IMPROVEMENTS IN BOILERS, AND APPARATUS FOR HEATING WATER AND GENE- RATING STEAM
Year: 1856

page_text: LETTERS PATENT to Thomas Dunn, of the Windsor Bridge Iron Works,
Pendleton, in the County of Lancaster, Engineer, for the Invention of
"IMPROVEMENTS IN BOILERS, AND APPARATUS FOR HEATING WATER AND GENE-
RATING STEAM."
Sealed the 8th July 1856, and dated the 16th January 1856.
PROVISIONAL SPECIFICATION left by the said Thomas Duun at the
Office of the Commissioners of Patents, with his Petition, on the 16th
January 1856.
I, THOMAS DUNN, of the Windsor Bridge Iron Works, Pendleton, in the
County of Lancaster, Engineer, do hereby declare the nature of the said
Invention for IMPROVEMENTS IN BOILERS AND APPARATUS FOR HEATING WATER
AND GENERATING STEAM, to be as follows:-
The first part of my present Invention consists in improvements applicable
to certain boilers for which Letters Patent were granted to me on the
Thirteenth October, One thousand eight hundred and fifty-three. My present
improvements.consist in placing some of the retort boilers at or about right
angles to the others, so as to form near the end of the boiler a down draught
and an up draught, and a mixing chamber; also in applying a water heater,
consisting of & chainber with tubes, through which the products of combustion
pass before entering the flue or chimney. A similar water heater may be
placed on one side of the down draught. Several up and down draughts may

page_text: be made by placing several of these water heaters upright, and conveying
the products of combustion between them and through the tubes passing
through them.
Where there is not sufficient room for the water heaters, I
place small retort boilers or pipes across the flues to cause the products of
combustion to impinge against the retort boilers placed above or near them.
Several of these small retort boilers or pipes may be placed in a recess to
absorb the heat of the products of combustion passing among them. In
making boilers of large dimensions, I place several retort boilers on each side
of the main flue, and apply fire-places under them also at each side; the
products of combustion there unite in a central flue; or, after passing through
the tubes of two water-heating chambers, air may be admitted to increase the
combustion if the above or any other of my improved boilers or apparatus for
heating water or generating steam. When it is desirable to reheat or sur-
charge the steam, I place the retort boilers somewhat apart and make holes
ihrough, or place the fire brick blocks which cover the spaces between the
retort boilers at a little distance apart, so as to allow part of the products of
combustion to rise between the retort boilers. A portable boiler may be made
by joining two horizontal series of retort boilers by junction pipes. When
this arrangement is adopted, the lower series is suspended in the flue, and
consequently the entire surface is exposed to the action of the heated products
of combustion. The ends of the retort boilers may be connected to two
water chambers, forming the sides of the fire hole and of the flue.
The second part of my Invention consists in the application of auxiliary or
additional parts to boilers that require to be enlarged. This may be effected
by constructing a double box with water spaces all round, and connected to
the main boiler by pipes and valves. Within this double box is placed one or
more fire grates, and the products of combustion pass through tubes in one
or more sides of the double box. The double casing may be round to contain
a single fire grate, or it may be oval, and divided into two spaces by a mid-
feather for two fire grates. Instead of a double casing, I also propose to place
a series of retort boilers, either lengthways or crossways, over the fire grate,
these retort boilers being connected to the main boiler by pipes and valves, as
above mentioned. When these additional or auxiliary parts are applied to
the ordinary Cornish boilers it is desirable to turn them upside down, so that
the larger space for water may be below the flues. Another mode of con-
structing theso auxiliary fire chambers is by making an upper and lower water
chamber connected by tubes, and by placing the grate bars so that the
products of combustion may pass between the tubes before going to the flues
of the boiler; and in constructing the bridges, I leave only the requisite

page_text: openings around the flue for the passage of the products of combustion,
thereby causing them to impinge against the sides of the flues.
