IMPROVEMENTS IN STEAM GENERATORA
Year: 1867

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in
the County of Middlesex, for the Invention of "IMPROVEMENTS IN STEAM
GENERATORA communication from abroad by Richard Joseph Nunn,
of Savannah, Chatham County, State of Georgia, United States of
America.
Sealed the 22nd October 1867, and dated the 24th May 1867.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition, on the
24th May 1867.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, do hereby declare the nature of the said Invention for "IMPROVE"
MENTS IN STEAM GENERATORS," to be as follows:--
The object of this Invention is to furnish a steam boiler or (generator) which
shall combine the essential requisites of compactness, strength, and safety to a
greater degree than any other steam boiler in use, and which, while it shall be
more economical as regards the weight of material used in its construction and
the quantity of fuel required for a given amount of steam shall furnish a much
greater extent of steam generating surface in proportion to its weight and
dimensions. And the Invention consists in constructing the boiler entirely of
[Price Sd.

page_text: tubes of such dimensions and calibre that the danger from explosion shall be
diminished at least fourfold when compared with the ordinary boilers now in
use, and in arranging and combining the tubes in such a manner that I can
stop off or remove a defective tube with very little difficulty or delay, main-
taining at the same time a perfect circulation of the water, and but slightly
interfering with the efficiency of the boiler.
The tubes of which the boiler is composed are all described as being either
vertical or horizontal in this example of the Invention, but they may be placed
at any angle as may be desired. The horizontal tubes lie both in a longi-
tudinal and transverse position. The longitudinal tubes (three on each side)
are placed one above the other on the outside of the boiler. The transverse
tubes run through the boiler, and are invisible with the exception of those at
the ends and on the top. I construct the boiler of a series or succession of
bents or slabs, each slab having a given number of vertical and horizontal
tubes, the vertical tubes standing in a row and the horizontal tubes lying at
given intervals one over the other, and each bent or slab consisting of but one
row or the thickness of one tube. Each slab may consist of eight vertical and
three horizontal tubes, or other numbers may be adopted. It would, perhaps,
be more proper to say that each slab is composed of sixteen vertical tubes, for
one of the horizontal tubes cuts the row and separates the vertical tubes,
leaving eight long tubes and eight short ones. The upper horizontal tube
may be called the steam tube. The next horizontal tube below is the low
water tube, and the next below or at the bottom is the cold water tube,
excepting where it forms the top of the fire chamber or furnace. The steam
tube extends out over the right and left hand vertical tubes, and each end
terminates with a flange; there is also a cock at each end between the flange
and the vertical tubes; it also has another cock near its left-hand end. The
low water tube has similar flanges and cocks between the flanges and the
vertical tubes. The upper tier of vertical tubes are connected with these
horizontal tubes, and the tier below, including the right and left hand vertical
tubes, are connected with the low water tube at its under side, and all stand
in line with those above. The lower horizontal tube as well as the cold water:
or lower tube of the other slabs which lie beyond the furnace terminate in the
right and left hand vertical tubes; these vertical tubes are closed at the
bottom ends, but near their lower ends short horizontal tubes are attached
provided with cocks and flanges, the vertical tubes being cut or separated by
the low water tube, and the separated portion being in two rows or tiers
occupying positions directly over each other, they form for all practical
purposes but one tier or eight tubes as regards their interior portion, and I

