A METHOD OR METHODS OF MAKING AND CONSTRUCTING CIRCULAR OR ROTATIVE STEAM ENGINES UPON AN ENTIRE NEW PRINCIPAL, AND EMPLOYING THE ELASTIC OR EXPANSIVE FORCE OF STEAM IN A MUCH MORE EFFICATIOUS AND ADVANTAGEOUS MANNER THAN HAS HITHERTO BEEN DONE
Year: 1808

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, THOMAS
MEAD, of Scott Street, in the Parish of Sculcoates, in the County of York,
Engineer, sendeth greeting.
WHEREAS His present Majesty King George the Third, by His Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Twenty-fourth day of August last past, hath given and granted unto the
said Thomas Mead, by the name and addition of Thomas Mead, of Scott Street,
in the Parish of Sculcoates, in the County of York, Engineer, his executors,
administrators, and assigns, special licence, full power, sole privilege, and
authority, to make, use, exercise, and vend, "A METHOD OR METHODS OF MAKING
AND CONSTRUCTING CIRCULAR OR ROTATIVE STEAM ENGINES UPON AN ENTIRE NEW
PRINCIPAL, AND EMPLOYING THE ELASTIC OR EXPANSIVE FORCE OF STEAM IN A MUCH
MORE EFFICATIOUS AND ADVANTAGEOUS MANNER THAN HAS HITHERTO BEEN DONE,"
within that part of Great Britain called England, His Majesty's Dominion of
Wales, and Town of Berwick-upon-Tweed, for the term of fourteen years
from the date of the said Letters Patent, and to have and enjoy the full
benefit and sole use and exercise of the said Invention during the term afore-
said, subject nevertheless to a proviso or condition in the said Letters Patent
contained, that if the said Thomas Mead should not particularly describe and
ascertain the nature of his said Invention, and in what manner the same is to
be performed, by an instrument in writing under his hand and seal, and cause
the same to be inrolled in the High Court of Chancery within one calendar
month next ensuing the date of the said Letters Patent, then the said Letters
Patent, and all liberties and advantages whatsoever thereby granted, should
utterly cease, determine, and be void.

page_text: NOW KNOW YE, that the said Thomas Mead, in compliance and per-
formance of the condition of the said Letters Patent, doth, by this instrument
in writing under his hand and seal, particularly describe and ascertain the
nature of his said Invention, and the manner in which the same is to be per-
formed, as well by a description in writing as also by delineations of apparatus
that will help to illustrate or exemplify his principles, that is to say:-
The principle of the Invention is not confined to engines of any particular
form of construction, but consists in making use of two movable pistons in
diaphragms in such a manner that they alternately revolve or move round their
axis or centres, as will be more fully explained in what follows. A and B, two
circular plates or shells of metal similar in their construction, having their
insides turned or otherwise made very true and correct. A is drawn with its
inside uppermost, and B with its outside uppermost. Each of these circular
plates or shells have a flanch and semicircular cavity formed for the reception of
the pistons which are afterwards described, and a recess or hollow part formed
round its centre for a small circular plate to turn in. Near to the edge of
each recess is a small groove running quite round it. In the bottom of each
groove
is placed a metallic ring N. The remaining part of the groove is filled
up with packing or wadding, which ring and packing or wadding may be
moved by screws going through each shell (see 0, 0, 0, 0, in the section and
shell B), and may be turned on the outside of the engine, after it is put
together at any time to make the small circular plates work steam-tight; on
the outside of each shell at its centre is a hollow pipe or boss for the recep-
tion of the spindles F and G. The plate A has also two holes at a, a, to which
pipes are fitted; one to convey steam into the shells, the other to conduct it
from them into a condenser, or wherever it may be required. C, C, two
pistons with grooves round them to admit of a packing or wadding. D and E
two small circular plates to which the pistons are connected or made fast; F and
G two shafts or spindles. The spindle F is made hollow to receive the spindle G,
which passes through it. H and I two arms made fast to the two spindles.
Each arm near its extremity carries a wheel J and K, which are generally
termed friction wheels; L, a fly or regulating wheel fixed to one end of a
shaft or movable axis, having in its front or side opposite to its axis a groove
running across its diameter for the reception of the friction wheels J and K,
which wheels, when the pistons are put in motion, work in it, and give motion
to the fly wheels and other machinery which may be connected with it; M is
a section of the two plates or shells A and B, when put together, to shew
more clearly the form into which they are turned or made; P, P, the steam
chamber for the reception of the steam and pistons; Q, the recess for the