The third part of my Invention of improvements in boilers and apparatus
for heating water and generating steam consists in so constructing such boilers
and apparatus, that the various parts thereof may readily be replaced or sub-
stituted one for another when injured, and be easy for transport; also that
they may present a large amount of heating surface. I construct a compound
boiler with three cylindrical parts; the centre one is supported from the two
outer ones or from the walls; or 1 support four or other convenient number of
cylindrical parts on water chambers furnished with tubes, which chambers
separate the fire grates from each other. In some cases the fire grates may
be made wider, and only the alternate cylindrical parts supported on water
chambers, the intermediate cylindrical parts being supported from the others.
The entire apparatus may be inclosed in a brick or iron casing.
Another improvementin boilers consists in placing them in a slantingdirec-
tion, and in causing the flue to coil around the boiler. The boiler may also bo
constructed of cylindrical parts, placed on different levels and connected by
valves; the lower parts are entirely full of water, and the upper parts contain
partly water and partly steam. A boiler may be made of many cylindrical
parts suspended over the fire grate by bearers. These parts can easily he
taken out and others substituted in their stead, or their positions transposed
when repairs are necessary.
Another modification of my improvements is in making the upper part of
the boiler semicircular, and the lower part in the form of two or more semi-
circles, the concave surfaces being exposed to the fire and flue, or the lower
part may be flat and stayed from above. I also make a boiler of three
cylindrical parts, the two lower ones on the same level touching or nearly
touching each other, and the top one in the centre above the others. The
flues are taken along each side of the upper part to reheat or surcharge the
stenin; or the three cylindrical parts may be of equal diameters,and soerected,
that when the parts subject to the action of the fire are injured, the positions
may be changed, so as to bring other parts over the fire.
Another of my improved boilers consists of a cylindrical part, with two or
more small cylinders or pipes containing water at each side of the fire; the
flues are brought along the outer surface of the said small cylinders or pipes.
A boiler may be made with four or other suitable number of cylindrical parts
placed on the same level, and a water-heating chamber with tubes through,
placed between the under surface of the cylindrical parts and the fire grate,
or their positions may be reversed. This water-hoating chambor can be

page_text: combined with a flat-bottomed or other shaped main boiler, or used alone
when used as an apparatus for heating water; in the latter case a cover of
sheet iron or bricks to form a flue is required. The water-heating chambers
can be placed vertically and the fire grates placed between; the outer sides
are then enclosed to form combustion chambers. This modification is appli-
cable to boilers for marine purposes, as each chamber is easily removed and
another put in its place. Additional chambers may be placed at right angles
to and beyond the others to form mixing chambers for the products of com-
bustion.
The water-heating chambers may be placed lengthways, and the tubes in
cach made of different diameters, the larger tubes being placed near the fire,
and the smaller more remote. By recessing the ends of the heating chambers,
a space may be left between each to form a mixing chamber. I also construct
chambers for heating water by rivetting together two plates of corrugated
metal, and placing washers between the plates to allow for the circulation of
the water. In constructing vertical boilers, I connect the ends of tubes to an
upper and lower plate; the fire grate is placed between the tubes, and the
products of combustion surround them, thereby heating the water in the
tubes. I construct a modification of the upright boiler of three or more
upright water-heating chambers, having tubes through them,and surround the
whole with a casing of iron or brick. I construct boilers for marine purposes
of an upper chamber containing water and steam; below this is the fire
grate. The draught is taken downwards, acting first on a water heater, and
then passing through tubes in a compartment of the boiler under the fire
grate, then into a flue below the boiler, and theuce up tubes in another
compartment of the boiler, and then to the flue or chimney.
