AN IMPROVEMENT IN THE BOILERS AND CONDENSERS OF STEAM ENGINES
Year: 1822

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
CLARK, of Dron, in the Parish of Leuchars, in the County of Fife, North
Britain, Esquire, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth did, by
His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-first day of
March, One thousand eight hundred and twenty-two, in the third year of His
reign, give and grant unto me, the said Alexander Clark, my exors, adñiors,
and assigns, His especial licence, full power, sole privilege and authority,
that I, the said Alexander Clark, my exors, adññiors, 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 "AN IMPROVEMENT IN THE BOILERS AND CONDENSERS
OF STEAM ENGINES;" in which said Letters Patent there is contained a proviso
that if I, the said Alexander Clark, shall not particularly describe and
ascertain the nature of my said Invention, and in what manner the same is
to be performed, by writing under my hand and seal, and cause the same to
be inrolled in His Majesty's High Court of Chancery within six calendar
months next and immediately after the date of the said Letters Patent,
that then the said Letters Patent, and all liberties and advantages what-
soever thereby granted, shall utterly cease, determine, and become void, as in
and by the same (relation being thereunto had) will more fully and at large
appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Alexander Clark, do hereby declare that the nature of my said Invention, and

page_text: the manner in which the same is to be performed, are particularly described
and ascertained in and by the Drawings hereunto annexed, and the following
description thereof (that is to say):-
My improvement on the boiler of a steam engine applies principally to
that description of engine which is to be worked by steam at high pressure.
The boiler is composed of a number of curved tubes placed in an erect position,
by which a greatly extended surface is exposed to the action of the fire; these
tubes are supplied with water from vessels into which their extremities are
inserted, the construction of which will be best seen by reference to the
Drawings. Fig. 1 is a cross section of the boiler and furnace, taken through
at the dotted line Y, Z, in the Fig. 3; Fig. 2 is a longitudinal section of the
same; and Fig. 3 is an horizontal section: the respective letters referring to
the same parts in each of these Figures. A is the fireplace; B, the ash
pit; C, the furnace containing the tubes. This space is closed above, below,
and on the sides with fire brick. D, D, are cast iron plates through which
the tubes pass; E, E, are the upper and lower parts of the boiler containing
distilled water, which flows through the perpendicular columns F, F, F, F ;
these columns support the upper part of the boiler, and, by means of bolts
and flanges, connect the whole together. G, G, G, &c., are the curved tubes
for generating the steam, upon the external surface of which the fire acts.
These are proposed to be made of sheet copper, about one tenth of an inch
thick, which, when brased or soldered with spelter, form the pipes or tubes,
about one inch diameter, and which are to be curved in the form shewn in the
Drawing, Fig. 2; this curve has for its object the capability of expanding or
contracting without fracture. The holes in the iron plates D, D, are bored
to receive the ends of the tubes; those in the upper plate are something larger
than in the lower one, in order to permit the tubes to pass down; the ends
of the tubes, being accurately fitted to the holes, are made to attach themselves
firmly thereto by means of a mandrel driven in, and, on withdrawing which,
a ferrule, of the same metal of which the tubes are composed, is introduced and
drove tight; the holes in the ferrules allow the free passage of the water, as
will be described hereafter. H, H, is a vacant space between the arch of fire
brick and the upper plate D, to prevent the heat of the furnace injuring the
plate. I is the waggon head of the boiler, and J the pipe for conveying
the steam to the engine. K, K, K, are flues by which the smoke escapes
into the chimney. L is the pipe by which the boiler is fed with water; the
lower part of the boiler, the plates D, D, and the waggon head, are
strengthened with flanges, as seen in the two first Figures of the Drawing.
Fig. 4 is the apparatus for working the damper and safety valve, and for

