CERTAIN IMPROVEMENTS IN PRO- PELLERS AND STEAM ENGINES, AND IN THE METHOD OF ASCERTAINING AND MEASURING STEAM POWER, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER USEFUL PURPOSES
Year: 1840

page_text: TO ALL TO WHOM THESE, PRESENTS SHALL COME, I, WILLIAM
MILL, of Blackfriars Road, in the County of Surrey, Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster; the Twenty-first day of September, in the fourth year of. Her reign,..
did, for Herself, Her heirs and successors, give and grant unto me, the said
William Mill, my exors, admors, and assigns, Her especial license, full power,:
sole privilege and authority, that I, the said William Mill, my exors, admors,,
and assigns, and such others as I, the said William Mill, my exors, admors,
and assigns, and such others as I, the said William Mill, my exors, adñiors, 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 that part of Her said.
Majesty's United Kingdom of Great Britain and Ireland called England,
Her Dominion of Wales, Town of Berwick-upon-Tweed, the Islands of,
Guernsey, Jersey, Alderney, Sark, and Man, and in all Her Majesty's Colonies
and Plantations abroad, my Invention of "CERTAIN IMPROVEMENTS IN PRO-
PELLERS AND STEAM ENGINES, AND IN THE METHOD OF ASCERTAINING AND MEASURING
STEAM POWER, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO OTHER USEFUL
PURPOSES;" in which said Letters Patent is contained a proviso, that I, the
said William Mill, shall cause a particular description of the nature of my said
Invention, and in what manner the same is to be performed, to be inrolled
in Her said Majesty's High Court of Chancery. within six calendar months

page_text: next and immediately after the date of the said in part recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in pursuance of the said proviso, I, the said William
Mill, do hereby declare that the nature of my said Improvements, and the
manner in which the same are to be performed, are fully represented in the
Drawings hereunto annexed, marked Figure 1 to Figure 24 inclusive, and
in the following description thereof, that is to say:―
My said Improvements, as far as they relate to propellors, exclusive of the
steam or other power by which they are moved, are represented in the Draw-
ings hereunto annexed, marked Figure 1 to 13 inclusive.
Figure 1 is a longitudinal view, chiefly in section, of a vessel fitted with a
propelling apparatus constructed according to my said Improvements; and
Figure 2 a stern view of the same. A, A, is a hollow space or wheel case in
the middle of the vessel, considerably below the water line, open at both sides
to the water, but made perfectly water-tight above and below, and at the stem
and stern. A plan of this hollow space or wheel case is given separately in
Figure 3. B is a horizontal wheel which moves on friction rollers in the
hollow space or wheel case A, and carries the paddle shaft in manner to be..
presently explained; C is the vertical axis or shaft of the wheel B, which
passes through a stuffing box in the top part of the wheel case A; A, and works
in metal bearings, one in the bottom of the wheel case, and the other
in a strong beam which runs across the vessel at a, a, and a, a, (Figure 3),
a circular plate or rail in the bottom of the space A, on which the friction
rollers run; D is a horizontal connecting rod, which connects the vertical
shaft of the propelling wheel with the steam engine or other moving
power with a reciprocating action; Figure 4 is a plan of the wheel B,
with the upper parts in -some-places removed, in order to exhibit
its internal construction; its depth or thickness being such as to fill the
wheel case A as much as possible without obstructing its free motion therein,
and of such a diameter as to project a little on each side of the vessel. It is
composed of two iron rings E;-E, one at the top and the other at the bottom,
with iron spokes F, F, radiating from each, which are secured to a nave Grin
the centre, also of iron. The spaces between the rings and spokes (excepting
as herein-after excepted) are filled up with wood, and the whole is covered in
by a metal plate or plates on both sides (as shewn in the upper part of
Figure 4), so as to exhibit the appearance of a solid disk filling the hollow
