CERTAIN IMPROVEMENTS IN THE MODE OF CONSTRUCTING AND WORKING STEAM ENGINES
Year: 1805

page_text: AUD
EARLE, of Liverpool, in the County of Lancaster, Merchant, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by His
Letters Patent under the Great Seal of His United Kingdom of Great Britain
and Ireland, bearing date at Westminster, the Twenty-sixth day of March,
in the forty-fifth year of His reign, give and grant unto me, the said Willis
Earle, my exors, adññiors, and assigns, His especial licence, that I, the said
Willis Earle, my exors, adññors, and assigns, during the term of years therein
mentioned, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, my Invention of
"CERTAIN IMPROVEMENTS IN THE MODE OF CONSTRUCTING AND WORKING STEAM
ENGINES;" in which said Letters Patent there is contained a proviso obliging
me, the said Willis Earle, by an instrument in writing under my hand and
seal, to cause a particular description of the nature of my said Inven-
tion, and in what manner the same is to be performed, to be inrolled in
His Majesty's High Court of Chancery within four calendar months 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
Willis Earle, do hereby declare, that my said Invention of certain improve-
ments in the mode of constructing and working steam engines consists of
the following principles, and is particularly described and ascertained by my

page_text: Statement thereof, and the Drawings, descriptions, and explanations hereunto
annexed, viz' :-
First, the principle of action and re-action by one and the same body of
steam, or its alternate action in contrary or other different directions employed,
whether in engines of the after-mentioned or any other construction, in such
a manner as to produce or be capable of producing two compleat working
strokes, or some equivalent or greater effect, by the expenditure of only one
charge of steam, and in engines of the after-mentioned or otherwise recipro
cative construction, one entire revolution of the engine.
Secondly, the principle of combined alternate action of distinct bodies
of steam respectively, in contrary or other different directions employed,
whether in engines of the after-mentioned or any other construction, so as to
produce or be capable of producing two double-working strokes, or one double-
working stroke in each direction, or some. equivalent or greater effect, by
means of the expenditure of only two charges of steam, such two double-
working strokes, in engines of the after-mentioned, or otherwise reciprocative
construction, being performed during one revolution of the engine.
Thirdly, the union in one impulse of two distinct bodies of steam, without
any contrarious action of their separate energies, the renewal of one of these
bodies causing no additional expenditure.
Fourthly, the employment of an enlarged portion of atmospheric pressure,
obtained through the previous agency of a compound impulse upon one or
more of the principles herein-mentioned, or otherwise of one powerful simple
impulse, not however precluding the aid of principles now in use.
Fifthly, the union of the powers of steam and atmospheric pressure in one
impulse.
Sixthly, a profitable regulation of the condensing system.
Seventhly, the principle of two cylinders or other steam vessels of unequal
size attached to or detached from each other, but having one common piston
rod or other working rod, receiving alternately in contrary directions an
impulse from the alternate action of one and the same body of steam on
a distinct piston or surface within each of the said two steam vessels; or
receiving alternately in contrary directions a double impulse from the com-
bined alternate action of distinct bodies of steam respectively on a distinct
piston or surface within each of the said two steam vessels; or receiving
alternately in contrary directions any impulse, whether simple or compound, or
simple in one direction and compound in the other, and however produced, from
any force or pressure exerted upon itself, or upon any piston or surface within
either of the said two steam vessels.

page_text: The steam engines to which my proposed improvements are applicable
may, for the most part, be constructed in the same manner as the double-
stroke engines of Messrs. Boulton and Watt. Some of the improvements
will, however, require that the piston of a steam vessel be exposed to the
influence of atmospheric pressure, as in the old engine of Newcomen. The
essential difference in each respect will be pointed out in the proper places.
It may be observed generally, that as greater power will be excited than
in common engines of equal size, any piston rod, working beam, or other
portion of machinery acted upon by such powers must be made of suitable
strength. The boilers also, and all the pipes conveying steam, with the
requisite valves, cocks, &c., will require to be made unusually strong. The
degree of strength must be proportioned to the power of the steam employed,
which is in great measure optinal, such, of course, is the size of the engine.
Suppose the chief part of Figure I. to represent part of an engine upon the
principle of Messrs. Boulton and Watt, (the other parts of the engine, such as
the boiler, air pumps, &c., may be supposed similar to some of those in present
use). It has a cylinder or steam vessel A of six feet stroke and twenty-four
inches diameter, furnished with a piston rod C, and a piston D, which piston
may be acted upon by steam on either of its surfaces, and from either side
whereof the steam may be condensed; so far it perfectly resembles Messrs.
Boulton and Watt's double-stroke engine. The improvements of an engine
constructed according to this Figure consists in the addition of the smaller
cylinder or steam vessel B, and of a continuation of the piston rod of A
passing into such steam vessel, to the end of which continued piston rod is
attached another piston E. By means of these additions, with suitable pipes,
and proper cocks, valves, or other equivalent instruments or contrivances,
any given quantity of steam is made to perform it office twice before
it is disposed of by condensation or otherwise. And the advantage of this
peculiar double action is, that an engine, without any admission of atmospheric
pressure, or the aid of any counterweight, and with only one charge of steam,
perform two working strokes instead of one, and accomplishes a compleat
revolution; or if two charges of steam are used during a revolution (as in
Messrs. Boulton and Watt's double-stroke engines), two double-working
strokes instead of two single ones are thereby given. Thus a quantity of
power is procured by means of these improvements, double to that which is
obtained from Messrs. Boulton and Watt's single-stroke engines in the one
case, and from their double-stroke engines in the other, and yet the absolute
quantity of steam, and consequently of fuel expended in their engines, and in

