IMPROVEMENTS IN THE CONSTRUCTION, WORKING, AND APPLICATION OF STEAM ENGINES
Year: 1797

page_text: CARTWRIGHT'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDMUND
CARTWRIGHT, of the Parish of Saint Mary-la-bonne, in the County of Middlesex,
A.M., do send greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Eleventh day of November, in the thirty-eighth year of His
reign, did give and grant unto me, he said Edmund Cartwright, my executors,
administrators, and assigns, His special licence, that I, the said Edmund
Cartwright, my executors, administrators, and assigns, 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
new invented "IMPROVEMENTS IN THE CONSTRUCTION, WORKING, AND APPLICATION
OF STEAM ENGINES;" in which Letters Patent there is contained a. proviso
obliging me, the said Edmund Cartwright, 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 six calendar months next and immediately 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
Edmund Cartwright, do hereby declare that my improvements in the con-
struction, working, and application of steam engines are as follows:-
1st. I construct the engine so as that the water or whatever other fluid I
make use of shall, in the course of its operation, whether in the state of
steami or otherwis, circulate throit,and, this without any communication with

page_text: the external air, and without any commixture of cold water or other extraneous
fluid.
2d. I make the working cylinder and the piston to act upon principles
similar to those of the common.sucking pump, the cylinder being supplied in
the same manner with steam as the barrel of the pump with water, save that
in the one case the valves are self-acting, in the other they have action given
them. In constructing an engine upon this principle the piston must be
provided with a valve in like manner as the sucker of a pump with a clack.
The piston valve being closed (which it is made to do by means of a spindle,
which goes through it, striking against a spring or weight at the top of the
cylinder), and the vacuum being opened, the piston makes its stroke, and
at the same time (the steam valve being then opened by the top of the piston
striking against a spindle which goes through the valve) draws steam into the
cylinder exactly as the sucker draws up water into the barrel of the pump.
The stroke being made, the piston valve opens (by the spindle which goes
through it striking against the bottom of the cylinder), and the piston is thereby
enabled to return freely thro' the steam in the cylinder (the steam, valve
being closed by a spring or weight, brought down by the piston rod striking
against it) in the same manner as the sucker of a pump returns thro' thie
water in the barrel. The piston valve then closes, and the steam valve opens,
and the stroke is repeated as before. Note, the steam and piston valves are
kept open when required by springs pressing against the spindles, which run
through each of them respectively; by means of this construction the con-
densation (as will appear by what follows) is always taking place during the
whole time of working, whether the piston is descending or ascending; were
this not the case the condensation, which, as I manage it, is regularly pro-
gressive and not instantaneous, would be too slow.
3d. To produce a vacuum, I condense, upon the common principles of
distillation, by the exterial application of cold to the vessel or appartus thro'
which the steam passes. This apparatus may be variously forced. That
which I most approve is composed of two metal cylinders, one within the
other, laid so near together as that the cold of their respective, surfaces may
act as immediately as possible upon the steam which is admitted between
them. The cylinders are kept cold-by standing in a refrigeratory of cold
water, so contrived as that-the-water shall come in.contact with the outside of
the exterior cylinder and the inside of the interior one. I purpose in some
cases to assist the condensation by having the condenser wrapped in woolen or
other cloths, and kept constantly wetted, and to have a strong current of air
blowing upon them to make the condensing water evaporate. This, or