My improvements in boilers also consist in employing conical vessels to
contain the water and steam. These conical vessels may be arranged horizon-
tally or vertically. They are very strong, easy of transport, and can be packed
in sinall compass, as they can be fitted one within the other.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Dunn in the Great Seal Patent Office ou the
14th July 1850.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I. THOMAS
DUNN, of the Windsor Bridge Iron Works, Pendleton, in the County of Lan-
caster, Engineer, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixteenth day of January, in the year of our Lord
One thousand eight hundred and fifty-six, in the nineteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Thomas Dunn, Her special license that I, the said Thomas Dunu, my
executors, administrators, and assigns, or such others as I, the said Thomas
Dunn, my executors, administrators, and as igns, should at any time agree
with, and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN BOILERS AND
APPARATUS FOR HEATING WATER AND GENERATING STEAM," upon the condition
(amongst others) that I, the said Thomas Dunn, my executors or admicis-
trators, by an instrument in writing under my, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and canso
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thoms Dunn, do hereby declare the
nature of my said Invention, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following
Specification thereof, reference being had to the accompanying Drawings,
in the several views of which similar parts are marked with corresponding
letters of reference:―
The first part of my present Invention consists of improvements applic-
able to the boilers for which Letters Patent were granted to me on the
Thirteenth day of October, One thousand eight hundred and fifty-three.
On Sheet 1, Fig. 1 represents a sectional elevation of a boiler for generating
steain, consisting of five or other convenient number of retort boilers, marked
a,a,placed horizontally; the steam generated in these retort boilers is conveyed
into the steam chamber 6, placed above them, in the manner set forth in the
Specification of the Letters Patentabove referred to, or in any other convenient
manner. c, c, are eight or other suitable number of cylindrical water heaters
placed in two vertical rows. All these retort boilers and water heaters are
supported at their ends by brickwork, and the products of combustion rising
from the fire grated pass under the retort boilers a, then along the flues and
mixing chamber formed by the two rows of vertical water heaters c and the
brickwork, and thence to the flue e, which is in communication with the
chimney, the direction of the products of combustion being indicated by arrows.

page_text: The supply of water is pumped into the uppermost water heater c through the
pipe, from whence it flows into the others through the pipe g, and into the
retort boilersa through the pipeh. The box h'contains a valve opening inwards,
to allow the water to flow into the pipeh from the water heaters, and to prevent
the steam and water from the boilers a, a, flowing into the water heaters.
The passages i and j in the brickwork are for admitting air to the flue,
in order to increase the combustion of the smoke. Fig. 1 a represents a
modification of this steam generator; the retort boilers and the water
heaters being surrounded by a double casing containing water, marked Z.
The products of combustion, after passing under the retort boilers a, a,
and around the water heaters c, c, are conveyed over the retort boilers a, a, to
reheat or dry the steam, and thence pass through the flue e to the chimney.
Fig. 2 represents a modification of the boiler shown in Fig. 1. In this
instance the cylindrical water heatersc are placed diagonally and horizontally,
and the products of combustion, after passing through the flues formed by the
sides of the water heaters c,are conveyed through the tubes in the multitubular
water heater & before they pass off to the fluce. The water heater k is a flat
vessel of wrought or cast iron, as shown at Fig. 2 a, the sides of which are
stayed by the tubes. The water heater & may also be of a circular form, as
shown at Fig. 2b, and it is supplied with water through the pipe f, and the
cylindrical water heaters c are supplied through the pipes g, g. I wish to
remark, that the water heater & differs materially from those hitherto employed,
inasmuch as the tubes in the water heater run from side to side instead of
from end to end lengthwise, whereby a deep flat vessel is obtained, which is
casily removed and replaced by a duplicate when repairs are necessary.
A modification of this steam generator may be constructed by placing a
flat water heater, similar to , in place of the first four cylindrical water
heaters c, c, and several up and down draughts may be obtained by placing
several of the water heaters k beyond the retort boilers.
In Fig. 3 the products of combustion,after pussing under the first five retort
boilers a, are conveyed through the tubes-in the four water heaters k, the
flue then passes over the retort boilers a, in order that the heated air and
gases in the flue may reheat the steam previous to their entering the flue e.
Fig. 4 represents a boiler composed of four water heaters (one of which
is furnished with tubes, and the others are without tubes), and three retort
boilers a. The fire grates d, d, are placed between the water heaters without
tubes, and the products of combustion pass around the water heaters and
through the tubes in the last water heater, and thence to the flues e and e
as indicated by the arrows.

