
cranks and travelling plate being effected by means of knuckle joints. Figure 3
is a side elevation of the travelling plate f. k is a screw, which works into the
eye or boss of the travelling plate; it is secured from moving in a longitudinal
direction by the gland n, which is affixed to the boss of the apparatus. o is
a worm wheel, which runs loose upon the end of the screw k, except when the
clutch O2 is made to gear into it. p is the spindle of an endless screw, which
gears into the worm wheel, as shewn in Figure 4. When it is desirable to
alter the angle of the blades the clutch O2 is put into gear with the worm
wheel, and by then turning the spindle p in one direction or other, it will
cause the whole of the blades to move simultaneously upon their own axes
through the intervention of the cranks e, e, the connecting rods h, h, and the
travelling plate f. When the blades have been set at the proper angle the
clutch is disconnected from the worm wheel, and the action of the screw k
upon the travelling plate keeps them in that position. By means of the
apparatus the blades may be made to form an angle to either right or left

page_text: hand, or to stand in a line parellel with the keel of the vessel at pleasure, and
thus may be employed to steer the vessel.
My third improvement in propelling consists in fitting the improved steering
apparatus just described, or other propeller, in the bows, or near to the stern of
a vessel, with the shaft at right angles to the keel, so that when the propeller
is put in motion the head of the vessel may at once be carried round to either
quarter according to the direction in which the apparatus is made to revolve.
This arrangement is particularly applicable to tug boats, for a boat so fitted
would be enabled to turn round in a space about equal to her own length.
Figure 1, Sheet V., is a longitudinal elevation of the hull of a vessel fitted with
this bow apparatus for steering; Figure 2 is a half plan of the same; and
Figure 3 is a cross section shewing the lines of the vessel.
A is a trunk
which passes right through the bow, open at top and bottom, but made perfectly
water-tight from the hold or interior of the vessel. B is the steering apparatus.
C, the mainshaft of the steering apparatus, which is placed "thwartships," as
before mentioned. It is carried by two bearings K, K, which are secured to
cross beams affixed to the vessel. The apparatus is put in motion by means
of a steam engine connected to the shaft F, through the intervention of the
bevil gearing J, J. Figure 4, is a longitudinal elevation on an enlarged scale,
partly in section, of the-apparatus and the shafts and gearing by which it is
connected with the steam engine. B is the steering apparatus. C, its shaft.
J, J, bevil gear, by which motion is communicated to the apparatus from
the intermediate shaft F. G, G, are two spur wheels gearing into cach
other; one is keyed to the shaft F, the other to the shaft E, to which latter the
power of the steam engine is applied. When it is desired to reverse the
direction of the revolution of the steering apparatus for the purpose of putting
the head of the vessel in an opposite course to that in which it moves, while
the wheels G, G, are in gear, the following changes are requisite:-The shaft E
is made to travel on end (from left to right, by means of the pinion R, which
gears into teeth turned on the shaft E,) until the wheels G, G, are disengaged
from each other; but while the shaft E is being pushed on end it causes
another intermediate shaft and pinion II to travel in the opposite direction
through the intervention of the connecting beam link L, so that both of the
wheels G, G, may gear into it, and it then becomes an intermediate wl:cel
between G, G, communicating motion from one to the other, and thereby
causes the shaft of the apparatus to revolve in the opposite direction. P is a
clutch, and T a lever, by which the shaft E may be engaged and disengaged
from the engine shaft O.
A fourth improvement in relation to marine propelling consists of an
apparatus for measuring and indicating the effective duty of propellers for

page_text: disconnecting them from the steam engine and turning round-the.engines and
machinery connected therewith when the steam is not up, as, for instance,
when effecting repairs, upon or examining the engine. This 'apparatus is
represented in Sheet VI. of the Drawings; Figure 1 being an elevation,
Figure 2 a plan, Figure 3 an end view, and Figure 4 a horizontal section.
A is the bed or foundation plate; D, the steam engine shaft; E, the inter-
mediate propeller shaft; B, B, the bearings or framework by which the shafts
are supported; F, a clutch, which is securely affixed to the shaft E, and is
carried round by the engine shaft, when in gear with it, as represented in the
Drawings, by means of feathers, which are affixed to the shaft and take into
grooves in the clutch; G and H are two discs or rings (separately represented
in Figures 5 and 7) which are bevilled on the outer edges of their two
opposite surfaces; K, K, K, are a set of antifriction rollers, which are
mounted in a frame, and occupy an intermediate position between the discs
Hand G. (A representation of these rollers and frame is given separately in
Figure 6.) The force exerted by the propeller upon the shaft E and the
clutch F is conveyed through the medium of the rollers K to the disc II, and
this force again is measured or indicated by means of a system of levers next
to be described. R, R, are two bent levers which have for their common
fulcrum the axis Y; the shorter ends of these levers bear upon the back of
the disc II, as indicated by dotted lines in Figures 1 and 4, and convey the
amount of pressure exerted upon that disc (by the propeller as above
explained) through the upright bow piece U to the lever V, and ultimately
through it to the spring balance W, upon the index of which the amount of
pressure exerted at any particular moment of time may be seen by inspection.
a, a, are stop pieces, which are removed from the sides of the brasses or
bearings O, O, during the time the pressure is being thus measured; these stops
allow the brasses to slide in the bearings, and give a sufficiency of play to the
levers to indicate the different pressures. When the propeller is to be dis-
connected from the engine the axis Y and levers R, R, are first removed
or dropped down; the disconnecting handle X is then turned round, by hand,
which, through the intervention of the endless screws N, N, and worm wheels
L, L, causes the two disconnecting bolts M, M, to revolve within the brass
screw boxes 0, 0, which again cause these bolts to move on end from left
to right, and to carry along with them the rings or dises H and G, as also
the shaft E, which disengages the propeller from the engine. By turning the
handle X in the opposite direction the shaft and engine are connected. When
for repair or other purposes it is necessary to turn the engine round, and when
the fires are out, the apparatus just described may be used for the purpose.
Qis a spur wheel, which is loose upon the engine shaft. P, P; are two-pinions,