page_text: injecting water into the boiler. In this Figure M is the water cistern, with
a valve at bottom, which is opened or shut by means of a chain or cord
passing over a pulley to a float in the boiler. N, a force pump, to be worked
by the engine, by which the water is injected through the pipe L to the
boiler. O is a vessel connected by a branch with the tube I, which vessel O
contains cold water; the lower part of this vessel communicates with the
cylinder P, where a piston is introduced, and loaded with weight equal to the
pressure at which the engine is intended to be worked. The boiler is to be
filled with distilled water up to the dotted line in the waggon head, after
this the fire is to be applied, and which, acting upon the external surface
of the tubes G, G, generates steam therein; the steam rising in. the tubes
accumulate in the waggon head I, and thence passes through the pipe J into
the engine; a considerable quantity of the water rising through the tubes
with the steam will return through the columns F, F, F, F, to the lower
part of the boiler, and again re-enter the small tubes G, G, at their lower
extremities, by which a constant circulation of the water is continued through
the boiler; should the pressure of the steam any any time exceed the force with
which the engine is intended to be worked, the water will be pressed back
through the pipe L, when the small pipe a at the lower part of the pipe will
prevent its return into the pump and cistern M and N, and direct it into the
vessel O and cylinder P, where its force will raise the loaded piston, by which
means a damper, connected to the chain Q, will be lowered into the flue of
the boiler, and consequently reduce the power of the fire; should the force of
the steam continue to raise the piston in the cylinder P after the flue is closed
by the damper, a safety valve may be opened by a weight attached to the
chain Q, which shall act upon a lever and open the valve; this, however, may
be effected by various other means.
My improvement in condensers of steam engines is applicable to situations
where there is a scarcity of water, and also to situations where there is an
abundant supply. First, where there is a scarcity of water, the condenser is
constructed as shewn in the Drawings Fig. 5, 6, 7, & 8; of these, Fig. 5 exhibits
a vertical section of the condenser; Fig. 6 is an horizontal representation of
the top part of the condenser; and Fig. 7, the bottom part: the respective
letters referring to the same parts in these three Figures. a is the eduction pipe
for conveying the steam from the engine; b, b, b, is a circular pipe or distri-
buting main; c, c, c, c, &c., are curved distributing branch pipes leading
from the main, closed at their outer extremities; and d, d, d, d, are perpen-
dicular condensing pipes connected to the branches through which the
steam descends. One of these curved distributing branch pipes c, with

page_text: its range of perpendicular condensing pipes d, d, d, &c., is shewn detached
at Fig. 8, for the purpose of better understanding its construction. The
perpendicular condensing pipes are connected at bottom with the branch
collecting pipes e, e, e, e, &c., closed at the inner extremity, as seen in
Figs. 5, 7, and 8, and these branch collecting pipes e, e, &c., deliver the water
from the condensing pipes into the main collecting pipe f, ff, f, from whence
it flows through the pipe g to the air pump of the engine, which throws it
into the cistern of distilled water M, shown at Fig. 4. In the centre space
within the circle of pipes above described is a fan h, revolving on a vertical
axle, which is turned by means of a pulley i, and strap leading from the
engine. k, k, k, is a circular cistern supplied from a cistern above, which
is filled by the engine with water, which falls from small holes in the bottom
of the lower circular cistern upon the surface of the pipes, the surplus of
which water will drop into a cistern below; these pipes are to be respectively
covered with cloth, (linen or cotton cloth answers best,) in order to retain
the water which falls from the circular cistern on the surface of the pipes, the
surplus of which water drops into a cistern below. The pipes here described
are proposed to be of copper, and no thicker than is necessary to sustain the
pressure of the atmosphere, and may be all united with soft solder, except the
eduction pipe. The operation of this condensing apparatus is as follows:-
The steam from the eduction pipe fills all the pipes below, and the heat from
the steam passing through the metal to the wetted cloth produces a consider-
able evaporation, which is greatly assisted and driven off by the wind
produced from the revolving fan and consequently cold, which condenses the
steam in the pipes, and the condensed water flows through the collecting pipes
to the pipe g, and thence to the air pump of the engine, which throws it into
the cistern in Fig. 4, as above mentioned. It is necessary that this appa-
ratus should be placed in an open situation, so that the evaporation may
readily escape into the atmosphere. From this description it will be clearly
understood that the same water may be used again and again until the whole
of it becomes evaporated; hence, the whole accession of water required for
carrying on the condensation will be no more than the quantity evaporated
from the surface of the tubes. In the pipe 9 is the valve l, to allow the steam
to escape when the engine and condenser are blown through previous to
setting the engine in motion. The cistern mi is for holding water to supply
the circular cistern or trough k. The valve n in the cistern m is opened after
the engine and condenser are blown through.
Secondly, when there is an abundance of water the condenser is proposed to
be constructed as shewn in Fig. 9. A is the main eduction pipe through

