IMPROVEMENTS IN STEAM ENGINES
Year: 1844

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
STEVELLY, of Belfast, in the County of Antrim, Professor of Natural Philo-
sophy, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Second day of March, in the seventh year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said John
Stevelly, Her especial licence, full power, sole privilege and authority, that I,
the said John Stevelly, my exors, admňors, and assigns, or such others as I,
the said John Stevelly, my exors, admors, or assigns, should at any time
agree with, and no others, from time to time, and at all times 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
Invention of "IMPROVEMENTS IN STEAM ENGINES;" in which said Letters Patent
is contained a proviso that I, the said John Stevelly, shall 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 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
thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John Stevelly, do hereby declare that the nature of my said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had

page_text: thereon, that is to say:-
My Improvements in Steam Engines are as follow:-
First, instead of conducting the process of condensation in only one vessel
called "the condenser," as at present, I use a succession of condensations in
apparatus, parts of which I term the "hot condenser" or condensers. This I
accomplish in such a manner as that, without interfering hurtfully with the
work of the engine, I can recover a large portion of the heat of the steam after
it has performed its office in the cylinder, and so heat the water that it is to be
sent into the boiler for its supply to a much higher degree than by the present
mode, and use it for other economical purposes where required, as for heating
mills and other premises, for heating the spinning troughs in flax mills, for
evaporating liquids, and so forth.
Secondly. In engines that turn a crank I combine a second cylinder, which
I call "the conjugate cylinder," so with the main cylinder or cylinders as that,
after the steam has performed nearly all the work usually obtained from it
in the main cylinder, a considerable amount of additional work may be
obtained from it in the "conjugate cylinder."
Thirdly. In locomotive and high-pressure engines I work against an atmo-
sphere of more or less perfectly condensed steam, instead of working, as at
present, against the full pressure of the atmosphere; and I supply the place of
the action of the blast pipe in locomotives without any more loss of power than
is at present uselessly though necessarily incurred.
Fourthly. I supply the boilers of high-pressure engines with water by a
self-feeding apparatus, requiring little attention on the part of the engine
driver, and in a great measure doing away with the great resistance to the action
of the pumps, at present arising from their working against the highly elastic
force of the steam in the boiler.
Fifthly. In marine engines I keep the cold condenser and air pump cold by
a different process from the present, and cool the mixed condensing water and
condensed steam which is not required for the supply of the boiler in such
a manner as that a small additional supply of fresh water will be sufficient to
keep the engines working.
Sixthly. In the cold condenser I only supply injection water while the steam
is actually passing into it, and not, as at present, in a constant and occasionally
useless stream, which frequently endangers the choking of the condenser.
Seventhly. I conduct the heat from the internal parts of condensers and
passages which require to be cooled, to the surface, where it is to be abstracted
by an apparatus of wire gauze, or of flatted wires.

page_text: Eighthly. I diminish or prevent the boiling over of the water from the
boiler into the cylinders called "priming," by a new and simple process.
Ninthly. I apply a hot condenser to single acting or pumping engines, such
as the Cornish engine.
First, to understand the manner in which I accomplish the first and second
of my improvements it is necessary to premise, that while a crank is "passing
its centres," as it is technically termed, the pressure of the steam through the
piston upon the connecting rod has no power to turn the crank, and for
a small distance before and after passing the centre its power is very trivial;
but since the motion of the crank is nearly uniform it takes at least an equal
time to describe a given arch in passing the centres, as it does to describe an
equal arch at the most effective part of its action. Now, I employ, more or
less, according to circumstances, of the time of that less effective part of
the stroke in the process of the preparatory condensation in the hot condenser
or condensers, as follows:-Figure 1 is one modification of a hot condenser,
and by considering the motion of the piston in the cylinder B of Figure 2,
the times of its several actions will be readily understood. In passing from
about a' to 6' or from b' to a' in the up or down stroke, the piston may be
said to the working most effectively; while in passing up from about b¹ to the
top and again returning to 6', or in going down from a' to the bottom and
returning again to a', less effectively. In Figure 1, P is a double-acting force
pump which drives forward the heated water to the boiler or "feeding boiler,"
given in Figure 4. C is a vessess of cast-iron or other proper metal, which
need never be larger than one fourth or fifth part of the cylinder, and in loco-
motives must be very short, as the water has very little time to pass through
it; in slow moving engines it is better to give it length. Into this the rose
head H conducts the water to be heated, and which partially condenses the
steam; this water is only admitted when the valve V₁ causes either the
passage y or y' to communicate with z' by covering both, leading the water
from its cistern, and y or y' to the rose head, at the same time the valve V
admits steam by uncovering a or a', which are passages cominunicating with
the eduction pipe from the steam cylinder. This takes place during the less
effective parts of the stroke at top or bottom, but during the most effective
parts of the stroke the box valve V, by causing a¹ and z, or x and z, to commu-
nicate, leads the remaining steam away to the cold condenser through for full
and final condensation.
Note. That where heated water is of much value it may be desirable that
when the eduction pipe is placed by the box valve in communication with the
cold condenser, the passage of the steam remaining in the hot condenser out