page_text: Fig. 5 is a longitudinal, and Fig. 6 a transverse, section of a boiler com-
posed of six retort boilers a, a, five cylindrical water heaters c, the largest of
which forms the bridge, and a multitubular water heater k. The above
parts, marked a, c, k, and I, are in connection with the flat chambers m, m,
which are stayed in the same manner as the fire box of a locomotive engine,
or in any other convenient manner. The steam is conveyed from the upper
part of the chambers m through the pipe n. The retort boilers a are placed
a little distance apart, and the space between them is closed with fire brick,
but they may be close together, as shown in Fig. 1, if preferred; or the space
may be closed by means of small water heaters, as shown at C', in Fig. 5.
In Figs. 7 and 8 only three cylindrical water heaters c, c, are used, and the
bridge is of fire brick, in the ordinary manner. In Fig. 9 the retort boilers
are placed in contact with each other, and the products of combustion are
made to heat the water with which the retort boilers are supplied by passing
over and partly around the water heaters c, c, one of which forms the bridge.
These water heaters are placed so that their lower surface is on or near the
level of the bottom of the flue, thereby causing the heated air and gases
passing towards the flue e to impinge against the under side of the retort
boilers a, and to absorb a great proportion of the heat, which would other-
wise be wasted.
On Sheet 2, Fig. 10 represents a section of a boiler of large dimensions.
In this arrangement there are two sets of retort boilers a, a, placed on cach
side of the central boiler n', into which the steam from all the retort boilers a
is collected by side pipes, as shewn in Fig. 1. Each set of retort boilers is
heated by a fire grate d, d. The products of combustion pass over the bridges
7. 1, along the flues, and then through the tubes in the multitubular water
heaters k, l, where they unite before entering the flue e On the right-hand
side of Fig. 10 I have shewn only one bridge 7, whereas two are shewn at the
left-hand side; but each side may have either one or two bridges l,if preferred.
By putting fresh coal on the fires alternately, the smoke will be to a great
extent consumed in the combustion chamber under the water heaters k, k,
before it enters the flue e. The air passages i are opened occasionally to
admit air to the flue, and thereby to increase the combustion of the air and
gases before they pass through the tubes in the water heaters k, k.
Fig. 11 is a longitudinal, and Fig. 12 a transverse, section of a steam gene-
rator, consisting of six or other suitable number of retort boilers a, a, and of
three water-heating cylinders or tubes c. c, placed near to the entrance to the
flue e. The retort boilers are placed sufficiently apart to admit the fire-brick
blockso, o, which are either perforated or placed a little distance asunder, so as

page_text: to allow part of the products of combustion to rise into the flue above the
retort boilers a, the object being to superheat or surcharge the steam before
it passes into the steam chamber, which may be made as shewn in Fig. 1, or
in any other convenient manner.
The steam generator shewn in Fig. 13 consists of a row of retort boilers a, a,
and another row of cylindrical water heaters c, c, connected together by
junction pipes. The products of combustion from the fire grate d pass around
and between the retort boilers and water heaters, thereby communicating the
heat to tho water contained in them in their passage to the flue e. The ends
of these retort boilers and water heaters may be connected to two water
chambers, similar to those marked m in Fig. 6, or they may be set in brick-
work, if preferred.
Fig. 14 is a section through a steam generator, composed of three or other
suitable number of boilers a, a, each with an internal flue a²; the grates d, d,
are placed below the boilers a, and are separated by a brick midfeather. The
products of combustion first pass beneath the boilers, then return through
the flues a, and then pass along the flues over the tops of the boilers to the
chimney, thereby reheating the steam. The two outer boilers a, a, rest upon
fire-brick saddles or blocks, and the centre one bears on the midfeather,
which forms the division between the grates and the flues.
I will now proceed to describe the Drawings illustrative of the second part
of my Invention, consisting in the application of auxiliary or additional parts
to boilers of the ordinary construction that require to be enlarged.