page_text: pump
which the steam passes from the engine; B, B, are two distributing pipes
which branch from the main. Fig. 10 is an enlarged representation of this
part, the same letters referring to the respective parts in both of these Figures.
Nine smaller distributing pipes C, C, C, branch off from the two larger pipes
B, B, which are seen in Figs.. 9 & 10. From these the steam flows into
eighty-one condensing pipes D, D, D, &c., shewn lengthways in the section of
the box E, E, Fig. 9, which contains them. The ends of these last-mentioned
pipes are shewn by dots in Fig. 10, which is an end view of the box bisected.
F, F, are two collecting pipes at the lower part of the range similar in construc-
tion to the distributing pipes shewn at B, B. The eighty-one condensing
pipes D, D, D, &c. lead into nine branch collecting pipes marked R, R, R, &c.
These nine again deliver the water from the condensed steam into the two large
collecting pipes F, F, and thence it passes through the tube G.to the air
of the engine which throws it into the cistern of distilled water for supplying the
boiler of the engine, as seen at Fig. 4. H is a cistern of cold water placed above
the condenser from which water flows through the valve and pipe at I into the
box E, E, and, filling it, flows over at the waste pipe J. The operation of this con-
densing apparatus is as follows:-The steam from the eduction pipe fills all the
branch and condensing pipes, and the heat from the steam, passing through
the metal of which the pipes are composed into the cold water in the box, pro-
duces the condensation of the steam; the condensed water flows through the
tube G to the air pump, as above said. In the pipe G is the valve L to allow
the steam to escape when the engine and condenser are blown through pre-
vious to setting the engine in motion. The valve at I and the valve at M are
connected together by the rod N, and two levers O and P are worked by the
handle at Q, by which, when the one valve is shut, the other is opened; thus,
the supply of water from the cistern is struck off from the box E, and the
water contained in the box discharged at the valve M, when the engine and
condensor are blown through. These tubes are proposed (with the exception
of the eduction pipe) to be made of copper united with soft solder, and need
not be thicker than is sufficient to support the pressure of the atmosphere and
water by which they are surrounded. As a further illustration of this con-
denser, Fig. 11 is added, which shews one of the longest ranges of condensing
pipes, with the end of the distributing pipe and end of the collecting pipe broke
off where joined to the other parts of the condenser. The parts of this Figure
are the same as those of Figures 9 and 10, which are marked by the same
letters. There are 5 longer and 4 shorter ranges, as seen in Figure 9. The
collecting pipes are the same as the distributing pipes, only reversed and
smaller, the steam requiring more room than the condensed water. It will be

page_text: observed, that although the Drawings and description may exhibit a particular
form, dimensions, and materials for the boilers and condensors, yet I do not
confine myself that mode of construction or particular metal. The boiler may
be made stronger if a higher pressure of steam is required, by making all the
parts that are represented cast iron, thicker, the bolts more numerous and
stronger, and the furnace tubes of a smaller diameter. They should not be
thick in the metal, as that prevents the heat passing through to the water,
accasioning expansion when heated, and contraction when cooled, of the exte-
rior surface in a disproportionate degree with the interior surface of the metal,
and, consequently, a greater wear and chance of fracture. The tubes may be
made to sustain a much greater expansive power by diminishing their dia-
meters, the strain being in proportion to their interior surfaces. These tubes
may be better secured in the plates D, D, Fig. 1, by countersinking the holes
on the upper side of the upper plate and the lower side of the lower one, and
staving in the ends of the tubes, and by making threads similar to those of a
female screw in the holes of the plates, into which threads, the mandril, by
being drove hard, will indent the copper. The tubes may be made straight till
above the floor of fire brick in the furnace, & until below the arch above the
furnace, which will make the boiler and furnace more easily constructed. The
arch and floor may each be made in one, two, or more pieces, and perforated
with holes for the admission of the pipes. A little fire clay put in along with
the pipes will make the holes as tight as necessary. When any of these tubes
require to be replaced, the bolts, two of which are seen at 1, 1, Fig. 1st, are
to be unscrewed, when the bottom may be lowered and taken away, and the
bolts, two of which are seen at 2, 2, are to be unscrewed, when the top may
be removed. The ferrules are stated to be of the same metal of which the tubes
are composed. This is to prevent the galvanic process destroying the parts.
The tubes and ferrules may, however, be of metal, either similar or disimilar,
and other than that herein mentioned. It is to be understood that when the
boiler is used with a condenser of the description of one of these in this Speci-
fication that the condensed water will be used over and over in the boiler, so
that after it is once filled with distilled water a very small additional supply
only is necessary to continue the operation, for no part of the water can escape
except what may pass through leaks of the engine, condenser, or boiler.
Besides the ordinary safety valve or valves with which boilers are generally
provided, it is proposed this boiler shall have one to be wrought by a piston,
as before mentioned; besides, every tube, of which there are upwards of 300
in this boiler, acts as a safety valve, for the strongest of them must burst long
before the boiler could blow up, and the bursting of them must be confined