page_text: avail myself of this arrangement by introducing tubes of much smaller
diameter, which stand in the axial centres of each vertical tube. I designate
these tubes circulation tubes; the top end of each passes through the steam
tube and is closed and secured in its proper position by screws whose heads
bear upon the top of the steam tube; one of these circulation tubes passes
down through the closed end of each of the vertical right and left hand tubes
of each slab and terminates in a cock; the lower ends of the rest of these
tubes pass through the top of the lower horizontal tube before mentioned and
terminate in closed pointed ends. These circulation tubes are perforated
with holes, the holes commencing about half way between the steam tube and
the low water tube and continue to the bottom of the latter. In the right
and left hand tubes the holes through the lower ends of these circulation
tubes commence at the bottom of the flue and continue to the end of the tubes
which enclose them. In the six other vertical tubes the perforations commence
at the top of the horizontal tube and continue to their ends. The circulation
tubes in the vertical tubes of the slabs back of the furnace pass entirely through
the lower horizontal tubes and are secured by screws, and terminate in cocks the
same as those in the outside right and left tubes, the lower holes commencing
at the bottom of the flue and continuing to their ends. The slabs which form.
that portion of the boiler back of the furnace are constructed in the same
manner, only the tube which here forms the top of the furnace is dropped
down in the slabs which stand beyond, and is situated at the bottom of the
boiler, and there forms the cold water or supply tube, lying on a level with
other outside horizontal tubes to be described hereafter which are also cold
water or supply tubes. The flanges upon the ends of the steam and low
water tubes are for the purpose of attaching those tubes to other horizontal
tubes which extend longitudinally on each side of the boiler. There are
three of these tubes on each side corresponding in height with the steam and
low water tubes and also with the short tubes which are attached to the right
and left hand vertical tubes. I will here add that these short tubes have.
check valves in communication with the longitudinal tubes; the ends of these
longitudinal tubes are closed and terminate in a flange, and upon the side of
each are short tubes corresponding in number and position with the number
and position of the flanges on the slabs. Each of these short tubes terminate
with a flange and cock between the flange and the main tube; these flanges
corresponding in number and position with the flanges attached to the slabs as
before stated, the intention, of course, is to connect them together, and by so
doing connect the whole system of tubes in the boiler, thus allowing the
water to circulate through every portion of the water space and the steam to

page_text: Occupy the steam space. The upper longitudinal tubes being but a con-
tinuation of the steam space in the upper tube of the slabs a portion of the
vertical tubes is designed also to form a steam space, that portion being about
half the space between the steam and low water tubes. It is obvious that 'by
disconnecting the flanges of any one slab the slab can be removed from the
boiler; in that case the cocks would be closed, thus shutting the slab off
from the rest of the boiler. When the slab is removed the boiler is again
ready for use, and after only a few minutes detention. Should a slab leak
and it is not deemed advisable to remove it, the several cocks would be closed
and would shut it off from the rest of the boiler; in this case the working of
the boiler would not be interrupted at all, the cock at the left-hand end of the
steam tube being opened to prevent overpressure in that. slab. To increase
the size and capacity of the boiler it is only necessary to increase the length of
the longitudinal tubes and add more slabs. The small interior circulation
tubes perform another duty besides aiding the circulation: they act as bolts to
bind the slabs together, being secured as they are at top and bottom by screws.
At the bottom the end passes through a screw nut before the cock is attached.
The system of tubes is now complete. The steam space and the low water
space are both surrounded with horizontal tubes, and the cold water or supply
tubes also surround the boiler, with the exception of the front. Each set of
horizontal tubes is in free communication with the others as well as with all
the vertical tubes in the boiler. As the vertical tubes do not stand so as to
touch each other it is necessary to fill up the spaces between the outside right
and left hand tubes and of all the spaces in the tier of tubes which surround
the boiler in order to form a perfect flue. The whole interior steam space, or
the space between the low water tube and the steam tube, is also filled with
noncombustible material to protect the surfaces of the tube from the direct
action of the fire. The right and left hand tubes are likewise protected from
the action of the fire. The cold water or supply tubes of all the slabs at the
back of the furnace are protected in like manner, but here the noncombustible
material forms the bottom of the flue. Solid metal plates are used for filling
the spaces between the vertical tubes, and also for protecting the steam space
of the boiler; these plates also form the bottom of the flue; two of these
metallic plates (the front and the back ones) have arms or brackets extending
out from the outside vertical tubes, which brackets are made to support the
three longitudinal tubes on each side of the boiler. The steam may be
discharged from any part of the steam space as may be most convenient, and
the force pump may be attached to the cold water or supply pipe in the same
manner,

