CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1840

page_text: PILBROW'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
PILBROW, of Tottenham, in the County of Middlesex, Esquire, send greeting.
WHEREAS Her present most Excellent Majesty Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Tenth day of September, One thousand eight hundred and
forty, in the fourth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said James Pilbrow, Her especial
licence, full power, sole privilege and authority, that I, the said James Pilbrow,
my exors, admors, and assigns, or such others as I, the said James Pilbrow,
my exors, aduiors, and assigns, should at any time agree with, and no others,
from time to time and at all times during the term of years therein ex-
pressed, should and lawfully might make, usc, exercise, and vend, within
England and Wales, and the Town of Berwick-upon-Tweed, and also in all
the Colonies and Plantations abroad, my Invention of "CERTAIN IMPROVEMENTS
IN STEAM ENGINES;" in which said Letters Patent is contained a proviso
that I, the 'said James Pilbrow, should cause a particular description of the
nature of my said invented improvements, and in what manner the same are
to be performed, to be enrolled in Her said Majesty's High Court of Chancery
within six calendar months next and immediately after the date of the said
in part recited Letters Patent, as in and by the same, reference being there-
unto had, will more fully and at large appear.
NOW KNOW YE; that in compliance with the said proviso, I, the said
James Pilbrow, do hereby declare that my said invented improvements consist

page_text: chiefly in a steam engine of a new construction, which I distinguish from the
present engines as "The Condensing Cylinder Engine."
It is intended to obtain that effect of steam or power which during the
stroke is now lost by an imperfect exhaustion of the cylinder; and also to
obtain a better extreme vacuum, which will enable the steam to be expanded
lower than can be done by the present engines. I condense the steam either by
an injection of the external water, which I regulate according to the speed and
wants of the engine by what I call the injection regulating valves attached to
the steam valves and worked by the eccentric, or by condensing by surface, using
the same water over and over again to prevent encrustation of the boilers.
My other improvement on the steam engine is a method of supplying and
regulating water to high or low pressure steam boilers without a force pump
and without taking such power from the engine.
The basis on which I found my chief improvement on the steam engine is
the following:
The power of the condensing engine depends (other things being the same)
upon the rapidity and perfection with which the cylinder is exhausted of the
steam which has just previously performed the stroke. This used steam, by
its adverse resistance to the piston, more or less prevents its full effective
power.
Steam can only be condensed as fast as it rushes from the cylinder
to the condenser, as fast as the injection can enter, and as fast as the water or
cold surface can absorb the latent heat of the steam. In physical science
there are certain conditions as in pure mechanics there are certain combina-
tions under which the best results are obtained, and where these are varied,
though the same end may be secured, it can only be by the same expenditure
of power, and frequently of more, so that what is gained one way is lost in
another; I consider, therefore, that for an engine to exert the most power, and to
perform the greatest duty, the temperature of the condensement should be from
ninety-six to one hundred degrees, which will give an extreme vacuum of
about 27°. To obtain this only the proper quantity of injection water must be
admitted. If, therefore, whilst the steam is being condensed the vacuum
guage shows a mean vacuum in the condenser of 24, 25, or 26, or anything
less than what is due to a temperature of one hundred degrees, it shews that
The exhaustion
the, steam is in the condenser waiting to be condensed.
valve, therefore, must be large enough to permit the escape of the steam from
the cylinder as fast as it can be condensed by the quantity of water propor-
tioned to keep the condensement at 100° degrees, and no increase in its area
would give a better mean cylinder exhaustion. More injection water would,
however, condense the steam with greater rapidity, and give a better cylinder