page_text: small circular plates; R, R, the hollow pipes or bosses for the spindles to work
in; S, S, S, S, flanches by which the shells are fastened together; T, a front
view of one of the pistons with its small circular plate, arm, and friction
wheels; J, the friction wheel; H, the arm; D, small circular plate; and C, the
piston. V, V, V, grooves for the reception of the packing or wadding which
is to be made fast therein. When the engine is to be put together, the arms
should be taken off from the spindles. The spindle G is then to be inserted
in the hollow spindle F, which, with their respective pistons and small circular
plates, are to be placed in one of the shells, and the other shell placed over
them. The shells are then to be fastened together with screws or otherwise
so as just to admit the pistons with their respective plates and spindles to turn
round in their respective chambers or channels nearly steam-tight. The arms
may then be made fast on the spindles, and the engine erected. When the
engine is to be erected or fixed for working, the following rules should be
observed: Place the direction of its axis in an horizontal or lateral direction
parallel with the direction of the axis of the fly, but nearly as much out of
that line as the length of one of the arms H and I, taken from the centre of
the spindle to the centre of its friction wheel, and at such a distance from the
fly as to admit of the friction wheel's moving freely in the groove on its face.
By so doing the axis of the engine will be placed eccentric with the axis of
the fly. The engine may be fixed in an iron or wood frame, and the fly
supported in the same or in a separate frame in the position before pointed
out. If the fly is then turned half way round upon its axis, one of the friction
wheels will remain locked or held fast in the groove near its centre, and the
piston with which it is connected remain nearly stationary in the steam
chamber between the holes a, a, while the other friction wheel, with its arm,
spindle, small circular plate, and piston, makes nearly one complete revolution
round their common centre of motion or the centre of the engine. If the
motion of the fly be continued till it has made one complete revolution round
its own axis, the friction wheel, which was locked or held fast in the groove
near its centre, will move off in the groove towards the circumference of the
fly, and, with its arm, spindle, small circular plate, and piston, make nearly
one complete revolution round their common centre of motion or the centre of
the engine, and the other friction wheel in its turn remain locked or held fast
in the groove near the centre of the fly, and the piston with which it is con-
nected remain nearly stationary within the steam chamber between the holes
a, a, and so on alternately as long as the fly continues in motion. Instead of
the hollow spindle F, and the solid spindle G, two other solid spindles may be
used, by applying one to each small circular plate, and passing them through

page_text: the opposite pipes or bosses, each having its arm and friction wheel as before,
but working in separate grooves mounted on .seperate axles, and united by
wheel-work. When the engine is to be set to work by the force of steam,
the steam is permitted to enter by one of the pipes into the steam chamber,
where, by its elasticity, it will press or act upon both pistons nearly alike, and
as one of the pistons is stopped or held fast by the aforesaid methods, the
steam cannot pass into the other pipe that way, but will force the other
piston round with its small circular plate, spindle, arm, and friction wheel, and
put the fly in motion, and continue it as before explained. A similar effect
may be produced with a concave globe or sphere having within it two movable
semicircular leaves (as a substitute for the pistons), with packings at their
edges, and united in the centre or axis of the globe with joints or hinges, and
having each of them an axis passing through the globe to receive the arms
and friction wheels, as before described, and with holes and pipes for the
admission of steam, &c. A great variety of other forms may be made use of
to produce a similar effect, as will be obvious to every tollerable mechanic, if
the principle on which the engine acts be retained. Engines on this principle
may be made of every requisite size, and are not confined to the action of
steam only, but may be put in motion with a current of air or any other
elastic fluid, or a current of water, or a current of any fluid, either elastic or
unelastic, if the fly wheels, or whatever may be substituted for them, be made
to drive the pistons by being turned upon their axles with a sufficient force.
They may be applied as powerful engines for extinguishing fire or for raising
or forcing water up to any height required, and may also be used as air pumps
for philosophical experiments, or for air pumps and condensers for steam
engines, and for many other useful purposes.
In witness whereof, the said Thomas Mead hath hereunto set his hand
and seal, the Seventeenth day of September, in the forty-eighth year of
the reign of our Sovereign Lord George the Third, by the Grace of
God of the United Kingdom of Great Britain and Ireland King,
Defender of the Faith, and so forth, and in the year of our Lord One
thousand eight hundred and eight.

page_text: AND BE IT REMEMBERED, that on the Seventeenth day of September,
in the year of our Lord One thousand eight hundred and eight, the aforesaid
Thomas Mead came before our Lord the King in His Chancery, and acknow-
ledged the Specification aforesaid, and all and every thing therein contained
and specified, in form above written. And also the Specification aforesaid
was stampt according to the tenor of the Statute made for that purpose.
Inrolled the Twentieth day of September, in the year of our Lord One
thousand eight hundred and eight.