page_text: those improved on my principles, will respectively be equal, at least the expen-
diture will be equal so soon as the engines are thoroughly warmed by the
steam, and in many cases the improvements will produce much more than
double power. The two first stated principles, and in a great measure also
the seventh, are those which are here more particularly alluded to.
I now proceed to explain the mode of operation. The capacity of the smaller
cylinder, Figure I., may be supposed to be one sixth or one eighth, or any other
suitable portion of the larger, but its length equal; let it, for example, be of one
eighth the capacity. Suppose then a vacuum to be created by the common or
any other means in the two steam vessels and the pipes G and H; the pipes
F and I, communicate with each other, and with the boiler, and are of course
filled with steam. The steam may be supposed to be of extraordinary strength,
for instance, eight times as strong as common steam, or steam equal to the
atmosphere in elasticity; (this strength is supposed merely for the sake
of rendering the explanation more intelligible. Steam of any greater or
less strength may be employed, according to the construction of the engine,
and other circumstances, it being always remembered that the stronger the
steam the greater is the power obtained, but also that the more fucl
is expended, and the greater the requisite strength of the apparatus.
Various considerations, according to the nature and quantity of the work
to be performed, affect the question, what strength of steam it may be most
acconomical to employ, but it may be affirmed generally, that economy can only
consist in employing equal means to greater comparative advantage). If the
pistons are supposed to be at the tops of their respective cylinders, the cocks
or valves being all shut, this steam must be introduced into the cylinder B
above its piston, and through the cock or valve 5; being eight times stronger
than common steam, it will impress a force upon that piston equal to the
whole of the force that would be impressed by common steam acting upon the
larger piston, which has a surface capable of being acted upon, that is, eight
times greater; whether, therefore, it be admitted during the whole, or only
during a part of the piston's motion, it will act with the same force that eight
times its bulk of common steam, introduced into the larger cylinder during a
similar period, would exert upon the larger piston. Suppose it to be admitted
during one fourth of the piston's motion, when that motion is completed it is
plain that the steam, originally of eight times the common strength, will have
dilated itself into the whole of the cylinder B, which will then be full of steam
of twice the common strength; now this cylinder is one eighth the capacity of
the larger one; when, therefore, the cock or valve of communication (6) is
opened, this steam contained in B is enabled to rush into the cylinder A under

page_text: its piston, and will press it for a short time with a greater force than common
steam, but continually rush into and dilate itself in A as the piston of A rises
by its pressure, and when this larger piston has reached the top of its cylinder,
the piston of B will also be at the top of that cylinder, and all the steam from
B will have passed into A; it is evident therefore that the steam thus intro-
duced into A will be exactly equal to one fourth of the capacity of A of
common steam dilated into the whole capacity of that cylinder; the effect
however, will not have been precisely the same as if common steam had been
introduced into A by a pipe from a boiler during one fourth of the piston's
motion, altho' the absolute quantity of steam is equal, for as the steam presses
equally in every direction, it acts against the piston of B at the same time
that it acts against the piston of A, and with equal force in proportion to the
respective surfaces; but the surface of the piston of B, in proportion to that
of A, is only as 1 to 8, so that the pressure on the former is overcome by that
on the latter, and there remains a balance of force in favour of the action upon
the piston of at least seven eighths of the whole pressure of the steam against
it. It would seem at the first view that this second action of the steam is not
quite equal to the first, but it must be remembered that for a certain period
the impulse on the piston A is given by the steam while in a state more con-
centrated than that of common steam, at first even having double (or nearly
double) its strength; by this disposition of the steam a much greater portion
of power will be gained than is lost by the counter pressure on the piston of
B, consequently the second action will be stronger than the first.
Having described one revolution of the engine upon this first-stated
principle, I ought to observe that the operation is repeated by opening 7, in
order to expose the steam contained in A to condensation in the usual manner,
and then re-opening 5 to re-admit steam from the boiler into B above its
piston, &c. Thus the effect of two charges of steam is produced by a single
charge, and in the most simple manner. The first principle may also
be exemplified by supposing the pistons at the bottom of their respective
cylinders vacud where required, and steam, as before, introduced from the
boiler into B, but thro' 1 under its piston; its action will be similar, tho' in the
contrary direction, to the first-described action of the steam let into B above
its piston; to produce its re-active working stroke let 2 and then 3 be opened,
the steam will rush with violence through the pipe G, and pass upon the upper
surface of the piston D, and with the same effects as, in the former instance,
the steam from above the piston of B pressed against the under surface of D,
except, indeed, for what power may be left by the circuity of the passage G,
and the expansion of part of the steam into it, a difference easily remedied. The

