IMPROVEMENTS IN STEAM BOILERS
Year: 1872

page_text: LETTERS PATENT to Andrew Stewart, James Stewart, and John
Wotherspoon, of Coatbridge, in the County of Lanark, North
Britain, Tube Manufacturers, for the Invention of "IMPROVEMENTS
IN STEAM BOILERS."
Sealed the 29th October 1872, and dated the 11th May 1872.
PROVISIONAL SPECIFICATION- left by the said Andrew Stewart, James
Stewart, and John Wotherspoon at the Office of the Commissioners
of Patents, with their Petition, on the 11th May 1872.
.
We, ANDREW STEWART, JAMES STEWART, and JOHN WOTHERSPOON,
of Coatbridge, in the County of Lanark, North Britain, Tube Manu-
facturers, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN STEAM BOILERS," to be as follows, that is to say :-
This Invention has for its object by an improved construction of a
simple and convenient kind to increase the efficiency and durability of
steam boilers.
The Invention consists in combining tubes of a peculiar form with
cylindrical or other shells or casings, water being in the tubes, and the
positions of the tubes being such as to occasion a vigorous circulation of
the water through them, whereby they are kept free from deposits,

page_text: and thus rendered more durable. The tubes have each one end of
smaller diameter than the other, but they are for the most part of their
length of the same diameter as the larger ends, the contraction being
formed near the smaller ends. With this construction a row of the
tubes can be fixed so as to touch each other, and thus form a close par- |
tition in any space across which they are put. The tubes are arranged
with their small ends alternately towards opposite sides, so that the
holes for them in the tube plates are large and small alternately, which
admits of their being fixed so closely together.
In one modification of boiler made with these improved water tubes :
there are two cylindrical shells placed horizontally at a little distance
apart; they are connected by a row of the tubes, and the fire is placed
under one end of the tubes, the fire gases passing thence along under
the tubes to the back end, and returning over them and under an
arch to the front end. From the front end flues are carried along :
the outsides of the two cylindrical shells back to the chimney. The
tubes are arranged with slight inclinations alternately in opposite
directions, which disposition causes a vigorous circulation across between
the two cylindrical shells.
In another modification a number of the tubes are made to connect ?
two arch-shaped casings, which are connected to an upper cylindrical
shell, the tubes being close together so as to form a close partition
over the fire, and forming a flue thence towards the back end of the
boiler.
SPECIFICATION in pursuance of the conditions of the Letters Patent, 25
filed by the said Andrew Stewart, James Stewart, and John
Wotherspoon in the Great Seal Patent Office on the 9th November
1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ANDREW
STEWART, JAMES STEWART, and JOHN WOTHERSPOON, of Coatbridge, 30
in the County of Lanark, North Britain, Tube Manufacturers, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eleventh day of May, in the year of
our Lord One thousand, eight hundred and seventy-two, in the thirty- 35

page_text: fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said Andrew Stewart, James Stewart, and John
Wotherspoon, Her special licence that we, the said Andrew Stewart,
James Stewart, and John Wotherspoon, our executors, administrators,
and assigns, or such others as we, the said Andrew Stewart, James
Stewart, and John Wotherspoon, our executors, administrators, and
assigns, 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 STEAM BOILERS,”
upon the condition (amongst others) that we, the said Andrew
Stewart, James Stewart, and John Wotherspoon, our executors or
administrators, by an instrument in writing under our, 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 cause 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 we, the said Andrew Stewart, James Stewart,
and John Wotherspoon, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following state-
ment in writing, reference being had to the accompanying Drawings,
that is to say:-
Our said Invention has for its object by an improved construction of a
simple and convenient kind to increase the efficiency and durability of
steam boilers.
The Invention consists in combining tubes of a peculiar form with
cylindrical or other casings, water being in the tubes, and the position
of the tubes being such as to occasion a vigorous circulation of the
water through them, whereby they are kept free from deposits, and are
thus rendered more durable. The tubes have each one end of smaller
diameter than the other end, but they are for the most part of their
length of the same diameter as the larger ends, the contraction being
formed near the smaller ends. With this construction a row of the
tubes can be fixed so as to touch each other, and thus form a close par-
tition in any space across which they are put. The tubes are arranged