page_text: vacuum, but this advantage would be counterbalanced by two evils, each
probably of equal or greater magnitude. One would be that as much or
more power would be lost than gained by the engine having to lift more water
out of a vacuum and to contend earlier against the weight of the atmosphere
(14 or 15lbs. on the square.inch in proportion to the vacuum) which would
be thrown sooner upon the piston of the air pump. The other evil would
arise from loss of duty, because the condensement being reduced so con-
siderably below the temperature of 96 or 100 degrees to get the better
cylinder exhaustion would require more fuel to convert again into steam. It
is a common error to suppose that the better vacuum beyond proper limits the
more power or duty, and I find that Mr. Watt was content with an extreme
vacuum in his condenser of only 27°, and thought it better so than by throw-
ing in a greater quantity of injection water to obtain a more perfect vacuum.
As, therefore, I consider it better to keep the condensement at 100 degrees,
which will give a condenser vacuum of about 27°, if the eduction and
injection passages are so proportioned that when the steam and injection
water meet, the water absorbs the caloric as quickly as the law of trans-
mission of heat permits, no increase of passages would enable the opera-
tion to be performed more speedily. A less mean exhaustion of the
cylinder will, however, follow than if the extreme condenser vacuum were
kept at 28 or 29, for in proportion to the condenser vacuum will be the
cylinder exhaustion. Mr. Watt nevertheless submitted (to obtain other
advantages of greater moment) to that loss of power which is owing to a
less perfect mean exhaustion of the cylinder. This loss of power arises from
the number of double strokes of the rotative engine, which cannot allow
time for the used steam to be evacuated from the cylinder and be condensed
before the piston has performed a great portion of its stroke, because, however
fast steam rushes to a vacuum, and however rapid its condensation (and both
are surprizingly rapid), it not only requires a cold medium, but also time to
condense it. However short that time may be it is very appreciable by the
indicator shewing throughout the stroke a less mean cylinder exhaustion than
the extreme condenser vacuum, for the steam keeps expanding and reacting in
the cylinder whilst being condensed, and the piston moves throughout its
course with diminished power, owing to the resistance of the unexhausted
steam. This resistance cannot wholly cease until the termination of the stroke.
Hence, from its commencement, when the piston for a short time is resisted
by steam of considerable density to its close, there is a great variation in the
vacuum in the cylinder, and a loss of power in proportion to its slowness of
exhaustion. This loss is estimated by Watt upon the general run of rotative

page_text: engines, where the condensement is from 100° to 107 degrees at a mean of
about 4 lbs. on the square inch, when the engine is loaded so as to exert its
intended duty. The piston of the Cornish single lifting engines, however, does
not make more than from three to eight single strokes a minute, or, taking the
stroke of Austen's engine at the Fowey Consals mine, which is nine feet, it
does not travel more than from twenty-seven to seventy-two feet a minute by
the pressure of the steam. The eduction valve is also opened a second or so
whilst the piston remains at the top of the cylinder, consequently, the time
enables the used steam to escape from the cylinder and become nearly condensed
before the piston moves. Meeting, therefore, with but little resistance from
any uncondensed steam, it works in a cylinder much more completely exhausted
than in rotative engines, and this superior cylinder vacuuin enables the steam to
act with considerably more effective pressure on the area of the piston, and
accounts in the greatest degree (in addition to other well understood causes) for
the superior duty of Cornish single-lifting engines. But if we take the least
number of strokes made in a minute by any rotative engine at only fifteen, the
cylinder requires to be exhausted thirty times a minute, the piston travelling, if
seven feet stroke, two hundred and ten feet a minute. Here, too, the continuous
motion of the crank prevents the piston, on its reversal, making the same
advantageous pause, and there can be no time for such engines to obtain the
same cylinder exhaustion. Though the crank at each reversal of the piston
gives a favorable slowness to it for the instant, yet this advantage is counter-
balanced by the exhaustion valve being only opened as slowly, which is not the
case with Cornish single-lifting engines, for there the eduction valve is thrown
open at once. Though some eduction valves are made in rotative engines to
open just before the piston commences.its reversal there is a loss of power in pro-
portion, because the steam is then sent to the condenser before it has done the
duty it would otherwise perform. The crank; wonderfully adapted for the
purpose, is beautifully bringing the piston to rest of itself, and the piston should
not (when travelling at its usual rate with expansive steam' properly applied)
be relieved by the opening of the eduction valve to make the piston nove still
more slowly just at that period when the crank is compelling it to move slow
enough; and to get the utmost duty from an engine, all that is appreciable
must be saved, as is the case with the Cornish engines, so, too, the larger the
éduction valve the greater loss of steam from clearage. The piston, if requiring
relief, is most economically relieved by previously working the steam as expan-
sively as it can be worked.
The following is the description of my "condensing cylinder engine" for
the purposes before mentioned, and which is applicable to Cornish engines, as