page_text: cut out of the solid metal of disconnecting bolts. M, M, which serve as collars,
(and form the points of resistance against which. the disc H bears when the
vessel is going a-head,) and serve also for turning the engine shaft; when used
for the last-mentioned purpose the disconnecting bolts are screwed forward
by turning the disconnecting handle X, while the brass screw boxes are kept
from turning round by means of the stops a, a, until the pinions P, P, come
into gear with the spur wheel Q, which is then keyed to the engine shaft.
The brass screw boxes are attached to the disconnecting bolts M, M, by pins
which are passed through the holes b, b; the screw boxes are then liberated by
withdrawing the stops a, a, which allows the screw boxes to revolve in their
bearings along with the disconnecting bolts M, M.. When these arrangements
have been completed, if the disconnecting handle be then turned round it will
give a slow motion to the engine shaft and engine, in any required direction.
Thirdly, my Invention consists of an improved mode of constructing. tug and
other vessels. I-propose to build them with an aperture through the bow or
fore part, sufficiently large to contain the steering apparatus before described,
with its shaft or axis laid "athwartships;" that is, crosswise and at right angles.
with the keel. Figures 1; 2; and 3, (Sheet V.) are representations of a vessel
constructed in this manner. A is the aperture; B, the stem; K, K³, K²,
the keel, upon which are marked the letters and figures corresponding to the
letters and figures marked upon the cross section Figure 3, and well-under-
stood in shipbuilding; D, D, the dead wood or inner stemsons, which in iron
vessels would be plates; F2 is the forebody post, which forms the bow under
water; it is carried up inside of the vessel to such height as may seem neces-
sary to give sufficient. strength to that part of the vessel, and it also forms the
after part of the trunk or aperture; F is the fore part. The construction or
form of the bow with the aperture or trunk A will be best understood by
comparing the body, plan, Figure 2, with the sectional plan of the forebody,
the sectional lines of which are marked to correspond with Figures 1 and 3.
The plan of construction is equally applicable whether the vessel is built of
wood or of metal. In every case the size of the aperture or trunk will depend
upon the size of the propeller employed..
Another improvement in the construction of vessels consists in forming the
run or stern post of vessels either of wood or iron, with metal plate or plates
upon it, for the purpose of carrying the propeller shaft bearing. When the
propeller itself is placed abaft the rudder great additional strength is given to
the stern post of the vessel. The metal plates should be laid flush with the
bottom of the vessel to prevent unnecessary resistance to the progress of the
vessel through the water..
And having now described the nature of my said Invention, and in what

page_text: manner the same is to be performed, I declare that the improvements which
I claim as constituting the said Invention are as follows:--
First, I claim a rotary steam engine with broad-headed pistons moving
on antifriction rollers and guides in combination with an internal drum and
external cylinder, constructed and arranged as above described.
Second, I claim as an improvement in steam engines the combining with a
rotary engine constructed as above described a separate cylinder or engine to
work the air pump.
Third, I claim as an improvement in propelling the raising and lowering
the propellers of screw vessels by means of the T shaped groove, the carriage
or bearing E, and vertical screw F, as represented in Figures 1, 2, and 3,
Sheet III., and before described.
Fourth, I claim as an improvement in propelling the altering the angles of
the blades of steering apparatus for bows of vessels by means of a travelling
plate f and screw k, in combination with the arrangements for throwing the
screw in and out of gear, as represented in Figure 1, 2, 3, 4, and 5, Sheet IV.,
and before described.
Fifth, I claim the constructing of vessels with apertures in the bows for the
reception of thwartship propellers or steering apparatus, as above described.
Sixth, I claim the constructing apparatus combined and arranged as above
described and represented in Figures 1, 2, and 3, Sheet VI., whereby the pro-
peller pressure may be indicated, the engine and propeller shaft disconnected,
and the engine moved round when the steam is not up.
In witness whercof, I, the said Henry Wimshurst, have hereunto set my
hand and seal, this Twelfth day of May, in the year of our Lord One
thousand eight hundred and fifty-one.