IMPROVEMENTS IN STEAM BOILERS
Year: 1877

page_text: LETTERS PATENT to Hermann Wedekind, of No. 158, Fenchurch Street, in the
City of London, Civil Engineer, for the Invention of "IMPROVEMENTS IN
STEAM BOILERS." A communication from abroad by Hermann Heine, of the
City of Berlin, Germany, Mechanical Engineer.
Sealed the 5th April 1878, and dated the 9th October 1877.
PROVISIONAL SPECIFICATION left by the said Hermann Wedekind at the
Office of the Commissioners of Patents on the 9th October 1877.
HERMANN WEDEKIND, of No. 158, Fenchurch Street, in the City of London, Civil
Engineer. "IMPROVEMENTS IN STEAM BOILERS." A communication from abroad
by Hermann Heine, of the City of Berlin, Germany, Mechanical Engineer.
This Invention relates more especially to improvements in steam boilers or
generators of the class known under the term of water tube boilers.
The boiler is formed of two portions, set one above the other, united at both ends
by vertical connections.
°
The lower part is formed of two cylindrical chambers connected centrally by one
The diameter of these
large cylindrical tube, which I call the central tube.
chambers is made somewhat larger than the diameter of this "central tube" in such
wise that one or several circular rows of small water tubes can be arranged round
the central tube.
The upper portion of the boiler may be constructed in a similar way to the lower
one, and in this case the two chambers of the lower boiler will be connected with
the two chambers of the upper boiler by the aforesaid vertical connections. In this
case the longitudinal axes of the lower and upper boiler, lying in one vertical plane,
will also be parallel and preferably set on a slight inclination; or the upper portion
of the boiler may also consist of a plain cylindrical vessel of the same length as the
lower portion. In this case the axis of the upper boiler will be horizontal, lying in
a vertical plane with the slightly inclined axis of the lower boiler, the two chambers
of the lower boiler being united by vertical connections to the upper boiler.
The central tube connecting the two cylindrical chambers is preferably made
large enough to be entered from within. The inner head plates of the two chambers
to which this central tube connects form also the tube plates for the water tubes,
which are spaced in one or several circular rows around the central tube.

page_text: Whenever the rows of tubes around the central tube are employed one inner and
one outer tube will by preference be set on the same radius, the diameter of the
outer tube being proportionally longer than that of the inner one on account of the
greater circular pitch allowable.
In the head plate of the front chamber there is formed opposite to each water
tube a hole of a diameter a little larger than that of the corresponding tube; each
hole can be closed by a cover, which fits tight against the inner side of the front
plate.
The covers can be open from without, and are held by a cross piece and a central
screw bolt in the same way as is usual for man-hole covers; said holes are intended
• for cleaning or tightening each water tube.
The water line in the boiler is such that the lower half of the upper boiler is
filled with water.
The front plate and the back plate of the front chamber are stayed against each
other by means of longitudinal stays; one portion being connected to the circum-
ference of the large central tube, and the balance arranged between the water tubes
accordingly, we may call the first ones "central tube stays," and the latter ones
"water tube stays." For both kinds the outside head plate of the chamber is held
by an outside and inside nut on each stay bolt, the other end of the same entering
a coupling nut which unites it to a short screw bolt. For the central tube stays
this screw bolt is formed with a flat circular head, which can be slipped into
corresponding holes of a flat, wrought-iron ring, rivetted to the end of the central
'tube, projecting on this side somewhat into the chamber. For the water tube stays
'this screw bolt is screwed with a shoulder against the one side of the tube plate of
the chamber before the tubes are put in.
The grate which is set underneath the lower portion of the boiler extends either
the whole length of the boiler or only a part of the length, and in the first case it is
preferably fired from both ends.
The gases are caused to circulate on those parts only, or nearly so, of the lower
boiler, which are situated between the tube plates of the front and back chambers,
and also on the corresponding part of the upper boiler. The fire gases being
confined from one side by a midfeather on a diaphragm, which is in contact with
the central tube for its whole length, between the two chambers, flow in one circular
sweep around the whole heating surface of the lower boiler. At the same time they
heat the lower half of the upper portion of the boiler and escape down to the flue on
the opposite side of the above diaphragm; or the said gases after having reached
the diaphragm may be led up again by another diaphragm, in order to circulate
over the upper half of the upper boiler, or over the surface of another or more
'boilers placed parallel to the first.