space or wheel case A. The wood between the rings may be bevilled off
when wheels of large diameter are employed, at the outer circumference (in

page_text: manner shewn at b, b.) to a feather edge, in order that it may present the less
resistance to the water. The friction wheels g, g, g. 9, are fixed in the body
of the wheel B, and protrude a little at the top as well as the bottom. H, H,
is a hollow revolving shaft, with a rectangular bore at each extremity, which
is passed through the wheel B from side to side, and turns freely therein for
the reception of the paddle shafts P, P. A view of this hollow shaft detached
from the wheel is given in Figure 5; it is formed of three parts, c, d, c, dove-
tailed into each other in the manner represented in the figure (5), and kept
fast in their places by the metal bearings i, i, i, i, the external picces c, c,
having a rectangular bore, and the middle one da circular bore. A view of
one of the paddle shafts, P, detached is given in Figure 6; the end, which
is inserted in the hollow revolving shaft, is made at the inner end of a circular
form, and at the outer end next to the floats of a rectangular form with a link
at the inner end, by which it is to be secured in its place in manner to be
presently explained. A rope or chain wis passed down from a capstan or
windlass K through a channel s made in the body of the wheel shaft C,
whence it is drawn through an orifice r in the hollow shaft H, and attached
to the link 'of the paddle shaft P. The top of the wheel shaft must of course
be carried above the water line of the vessel, to prevent any water rising and
flowing over through the channel s. The leaves or floats on each paddle shaft,
which may be either one, two, or more in number, are suspended from it
loosely by means of hinges, on which they fall back against the arm in either
direction, so that, when moved through the water in a direction contrary to
the line of motion of the vessel, they oppose their entire surfaces to it, as
represented on the starboard side of Figure 2, and when moved in the same
direction as the vessel, they open and present their edges only to the water, as
shewn on the opposite side of Figure 2. Each leaf or float may consist of
three parts connected by hinges in the manner represented in Figure 6. In
adjusting the paddle shafts, one of them (it is indifferent which) must be
secured before the other; and the one which is first secured must have its
rope passed once round the hollow revolving shaft H, which is readily effected
(after it has been attached to the link g and drawn into its place) by
giving one full revolution to the revolving shaft. The other paddle shaft being
then secured in its place, with its rope passing direct to the windlass without
any such coil, it follows that any subsequent turn of the windlass which causes
the first to be uncoiled from the revolving shaft must cause the other to be
coiled upon it. A ready means is thus obtained of reversing the action of the
paddles at pleasure, for as each paddle rope is coiled or uncoiled to the extent
of half a revolution of revolving paddle shaft, it causes the position of the

page_text: paddles in the water to be reversed. Two grooves t, t, are made in the exterior
of the revolving shaft H, for the paddle ropes to work in, which ropes are
wound once round the windlass K in opposite directions to each other, and
then drawn tight and secured. A wheel lock W, of the peculiar description
represented in the separate view, Figure 12, is employed to hold fast the wind-
lass. The body of this lock is composed of a front plate B', and a back plate
B² (the former of which is removed in the Drawing in order to show the
interior construction) connected by a ridge or partition piece in the middle C²,
the two sides being left open; at the bottom there is a small toothed wheel
a², which turns on a pin which passes through the two plates; D³, D², are two
clutches secured. by pins passing through them and the two plates, on which
pins the clutches move their upper ends, being pressed outwards by two springs
d', d, which bear against the central ridge. When both these clutches are
pressed outwards they take into the teeth of the small wheel a², and prevent it
moving either way, but when either of the clutches is pressed up within the