page_text: of its other port may be prevented by lengthening the ends of the valves V, so
as to have stop slides beyond the passages which admit the steam into the hot
condenser. By this means the full of the hot condenser of steam at the
tension, corresponding with the temperature of the heated water, will be saved
from passing into the cold condenser each stroke of the valve, otherwise,
however, the preparatory condensation in the hot condenser will be carried to a
greater extent. The valves V and V', and the piston of the pump P, are
worked in the usual manner, by excentrics or rocking shafts, or other means
well known and in common use, and the modes of causing the valves to open
at the proper relative times are well known. When more hot water is
required than is necessary for the supply of the boilers, it may be obtained by
increasing the quantity of injection water, and by surrounding the eduction
pipes and hot condenser with water contained in a cistern; and in flax and
cotton mills the hot water from this cistern may be led off by pipes from its
upper part, which, after branching off and leading the hot water to heat and
supply the mill, may again return the water in a more or less cooled state into
the bottom of this cistern; and a sufficient circulation of the water may be
kept up, if required, by a piston with valves being caused to move back and
forward loosely in one of the trunk pipes, the double purpose being thus
attained of heating the mill supplying the spinning troughs, &c., and cooling
the water for partially condensing the steam. In cases where hot water is
not required, or where condensing water is scurce, the surface of the eduction
passages may be increased, and those passages prepared, as described under
the third and seventh heads of these improvements, or their surfaces cooled by
the evaporation of useful liquids, or of water which has been already partially
heated in previous condensations, and the loss of which, by evaporation, can be
afforded. These evaporators or coolers may be also placed in a funnel like a
chimney to cause a draught of fresh air, and on board ship the hot condenser
and eduction passages, being kept surrounded with sea water in a closed vessel
or chamber, the upper part of which is made to communicate by a pipe with
the cold condenser, a supply of condensed and therefore fresh water may be
obtained to compensate waste at the safety valve, and leakages of steam without
the consumption of any additional fuel. The necessity for the contrivance of
the hot condenser is, that if the steam be at once permitted to expand into a
vacuum its temperature sinks so low that it requires a large mass of con-
densing water or other cold substance to abstract its constituent caloric, while
the temperature of this cooling substance is comparatively little raised by the
process.
Secondly. Figure 2 explains my method of applying the conjugate cylinder.

page_text: The pistons A and B work two cranks on the same shaft, or working together
(the two cranks and their connections with the pistons are not shewn in the
Figure), set at right angles to one another, or so set relatively to one another
as that while A is at the less effective part of its stroke B is at the more effective
part of its stroke, and vice versa. The steam is admitted to A, and educted
from it at proper intervals by a system of valves precisely the same as any of
those in common use, but which are not shewn in the Figure, to avoid compli-
cation. Before the piston A reaches the position a the communication of the
boiler with the lower part of the cylinder A must be closed, and soon after B
passes the lowest part of its stroke the valve v opens the lower port, and
permits the steam from A to communicate pressure to the under surfaces of
both pistons; the two pistons move upwards, and as B approaches the position
b, and A having passed the top of its stroke and is now returning towards a, the
valve v closes, the lower port of communication between the two cylinders, and
by the time they have reached these positions the steam is to have been let off
freely from the under side of A, by the eduction valve, to the cold condenser.
The passage to the cold condenser from A or from B may be furnished with an
apparatus for hot condensation, similar to that described under the ninth head
of these improvements, by which much of the heat can be recovered from the
steam passing from A or B, after it has performed its full functions, where that
is desirable; then the box valve v, causing the under part of B to communicate
with the passage z, which leads away to the hot condenser, the steam from
the lower part of B is partially condensed in the hot condenser, while B is
passing the top of its stroke and returning back towards b, by which time the
box valve v, still maintaining the free communication between the lower port
and z, the valve V in the hot condense., Figure 1, has let off the steam to the
cold condenser, and B passes down from b¹ to a', with full exhaustion on the
lower side of its piston, while the steam from the upper side of A is now
pressing down its upper surface; soon after it passes a', the valve v, on its return;
closes the lower part of B, and soon after B passes the lowest part of its stroke
the valve again opens the communication between the lower parts of
A and B, and the series of actions just described recommences. The action of
the steam on the tops of the pistons, and the succession of actions on the
upper sides, are so precisely similar to that now described for the lower sides as
to need no further description; indeed the terms top and bottom, upper and
under, higher and lower, are to be understood as used merely to distinguish the
ends of the two cylinders, which may be laid on their side, or at any angle to
the horizon, which under particular circumstances it may be necessary or
desirable. It may be supposed that the best time to close the ports or valves