In order to be able to clean the outside surface exposed to the products of com-
'bustion there may be fitted in each chamber, instead of some of the aforesaid water
'tube stays, hollow stays or tubes, which allows steam to be blown in between the
water tubes from the outside while the boiler is being fired.
For the same purpose suitably arranged man-holes may be provided in the end
walls through which the water tubes in the outside row will be directly accessible.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Hermann Wedekind in the Great Seal Patent Office on the 9th April
1878.
HERMANN WEDEKIND, of 158, Fenchurch Street, in the City of London, Civil
Engineer. "IMPROVEMENTS IN STEAM BOILERS." A communication from abroad by
Hermann Heine, of the City of Berlin, Germany, Mechanical Engineer.
This Invention relates more especially to improvements in steam boilers or
generators of the class known under the term of water tube boilers.
The boiler is formed of two portions, set one above the other, united at both ends
by vertical connections.
The lower part is formed of two chambers, the shape of which may be wholly or
partly cylindrical, connected centrally by one large cylindrical tube, which I call the
"central tube." The diameters of these chambers are made somewhat larger than
the diameter of this " central tube" in such wise that one or several rows of small
water tubes can be arranged round the central tube.
one.
The upper portion of the boiler may be constructed in a similar way to the lower
In this case the two chambers of the lower boiler will be connected with the
two chambers of the upper boiler by the aforesaid vertical connections, which may
be of a rectangular section of the same depth, measured parallel to the axis of the
boiler as that of the chambers. In this case the longitudinal axes of the lower and
upper boiler lying in one vertical plane will also be parallel and preferably set at a
slight inclination; or the upper part of the boiler may also consist of a plain
cylindrical vessel of about the same length as the lower portion. In this case the
upper boiler will be horizontal, lying in a vertical plane with the slightly inclined
axis of the lower boiler, the two chambers of the lower boiler being united by
vertical connections to the upper boiler. The front chamber, the centre of which is
nearest to the axis of the upper boiler, will be connected to the latter by a rectan-
gular neck of the same depth as the chamber. The back chamber, being farther
apart from the axis of the upper boiler, will join the same in the same manner as
the front chamber, or by a connection of preferably cylindrical section.
The central tube connecting the two cylindrical chambers is generally made large
enough to be entered from within. The inner head plates of the two chambers to
which this central tube connects form also the tube plates for the water tubes, which
are spaces in one or several circular rows around the central tube.
Whenever two or more rows of tubes are employed around the central tube, in the
first case, one inner and one outer tube may by preference be set on the same radius,
the diameter of the outer tube being proportionally larger than that of the inner one
on account of the greater circular pitch allowable; or all the tubes may have the
same diameter, and be spaced on their corresponding circular lines.
In the head plate of the front chamber, and, if found convenient, also in that of
the back chamber, there is formed opposite to each water tube a hole of a diameter
a little larger than that of the corresponding tube. Each hole can be closed by a
cover, which fits tight against the inner side of said plates.
The covers can be opened from without, and are held by outer covers of the saine
size as the inner ones, and by a central screw bolt. The outer covers tend to support
the head plates against the inside pressure of the boiler. Said holes are intended for
cleaning and tightening each water tube.
The water line in the boiler is to be kept at such a height that the lower half of
the upper boiler is filled with water.