page_text: operation may be repeated by opening 4 for the condensation of the steam
in A, now above D, and then re-opening 1 to re-admit steam into B under its
piston. The second principle stated is nothing more than a combination of
the two modes above described of carrying the first into effect. It is only
necessary to observe, in regard to the third principle, that a receiver G (as in
Figure II.) being substituted for part of the pipe G, the steam either from
above or below the piston E, or both from above and below it, may, after per-
forming its first oflice (as in the before-described operations), wholly pass or
be pressed into the receiver, or else be suffered partially to delate therein, the
remainder being in any manner condensed or otherwise expelled from B (a
condensation of steam immediately from B is however not desirable), then
either in the upward or the downward stroke of the engine, the steam in this
receiver, or rather a certain regulated portion of such steam, may be suffered
to enter A either under or above its piston, and its action upon such piston will
not in any degree counteract, but altogether assist, the impulse of the steami,
which may be employed to act at the same time upon the piston B. The
fourth principle of operation is the admission of the power of the atmosphere
upon the outer surface of the piston of the larger cylinder in an engine like
Figure II., which may be accomplished by removing the covering plate K and
closing the communications of H and G with the top of A; this, in many
cases, may be very desirable. By employing any of the modes alluded to in the
statement of that principle, a larger portion of atmospheric pressure may be
obtained (tho' with a different degree or species of advantage) than by the
common methods). The fifth principle may be exemplified by the employment
in aid of any atmospheric impulse upon the piston D, of steam introduced at 5
to act upon E, the piston of the small cylinder. The sixth principle is a
stopping or diminution of the process of condensation as an economical means
of lessening the action of the engine when less power is wanted; it is effected
by contracting or closing the cock or valve of communication with the con-
denser at some required point, before the piston has compleated its motion. It
may often be an eligible process when atmospheric pressure is used, as it saves
a quantity of steam (for instance in the cylinder A) for the returning stroke.
The seventh principle involves those peculiar constructions of the engine which
seem best adapted to the employment of any of the principles; this is all that
need be said of it in addition to the statement of the principle itself, the Draw-
ings, and the explanations already given. But it must be observed that the
other principles are capable of employment in engines differently constructed,
and that their employment in any mode whatever will be an infringment of
my Patent:....
--

page_text: In order not to make this description too tedious, many minute cir-
cumstances of advantage and disadvantage have purposely been left unnoticed,
but the general result will, undoubtedly, be as stated; the admission of steam
into the cylinder B, during only one fourth of the piston's motion, has been
taken as the process of fairest comparison, because it is advantageous for the
common engines, and the contrary for their improvements, which procure on
the whole much greater comparative power the greater the quantity of steam
employed. To avoid tediousness, the mention of the period of closing any of
the cocks or valves, &c., has also been omitted. It must be obvious that the
upright position of the steam vessels, &c. is matter of indifference, and that by
the aid of suitable machinery they are capable of being placed and worked in
any direction which may be thought necessary. It is also to be observed, that
by means of additional machinery upon the principles herein stated, the benefit
resulting from my improvements is capable of farther extention. The Drawing
being accompanied by explanation, will doubtless be sufficiently intelligible;
they are calculated to illustrate the distinctive principles of some of my
improvements, but minute exactness has been thought unnecessary. It is not
essential to lay down rules for the comparative capacities of any steam vessels
or separate receiver proposed to be employed; circumstances must determine
their respective proportions, as likewise the minutic of all other parts of the
construction of any engines upon any of my principles, as well as of the mode
of working them.
In witness whereof, I, the said Willis Earle, have hereunto set my hand
and seal, this Twenty-third day of July, in the year of our Lord One

page_text: NB. 10 20 30 40 50 60 70
Denote Situations for focks or
Vales or other equivalent contrivances
to be used as may be found mast
eligible and to be openid and shut
as usual by the action of the Engine
cr otherwise as may be deemed
ernedient