page_text: whatever other condensing apparatus is made use of, has a constant and open
communication at all times with the steam cylinder. The condensed fluid
falling to the bottom of the condensing apparatus is propelled by a pump
thro' a pipe back again into the boiler, the pipe thro' which it is propelled
passes thro' a box, in the top of which is a buoyant valve, so constructed, by
means of a ball cock or otherwise, as to suffer the air when it rises to a certain
height in the box to escape; the fluid as it rises buoys up the ball cock and
shuts the valve, and then following on repasses into the boiler. By means of
this valve the engine after a certain period becomes nearly, if not totally,
purged of all it's air or elastic vapour, in consequence of which a vacuum,
little, if any, short of an absolute one, is obtained, which upon any other prin-
ciple hitherto practised it is known to be impossible.
4th I make the piston entirely of metal, without any packing whatever,
which is thus done: --The base of the piston being somewhat less than the
bore of the cylinder, and it's surface being made as true and smoothi as may
be, a flat metal ring equally true and smooth is laid upon it, divided into
segments (whose ends are also accurately fitted to each other), which ring
completely fits the cylinder; within the ring lies a spring pressing it outwards,
but so contrived by taking its bearings from two adjoining segments as that
the ring, should it expand, will only open between the segments from which
the spring takes its bearings. This opening is secured by a segment of a
ring lying upon it, and another behind it, which two segments are also kept
to their places by springs pressing them outwards. The whole is kept from
rising off from the base by another flat ring accurately fitted and held down
by an adequate pressure, but not so great as to impede the segments from
gliding freely upon the base. The piston rod is also packed upon the same
principle, that is to say, solely with metal, which is thus done:-The top of
the cylinder being made true and smooth, a flat ring cut into segments lies
upon it and embraces the piston rod, towards which it is pressed inwards by
springs; this ring is enclosed by another, divided into segments, and to which
it is pressed inwards by springs. The segments of the inner and the outer
ring must be so placed as to break joint. The two rings are covered by a
third, which is held down by any adequate pressure, as in the piston; the
whole may be incircled by a box forholding oil, &c.
5th. I construct the rotary engine of Mr. Watt, the Patent for which is
dated March the 12th, 1782, and is now expired, so as that it shall act with
double power and without the necessity of a heavy fly wheel, as directed in
his Specification (to which Specification I refer for the more perfect under-
standing of his Invention), which is thus done:-The axis has any unequal

page_text: number, of not less than three, which number I account the best, of what
Mr. Watt calls pistons, upon it, so disposed that no two shall be opposite.
In the cylinder in which the axis revolves are two valves at opposite sides of
the cylinder. On one side of each valve is a pipe for the admission of steam,
on the other a pipe communicating with the condenser. Or I make the
number of pistons equal and opposite, and the number of valves, steam pipes,
and condensing pipes, unequal and not opposite; or 1 make the valves attached
to the axis, and, in place of the valve, I make fixed divisions in the cylinder in
,the manner prescribed by Mr. Wait. It is obvious that, the number of
pistons and valves not corresponding, some one or other of them will always
be in action on one side or the other of the cylinder. The engine con-
sequently will have no tendency to stop, and therefore a fly wheel will not be
,absolutely necessary, especially a heavy one...
6th. I work the.engine not only with water, but also with ardent spirit
or aether, or any other spirit, more volatile than water, either wholly or in
part; or with distiller's wash, or with any other fermented fluid yielding ardent
spirit by distillation.
7th. I purpose to apply the engine not only as a mechanical power; but
also as a still one and at the same time. In this case the condensed fluid
instead of being returned into the boiler will fall into a proper receiver,
perhaps it will be best after it quits the engine to go into a worm pipe, that
it may have time to get sufficient cold before it falls into the receiver.
Lastly, all these several improvements I mean to apply either collectively
.or separately, wholly or in part, to all engines that are in public use, and to
.all other engines at the expiration. of their respective Patents. The annexed
Drawing, to which the following figures and letters refer, will farther
explain the above Specification,
Fig. 1. A, the cylinder; B, the steam valve; C, a spring fitted to the piston
rod for shutting the steam valve; D, pipe communicating with the condenser;
E, the condenser; F, F, the internal cylinder of the condenser; G, G, the
external cylinder of the condenser; H, pipe leading from the condenser to
the pump; I, the pump; K, pipe leading from the pump to L the air box;
M, pipe leading back into the boiler.
Fig 2, plan of the piston. A, B, C, D, E, F, segments of the flat ring
lying upon the base; G, segment covering the opening (both at the top &
behind) between the segment A & F; H, the spring pressing the segments
outwards; 1, a spring lying at the back of G.
Fig. 3 shews the piston with the segments covered.
Fig. 4 & 5, sections of the piston shewing the valve.

page_text: Inrolled the same Fourth day of May, in the year above written.