case so as to be flush with its outer edge, the wheel is left free to turn in one
direction. A wheel lock so constructed is attached to the framework of the
capstan or windlass as shewn in the elevation Figure 1, and takes into
another wheel X, fixed firmly to one end of the windlass; a cord or rope is
attached to the upper end of each clutch, and passed through a hole in-the-
centre of the top end of the front plate of the wheel lock, whence it is carried
down and fastened at the end to a treadle f, attached to the deck, so that when
it is desired to unlock the windlass and turn it in either direction, all that is
necessary is to press down with the foot the treadle which commands the clutch
sought to be unlocked, when the windlass may be moved round as required;
should it be desired to detach either of the paddle shafts from their respective
ropes for the purpose of repair or otherwise, this is done by easing the rope
from the windlass, when the shaft may be-drawn out and unhooked from the
rope. This may be done by a person on the deck of the vessel by means of a
long pole with a hook at one end, as represented in Figure 9, and after the
paddle-shaft is unhooked, a temporary shaft o, with a link at the end, must be
made fast to the rope, as shewn in Figure-8, to prevent the end of it being
drawn back too far through the hollow shaft H, till the paddle shaft is required
to be again attached, when the shaft o is removed. The horizontal wheel at
each stroke of the engine (communicated to it through the horizontal and
vertical shafts C and D) performs about one third of a revolution, or just so
much as to produce one complete sweep of the paddle shaft from m to n
(Figure 3). The sets of paddles act alternately, but in consequence of the
motion being taken from the central axis C, the vessel is moved forward in a

page_text: perfectly straight line. In order to give the paddle shafts as much stroke as
is productive of useful effects, and at the same time to exclude the water
as much as possible from the wheel case, the angular corner spaces which
are left unoccupied by the wheel B are filled up with rollocking pieces T, T, of
Instead of
the shape represented in Figure 1, and secured there by screws.
the wheel being composed, as I have described, of wood and iron, it may, when
not of an inconvenient large diameter, be made of one plate of iron altogether,
with spaces for the paddle shaft, tube, and friction wheels cast in it; and
instead of the arrangement before described, whereby the action of the paddles
can be reversed at pleasure, a simple arrangement may be adopted, as shewn
at Figure 7, whereby the paddle shafts may be secured in their places in the
wheel, but cannot be reversed without drawing them out, unfixing, and refixing
them. Instead of the hollow reversing shaft, two sockets or inlets are formed
in.the wheel directly opposite to each other for the reception of the paddle
shafts P, and the ropes or chains attached to the shafts are passed through
orifices ff which lead into the inclined channels p, p, in the wheel shaft C, and
coming out at the points v, v, just above the stuffing box, are secured there by
cleats affixed, to the shaft. After the ropes have been fixed in their places the
outer orifices v, v, of the channels p, p, are made water-tight by means of plugs.
In Figure 10 I have shewn an arrangement whereby two wheels and sets of
Each wheel has a separate
paddles may be employed one above the other.
case, and is secured to.a separate shaft c, c; but they are so connected by gear-
ing that the two sets of paddles on each side shall have a constant alternating
action not only in respect to each other, but of the paddles on the opposite side,
whereby there shall always be on each side of the vessel one paddle or set of
paddles acting in the same direction, to propel the vessel with the entire sur-
faces opposed to the water, and two with their edges only presented. Two
cogged quadrants j, j, are attached to the upper part of the under wheel, one
before and the other behind the vertical shaft C, and two similar cogged quad-
rants to the bottom of the upper wheel. These quadrants take into pinions k, k,
which work in metal bearings in the solid wood between the two wheel cases.