page_text: vand v', and to open the eduction pipe from A to the cold condenser, is soon
after the piston A has reached the top or bottom of its stroke, or at that
instant; but let it be remembered that whatever A loses in passing from the
top to a, or from the bottom to b, by working against the expanded steam,
is at the less effective part of its stroke, while an equal pressure is communi-
cated to B by the intervening steam at a more effective part of its stroke, and
the longer it can be kept open (a due regard being had to the proper working
of A, at the most effective part of its stroke, the steam is in a more condensed
state when let off from B to the hot condenser, and will therefore give off
more of its heat. The admission of steam to A, and its exhaustion from it,
may be managed in the usual and well-known ways, only care must be taken
that the exhaust valve must not open until the valve v or v', as the case may
be, has closed the communication between A and B. The steam may be cut
off in A so as to work with any expansion which the circumstances under
which the engine is working may admit of or require, or which may in practice
be found most economically to suit the working of the conjugate cylinder. In
order that a conjugate cylinder may be adapted to one now in use without
incurring the expence of a new main cylinder, adapting pieces, one of which is
shewn in Figure 2', may be fitted to the top and bottom parts of the cylinder,
so that the flange A may fit the port of cylinder A, and the passage B,
Figure 2', may give the connection with the conjugate cylinder B, while the
passage C serves for working the common valves for admitting the steam to
and exhausting the main cylinder A. In locomotive and marine engines, one
of the two cylinders usually employed may be made to act as a conjugate to
the other, working the steam, if requisite, at somewhat higher pressure, or
a conjugate of double size may be made to receive the steam at the same time
from both the main cylinders, and thus great additional power gained, and no
more steam used than in the present mode of working; but if two conjugate
cylinders be used the action on the crank shaft could be rendered much more
uniform than it now is.
Thirdly, Figure 3 explains my mode of using the cooling power of the air
through which a locomotive engine must run, to condense the steam on its
eduction more or less perfectly. The condenser consists of pairs of plates of
metal (copper plates, as thin as is consistent with their bearing the pressures
to which they will be subjected, as the best conducting of the cheaper metals
will answer best) ribs, either solid or hollow, of a rectangular shape, and
from one quarter to one half inch thick, are to be interposed between these
plates, and are to be so brought up alternately fully to the ends of the spaces
between the plates, and to stop short of those ends, as to keep the plates at

page_text: the distance of their thickness from one another with sufficient firmness, and
yet to permit the steam to circulate freely among them; the plates are to
be either rivetted to the ribs, or fastened by small nuts and screw bolts passed
through both the plates and the ribs, and made air-tight by any of the well-
known compositions for that purpose, such as red and white lead mixed with
oil or gold size; the edges of the plates where they come together may be
either soldered together, or otherwise fastened air-tight. These double plates
are to be so arranged, as that the steam when let into the spaces between them
and the ribs may circulate through all, while the air which passes around and
between them as they move on in the front of the engine, is to be conveyed
to the ash box, or partly to top of chimney, in a strong blast to blow the fire,
by passages formed by the plates, and by the box in which they are arranged,
which box is to be open in front, the cross section of which front may be as
large as that of the largest carriage in the train, and may descend to within
a foot or less of the rails; the sides and back of the passage leading from this
cooler or condenser to the ash box must be furnished with registers under the
command of the engine driver, which he can open or close more or less, so as to
diminish or increase the blast in the fire box, and these registers should be
kept as open as will consist with maintaining a sufficient blast.
Figure 3 is one modification of such a cooler or condenser, the necessary
or proper supports for it being omitted in the Figure to avoid complication.
The back of it is of sheet iron, to keep of the heat radiated from the smoke
box of the engine; its top may be a small reserve cistern for water if required;
its sides and bottom are double metallic plates, put together as before described;
the middle plates may be arranged something like the shelves in a bookcase,
being rivetted or fastened air-tight to the side plates, in which stops and pas-
sages may be arranged, so as to cause the steam to circulate successively
through the several pairs of plates. In the Figure the upper double plate
bends down along the back to nearly the middle of the passage to the ash
box, the steam from the exhaust pipes of the cylinders or conjugate cylinders,
if used, being led into this at its lower part by the tubes E, which lie on
each side; these plates must be wider apart within than the others need be,
and the pipe leading to E should be wide, to admit of the first rush of the
steam at the front of these highest double plates; the steam may be admitted
into a compartment in the side plates, and thence into the second of the
double plates, which may also bend down at the back a part of the distance
towards the passage to the ash box, thence the steam may pass by the side
plates to the next, and so on, as shewn by the shading and numbers in the
Figure, to the lowest of the double plates at the bottom; the side plates may