The front plate and the back plate of the front chamber, as also the corresponding
plates of the back chamber, if found desirable, are stayed against each other by
means of longitudinal stays, one portion being connected to the circumference of the
large central tube, and the balance arranged between the water tubes. Accordingly,
I may call the first class "central tube stays," & the latter "water tube stays." For
both kinds the outside head plates of the chambers may be held by an outside and

page_text: inside nut on each stay bolt. The central tube stays are attached with their other
ends either directly to the central tube, projecting somewhat into the chamber, or to
lugs, which are screwed or rivetted to the inner plate close to the circumference of
the central tube. The attachment of these stays may be made by means of a forked
end and a coupling bolt, or any other suitable device; or they may, as well as the
water tube stays, which are either solid or tubular, be tapped directly into the inner
plate. In the second case, the water tube stays being hollow, they may be expanded
into properly tapered holes formed in the two sheets which they are intended to stay
against each other. Furthermore, the central tube stays may be carried, when both
chambers are to be stayed, close to the inside circumference of the central tube from
head plate to head plate of each chamber. All other parts of the boiler being
cylindrical, and obtaining no large dimensions, this system of boiler can be made to
.convey steam of a high pressure.
The grate, which is set underneath the lower portion of the boiler, extends either
the whole length of the boiler, or only a part of the length, and in the first case it is
preferably fired from both ends. The grate may also be placed crossways underneath
the boiler, and be fired from the side of the same.
The gases are caused to circulate on those parts only, or nearly so, of the lower
boiler, which are situated between the tube plates of the front and back chamber,
and also on the corresponding part of the upper boiler. The fire gases may be
confined from one side by a midfeather or a diaphragm, which is in contact with
the central tube for its whole length between the two chambers, and they flow in
one circular sweep around the whole heating surface of the lower boiler. At the
same time they heat the lower half of the upper portion of the boiler, and escape
down to the flue on the opposite side of the above diaphragm; or the said gases,
after having reached the diaphragm, may be led up again by another diaphragm in
order to circulate over the upper half of the upper boiler, or over the surface of
another or more boilers placed parallel to the first; or the gases, by dropping the
aforesaid diaphragm, which comes in contact with the central tube, may be made to
circulate equally around both sides of the lower boiler, ascending to the top of it;
they are thence either carried sideways, or are made to circulate in the same manner
as before around the upper boiler; but, howsoever the gases may circulate, the area
through which they are made to pass always extends the whole length of the water
tubes, and is confined on either end by the tube plates. The consequence is that
the whole length of a tube is exposed to gases of equal temperature.
In order to be able to clean the outside surface exposed to the products of com-
bustion there may be fitted in each chamber, or one of them, the hollow stays already
mentioned above, which allow steam to be blown in between the water tubes from
the outside while the boiler is being fired.
For the same purpose suitably arranged man-holes may be provided in the end
walls, through which the water tubes in the outside row will be directly
accessible.
Having now set forth the nature of this Invention, I shall proceed to more fully.
describe the mode of carrying out the same by means of reference to the two Sheets
of Drawings hereunto annexed.
Similar letters of reference indicate corresponding parts.
Figs. 1, 2, 3, on Sheet No. 1, show the general arrangement of the boiler.
A is the central tube of the lower boiler, which connects the two chambers B¹
and B2; C are the water tubes set concentrically in one, two, or more rows arranged
around said central tube. The upper boiler D, which may be either a plain cylin-
drical vessel, as shewn, or of a construction similar to that of the lower boiler, is
united by two vertical connections E' and E2 of suitable shape to the chambers of
the lower boiler.
On Fig. 1 the fire-gases are seen to rise, as indicated by the arrows, from the
grate F up both sides and around the lower boiler. Having by means of the side
walls been caused to pass over the lower half of the lower boiler, between the water
tubes and the central tube, they then play round the upper half of the lower boiler,

page_text: and expand from amongst the water tubes into the space formed between the lower
and upper boiler. Having circulated over the heating surface of the upper boiler in
a similar way, they flow off through the aperture G.
On Fig. 2 the water line is shewn to the inclination at or about which it is pre-
ferred to set the whole boiler.
On Fig. 3 the gases are seen to be guided by means of a so-called midfeather H,
which is placed in this case underneath the lower boiler, but may be carried against
the central tube in any suitable direction. The gases rise, as indicated by the
arrows, from the grate F on the one side of the midfeather H, and flow in one
circular sweep around the whole heating surface of the lower boiler. At the same
time they come in contact with the lower half of the upper boiler, and escape
through the aperture G on the other side of the diaphragm. Thence they may be
carried off directly to the flue, or, by means of another diaphragm, across the top of
the aforesaid boiler; or they may circulate, as represented in Fig. 3, in the same
manner, across the heating surface of a second boiler, placed parallel to the first, in
order finally to be let off through the flue G'.