page_text: hercin-after described, the duty of which will be increased thereby, though not
nearly in the same proportion as in rotative engines.
A, Sheet No. 1, is a Drawing in section of an engine on my construction. The
condenser, as well as the air pump of the present engines, I do away with, and
condense the steam in what I call the condensing cylinder, the action of which
is double and the piston solid. It, therefore, receives the pressure of the steam
during the process of condensation (which power is now thrown away in the
present condenser), and also acts in the capacity of a double-action air pump A.
Figure 1 is the steam cylinder; 2 is the piston, and 3 the rod as usual; four is
alternately the steam and eduction passage for the lower part of the steani
cylinder; and five is the same for the upper part; six and seven the passage
alternately communicating from the steam to the condensing cylinder; eight
and nine, the slide valves adapted for my engines, though the D valves now
used are equally applicable with the centre passage stopped up as herein-after
described; ten represents the entrances of the steam from the boiler to the
valves; eleven is the rods moving the valves 8 and 9, working through their
stuffing boxes; twelve and 13 are the piston and rod of the condensing
cylinder (14), which is here represented of the same capacity as the steam
cylinder; fifteen is the passage through which the coudensement and injection
water, and any air or gas, are expelled at the conclusion of the descent of the
piston of the condensing cylinder into the hot well (16) to supply the boiler, and
which is prevented returning to the condensing cylinder by the valve 17;
eighteen is the passage with a perforated nozzle for the injection water to
condense the steam beneath the piston of the condensing cylinder, through
which passage the injection water passes when permitted to do so by the
injection regulating valve (19), which valve is attached by the rod 20 to the
steam slide valve 8; twenty-one is the passage through which the condense-
ment and injection water, and any air or gas are expelled at the conclusion of
the ascent of the piston of the condensing cylinder into the hot well as before,
and which is prevented returning by the valve 22; twenty-three is the passage
with a perforated nozzle for the injection water to condense the steam above
the piston of the condensing cylinder, and through which passage the injection
water passes when permitted to do so by the injection regulating valve 24,
which valve is attached by the rod 25 to the steam slide valve 9. The
injection pipe leads as usual from the external water, but bas a branch
above and below the condensing cylinder at figures 26. and 27. The
following will be the action of the condensing cylinder engine:-The air will
be first expelled by blowing through in the usual way, which. done, the
cylinders and passages will be filled with steam. Supposing the pistons at