It follows that on motion, being given to either wheel it causes the other to
move in a contrary direction. Instead of gearing just described, the wheels
may be faced to the extent of the sweep which they take at each stroke of the
engine with pinion levers, and these made to take into a cog wheel as shewn
in the Drawing, Figure 10%, stationed at either end of the wheels, but more
conveniently, perhaps, in front. For the hinged paddle, such as I have here-
tofore described, a paddle may be substituted such as represented in Figure 10³,
and is made at the end of each backward stroke to turn flat round and opposes
:

page_text: its edges only to the water in the return stroke. In order to effect this change
in the position of the paddle, a pinion K is made fast to one end of the wind-
lass, (which in this arrangement is placed, for the sake of greater convenience,
under the upper deck,) and upon the end of the axis outside the pinion, a lever
L, having attached to it two wheel locks such as that represented in Figure 12,
and before described, is affixed so as to turn freely when required, and project-
ing at its upper end through the deck. The toothed wheel a² of the upper
wheel lock takes into the pinion K2 on the end of the windlass, and the toothed
wheel as of the lower wheel lock takes into a quadrant M fixed upon the large
beam. A vertical rod N2, which has a reciprocating motion in common with
the engine, carries at top a horizontal pin n³, which at the end of each stroke
catches against one of the clutches of the lower wheel lock, and pressing it
home, sets the wheel a free to traverse to the opposite end of the quadrant,
whereby the upper half of the lever L² is thrown over into the position indi-
cated by the dotted lines, and carries with it, by means of the pinion K³ and
upper lock wheel, the windlass, which in its turn causes the hollow revolving
shaft to make about a quarter of a revolution, which is sufficient to give the
feathering motion to the paddle, Figure 10%, before described. When the
course of a vessel fitted-with--these paddles is to be reversed, the lever L is
moved over into the opposite position without moving the windlass, which -is--
effected by unlocking the two wheel locks on opposite sides, so as to allow of
its being moved in the direction required. The consequence will be, that in
the next stroke of the engine the paddle will not be feathered, but will propel
the vessel in a direction opposite to that in which it was previously moving.
And I declare that my said Improvements, so far as they relate to steam
engines, are represented in the Drawings hereunto annexed, marked Figures
14 to 24 inclusive.
Figure 14 is a side view,- and. Figure 15 a longitudinal section of so
much of a steam engine as comprehends the parts to which my Improve-
ments liave reference. A3, A3, is a rectangular frame work, B² an axis which
works in bearings in the centre upright of the frame work, and carries on the
middle of it a cog wheel, C, shewn separately in Figure 16. The cogs of
this wheel move in angular slots c³, 3, (shewn in the vertical section Figure-15)
as they are acted upon by the double-ringed accentric D³ (a plan of which is
shown separately in Figure 17), which is held in a position coincident to
the sides of the cog wheel by a cross rod d³, d³, which is supported by
standards affixed to the insides of the centre uprights, and passes through the
projecting arms e³, e³, at one end of the eccentric; E³, E³, are two horizontal
steam cylinders placed the one directly above the other, the upper one having

page_text: a rack at bottom throughout its whole length, which takes into the cog
wheel C³ at top, and the lower one a similar rack at top, which takes into
the bottom part of the cog wheel; each cylinder has a broad square flange at
each end, and the two cylinders are connected at their opposite ends by
vertical bars, 7, which are secured at top and bottom to their respective
flanges; at each end of the upper cylinder, immediately behind the flange,
there is a grooved wheel h³, which runs along a rail 3, inserted in the top
piece of the framework. The lower cylinder has a like pair of wheels on the
lower side of it, which run upon a similar rail ³, inserted in the floor of
the framework. The cylinders are by the means just described maintained in
a constant state of parallelism in respect to each other. F, F, are the pistons
of the two cylinders, and, unlike pistons of the ordinary form, they are fixed and
stationary at the centre point of the range of action of the cylinders; each piston
rod passes right through its cylinder (suitable stuffing boxes being provided at
cach end of the cylinder for the purpose), and rests at each extremity in bearings
in the outer uprights of the framework. The lower piston rod is of larger