Instead of the fire-gases being evolved from a grate underneath the boiler, they
may also be led from the producer of a gas furnace; or the water gases from blast
furnaces, or from puddling, reheating, or other reverberatory furnaces, may be applied
to the purpose.
In the application of my boiler to marine purposes two series of boilers are pre-
ferably set up side by side, and in communication with each other. On Sheet No. II.
Fig. 1a gives a cross section, Fig. 1b a front view, and Fig. 2 a longitudinal section
of this marine boiler.
The upper boiler is constructed in a similar way to the lower one. A¹ is the
central tube of the lower boiler, and A2 of the upper boiler, the chambers or
water spaces. B1 and B2 of the lower boiler form with those of the upper boiler B
and B continuous chambers B', B¼, and B2, B3. In this case the vertical connec-
tions form part of the continuous chambers. The central tube of the lower boiler
is surrounded by two concentrical rows of water tubes, that of the upper boiler by
only one row. The longitudinal axes of the lower and upper boiler are set parallel
and in the same vertical plane, and the whole boiler is set to the amount of inclina-
tion, or thereabouts, indicated by the water line on Fig. 2.
Each boiler is carried by means of the vertical tubes I and I, which support
directly the two chambers on longitudinal mud-drums K, inclined in the same
degree as the boiler itself. Each mud-drum sustains the whole weight of the boiler,
resting at either end on suitable bearings.
Between boilers No. 1 and No. 2 may be fitted a row of vertical water tubes L,.
communicating at their lower ends to a mud-drum K³, and at the upper ends to a
drum K, which itself is connected to the front and back chambers of the two
boilers.
Between the vertical tubes L may be inserted suitably shaped fire-bricks, forming
a partition wall separating the grate surfaces of the two boilers; but, if desired, this
division may be altogether omitted.
The circulation of the gases in the first place depends on the diaphragm H, which
extends the whole length of the central tube. The gases rise from the grate F,
following the course indicated by the arrows. Being hemmed in by the upper
diaphragms M & M', which also extend the whole length of the central tube of
the upper boiler, the gases play in a circular sweep around the heating surfaces of
the lower boiler, at the same time heating the lower surface of the upper boiler, and
are conducted by the diaphragms M² & M³ and by a partition N downwards and
past the other side of these partitions into the flue G¹. The said partition is formed,
as shewn, of a water space communicating at either end at top and bottom with the
chambers of the boiler. The gases being confined on this upward course by an outer
casing O running up from the wall P, which closes in the grate, sweep over the
upper heating surface of the upper boiler before reaching the flue G¹.

page_text: As represented in Fig. 2, the boiler is fired from both ends through the fire-doors F¹,
the grate surface F being divided by a fire-bridge.
For short boilers, firing from one end will of course be sufficient.
The feed water enters the mud-drums K at their lowest point through the nozzles Q,
all being connected by the feed pipe. The steam spaces of the two boilers are con-
nected by the steam pipes R.
Fig. 3, and Fig. 3b, Sheet II., show a different mode of setting the boilers, with
attendant changes in the circulation of the gases. Fig. 3a gives a cross section, and
Fig. 3b, a front view.
The general construction of the boiler may correspond to the one illustrated by
the longitudinal section of Fig. 2, but in this case the lower boiler is built with
3 concentrical rows of water tubes surrounding the central tube, and the upper
boiler with one row.
The boiler is set directly between 2 vertical fire-brick walls P, the outside of
which may be well secured by stay plates, or in any other way. These walls nearly
touch the outermost water tubes of the lower and upper boiler, and project above
the centre line of them to the inside, thus hugging the water tubes lying in the
corresponding height.
The gases rise from the grate F, as shewn by the arrows, and play on either side
around the lower half of the lower boiler.