page_text: I do not broadly claim constructing steam boilers or generators exclusively
of tubes or pipes, nor do I broadly claim the use of interior circulation tubes,
as I am aware that they are not new.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Melville Clark in the Great Seal Patent Office on
the 22nd November 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of May, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirtieth year of Her reign, did,
for Herself. Her heirs and successors, give and grant unto me, the said
Alexander Melville Clark, Her special licence that I, the said Alexander
Melville Clark, my executors, administrators, and assigns, or such others as I,
the said Alexander Melville Clark, my 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 "IMPROVE-
MENTS IN STEAM GENERATOES," a communication to me from abroad by
Richard Joseph Nunn, of Savannah, Chatham County, State of Georgia,
United States of America, upon the condition (amongst others) that I,
the said Alexander Melville Clark, my executors or administrators, 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 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 I, the said Alexander Melville Clark, do hereby
declare the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement, reference being had to the Sheets of Drawings hereunto annexed,
and to the letters and figures marked thereon (that is to say):-
The object of this Invention is to furnish a steam boiler or generator which
shall combine the essential requisites of compactness, strength, and safety to a
."

page_text: greater degree than any other steam boiler in use, and which while it shall be
more economical as regards the weight of material used in its construction,
and the quantity of fuel required for a given amount of steam, shall furnish a
much greater extent of steam generating surface in proportion to its weight
and dimensions. And the Invention consists in constructing the boiler entirely
of tubes of such dimensions and calibre that the danger from explosion shall
be diminished at least fourfold when compared with the ordinary boilers now
in use, and in arranging and combining the tubes in such a manner that I can
stop off or remove a defective tube with very little difficulty or delay, main-
laining at the same time a perfect circulation of the water, and but slightly
interfering with the efficiency of the boiler.
To enable others skilled in the art to make and use this Invention, I will now
proceed to describe its construction and operation, reference being had to the
accompanying Drawings formning a part of this Specification, and to the letters
of reference marked thereon.
Figure 1 represents a front elevation; Figure 2, a plan or top view; Figure 3
is a vertical section through the line x, x, of Figure 1; Figure 4 is a hori-
zontal section through Figure 1, at y, y; Figure 5 is a side elevation, partly
sectional, and Figure 6 is a small front view of the arch plate of the boiler.
Similar letters of reference indicate like parts in the Drawings.
The tubes of which this boiler is composed are all either vertical or
horizontal in this example of the Invention, but they may be placed at any
angle, as may be desired. The horizontal tubes lie both in a longitudinal and
transverse position. The longitudinal tubes (three on each side) are placed
The transverse tubes run
one above the other on the outside of the boiler.
through the boiler, and are invisible, with the exception of those at the ends
and on the top, as seen in the Drawing.
I construct the boiler of a series or succession of bents or slabs, each slab
The vertical tubes
having a given number of vertical and horizontal tubes.
standing in a row, and the horizontal tubes lying at given intervals one over
the other, and each bent or slab consisting of but one row or the thickness of
one tube. In the Drawing the slab is represented as consisting of eight vertical
and three horizontal tubes. It would perhaps be more proper to say that each
slab is composed of sixteen vertical tubes, for one of the horizontal tubes cuts the
row and separates the vertical tubes, leaving eight long tubes and eight short
The next
ones. The upper horizontal tubes may be called the steam tubes.
horizontal tube below is the low water tube, and the next below or at the
bottom is the cold water tube, excepting where it forms the top of the fire
chamber or furnace. I will now commence at the front end of the boiler,