diameter than the other, and hollow, so that at one end it serves as a pipe to
convey steam from the boiler into the cylinder, and at the other to convey
the used steam to the condenser or the atmosphere. The body part of the
upper piston is solid; the body part of the lower piston m³ is constructed
in manner represented in the vertical section Figure 15, and in the detached
horizontal section Figure 18, and in the transverse section Figure 19. It
has four holes or channels ³, 12, no, no, passing right through it; two small
cylinders G, G, closed at both ends, but hollow in the centre, each with two
orifices at p, p, are inserted in the holes n' and 26, and two small pistons
HS, H, are inserted in the holes n³ and n³. The two small cylinders and two
pistons, the rods included, are about twice the depth of the body part of the
main piston F, and are connected at top and bottom by two circular plates
,, common to all four, the cylinders being made fast to the plate at their
extremities, but the rods of the piston being allowed a little play to and fro
in their bearings. The whole of this four-way piece moves up and down
through the body part of the main piston F³, according as it is acted on in
manner to be now explained, and the two small cylinders having flanges at
their extremities which press against projecting flanges on the faces of the
holes and , so that when brought up close against these holes the
latter are made perfectly steam-tight. On the steam being admitted into
the interior of the main piston F (at which time the four-way piece is supposed
to be drawn out at one end and to press close on the body part of the main
piston at the other),. it passes through the double way into the. holes 22³

page_text: and n.at the ends above the body parts of their respective small pistons, and
escapes thence into one end of the cylinder, which it causes to move forward
on its rack and wheels to the end of the piston rod; simultaneously with the
arrival of the cylinder at one end of the piston rod, the opposite end of the
cylinder presses against the drawn out end of the four-way piece ³, n³, n³,
and 2, and presses it up against the body part of the main piston, which pro-
duces an immediate change in the action of the steam. The used steam then
escapes through the small orifices p³ in the small cylinders G3, G³, into the
other double way S³, and thence into the interior of the outer end of the
hollow or main piston rod B³, whence it escapes into the condenser or the
atmosphere, while at the same time a fresh supply of steam is passing through
the double way,, into the holes 1 and 2, and thence into the opposite
end of the cylinder to produce the return stroke of the piston, and so this
action will continue as long as steam is supplied from the boiler. The two
cylinders E, E, communicate with each other by the pipes L, L, at each end,
and being strongly connected together partake of the same reciprocating
action, which reciprocating is converted into rotary motion in the following
manner equidistant between the two racks, attached to the cylinders is a
trundle or cog wheel, similar-to..that represented in Figures 15, 16, and 17,
is mounted on a shaft working in suitable bearings; the cogs.of this trundle
move on the angular slots in its sides within a sinaller circle eccentric to the
axis of the trundle. In consequence of this arrangement the trundle takes
alternately into the upper and lower racks, and converts the converting
motion of the cylinders into continuous rotary motion in one direction.
To enable the engineer to shut off the steam at the half or any other
part of the stroke, a stop-cock M³, M³, which commands the main induc-
tion pipe N3, is armed at top with a wheel which is toothed throughout
five eighths of its periphery, and..takes into the rack end of the slide rod O³,
which passes from the induction end of the engine to beyond the centre
part of the framework and slides in any convenient bearings. On the
outer side of this rod there are three projecting pins, o, ot, and 06, which
take into the slots of three-levers affixed to the frame work or other parts at
suitable distances, the pins and levers, o' and o, serving-to-let on the steam,
and the pin and lever o to shut it off at half stroke. The slide rod O³ is
moved backward and forward at each stroke of the engine, and moves the
toothed wheel on the top of the stop-cock which takes into the rack end of the
rod, and the pins, 03, 0', and 6º, are acted upon by the projecting horizontal
pins 0, 0, 0, attached to the flanges of the cylinders. By shifting the position
of the pin and lever o, and introducing a second pin and lever, they may of

page_text: course be made to shut off the steam at any other part of the. stroke desired.