Fig: 1 is a longitudinal section, and Fig. 16 an end elevation, of a common
cylindrical boiler. To this boiler, which is marked p, is connected the fire
box 9. This fire box is constructed of two metal plates, which are connected
by stays, like the fire box of a locomotive engine. Within the fire box q are
two sets of grate bars d, d, divided by a midfeather, as shewn in Fig. 16. The
space between the two plates of the fire box is kept full of water by the supply
pipef, which passes through the body of the boiler, in order that the water
may be warmed before it is supplied to the fire box-; the steam from the boiler
and the firebox is collected in the dome 71. This fire box is equally applicable
to two flue boilers, altho' only one flue is shewn in the Drawing; and it is
evident that by the addition of such a fire box a great amount of heating
surface is obtained. Fig. 17 is a section through a circular fire box, con
structed on the same principle as the one marked 2, in Figs. 15 and 16; and
Fig. 18 is a section through an oval fire box, of the same description, bu
furnished with a midfeather, by which the fire grate d is divided into
two compartments.

page_text: Fig. 19 is a section of two ordinary Cornish boilers placed together, with
the flues to one side instead of being in the centre, as usual. These boilers
may also be placed with the flues uppermost, so as to give the greatest space
for water and sediment at the bottom. This double boiler may be supplied
with a fire box similar to either of those shown in Figs. 16, 17, and 18.
On Sheet 3, Fig 20 is a longitudinal section of a common cylindrical boiler
P, to which another modification of my improved fire box is applied. In this
instance. four or other suitable number of retort boilers 7, 7, are placed over.
the fire grate d, and a cylindrical water heater is employed for the bridge;
these retort boilers and the bridge are connected by pipes and valves to the
main boiler p. In Fig. 21 the retort boilors r, r, are placed in a semicircle,
and with their axes in the same line as that of the main boilerp; the steam
is conveyed through the pipes s to the steam dome on the main boiler, and
the fire grate d is divided into two compartments by a brick midfeather.
Fig. 22 is an end view of two Cornish boilers placed in the position shewn in
Fig. 19, to which another modification of my improved fire box is applied.
The fire box consists of a number of retort boilers r, r, placed in an oval
surrounding the grate d. Fig. 23 is another mode of applying my improved.
fire box to two boilers.
The third part of my Invention consists in constructing boilers and
apparatus for heating water and generating steam so that the various parts
thereof I may readily be replaced or substituted one for another when injured,
and be easy of transport; also that they may possess a large amount of
heating surface. The following Drawings illustrate this part of my Invention:-
Fig. 24 is a transverse section, and Fig. 25 a longitudinal section, of a
boiler composed of three cylinders t, t, made of any suitable length, the centre,
one of which is supported by means of the bridles u from the two outer ones;;
or the three cylinders may be supported by the brickwork, or partly by the
brickwork and partly by one of the multitubular water-heating chambers k.
The products of combustion from the fire grated pass over and through the.
tubes in the bridge formed by the first water-heating chamber k, then over-
and.through the tubes of the second chamber k, and then through the,
tubes of the third chamber k, from whence they pass to the flue e.
Fig. 26 is a transverse section of a steam generator, composed of four or
other suitable number of cylinders t, t, supported on the water-heating cham-
bers k, k, between which are the fire grates d. d. The products of combustion,
after passing along the flues under the cylinders t, t, return in the side flues.
e, e, and thence pass to the chimney. Fig. 27 is a longitudinal section of a.
steam boiler, composed of cylinders t, t, as in tho .foregoing Figure. The.

page_text: products of combustion, after passing over the bridge, circulate around the
cylindrical water heaters c, c, and then pass through the tubes in the water-
heating chamber k, and thence to the flue e. The steam is collected in the
horizontal dome b, and the water is conveyed from the water heaters to the
cylinders t, t, by side pipes, as before described. In some cases the fire grate's
may be made wider, and only the alternate cylinders t supported on water-
beating chambers, the intermediate cylinders being supported by the others,
as in Fig. 24. The steam generators shewn in Figs. 24, 25, 26, aud 27 are
set in brickwork, but iron casings may be employed instead.