page_text: Figure 1, and describe one of these slabs more particularly. The one in view
is the first of a series of slabs which form the fire-box or furnace.
A represents the two outside or right and left hand vertical iubes; A¹. the
lower row of vertical tubes between the outside ones; and a represents the
upper row of vertical tubes; B represents the upper horizontal or steam
tube; B', the lower water tube; and b. the lower horizontal tube forming
the top of the fire chanìber or furnace as far back as the furnace extends.
The steam iube B extends out over the right and left hand vertical tubes,
and each end terminates with a flange c; there is a cock D at each end
between the flange and the vertical tubes; it also has another cock D' near
its left-hand end. The low water tube B' has the same flanges at E, E, and
cocks between the flanges and the vertical tubes. The upper tier a of
vertical tubes are connected with these horizontal tubes, and the tier below,
including the right and left hand vertical tubes are connected with the tube B¹
at its under side, and all stand in line with those above. The tube b, as
well as the cold water or lower tube of the other slabs which lic beyond the
furnace, terminate in the right and left hand vertical tubes A, A; these vertical
tubes A, A, are closed at the bottom ends, but near their lower ends short
horizontal tubes H are attached, which terminate in flanges h, and have
each a cock h' between the flange and the vertical tube. The shaded tubes
seen in the Drawing represent the back end of the furnace, the vertical tubes
being cut or separated by the low water tube B', and the separated portion
being represented in two rows or tiers occupying positions directly over each
other, they form for all practical purposes but one tier or eight tubes as regards
their interior portion; and I avail myself of this arrangement by introducing
tubes of much smaller diameter, which stand in the axial centres of each vertical
tube. I designate these tubes circulation tubes; the top end of each passes
through the steam tube B, and is closed and secured in its proper position by
screws, whose heads bear upon the top of the steam tube; these screws are
represented by in the Drawing; one of these circulation tubes passes
down through the closed end of each of the vertical right and left hand tubes
of each slab, and terminates in a cock G. The lower ends of the rest of these
tubes pass through the top of the horizontal tube b, and terminate in closed
pointed ends, as seen in the Drawing. These circulation tubes are perforated
with holes, the holes commencing about half-way between the steam tube B
and the low water tube B', and continue to the bottom of the tube B¹. In
the right and left hand tubes the holes through the lower ends of these
circulation tubes commence at the bottom of the flue, and continue to the end
of the tubes which enclose them.. In the six other vertical tubes the perforations

page_text: commence at the top of the horizontal tube b, and continue to their ends.
The circulation tubes in the vertical tubes of the slabs back of the furnace
pass entirely through the lower horizontal tubes, and are secured by screws
and terminate in cocks the same as those in the outside right and left tubes,
the lower holes commencing at the bottom of the flue and continuing to their
ends. The slabs which form that portion of the boiler back of the furnace are
constructed in the same manner, only the tube b which here forms the top
of the furnace is dropped down in the slabs which stand beyond, and is
situated at the bottom of the boiler, and is there the cold water or supply
tube lying on a level with other outside horizontal tubes to be described here-
after, which are also cold water or supply tubes. The flanges upon the ends
of the steam and low water tubes B and B' are for the purpose of attaching
those tubes to other horizontal tubes, which extend longitudinally on each side
of the boiler. There are three of these tubes on each side corresponding in
height with the steam and low water tubes, and also with the short tubes H,
which are attached to the right and left hand vertical tubes. I will here add
that these short tubes H have check valves communicating with the longitudinal
tubes and seen at n, Figure 4. These longitudinal tubes are indicated in
the Drawing by the letters K, L, m; their ends are closed and terminate in a
flange ; upon the side of each are short tubes G', corresponding in number
and position with the number and position of the flanges on the slabs. Each
of these short tubes terminates with a flange, and have each a cock between
the flange and the main tube; these flanges are marked e, and the cocks c
in the Drawing; these flanges corresponding in number and position with the
flanges attached to the slabs, as before stated, the intention of course is to
connect them together, and by so doing connect the whole system of tubes in
the boiler, thus allowing the water to circulate through every portion of the
water space, and the steam to occupy the steam space, the upper longitudinal
tubes K, K, being but a continuation of the steam space in the upper tube B
of the slabs. A portion of the vertical tubes is designed also to be steam
space, that portion being about half the space between the steam and low
water tubes B and B'. It is obvious that by disconnecting the flanges of
any one slab the slab can be removed from the boiler; in that case the
cocks c would be closed, thus shutting the slab off from the rest of the
boiler. When the slab is removed the boiler is again ready for use, and after
only a few minutes detention should a slab leak, and it is not deemed
advisable to remove it, the cocks D. F, and h would be closed, which would
shut it off from the rest of the boiler. In this case the working of the boiler
would not be interrupted at all, the cock D¹ being opened to prevent over-