The gases hemmed in from the sides by the walls P are made to pass through
the spaces left along the water tubes, between the different rows of them, as well as
the central tube. Having ascended beyond the inside projections formed by the
walls P the gases escape from amongst the tubes of the upper half of the lower
boiler, expand into the space formed by the lower and upper boiler, and closed in
by the walls P, and thence circulate across the heating surface of the upper boiler
in the same manner as described for the lower boiler. Having reached the top of
the boiler they are let off, being confined by the longitudinal roof which covers
both boilers, to the flue G¹.
Fig. 4, which is a longitudinal section of Fig. 3b, shows how the boiler may be
combined to form a double boiler, with a middle chamber B2, B3, and two end
chambers B¹, B. The two boiler series thus formed may by preference be mounted
on a common mud-drum K which is placed crosswise underneath the middle
chambers of the two boiler series.
As represented by Fig. 4, either end of the boiler has a certain inclination towards
the middle chamber, allowing the steam to rise towards the end chambers, but the
whole boiler may as well be built quite horizontal. In order to be certain in this
case of a perfect circulation of the water through each water tube it will be con-
venient to run right through the middle of each water tube a small circulating tube
projecting to some extent on either end into the chamber, and having small holes or
a longitudinal slot on the top as far as the circulating tube runs inside the water
tube. Of course the water which passes in any direction out from the water tube is
repulsed without being interfered with by means of the circulating tube taking the
water from either chamber from different strata of the same.
Figs. 5 to 11 on Sheet No. II., indicate details of the above-described boiler.
Fig. shows a part of the front view of the front chamber, as represented by
Fig. 1 and 2 of the same Sheet, and Figures 6 and 8 give cross sections of this
chamber.
Fig. 5 shows the position of the water tubes in two concentrical rows around the
lower central tube, and in one row around the upper one. In this case one outer
and one inner tube of the lower boiler are always placed on the same radius,
the diameter of the outer tubes being larger in proportion to the greater pitch
allowable.
The holes marked a¹, a³, a³, Fig. 5, are cut into the front plate of the chamber,
directly opposite to each water tube, and of a somewhat larger diameter, in order to
pass the tubes easily through.

page_text: Fig. 6 shows the water tubes C, which are fastened in the inner plate b; c shows
a part of the central tube; d is the side sheet of the chamber, and e the front plate
of the same, in which the before-mentioned holes are cut.
Each hole (Fig. 7) is closed by an inside cover fl, and by an outside one f*; both
are coupled together by a central screw bolt g.
tr
If desired the inside cover f¹ and the central screw bolt g may, in the shape of a
pressed forging," form one piece. Both covers may be packed by a copper wire
or any other suitable joint. The outer cover få tends to support the front plate e
against the internal pressure from within.
The back chamber may also be provided with holes and corresponding covers on
its head plate, opposite to the other end of each water tube. Right opposite to the
central tube of the lower and upper boiler the front plate of the front chamber is
provided with man-holes h' and h², rivetted to it with a circular flange. A light
casing covers the head plates of both chambers.
As, with the exception of the inner tube sheets and the head plates of the two
chambers, the boiler is wholly constituted of cylindrical surfaces, only those flat
parts of the boiler have to be braced. The inner tube sheets are stayed against each
other by the two central tubes and the water tubes surrounding them. But the
head plates of the two chambers being nearly altogether flat ought to be stayed
against the tube sheets.
Figs. 5 and 8 show the arrangement of the stays, which may be divided into two
classes.
The first kind, as indicated by k, and which I term central tube stays, is either
directly attached to the central tube itself or close to the circumference of the same.
The central tube may project somewhat into the chamber, and the stays k may be
jointed with a forked end and a pin to the end of the central tube, which is
strengthened by a ring rivetted on. The front plate c may be held by an inside
and outside nut. Or, the central tube (Fig. 11) may not be allowed to at all projects
into the chamber, and in this case the central tube stays will either be mado
removable as those above, and then be attached to suitable lugs fastened in the tube
sheets b, as shewn in Fig. 11, or be fitted in the same manner as to be described
presently for the second kind of stays marked m.