Fig. 28 represents one or more long cylindrical steam generators or water
heaters & placed in a slanting direction; the products of combustion from the
fire grate dare conveyed through the flue u', which is coiled around the steain
generators or water heaters, thereby causing a large surface thoreof to be
exposed to the action of the flame and heated gases before they escape to the
chimney. In Fig. 29 the steam generator is composed of two or more cylin-
drical portions, marked vand w, placed at different levels, and connected. by
pipes or valves; the lower portion acts as water heater for the upper portion,
the supply of water entering by the pipe f. The water heater w may be
multitubular, or provided with flues, if preferred.
Fig. 30 represents a steam generator, composed of six or other suitable
number of retort boilers a, a, suspended from the beams. The products of
combustion from the fire grates d pass under the retort boilersa, and then are
conveyed over them to reheat the steam, or they pass at once to the flue
leading to the chimney, if preferred. A steam generator of this description
offers particular advantages for repairs, as the position of the retort boilers
can be transposed with facility, or any of them can be removed and another
put in its place with very little loss of time. The fire grate is shewn very
wide, in order that peat or other light fuel may be consumed.
.
Fig. 31 is a section of a boiler marked y, the upper portion of which is
semi-cylindrical, and the lower portion in the form of two semi-cylinders,
which are stayed from above; by this means a greater heating surface is
obtained than when the boiler is cylindrical, and a new bottom of this
description may be applied to an old crown of a boiler.
Fig. 32 is a section of a steam generator, marked 2, the upper portion of
which is semi-cylindrical, and the lower portion is flat and stayed from the
upper part. This shape affords a large space for the steam, and sufficient
heating surface for the action of the flames and heated gases rising from
the fire grate d; a new bottom may in this instance be applied to an old
crown, as in the above Figure,

page_text: .
Fig. 33 is a section of a steam generator, consisting of a cylindrical vessel A,
and the two cylinders B placed below A. The cylinders B are in com-
munication with each other, and with the one marked A, by means of
pipes, valves, or openings; the lower cylinders B are placed close together.
The products of combustion from the fire grated pass under the cylinders B,
then through the tubes in the water heater k, and return through the
space A³, between the cylinders A and B, and through the flues A', from
whence they pass to the chimney. If it should be requisite to reheat or
surcharge the steam, the level of the water is kept below the upper part of
the flue A¹
Fig. 34 represents a modification of the above-described steam generator.
In this instance three cylinders C, of equal diameter, are connected by
pipes; the two lower cylinders form the water heaters for the upper one.
.One of the advantages of this and the foregoing arrangement is, that when
the parts subjected to the action of the flame are injured, the positions of
the three cylinders may be changed, so as to bring other parts directly over
the fire grate d; these cylinders may be made with an internal cylinder, as
shewn by a dotted circle. When this mode of construction is adopted, the
internal cylinders act as flues, thereby offering very large heating surfaces
to the action of the products of combustion.
Fig. 35 is a section of a steam generator, consisting of a cylindrical chamber
D, and six or other suitable number of water-heating tubes E, E, half of
which are placed on each side of the fire grate d; these water heaters may
extend the whole length of the steam generator to form the sides of the
flues, along which the heated air and gases are brought, back after passing
under the cylinder D.
Fig. 36 represents a steam generator, composed of four or other convenient
number of cylinders F, F, between which and the fire grate d is the water-
heating chamber k,furnished with tubes, to allow part of the products of com
bustion to rise up and impinge against the under surface of the cylinders F.
The steam from these cylinders is conveyed by pipes to a steam chamber,
like b in Fig. 1, and the water is conveyed from the chamber k to the upper
cylinders by the pipes g. I wish to observe, that the chamber k
may also be
placed above the cylinders F, if preferred.
On Sheet 4, Fig. 37 is a section of a multitubular chamber or vessel, similar
to k, before described, which may be used as a steam generator or a water
heater by being placed over a fire grate d; the chamber is strengthened or
stayed by the tubes passing through it, and these tubes allow a portion of the
products of combustion to enter the upper flue formed by the iron or.brick

page_text: arch, shewn in the Drawing. When the lower surface of the chamber k
has become injured by the action of the flame it is turned upside down, the
side pipes for the steam and water being in duplicate.