Qis a three-way cock for shutting off the steam at any required portion of the
stroke by hand, and will form a communication between the steam boiler and
the atmosphere and the interior of the cylinders. In order that the action of
an engine on this plan may be reversed, there must be two cog wheels of the
description of C placed on the main shaft, with arrangements for putting them
in and out of gear alternately, to facilitate which some of the teeth at the outer
ends of the cylinder racks must be cut away; or the racks may be fixed at the
sides of the cylinders instead of the top and bottom, and trundles of a larger
diameter fixed on the shaft at each side of the cylinders. The reversing of the
motion may also be effected by an arrangement such as is represented in
Figures 20, 21, and 22. A double rack Rs, R³, may be affixed to the top of
the lower cylinder, with cross bars at bottom connecting the two racks; and
instead of the cogs of the trundle moving in angular slots, they must move
in slots radiating from the centre, as particularly shewn in Figure.20. A wheel
lock of the construction represented in Figure 12, and before described, .is
inserted between the racks just in front of the trundles, so that the small toothed
wheel at its lower end shall work into the cross bars between the racks (after
the manner of cogs), and it is prevented from slipping out by two projecting
shoulders,, shown in the detached section at view Figure 22, which bears
upon the two ends of the axle of the small toothed wheel at top; this wheel
lock is held fast between two prongs projecting from the two rings of the
eccentric D,, and united at their inner ends by a cross bar. From the back
of the eccentric circle two long arms w, w, extend to the outer upright of the
framework, gradually approximating to each other till they terminate in one
common point, where they are secured to the upright. Two side plates Y³, Y³, of
the form represented in Figure 2, are affixed to the centre uprights, one on
each side, and in the front end of each of these plates there are two angular
slots z³, z³, in which the ends of two of the bars of a swing frame a, made
of four bars crossing each other at right angles, rise and fall freely; a long
double lever X, X³, of the same form as w³, w³, is attached to this swing frame,
and carried out a little beyond the upright of the framework at the opposite end
of the engine, where it is attached to a vertical lever b', which carries at its upper
end a wheel lock of the form represented in Figure 12, and before described,
which wheel lock works into a quadrant affixed to a projecting piece of the
framework. According to this arrangement it will be observed that the upper
part of the wheel lock placed between the racks is enclosed within the centre
square of the quadrangular swing frame a', so that as the engine moves to and
fro the wheel lock bears against one or other of the bars of the swing frame, and

page_text: set the toothed wheel free to work in one direction, in consequence of the clutch
being pressed home within the plates of the wheel lock; and further, the two bars
b*, *, of the swing frame being one higher than the other, it follows that as
the rack is moved backwards and forwards by the cylinders the wheel lock
takes at one motion a more perpendicular position, and at another a more
inclined position, which causes the eccentric circle of the trundle to rise and
fall. The reverse of the motion is effected by pulling forward the long lever
X, which reverses the relative position of the two bars b, b. When a steam
engine with moveable cylinder and stationary piston is applied to move the
propellers first herein-before described, only one cylinder and piston are
necessary, as represented in the Drawings, Figures 1 and 10, and the con-
nection is effected by a vertical arm D2, fixed in the centre at top of the
cylinder, & runs on a friction roller in a slot in the horizontal shaft pro-
jecting from the vertical shaft of the horizontal wheel B. A rotary motion
may be obtained from the reciprocating action of the single cylinder engine by
means of a projecting arm or arms, with connecting rods and cranks in the
usual manner.
And now to describe my said improved method of ascertaining and
measuring steam power, I declare that the same is represented in Figures 23
and 24 of the Drawings hereunto annexed. I make use for this purpose of a
portable steel-yard balance D'; the beam and other appendages of which, with
the exception of the shifting weight, are enclosed in a hollow case f, which
case is of a determinate weight, and serves the place of the usual shifting
weight, having a hole at the top by which it is moved along the long arm of
the balance. To the top of the boiler I affix a lever with a short and
long arm and resting on standards C, and pressing on the top of the safety
valve B; to the long arm of this lever there is attached a ball g of a deter-
minate weight, which is immoveable, equal to the maximum pressure at which
it is desired to work the engine. When-it-is.desired to ascertain how much
the pressure in the boiler is less than the weight with which the-valve is.
loaded, I attach the hook at the short arm of the steel-yard balance to the
ball g, and then by applying the shifting weight to the long arm ascertain how
much is required to raise the valve the difference between which and the
known weight of the ball g' is of course the quantity desired to be ascertained.