page_text: pressure in that slab. To increase the size and capacity of the boiler it is only
necessary to increase the length of the longitudinal tubes K, L, M, and add
more slabs. The small interior circulation tubes perform another duty besides
aiding the circulation; they act as bolts to bind the slabs together, being
secured as they are at top and bottom by screws. At the bottom the end
passes through a screw nut before the cock is attached. The system of tubes
is now complete. The steam space and the low water space are both
surrounded with horizontal tubes, and the cold water or supply tubes also
surround the boiler, with the exception of the front. Each set of horizontal
tubes is in free communication with the others, as well as with all the vertical
tubes in the boiler. As the vertical tubes do not stand so as to touch each
other it is necessary to fill up the spaces between the outside right and left
hand tubes, and of all the spaces in the tier of tubes which surround the
boiler in order to form a perfect flue. The whole interior space or the
space between the low water tube B' and the steam tube B is also filled with
non-combustible material to protect the surfaces of the tubes from the direct
action of the fire. The right and left hand tubes are likewise protected from
the action of the fire. The cold water or supply tubes of all the slabs back of
the furnace are protected in like manner, but here the non-combustible material
forms the bottom of the flue.
In the Drawings I have shown solid metal plates as filling the spaces
between the vertical tubes, and as also protecting the steam space of the
boiler. These plates also form the bottom of the flue. Two of these metallic
plates (the front and the back ones) have arms or brackets extending out from
the outside vertical tubes, which brackets are made to support the three
longitudinal tubes on each side of the boiler. There may be more or less of
those brackets as may be deemed necessary.
Neither is it considered very
important that there should be as many cocks in the horizontal tube as is
represented, such as may be found unnecessary in actual service of the boiler
may be dispensed with. The front or arch plate of the boiler is represented
in Figure 6, showing the brackets and the ends of the longitudinal tubes and
a portion of the transverse horizontal tubes. The bar that holds the front end
of the grate is represented at P; the grate itself by the letter R. The steam
may be discharged from any part of the steam space as may be most con-
venient, and the force pump may be attached to the cold water or supply pipe
in the same manner.
Having described the nature of this Invention, and the manner of perform-
ing the same, I wish it to be understood that I do not confine myself to any
particular size, length, or number of tubes, nor to any particular position for

page_text: them to occupy, nor to any particular form or shape of boiler, so long as it is
composed entirely of tubes or pipes connected together in the manner I have
described, or in any manner substantially the same, for I am aware that tubes
may be connected by screws as well as by flanges, and that the small interior
circulation tubes may be attached and secured in other ways from that which
I have described. My method of construction or forming the joints and
connections is the best which occurs to me now, although it may be varied as
experience and practice may dictate. I do not broadly claim constructing
steam boilers or generators exclusively of tubes or pipes; nor do I broadly
claim the use of interior circulation tubes, as I am aware that they are not
new; but what I claim as the Invention to be protected by the herein-before
in part recited Letters Patent is,-
First, I claim the arrangement of boiler constructed entirely of tubes or
pipes when such tubes or pipes are arranged and connected together and
protected from the direct action of the fire, substantially in the manner herein
described.
Secondly, I claim the interior circulation tubes herein described when the
said tubes are perforated in the manner and secured in their position in the
manner substantially as described when used in the vertical tube of a boiler
as and for the purposes set forth.
In witness whereof, I, the said Alexander Melville Clark, have here-
unto set my hand and seal, this Twenty-second day of November, in the
year of our Lord One thousand eight hundred and sixty-seven.