Fig. 38 is a vertical section of a steam generator, formed of two chambers
h, k, with a fire grate & between them; the space between the chambers k,k,
is closed by a cylindrical vessel k4, containing steam and water, as shewn;
or the space may be arched over above, and the products of combustion
pass around the chambers k.and thence into side flues which are in commu-
nication with the chimney; the pipe g is for supplying water to the chambers
k, which have another pipe gl above to carry the steam to the cylindrical
vessel. These chambers can be turned, so as to bring alternately each
sido toward the fire grate.
Fig. 39 is a plan, and Fig. 40 an elevation, both in section, of a water-
heating apparatus. In this arrangement, the chambers k, k, form cach threo
sides of a square, within which the fire grates d,d, are placed. The chambers
k, k, are placed at the end of those marked k, and the products of com-
bustion pass through the tubes of all these chambers, as shewn by the arrows,
they then pass through the tubes of the chamber k³, and then enter the flue e,
which is in communication with the chimney. The spaces between the
chambers k, k, and form mixing chambers, and by putting fresh coal on
'the fire grates alternately the smoke is to a great extent consumed before it
arrives at the chamber k².
Fig. 41 is a longitudinal section of a water-heating apparatus, composed
of three chambers G, G', and G2; the first contains the fire grate d and the
bridge, the second contains one or more large tubes for the passage of the
products of combustion, and the third contains three or more smaller tubes.
These chambers are recessed at their abutting ends to form the mixing
chambers H, so as to increase the combustion of the smoke before the
-heated air and gases pass through the tubes in the chamber
.whence they are conveyed to the chimney.
from
Fig. 42 is a longitudinal section of a water-heating apparatus, composed
of the chambers I and J, which are in communication with each other by
means of pipes; these chambers are constructed by rivetting together two
plates of corrugated metal; the plates are held apart to allow for the circu-
lation of the water by means of washers, through which the rivets pass. The
products of combustion pass along the flue formed by the lower side of the
upper and the upper side of the lower chamber; the flue is thon taken over
the upper chamber, and thence to the flue e, or it may return again along
the under side of the lower chamber.

page_text: Fig. 43 is a plan, in section, of any improved vertical steam generator. The
fire grate d is surrounded byeleven or other suitable number of verticaltubes
K, containing water; these tubes are connected above and below to plates,
the feed water is supplied through pipes connected to the lower plate, and
the steam is conveyed away through pipes connected to the upper plate.
Figs. 43, 43, and 43° are three sections of this vertical boiler, representing
various modifications in the mode of construction. In these views K' is a
circular vessel, the lower surface of which is made with several circular
grooves or corrugations. The tubes K are connected to the crown piece
K by pipes or otherwise, and this crown piece may be applied to boilers
of the ordinary construction. Fig 434 is a plan of Fig. 43*.
Fig. 44 is a plan, in section, of another vertical steam generator, com-
posed of four flat chambers L, furnished with tubes, through which the
products of combustion from the fire grate & pass to the flues formed by the
d
sides of the chambers L, and the brick or iron casing surrounding them.
A fifth flat chamber without tubes is placed upon the other four, forming
the sides of the steam generator.
Fig. 45 is an elevation, and Fig. 46 a plan, of another of my improved
vertical steam generators, composed of twelve or other convenient number
of conical vessels M, placed around the fire grate d; these conical vessels
when united together have a passage above for the escape of the products
of combustion to the chimney.
Fig 47 represents a section of two of these vessels placed within cach
other, to show how they may be packed for transport; the branch pipes are
also shewn for the supply of water, and the steam is conveyed away at the
small end of the cone. These conical vessels may be placed horizontally
or vertically.
Fig. 48 is a vertical section of a steam generator, particularly suitable for
marine purposes, composed of a flat chamber Q, containing water and steam;
the fire grate & is placed under one end of the chamber Q, and the products
of combustion, after passing over the bridge formed by the upper end of
the chamber N, enter the flue between one side of the chamber N and one
side of the chamber O; the heated air and gases then pass through tubes
in the chamber N, and enter the flue under the chambers N, O, and P, which
latter has tubes for conveying the heated air and gases to the fluc e.