The same method may be also adopted to increase or diminish the pressure of
the steam in the boiler, that is to say, by applying additional weight through
the inedium of the portable steel-yard balance before described to the short
arm of the safety valve lever the weight on the safety valve will be increased,
and by applying them to the long arm the weight on the safety valve will be

page_text: diminished. The short arm of the safety valve lever should be enclosed in a
box under lock and key, so that the weight on the safety valve may not be
carelessly or wantonly increased.
And having now described my said invented Improvements, and the manner
in which the same are performed, I declare,
First, as regards my said Improvements in propellers, that I do not limit
myself to the use of the horizontal wheel before described in the centre of
the vessel, but that the same may be also applied at the stern and under the
bows, or at any other suitable part; and that what I claim generally is, the
method of propelling vessels herein-before- described by paddles entirely
immersed in the water, and deriving a reciprocating action in the line of
motion of the vessel from the movement of a horizontal wheel.
Second, as regards my said Improvements in steam engines, I declare that
what I particularly claim as of my Invention is the employment of a cylinder
and piston, or cylinders and pistons, the former of which are moveable and the
latter stationary and hollow, and the arrangements herein-before described
for adapting the same to practical purposes.
And third, as regards my Improvements in ascertaining and measuring
steam power, I declare that what I claim is the method herein-before
described of applying a balance on the steel yard principle to a lever resting
on the safety valve, with a weight of a fixed amount attached to one end
thereof.
And I declare that the parts of the said improvements which I consider
applicable to other useful purposes are,―
First, the wheel lock represented in Figure 12 of the Drawings hereunto
annexed and before described, which may be used to advantage in most cases
where it is required to hold or retard wheels, and also for various other useful
purposes.
Second, the wheel or trundle represented in Figures 15, 16, and 17, with
moveable cogs and eccentric circles, which is applicable to many other
descriptions of machinery besides steam engines.
And Third, the application of a balance on the steel-yard principle, to
increase or diminish, in manner before described, the weight of the safety valve
of steam boilers; as also the employment for weighing purposes in general of
the portable steel-yard balance before described, the beam and appendages of
which are enclosed in a case, which case serves the purpose of the usual shift-
ing weight or counterpoise.
And I further declare generally, with respect to all my said Improvements,
that I do not limit myself to any of the materials or proportions or precise
.

page_text: .
And
arrangements herein-before mentioned or represented in the Drawings
hereunto annexed; but what I claim in each case is the general method of
operation described, however the same may be varied or modified or changed,
as long as there is no material departure from or alteration therein.
such my said Invention being, to the best of my knowledge and belief,
entirely new, and never before used within that part of Her Majesty's United
Kingdom of Great Britain and Ireland, called England, Her Dominion of
Wales, Town of Berwick-upon-Tweed, or in the Islands of Guernsey, Jersey,
Alderney, Sark, and Man, or in any of Her Majesty's Colonies and Plantations
abroad, I do hereby declare this to be my Specification of the same, and that
I do verily believe this my said Specification doth comply in all respects fully,
and without reserve or disguise, with the proviso in the said herein-before in
part recited Letters Patent contained: Wherefore I hereby claim to main-
tain exclusive right and privilege to my said Invention.
In witness whereof, I have hereunto set my hand and seal, this Twentieth
day of March One thousand eight hundred and forty-one.
WILLIAM (L.S.) MILL.
AND BE IT REMEMBERED, that on the Twentieth day of March; 'in
the year of our Lord 1841, the aforesaid William Mill came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and everything therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Inrolled the Twentieth day of March, in the year of our Lord One thou-