page_text: the positions shewn in Figure A, Sheet No. 1, the steam piston being at the
bottom, and the piston of the condensing cylinder at the top, the lower
valves 8 and 19 being moved to the left by hand gear, the injection water
will flow in the usual manner in the direction of the arrows into the con-
densing cylinder under its piston, and make a vacuum by condensing the
steam contained therein. The engine is now ready to start; the piston of the
condensing cylinder being at the top of the cylinder, and the space below at
the vacuum.
The steam piston will therefore be at the bottom of its cylinder,
and the space above it steam; the cranks of each engine being set in opposite
directions, or at the opposite end of the beam, as shewn in the Drawing D.
The valves 9 and 24 being moved to the left in the direction of the arrow,
the cominunication through the passages 5 and 7 will be opened between the
upper part of the steam cylinder and the upper part of the condensing
cylinder; and by the same movement the injection water will flow through the
injection passage 23 to the upper part of the condensing cylinder, to condense
the steam as it is entering from the top of the steam piston. By the same
movement the valves 8 and 19 are moved in the direction of the arrow to the
right, by which the communication is also opened between the boiler, by the
passage 10 and 4, to the under side of the steam piston. The injection water
under the piston of the condensing cylinder will by the same movement be
cut off by the valve 19. The engine will then commence its full operation, by
both pistons starting into action; the condensing piston descending, and the
stean piston ascending. The under part of the steam piston is therefore
receiving the full elastic force of the steam from the boiler, and its upper
surface is resisted by the steam as it flows into the condensing cylinder to be
condensed, as is now the case in the condensers of the present engines. But
the communication being open between the upper part of the steam piston
and the upper part of the piston of the condensing cylinder, whatever pressure
during the process of condensation from unexhausted steam that retards the
steam piston will be given out to the piston of the condensing cylinder; and
as there will be throughout a more perfect vacuum on the other side of this
piston than can now be obtained in the condenser of the present engine, even
at the termination of the stroke, the same effective pressure will in reality be
obtained as if the steam piston commenced its stroke with a nearly perfectly
exhausted or vacuous cylinder, whereas that uncondensed steam which, during
its condensation in the present engine retards the action of the piston, and
deducts so much from its effective power, cannot be given again in favour of
the engine, because it is being condensed where there is no piston, and is
therefore wasted. The steam piston having arrived at the top, and the con-

page_text: denser piston at the bottom of their cylinders, all condensement and air
produced by the admission of the first injection are expelled by the downward
stroke of the condenser piston through the passage 15 to the hot well. Whilst
this downward stroke of the condenser piston was being made, the steam was
entering the upper part of the condensing cylinder from the steam cylinder
(as before observed), and was being condensed by the injection water through
the passage 23; and by the time the condenser piston arrives at the bottom
will be completely annihilated. The eccentric will then in the usual way
reverse the valves, by which a communication will be made between the boiler
and the upper part of the steam piston, and between its under part and the
under part of the condenser piston; whilst by the same movement the injection
passage at the top will be shut, and that at the bottom of the condenser piston
opened. The upper part of the steam piston will then receive the full steam
pressure; and its under part, and the under part of the condenser piston, will
be placed in equilibrium (as before was the case with the upper parts), by the
vapour between them. The nearly perfect vacuum having been already
obtained by the last stroke, as just described, on the upper side of the con-
denser piston, gives the piston its full effect from the commencement of the
stroke; and by the time this stroke is finished, the steam between the two
pistons will also be condensed, and the same good vacuum be again formed on
the other side ready for the next stroke.
way
Having thus described one up and one down stroke, the valves being worked
by the eccentric, this action will be continued, and the engine will work with
the effect described. The chief power or vacuum by which condensing rotative
engines of the present construction are worked, is obtained only by condensing
the steam whilst each stroke is actually being made, whereas in my engine the
chief power or vacuum is already formed by the previous stroke. It is in this
that every reversal of the piston commences with a ready-made vacuum,
and thereby gives the increase of power between the mean of the resistance of
the unexhausted steam from the imperfect exhaustion of the cylinder of the
present engines, and a vacuum from the commencement of the stroke. My
object is not so much to get any pressure from uncondensed steam on my con-
denser piston, as to totally annihilate the used steam just before the alternate
reversal of the condenser piston, that the steam piston may have the full effect
of the working power or vacuum to begin the stroke with. This vacuum, too,
is superior from the commencement of the stroke to what is found in the
condenser of the present engines at its termination, on account of my
double-action condenser piston alternately expelling through the valves and
passages 15, 17, and 21, and 22, the condensement and air of each evacuation