These
This second kind of stays m, which are spaced between the water tubes, I call
"water tube stays." These may be tapped directly into the tube sheet b, the other
end holding, by means of an inside and outside nut, the front plate e.
water tube stays may be solid, but in most cases it will be preferable to make them
hollow, forming them by preference of so-called "double extra strong wrought-
iron welded tubes" of convenient section. These hollow stays not only give evidence
of any failure taking place by the steam or water escaping to the outside, but they
allow, by means of steam jets being blown through them, the outside surface of the
water tubes to be thoroughly cleansed from ashes and other products of combustion.
These hollow stays m may be put in as before described, or as shewn in Fig. 9,
which gives a longitudinal section of one hollow stay m, as fastened into the two
plates band e. The holes in the two plates through which the stay has to pass are
countersunk from the outside, and the heated ends of the stay expanded into them
and rivetted over. The upper boiler (Fig. 5) having one row of water tubes only,
the central tube stays k are required. As already stated above, the central tube
stays may also be carried close to the inside circumference of the central
tube in the form of longitudinal stays from head plate to head plate of each
chamber.
Fig. 10 shows part of the front view of the front chamber of the boiler, as repre-
sented by Figs. 3 and 4; also Fig. 11 gives a part of the longitudinal section of the
same. In this case, three concentrical rows of water tubes are employed, the tubes
having uniform diameters, and being spaced on the different rows.
It will be easily perceived that this system of boiler is very accessible from
within. On opening the man-holes h' and h², the central tubes can be easily

page_text: entered, from which every part of the boiler can be inspected, and, if necessary,
repaired. Each water tube can be cleaned or tightened by unscrewing the
two covers f¹ and få in the head plate of the front chamber; and, if desirable,
there may be similar covers on the other end in the head plate of the back
chamber.
The mode in which I prefer to apply my Invention to a stationary boiler for
ordinary purposes is represented by Figs. 4, Fig. 4b, and Fig. 5, Sheet No. 1.
Fig. 4 shows the front view, and Fig. 4b a cross section, close to the back chamber
of the boiler.
A is the central tube; B₁, the front, and B2, the back chamber of the boiler; Care ]
the water tubes, surrounding the central tube in two concentrical rows; D is the
upper boiler, being in this case a plain cylindrical vessel lying horizontal. The
front chamber B¹ may, as shewn in Figs. 4 and 5, be joined to the upper cylindrical
boiler, the vertical connection being formed by an extension of the chamber itself.
The back chamber B2, which is perfectly cylindrical, is joined by a cylindrical neck
E2 to the upper boiler, which, being horizontal, gives to the lower boiler a proper
inclination. But the vertical connection of the back chamber may also be an
extension of the chamber itself. The back chamber may be made, as shewn in
Fig. 5, for boilers worked under medium pressure. The back plate being
properly dished in this case, no staying will be required, and therefore the
back chamber will be entirely accessible. But for chambers of a large
diameter, and when a high pressure of steam is used, it will be necessary to
make the back plate flat, and to stay it against the corresponding tube sheet of
the back chamber.
The stays for the front and for the back chamber, when such are used, as also the s
covers for closing the hand holes opposite to each water tube, will be arranged
according to the same general system as fully explained above for marine
boilers.
Each boiler is likewise, as shewn above, set on the mud-drum K, by means of the
two vertical tubes I and I, which carry directly the front and back chamber. But
this mud-drum K, as also the vertical tubes 11 and I2, may be done away with
altogether, and then the water may be fed into a pipe of larger diameter, which is
placed centrally into the central tube, extending nearly the whole length of it, and
being attached to the inside of the head plate of the back chamber. This pipe being
closed at the upper end gives outlet to the feed water through small holes along
the upper side.
This arrangement, by which the feed water is gradually warmed
by the water of the central tube surrounding the same, may of course also be used
for marine boilers. The boilers have to be supported in this case on suitable columns
or in any other way.
The gases, as indicated by the arrows, rise from the grate F lying on one side
of the midfeather or diaphragm H. The grate surfaces of the two boilers are here
separated by the wall P, but by leaving out this wall they may be united to form
one continuous grate. The grate is fired through the fire-doors F¹, and if desirable,
it may extend the whole length of the boiler, and be fired from both ends. The
gases, after having swept around the heating surface of the lower boiler, and having
been in contact with the lower half of the upper boiler, are drawn off on the other
side of the midfeather H, by the passage G, extending the whole length of said
midfeather. On their downward course to the flue G¹, which leads to the chimney, the
gases may be made to play round the mid-drum K, as shewn in Fig. 4b, and leaving
the same they descend through two flues G2, which may be also extended into one
narrow opening of the same length as the aperture G into the flue G'; S, S, indicate
dampers.