The
various parts of this boiler are enclosed within the casing %. I wish it to be
particularly noticed, that this arrangement differs materially from the
Lordinary arrangement of boilers, inasmuch as the hottest part of the fire is

page_text: applied to that part of the boiler which is nearest to the exit of the steam;
the heat then descends to the other parts of the boiler, by which means
the temperature of the water is gradually increased.
On Sheet 5, Fig. 49 is a sectional elevation, and Fig. 50 a plan, also in
section, of a modification of the boiler shewn in Fig. 48. In this arrange-
ment, the products of combustion, after passing under the chamber Q, pass
downwards, and then enter the tubes through the upper part of the cham-
ber R, from whence they pass through the tubes in the lower part of the
chamber, and thence go to the chimney through the flue e. The chamber
R is in communication with the casing Z by the partition Z¹, and the coal
or other fuel for the boiler is contained in the space below the bottom of
the ash pit, as shown at Fig. 49.
..
Fig. 51 is a sectional elevation, and Fig. 52 a plan, also in section, of
another modification of this part of my Invention. The products of com.
bustion rising from the grate d rise upwards in the flue. T. formed within
the circular boiler S; they then descend into the flue T, which conveys
them to the flue e, and thence to the chimney. The greatest heat is com-
municated. immediately under the part of the boiler from whence the steam
is taken off, and the flue T¹ is furnished with tubes to stay the sides of the
flue, and to form communications for the water from the central to the
outer portion thereof.
In Figs. 53 and 54 the boiler S is made with an internal circular com-
partment, containing the flue T, and with an annular grated; the products
of combustion from the whole grate d unite above and descend the flue T
(which may also be provided with cross tubes) to the flue c, and thence pass
to the chimney. The pipes V, shown by dots in Fig. 54, serve to connect
the upper portion of the boiler to the inner part.
Figs. 55 and 56 are similar to the foregoing two Figures, with the excop-
tion that the grates d are separate, and that the flue T3 is formed between
the parallel sides of the partitions in the boiler S.
The object of the herein-before described improvements in boilers and
apparatus for heating water and generating steam is to economise fuel, by
the more advantageous application of the products of combustion, to increase
the strength, to facilitate repairs,and to render the boilers and other apparatus
for heating water and generating steam easy of transport.
Having thus particularly described the nature of my Invention, and the
manner of performing the same, I wish it to be understood that I do not
limit myself to the details shewn, as the same may be varied without depart-

page_text: ing from the peculiar character of my Invention, and I do not claim any of
the well-known parts which are shewn and referred to for the purpose of illus-
trating the application of my improvements; but what I do claim is,―
First, the improvements applicable to the boilers for which Letters Patent
were granted to me on the Thirteenth day of October, One thousand eight
hundred and fifty-three, as shewn and described in reference to Figs. 1 to 14.
Secondly, the application of fire boxes, such as those marked 9 and 1 in
Figs. 15 to 23, with the parts in combination therewith, when applied as
auxiliary or in addition to boilers of the ordinary construction, for increasing
their power of generating steam.
Thirdly, the improvements in boilers and apparatus for heating water and
generating steam, shewn and described in reference to Figs. 24 to 47, where-
by the various parts of which they are composed may be easy of transport,
readily replaced or substituted one for another, and possess a large amount
of heating surface.
Fourthly, the improved modes of constructing boilers, shewn anddescribed
in reference to Figs. 48 to 56, whereby the greatest heat is applied near the
surface of the water, and afterwards descends towards the lower part of
the boiler.
And, lastly, I claim the combination of any two or more of the improve-
ments shewn or described.
In witness whereof, I, the said Thomas Dunn, have hereunto set my
hand and seal, this Fifth day of July, in the year of our Lord One
thousand eight hundred and fifty-six.
Witness,
H. B. BARLOW,
Manchester.
THOMAS DUNN. (L.s.)