page_text: of the steam cylinder. I shall always have on the other side of my condenser
piston water at a temperature of ninety-six or one hundred degrees (being
the condensement of the previous stroke), and which is not one pound
on the inch; yet by discharging to the hot well all air, gas, and condense-
ment arising from every evacuation of the cylinder, the accumulation of
the air and gas of two condensements cannot take place in my engine to
give by its greater density the same resistance to the piston as is found
in the condenser of the present engine, and this will enable the steam to be
expanded lower than can now be used. If I should find it more advanta-
geous to have still less injection water and liberated air to expel, I shall enclose
iny condensing cylinder in a tank, as represented in the Sheet No. 2, Fig. D,
and keep cold water circulating between by a small pump to be worked by the
engine, or if my boiler supply and regulator is adopted the present force pump,.
which then would not be required, would amply suffice. By having two or
more condensing cylinders; with pistons of the same size as the steam cylinder,
and connected with the beam, surrounded by cold water supplied by a pump,
and valves between the cylinders, for the admission of the steam as it progres-
sively becomes condensed from the steam cylinder, I can retain my principle,
and use the same water over and over again in the boilers, and thus prevent
their encrustation; but owing to the friction I greatly prefer my simple princi-
ple by injection as before described. In adapting my condensing cylinder to
the present engines it is not necessary to remove the steam cylinder, but only
the condenser and air pump, and to substitute a cylinder and solid piston of
the same size as the steam cylinder. Where the steam in marine or other
rotative engines is used at from three to six pounds in the boiler, and is ex-
panded as low as it can be used, and taking the mean of the resistance of the
unexhausted steam at about four pounds, on the square inch, as established
in the practice of Mr. Watt (the condensement being kept at one hundred
degrees, with the object of obtaining most duty, as before mentioned), I ex-
pect by this alteration either to increase the actual power about forty per cent.
with the same fuel, or by cutting off the steam earlier to obtain the same
power, with a saving of nearly one half of the fuel, at the option of the parties.
This saving will remain after deducting the usual difference for more friction
between the size of my condensed piston and that of the air pump removed,
the additional power to work which will, I consider, be obtained merely from
the better extreme vacuum I shall ensure. The clear gain left is founded on
the average order in which engines are generally kept. With the very best
engines the gain will seldom be less under the condition of most duty before
described. My alteration will be about the same weight as what is removed,

page_text: but besides the saving of tonnage and expence from less fuel, much tonnage
will be saved, by considerably less than the usual quantity of water being
required in the boilers. Where, however, all things are made from the first
proportioned to each other, the saving in space by a more compact engine than
the present, and in expense, further space and weight, by requiring boilers of
much less size and holding much less water, will be considerable, independent
of the saving in fuel. If my valves are not applied, the D valve, with the
centre passage stopped up, is applicable to my engine as follows:-Figure 1,
B, Sheet No. 1, represents part of the steam cylinder; 2, part of the steam
piston 3, part of the condenser cylinder; 4, part of the condenser piston';
5, the steam passage from the boiler; 6, the valve or part which usually has a
passage through it, but here must be solid; 7 is alternately the steam and
eduction passage from the lower part of the steam cylinder; 8, the passage to
the lower part of the condenser cylinder; 9 is alternately the steam and educ-
tion passage to the upper part of the steam cylinder; and 10 is the passage to
the upper part of the condensing cylinder. These valves being worked by the
eccentric perform the required duty, and if used the injection regulating valves
must be attached thereto by a bell crank lever, in a manner similar to what I
have shewn in the valves to my engine to pass the centres with only one engine,
in Drawing C, Sheet No: 2. Whether my valves or these D valves are used
the injection water will not need the attention of the engineer in case of the.
stopping of the engine or the variation of its speed. He must first set the
usual cock to allow the proper quantity of water to pass through the injection.
pipe to the regulating valves, and the admission and exclusion of the injection
water will afterwards be regulated by the speed of the engine, and stop when
that stops, and continue when it again commences. By an arrangement of
my engine, as shewn in Sheet No. 2, Figure C, it will pass the centre or dead
points of the crank with only one engine. It is the same in other respects as
my engine before described, with the following difference, that the condenser
piston will only be at its half stroke when the steam piston is at the top or
bottom of its cylinder, and the reverse; a double set of valves are also neces-
sary, and must be worked by two excentrics, so arranged as to admit of the.
steam passing alternately to the upper part and under side of the condenser
piston, as well from the top as from the bottom of the steam cylinder, at every
half stroke its piston makes; for instance, the piston of the condensing cylinder
(14) is shown at half its stroke descending, the steam piston being at the
bottom at a dead point. The valves being shifted, the steam passes from the
boiler to the under side of the steam piston, and the steam above it which
urges it down will pass by the valves 3 and 4 to the upper side of the con-