The interior of the boiler is accessible through the man-holes h¹ and h²; the
heating surfaces of the boiler can be cleaned in the same way as described for the
marine boiler, as also through the doors T at the back end,

page_text: Figures 6, 7, 7b, & 8, show a boiler constructed on the same general plan for heating
purposes, especially for hot water. In this case the upper and lower boiler are
preferably made alike.
A' is the central tube of the lower boiler; A2 of the upper one; B, B+, is the
front; and B2, B3, the back chamber; which in this instance may be formed of cast-
iron shallow boxes screwed or rivetted to the inner tube plates]b; or even the whole
box, including the plate b, may be cast in one piece. The vertical connections
between the lower and upper boiler form part of the box, which in this instance,
wherein but a small pressure has to be sustained, may be of a rectangular shape
(Figs. 6 and 8); C are the water tubes surrounding concentrically the central tubes
A and A. Opposite each central tube a circular cover U is provided on the out-
side of each chamber; this cover, giving free access to the whole area of the central
tube and the water tubes surrounding it is fastened in the usual way by means
of screw bolts.
The grate is placed, in this instance, across the lower boiler in the middle of the
length of the same, and is fixed from the side through the fire-door F¹. The side
walls P, closing in the whole boiler, are provided with suitable projections (Fig. 6)
butting above the centre line of the upper and lower boiler against the corres-
ponding water tubes, and thus forcing the gases to circulate as indicated by the
arrows, and in the same manner as described for the marine boiler represented by
Figs. 3a & 3b, Sheet No. II.
In order to spread the gases uniformly along the whole length of the boiler, two
apertures G (Fig. 7a) are provided, which open into a channel-shaped casting V
leading into the chimney W.
The heating surface of the boiler for cleaning it from ashes, etc., is accessible
through the doors or hand-holes T. By the pipe X the water enters the boiler
and leaves it by the pipe X¹. The whole boiler is preferably set to a slight incli-
nation.
The same arrangement of boiler, or a modification of it, by making the upper
boiler in the form of a plain cylindrical vessel, may of course also be used for
generating steam. And in this case two boilers may be connected in such a
manner that only one boiler is fired, and the gases having risen to the space
between the lower and upper boiler, are carried sideways to this same space of the
second boiler, and then be made to sweep in a downward course over the heating
surface of the lower part of the second boiler.
Having thus fully described the nature and mode of carrying out this my said
Invention, I wish it to be distinctly understood that I claim,―
First. The construction of a water-tube boiler, horizontal, or nearly so, constituted
of one upper and one lower portion or section, either or both formed of a central
cylindrical tube and cylindrical end chambers, with water tubes connecting said end
chambers outside of and concentric with said cylindrical tube, in combination with
necks or connections between the upper and lower sections of the boiler at or near
the opposite ends thereof, substantially as specified.
Secondly. The construction of a water-tube boiler, horizontal, or nearly so, con-
stituted of one upper and one lower portion or section, either or both formed of a
cylindrical tube and end chambers, so shaped as to connect by direct extensions
of said chambers the upper and lower sections of the boiler in combination with
water tubes connecting said end chambers outside of and concentric with the said
central cylindrical tube, substantially as specified.
Thirdly. The combination of two or more boilers in the form, as specified, to one
common steam generator.
Fourthly. The inside covers as united with the outside covers, closing holes in
the outside head plate of one or either chamber, and opposite to each tube, and for
the purpose as specified.

page_text: Fifthly. The conduction of the gases on the heating surfaces of this form of
boiler, substantially in the manner shewn and described.
In witness whereof, I, the said Hermann Wedekind, have hereunto set my hand
and seal, this Eighth day of April, in the year of our Lord One thousand
eight hundred and seventy-eight.
HERMANN WEDEKIND. (L.S.)