page_text: •
with their small ends alternately towards opposite sides, so that the
holes for them in the tube plates are large and small alternately, which
admits of their being fixed so closely together.
And in order that our said Invention and the manner of performing
the same may be properly understood, we hereunto append a Sheet of
explanatory Drawings to be herein-after referred to, and representing
two modifications of boilers as constructed with our improvements. In
these Drawings the same reference numerals are used to mark the same
or like parts wherever they are repeated.
Figure 1 is a front end elevation partly in transverse vertical section
of one modification of our improved boilers; and Figure 2 is a corrc-
sponding longitudinal vertical section. In this modification there are
two cylindrical shells 1, 2, placed horizontally at a little distance apart,
and connected at the ends by similar but shorter shells, 3, 4. In the
rectangular space enclosed by the four shells 1, 2, 3, 4, the two side
shells 1, 2, are connected by a row of our improved tubes 5, which form
an approximately horizontal partition. The tubes 5 are arranged with
slight inclinations alternately in opposite directions, which disposition
causes a vigorous circulation across between the two shells 1, 2. The
tubes 5 are fixed in the ordinary way in long flat plates 6 introduced
into the construction of the side shells 1, 2, along their inner sides; and
siphon branches 7 may or may not be fixed on the small ends of the
tubes 5, and inside of the shells 1, 2, to cause the circulation to tako
place from the lower parts of those shells. A number of similar tubes 8
are made to connect two pairs of arch-shaped casings 9, 10, which
are connected to the upper shells 1, 2, by pipes 11, the tubes 8 being
close together, so as to make close partitions over the fire-grates 12,
and forming flues 13, thence towards the back end of the boiler.
the back end of the tunnel-shaped flues 13, formed by the two sets of
tubes 8, the fire gases pass into a space 14 formed within the brick-
work 15, which encases a large portion of the boiler; and from the
upper part of this space 14 they enter a space 16 between the lower sets
of longitudinal tubes 8 and the upper set of transverse tubes 5, finally
passing off to the chimney by a side flue 17 indicated by dotted lines
near the front end of the space 16.
At
In a second modification the lower sets of longitudinal tubes 8, with
their arch-shaped end casings 9, 10, are omitted, and the fire is placed
under one end of the transverse tubes 5, the fire gases passing thence

page_text: along under the tubes to the back end, and returning over them and
under an arch to the front end. From the front end flues are carried
along the outsides of the two cylindrical shells 1, 2, to the chimney; or
the fire gases may pass from back to front along these side flues, and
return back to the chimney along the middle flue over the tubes 5.
A third modification is shown in vertical section in Figure 3, and in
horizontal section in Figure 4. In this case three nearly horizontal
partitions 18, 19, 20, are formed of tubes 21 substantially the same as
those (5,8,) herein-before described, in so far that they are contrived to
touch each other throughout the larger portion of their length, whilst
the modes of fixing their ends are different. The back ends of the
tubes 21 are held in a water casing 22, which communicates with a
cylindrical shell 23 at the top, and which has parts slightly inclined so
as to be at right angles to the slightly inclined tubes 21, or the whole
of it may have one continuous inclination. The back ends of the tubes
are formed with contracted necks 24, which are passed across and
through both sides of the casing 22, and which are perforated at the
part within the casing for the passage of water and steam from the tubes
into the casing. The necks 24 are formed with conical shoulders to fit
against the inside shell of the casing, and conical rings are slipped over
the outer ends to fit conical holes in the outer shell, the extreme ends
being screwed to receive nuts 25, which securely fix and tighten the
parts together.
The ends of the tubes may be plugged and welded, or otherwise
closed; or the nuts 25 may be made with caps to cover open ends. The
front ends of the tubes 21 may be fixed into a water casing in the same
way; but we prefer to connect them together in the manner shown in
the Figures, which admits of single tubes being easily taken out and
replaced. The front ends of the tubes are reduced and screwed into small
circular boxes 26, 27, which are bolted together in a manner easy to be
understood from Figure 4, so as to combine to form horizontal passages 28
across the end of each partition 18, 19, 20. Each such horizontal
passage 28 is at one or at each end connected by a return pipe 29 with the
back water casing 22. The circular boxes 26, 27, are alternately large and
small, and two enlarged views of each are shown in Figures 5 and 6
respectively, the larger boxes 26 being formed with notches to receive
the connecting bolts in a convenient manner. The fire-grate 12 is
placed at the front end beneath the lower partition 18 of tubes, and tho

page_text: fire gases first pass along under that partition towards the back end near
which the tubes are flattened vertically, so as to form narrow open-
ings 30. Through these openings 30 the gases enter the space between
the lowest partition 18 and the middle one 19, and they pass through
similar openings at the front end of the latter to the space between it and t
the top partition 20, finally leaving such space through openings at the
back end of the top partition 20 into the flue 31 leading to the chimney.
The connecting boxes, 26, 27, are made by preference of malleable cast
iron, and supporting blocks 32 are placed between the tiers.
Having thus particularly described our said Invention, and the manner 1
of performing the same, we have to state that we do not restrict ourselves
to the precise details herein described or delineated; but that what we
believe to be novel and original, and claim as the Invention secured to
us by the herein-before in part recited Letters Patent is,―
1. The combining of tubes with cylindrical or other shells or casings, 1
such tubes being arranged to touch each other and form partitions,
substantially in the manner and for the purposes herein-before
described.
2. The contracting of one end of each tube and the combining of the
tubes with the small ends lying alternately in opposite directions, sub- 2
stantially as herein-before described.
In witness whereof, I, the said Andrew Stewart, on behalf of
myself, the said James Stewart, and the said John Wotherspoon,
have hereunto set my hand and seal, this Eighth day of
November, in the year of our Lord One thousand eight hundred 2
and seventy-two
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
ANDREW STEWART. (L.s.)