page_text: denser piston and urge it down, a vacuum having been made below it by the
usual injection through the passage and regulating valve 9. . When the con-
denser piston arrives at the bottom the valve 4 will be shut, which prevents the
whole of the used steam entering the top of the condenser piston. The
valve 6 will be at the same time opened, the other valves remaining as they
were when the rest of the vapour above the steam piston (which had not
wholly escaped) will pass by the passage 10 to the under side of the condenser
piston, the upper side of which has become a vacuum by the injection water
through the regulating valve 11. The steam piston having then arrived at
the top, the steam valve 7 and the eduction valve 8 will be opened, and the
steam valve 5 and eduction valve 3 will be shut, the valves 4 and 6 remain-
ing as they were. Thus the used steam will escape from the under part of the
steam piston to the under part of the condenser piston, forcing it upwards, and the
valves be varied at every half stroke of the engine, and enable it to pass the centres.
The condensement will be thrown out through the passages 12 and 13 in the same
way as described in reference to Figure A. Figure D, Sheet No. 2, represents a
compact arrangement of my engine first described when adapted for marine
purposes, where side levers are preferred, the condenser cylinder being enclosed
in a cold water tank. For land and Cornish engines the condensing cylinder
of the same size as the steam cylinder may be placed immediately under it, or
otherwise, the present air pump and condenser being dispensed with. The
piston rod of my condensing cylinder may then be attached to a cross head
attached to the steam piston rod, or be connected to the end of the working
beam.
My object in applying my principle to the Cornish engine is, that I shall pro-
cure a better vacuum by sweeping out my condensement and air at every stroke,
and though Cornish engines get a better mean cylinder exhaustion than rotative
engines, still they cannot ensure a perfectly exhausted cylinder from the com-
mencement of the stroke, an equivalent to which I shall obtain by my engine,
and thus carry out the expansive principle still further than can now be done
even in Cornish engines. Sheet No 1, Figure E, represents my method of
supplying and regulating high or low pressure steam boilers with water without
any force pump, but in a way which takes no such power from the engine. 1
is a section of part of a steam boiler; 2, the supply pipe leading from the hot
well or cistern of supply, which must be on a level with this apparatus; 3 is a
solid metal bracket fastened to the end or side of the boiler, having its upper
surface ground smooth, upon which works a hollow slide or box 4, which has
its lower edges and surface ground so as to make a steam-tight joint when
sliding on the bracket 8; is a rod attached to the slide passing through a

