A CON- DENSING WIND ENGINE, CAPABLE OF BEING APPLIED TO ALL KINDS OF PURPOSES IN WHICH EITHER STEAM, WIND, WATER, OR HORSES ARE USED
Year: 1799

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
MEDHURST, of Battle Bridge, in the Parish of Saint James, Clerkenwell,
Engineer, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-eighth day of February, in the thirty-ninth year of
His reign, give and grant unto me, the said George Medhurst, His especial
licence that I, the said George Medhurst, during the term of years therein
mentioned, should and lawfully might use, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, my Invention of " A CON-
DENSING WIND ENGINE, CAPABLE OF BEING APPLIED TO ALL KINDS OF PURPOSES IN
WHICH EITHER STEAM, WIND, WATER, OR HORSES ARE USED;" in which said Letters
Patent there is contained a proviso obliging me, the said George Medhurst, by
an instrument in writing under my hand and seal, to 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 His Majesty's High Court of Chancery
within one calendar month after the date of the said recited Letters Patent, as
in and by the same (relation being thereunto had, may more fully and at large
appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
George Medhurst, do hereby declare that the nature of my said Invention is
described in the Drawings hereunto annexed, and in manner following:-
First, I condense or compress the air of the atmosphere (by machinery to
be described hereafter) in a strong and close vessel, which I call the magazine,

page_text: by means of a wind mill, so as to make it from ten to twenty times more dense
than it is in its natural state..
Secondly, I conduct that dense air from the magazine through a pipe to the
top of a cylinder, where it acts upon a piston by its elasticity, without the aid of
fire, and by these means keeps the machinery in constant motion for a time
proportioned to the capacity of the magazine, though the wind do not blow.
The object of my Invention is to accumulate and preserve the irregular power
which the wind produces, so that it may be applied to machinery to produce
a uniform and regular motion whenever it is wanted. The windmill sails I
construct in the usual vertical manner, or when a greater power is required
than can be obtained by that manner, I construct them as follows:-A broad
ring or hoop of wood or metal, B, B, B, B, Fig. 1, is fixed upon the extremity
of the arms C, C, C, C, having a smaller one, A, A, A, A, concentral with it,
and of such diameter as to include about one half of the space included by the
first. The two rings are supported by the arms C, C, C, C, which extend
from the axis to the outer ring, and against the wind by rods of a metal
from the extremity of the axis, continued out beyond the plane of the sails for
that purpose. The sails are fixed between the rings A and B, sufficient in
number and size to fill nearly the whole of that space, leaving it open within
the smaller one, to allow the wind a free passage. To apply my machinery to
a wind mill previously built, I fix a wheel B, Fig. 2d, upon the upright shaft
of the mill, which turns another wheel C, C, C, fixed upon an horizontal one;
upon
the rim of this weel, as at D, is a strong pin, which takes hold of the end
of the rod D, D, the other end of which is jointed into the piece of timber E, E,
and on the lower end of this piece is an iron wheel without teeth, to run upon
the inclining plane F, F, F, which plane is set at a greater or less angle by
means of the screw E, G; the upper end of the piece E, E, is jointed into the
end of the beam H, H, which turns upon a fixed centre at I, and is jointed at
the other end to the rod of the condensing piston L, which works in the barrel M ;
and to this barrel is screwed the pipe N, which leads to the magazine, placed
without the building or underground, as most convenient. There are two
valves P, P, at the bottom of the barrel M, one to admit the air into the barrel
from the atmosphere when the piston ascends, and the other to admit the air
from the barrel to the magazine when condensed by the descent of the piston.
As the wheel C is turned round it draws the rod D, D, by the pin D, which
drives the wheel E up and down the inclining plane, whereby the end of the
beam H, H, is made to rise and fall, and to work the piston rod at the other
end. By means of the inclining plane and screw the condensing piston is
made to work a long or a short stroke, according to the strength of the wind

page_text: and the density of the air in the magazine: When the wind is strong, or the
air in the magazine not much condensed, the inclining plane is to be set at a
great angle, that the piston may make a long stroke, and drive into the magazine
a greater quantity of air; but when the wind is weak, or the air in the
magazine strongly condensed, the inclining plane must be set at a less angle, but
which of course should be the greatest at which it will work. By these means the
full effect of the least wind wind will be obtained, as well as of the greatest;
and, in consequence of the wheel at the end of the piece E, E, being drawn up to
that point F, on which the inclining plane turns, the condensing piston will go to
the bottom of the barrel every stroke, whether the angle is great or small. To
raise and depress the inclining plane, as occasion requires, I construct a regulator,
as follows: The horizonal wheel a is fixed upon the iron spindle a, a, and is turned
by the wheel B, and upon two round parts near the bottom of the spindle a, a,.
are placed two mitre wheels X and W, which have each of them round holes
in their centres, that the spindle a, a, may turn round within them while they
remain stationary. The teeth of each of these wheels work in the teeth of
another vertical wheel Y, fixed upon the end of the long spindle Y, N, and
upon the other end is fixed the wheel N, the teeth of which work in the teeth
of the wheel O, and this last wheel is fixed upon the nutt of the screw G, so
that whenever the. wheel O is turned round either way, the screw G, with the
inclining plane, is either raised or depressed. That part of the spindle a, a,
that is between the wheels X and W, is square, and has upon it a coupling box.
V, made to slide up and down between the wheels. This coupling box is con-
nected by the rod L to a centrifugal regulator, made in the usual manner, and
kept in constant motion by the spindle a, a. As the balls of the regulator are
thrown further from their centre of motion by the increased velocity of the
windmill, the coupling box V will be drawn up by the rod L, so as to take hold
of the wheel X, and cause that wheel to turn round with the spindle a, a,
whereby the wheel wheel O, with the nutt of the screw, will be turned, and the.
angle of the inclining plane increased. But when the velocity of the windmill
is so small that the balls of the regulator fall close in, the coupling box V will
be let down so as to let go its hold of the wheel X, and take hold of the wheel.
W, whereby the wheel O, with the nut, will be turned the contrary way, and
the inclining plane set at a less angle. By this means the engine will adjust the
inclining plane, so that the quantity of air driven into the magazine will always
be the greatest that the strength of the wind and the charge of the magazine
can admit of. When the windmill is erected for the purpose of a condensing
wind engine, and the situation and circumstances permit, instead of the upright.
central shaft A, A, and wheels B and C, I make a cast iron crank upon the