page_text: to the furnace, which can be no harm. Ine advantages of this construction
of boiler therefore, are, 1st, its capability of working with high-pressure steam
without any danger of exploding; 2nd, will occupy very little space compared
with the power gained, and will diminish the size of the engine in nearly the
same proportion; 3rd, will expose great surface to the action of the fire, and
in consequence of the metal being thin of which the tubes are composed, they
will take in the heat very rapidly, perhaps 3 or 4 times as fast as an ordinary
boiler of the same extent of surface exposed to the fire; 4th, exposes little
surface to the external air, and that part which is exposed being very thick of
the metal, very little of the heat can pass through and escape; 5th, being
wrought with distilled water will seldom or ever require to be cleaned out, and
will not be liable to have a concretion of stone, salt, or other substance on the
interior surface, which in ordinary boilers frequently prevents the heat passing
to the water, and is the cause of the metal at that place becoming red hot
and burning to a hole, by which the boiler is rendered unserviceable. The
advantages of these constructions of condensers are:-1st, they are applicable
to any ordinary engine; 2nd, affords an opportunity of charging the boiler with
the same water over and over, so as to require a very small addition, and there-
fore to work the boiler and engine with distilled water, by which the boiler and
engine, particularly the former, is less liable to decay; 3rd, affords an oppor-
tunity of building engines where there is a very small supply of water; 4th,
requires a much smaller air pump, and therefore less power to work it; 5th,
the latter description of condenser is particularly applicable to steam vessels,
as it enables them to go to sea without allowing salt water into their boilers,
the salt from which often destroys or injures them.
Advantages of the boiler and condenser when used together:-1st, when
wrought to the pressure to which the boiler is calculated, will be a saving of nine
tenths of the whole fuel which is now used in ordinary low-pressure engines; 2nd,
as applicable to steam vessels, the engine boiler and condenser occupy little space
in proportion to the power gained, and the quantity of fuel necessary being so
small that they can perform long voyages with the power of steam which has already
been so extensively introduced into that mode of navigation. The production of
steam depending on the extent of surface exposed to the fire, and the condensation
of it depending on the extent of surface exposed to the cooling cause, determines
the size of both boiler and condensors, for they must always bear a proportion
to the power required and the kind of engine to which they are respectively
applied; but it must be remarked, that where the evaporating condenser is
used the surface of pipes must be greater than in the other. There are small
cross bars placed between the rows of tubes to support and keep them in their

page_text: places, the ends of which are seen at Fig. 9. This condenser has a consider-
able slope to make the condensed water run off the more readily.
I claim as my Invention,―
1st, raising the steam in small curved tubes;
2nd, making those parts of the boiler which are not exposed to the action
of the fire thin in the metal ;
3rd, making those parts of the boiler which are not exposed to the action
of the fire very thick and very strong, much stronger than the other parts in
proportion, and in guarding those parts that are so made thick from the fire
to prevent injury by expansion or contraction;
4th, combining the boiler with either of the condensers before described, by
which it can be wrought with distilled water only with a very small additional
supply;
5th, condensing the steam from engines by the evaporating condensor first
described or the other condenser last described.
In witness whereof, I, the said Alexander Clark (party hereto), have
hereunto set my hand and seal, this Twenty-first day of September,
in the year of our Lord One thousand eight hundred and twenty-two.