page_text: stuffing box 6 in the boiler, communicating to any convenient part of the engine
or machinery, to be worked backwards and forwards by it. The following is
its operation:-The surface of the bracket on which the slide moves being first
adjusted to the required water level of the boiler, the slide being in the situa-
tion shown in the Drawing E, the hollow space 7 will be-filled with water from
the hot well or cistern, through the pipe 2, and the engine pushing this slide
towards the figure 8 by the rod 5, the slide then takes the situation shewn
by the dotted lines, and the water will fall out of the hollow 7 into the boiler.
When the surface of the water shewn by the blue line 9 rises to the level of
the bracket, the water will not then leave the hollow slide, but be carried back
again until the water has fallen the slightest degree below the level, to permit
it to fall out so that the water can never rise above its proper level in the boiler
nor sink below it during the action of the engine. Having discharged tho
water, the hollow slide will return full of steam to its former position by the
motion of the engine, and meeting with the water as before, the steam will be
condensed and the hollow 7 be again filled and again supply the boiler by the
action of the engine. The foot of the slide 10 will cover the orifice of the
supply pipe while the water is being discharged into the boiler, and thus prevent
the steam blowing out through the supply pipe. If required to supply by this
means the loss from blowing out, the hollow of the slide must be made of such
capacity as to contain much more water than is evaporated at each stroke,
which in a few strokes of the engine will make up for any deficiency by blowing
out or by blowing off at the safety valve, and thus, whether the steam be five hun-
dred pounds or one pound pressure, the engine will supply the boiler with water
without a force pump, or taking such power to work it give it what it requires, but
can never overfeed it. The injection water being regulated as before described
by the engine itself according to its speed, and the water in the boiler maintained
always at the same height, with certainty, exactly proportioned to the evapora-
tion, relieve the engineer of these duties, ensure more accuracy than mere human
attention, and prevent any accident that might arise from neglect. All the
power, too, in a given quantity of steam is obtained from it by my condensing
cylinder to the smallest particle that the steam engine is perhaps in its nature
capable of receiving, and which, more or less, cannot be obtained to the same
extent in the present engines. These, together with the additional saving
that will arise from carrying the expansive principle to its utmost limit,
owing to my better extreme vacuum, induce me to consider that the steam
engine will now be made a still more economical and self-acting machine by
my improvements

page_text: I claim, therefore, as my Invention the condensing cylinder engine to save
the effect of steam or power, which during the stroke is now lost by an imper-
fect exhaustion of the cylinder as before described, and to obtain a better
extreme vacuum by which the expansion of steam can be carried out to a
greater extent than in the present engines. I do not claim the framing or
connecting or other parts of such engine; but simply the substitution for the
separate condenser, and distinct air pump of the present engines of a condensing
cylinder combining both in one to condense the steam therein by injection (the
plan of regulating which by the engine according to its speed I also claim),
such condensing cylinder being fitted with a solid piston acting as a double
action air pump for the purposes before described. It is obvious this Invention
or improvement does not depend on the form of such condensing cylinder;
though it should not be of less capacity. I prefer it, however, of the same
form and capacity as the steam cylinder, and surrounded by a tank supplied
with cold water. I claim, as before described, the alternative of condensing
by surface by two or more cylinders and solid pistons surrounded by water in
tanks, to be supplied by force pumps, the surface of the cylinders to be pro-
portioned to the steam required to be condensed, though I think. condensa-
tion by injection more simple and more rapid. I claim as part of my Invention
the arrangement of my condensing cylinder engine, to pass the dead points
with one engine as described. And I claim also as my Invention the particular
method of supplying and regulating water to high or low pressure steam boilers
without a force pump, and without taking such power from the engine as
described.
Such my Inventions being to the best of my knowledge and belief. entirely
new, and never before used within that part of Her said Majesty's United
Kingdom of Great Britain and Ireland called England, Her said Dominion of
Wales, and Town of Berwick-upon-Tweed, and Her Plantations, and
Colonics 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 do hereby claim to maintain exclusive right and privilege to iny said
Inventions.
In witness whereof, I, the said James Pilbrow, have hereunto set my.
hand and seal, this Ninth day of March, One thousand eight hundred
and forty-one.
JAMES (L.B.) PILBROW.

page_text: AND BE IT REMEMBERED, that on the Ninth day of March, in the
year of our Lord 1841, the aforesaid James Pilbrow came before our said
Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing 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 Ninth day of March, in the year of our Lord One thousand