page_text: pass into two small oblong reservoirs R, R, for the condensed water; these
are to be each divided by internal divisions into a front and back compart-
ments; and two small double-acting force pumps, lying at a little lower level,
empty these compartments of the condensed water, and force it up to the
reserve cistern, from whence it may be conveyed to work the hot condenser,
or, if the supply of water carried be more than sufficient to compensate for
.steam waste during the journey, it may be allowed to run in numerous small
streams over the hotter plates, so as by its evaporation to augment the refri-
geration. The small pumps may be worked by excentrics placed on the
axle of the fore wheels of the engine, and need not be thrown into action
until the train is in full motion; blow valves also must be placed in the front
compartments of these reservoirs, and should uncondensible airs accumulate
between the plates, the condenser or cooler may be blown through by a pipe
from the safety valve with steam that would be wasted during stoppages;
spare blow valves may be also placed in the back compartments; and in
stationary engines, particularly high-pressure engines, I propose to convey
the air from a similar cooler into the ash pit, so as both to supply heated air
to the ash pit, and have the cold air drawn into it to increase its cooling
efficacy by the draught of the fire; and I also propose to combine partial
condensation, by such a cooler, with final and full condensation, in a cold
condenser of the common kind.
Fourthly. Figure 4 shews the self-acting supply boiler for high-pressure
boilers. B is the main boiler; B', the supply boiler into which the water is
pumped from the hot condenser, and which may be placed in the smoke box
or that part of the flues where the heated airs from the furnace are just about
to pass into the chimney after their action on the boilers. A cock C has a
hole passing half way up through the axis of its spigot, and then turning off
at right angles towards the side; this passage causes the inside of Bt to com-
municate with the open air by the passage a, in one position of the cock, but
when it turns a little round it shuts a, and opens a passage by b to the top of
the main boiler B; proper stops, such as those in use in gas cocks, are to
confine the action of the cock, so as not to pass beyond these two passages.
When the water in B sinks below a safe level, the float stone f sinks also,
and by a wire w, acting on the lever hand crank d, works the handle h of
the cock, shutting a and opening 6, and thus permits the water to pass
through p, from B¹ into B, a ball valve preventing its return. When frises,
a spring draws back the handle of the cock h, so as again to
close b. When B' has been filled with water by the condenser pumps, the
float valve rises up against the passage in the spigot, and by confining the
open a and