page_text: iniddle of the axis of the sails, as d, Fig. 3; to this rod a crank is attached,
which reaches to the lower part of the building, and takes hold of and turns in
a sockett at the end of the cast iron piece e, f, e; this piece turns upon a fixed
centre at f, and to the lower end of it is jointed the rod D, D, which moves
the wheel upon the inclining plane, as described in Fig. 2, and I apply the
regulator to this machinery by means of a small fly wheel and crank commu-
nicating by a rod to the lower end of the piece e, f, e. Q, Q, Fig. 2, is the
pipe through which the dense air passes from the magazine to the cylindar R,
which is either at top and bottom, and has a cylindrical rod and stuffing box,
as is usual in steam engines, with a joint and roller at Q, to keep it parrelled, or
is open at bottom, and is connected by the rod under the piston to the frame S, S,
as represented in the Figure. The cylindrical rod or the frame S, S, is jointed
to the end of the beam T, T, which turns upon a fixed centre at W, and to the
other end of it is jointed the heavy iron rod W, W, which is connected to the
crank of the fly wheel X; to this end of the beam also the pump rods are
connected when the engine is applyed to raise water; or instead of applying
the rod W, W, immediately to the crank, I connect the end of it to the two
short pieces B, B, Fig. 4, one of which turns upon a fixed and firm pin at C,
and the other is jointed to the rod D, which rod is connected to the crank, and
by this means the fly-wheel receives a double velocity. There are two valves
at the top of the cylinder R, Fig. 2, to be opened and shut by the engine, one
to admit the air from the magazine into the cylinder, and the other to let the
air out of the cylinder when the piston is driven to the bottom. In consequence
of the air in the magazine being at different times of various degrees of density,
the valve that admits the air from the magazine must be shut when the piston
in its descent is at different distances from the top of the cylinder, that the
quantity of force which the piston receives in the whole descent may be equal,
altho' the density of the air is different, and this is to be managed by placing
the sliding rod that shuts the valve higher or lower on the frame S, S, and may
be made to adjust itself by a regulator.
Fig. 5 represents an air vessel and piston, by which a rotatory motion is ob-
tained without valves, applicable to small engines, or where a fly wheel cannot be
admitted. A, C, E, D, B, is a section of the vessel made of cast iron, having a
curve superficies, and flat ends. In the inside of the vessel and round the curve
runs a flat spiral division, fixed to the curve, and close to the boss of the axis
O, P, R. This spiral passes round from A to B, from B to C, from C to D,
and from D to E, where it ends. The axis I, L, passes through one of the flat
ends of the vessel, through the middle of it, and terminates in the opposite
end, and has a boss O, P, R, U, upon it, which fills up the middle part of

page_text: the vessel. The boss and part of the axis has a longitudinal slit through it,
to admit the flat circle A, C, E, S, T, to turn within it on a centre at N.
This circle is divided into two equal leaves, each of which fit the space
between the spiral division. The dense air admitted at F will press
upon the leaf that occupies the space between A and C, and drive it round,
together with the axis I, L. As the leaf goes round it passes between B and
D, and from thence to C and E, when another leaf of the circle will have
entered between A and C, upon which the air from the magazine will act as
before. The air, when it is dilated, and has left the spiral, will issue out of the
hole at Z. The form of the magazine I make spherical, or cylindrical with
semispherical ends, according to the situation and circumstances, and the mate-
rials, copper plate, iron or cast-iron, and when large, cast or wrought into
segments and screwed together, and paint and varnish the inside to make
them air tight, and where it is practicable I make an excavation under ground,
so much below the surface that the incumbent earth may be sufficient to resist
the force of the combined air, and line the excavation with lead, copper, or
cast-iron, or with bricks or tiles cemented together, and covered on the inside
with pitch, paint, varnish, or any bituminous matter, to render it air tight, and
to and from the magazine conduct the air by a strong cast-iron pipe, on or
near the top of which must be a safety valve for the security of the magazine,
and a stop cock to close the pipe occasionally.
In witness whereof. I have hereunto set my hand and seal this Twante