page_text: air soon prevents the admission of more water, which may then pass, by a
branch of the supply pipe, either to a second supply boiler, which may fill
while B is emptying, or to the reserve cistern. Also the float valve v must
be heavy enough to open by its own weight when it loses the support of the
water as B' empties. The pipe which leads the water into B¹ from the pumps
should also have a ball valve and a handle to work h, or another similar acting
cock should be at the command of the engine driver, to feed the boiler by
hand if requisite; also a handle by which water may be admitted from the
reserve cistern into B', if at any time the pumps should supply less than the
evaporation required. In locomotive and marine engines the float f must
be prevented from acquiring an injurious lateral or swinging motion by proper
and strong guides, but which shall freely permit its vertical motions.
Fifthly. In marine engines I keep up a constant and abundant supply of
cold sea water, to a cistern in which the cold condenser and air pump are set,
by pipes leading in from the bows of the vessel, and leading out just abaft
the action of the paddle floats, the draught caused by the action of which will
keep up a sufficient constant flow, the abundance of which can be regulated
by the size of the pipes, which must be proportioned to the size of the engines
and the quantity of steam to be condensed; I also send the fresh water, after
it has been heated by previous condensations, from the reserve cistern through
passages prepared as described under the seventh head, and surrounded by
this cold sea water; the fresh water thus cooled passes into another cistern,
from which it is again admitted in jets into the cold condenser, either by a
small force pump, or by a valve lik V', in Figure 1, or by a rocking cock.
Sixthly. The mode of accomplishing my sixth improvement has been already
sufficiently exemplified in explaining my first and fifth.
Seventhly. By interposing frames with wire gauze or flattened metal wires
(copper is the best) in the passages, made sufficiently wide, through which
steam or hot water to be cooled has to pass, the heat will be conducted by
the metal more rapidly to the surfaces from which it is to be abstracted than
it will be carried by the fluids, and yet sufficient water or steam way may be
secured. Figure 7 and Figure 71 represent an oblong and a circular frame,
so filled with flattened wires; and Figure 7" shews the individual flattened
wires, the turned up parts at the ends determining their distances in the
frames. The metallic contact between the wires or gauze and their frames
may be completed, if desired, by a deposit of the same metal by the electrotype
process.
Eighthly. I prevent or diminish priming in the boilers by surrounding the
outside of the ascending part of the steam pipe, as it rises from the steam

page_text: chest, with a funnel F, of wire gauze, extending from the pipe to the sides of
the steam dome, which, while it catches the water carried forward by the
steam, and conducts it down to its narrower end, and so back into the boiler,
leaves abundance of steamway at its wider part. I also surround the mouth
of the same steam pipe by a spheric-shaped cap C of wire gauze, to catch any
water which may escape the funnel. These are represented in Figure 8.
Ninthly. By placing an apparatus of extensive surface, and filled inside
with frames of flattened wires or wire gauze, described under the seventh head
as a part of the equilibrium passage, and affording as much, or nearly as
much, steamway as the equilibrium pipe, and placing this modification of a
hot condenser in a small cistern, so as to keep it surrounded with water
previously heated somewhat in the cold condenser. The steam of a single
acting or pumping engine, when establishing the equilibrium, will part with a
considerable portion of its heat; the water from the cistern may then be used
to feed the boiler, and thus fuel will be saved. The more the steamway
among the flattened wires can be contracted, without interfering hurtfully
with the working of the engine, the more heat will be recovered from the
steam, and a similar simple hot condenser may be applied to ordinary crank
engines.
Note. That none of the Figures are drawn to a scale, as the particular
dimensions of the several parts depend so much upon circumstances which
must vary, that it would be impossible to embrace all the cases to which the
actions are intended to apply. Also, it is not intended that all the contrivances
described must be adopted together, but only so many of them as shall be
useful or required under the circumstances of each case.
Having thus described the nature of my Invention, and the best means I
am acquainted with for performing the same, I wish it to be understood that
I do not confine myself to the precise details, so long as the peculiar character
of any part of my Invention be retained. But what I claim is,-
First, the mode of arranging apparatus, whereby the steam passing from
an engine is acted on by a succession of condensers, which I have called hot
condensers, so as to recover more or less the heat of the steam.
Second, the mode of combining a second cylinder (acting on a second crank
on the same shaft, or working together,) and what I have called a conjugate
cylinder, as herein described.
Third, the so arranging apparatus for condensing steam by atmospheric air,
that the air thereby heated may be used for exciting combustion of the fuel in
the furnance, and the draft of the furnace made to aid the cooling efficacy of
the air.

page_text: Fourth, the mode of supplying water to high-pressure boilers by means of
the float facting on a cock c, combined with the pipes a, b, as described in
respect to Figure 4.
Fifth, the mode of supplying surface, condensing, or cooling water from the
bows of a vessel, when combined with and facilitating the motion of such
condensing water by the paddles, as herein described.
Sixth, the mode of introducing condensing water into the condenser, whereby
it is only introduced when the steam is flowing into the condenser.
Seventh, the mode of employing flattened wire or wire gauze as a means of
conducting heat from passing fluids to the surface, as described in respect to
Figures 7, 71, 711.
Eighth, the mode of applying wire gauze F and C, as a means of preventing
"priming," as described in respect to Figure 8. And
Ninth, the mode of applying what I have called a hot condenser to single
acting or pumping, as well as to ordinary crank engines, as herein described.
In witness whereof, I, the said John Stevelly, have hereunto set my
hand and seal, this Twelfth day of August, in the year of our Lord
One thousand eight hundred and forty-four.