IMPROVEMENTS IN THE CONSTRUCTION OF STEAM BOILERS
Year: 1867

page_text: LETTERS PATENT to Thomas Holt, of Trieste, in the Empire of Austria,
but now residing at the Terminus Hotel, in the Borough of Southwark,
Engineer, for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF
STEAM BOILERS."
Sealed the 22nd November 1867, and dated the 10th June 1867..
PROVISIONAL SPECIFICATION left by the said Thomas Holt at the
Office of the Commissioners of Patents, with his Petition, on the
10th June 1867.
I, THOMAS HOLT, of Trieste, in the Empire of Austria, but now residing at
the Terminus Hotel, in the Borough of Southwark, Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE CONSTRUCTION
OF STEAM BOILERS," to be as follows:-
The object of this Invention is to obtain an increased heating surface in
stationary, marine, and locomotive steam boilers, and at the same time to
simplify the construction of such boilers. This end I attain by the use of a
novel arrangement of flattened tubes or chambers which form the passages or
flues for the flame and heated gases to pass through while the water circulates.
freely between them. The tubes or chambers are set parallel to each other,
and in such relative positions that an easy access to the rivets used for con-
necting the tubes or chambers together will be provided, and the surface of
the tubes or chambers by contracting and expanding under variations of
temperature will tend to prevent the adhesion of scale or deposit.

page_text: In constructing a high-pressure land boiler I use by preference a cylindrical
shell either vertical or horizontal, and I form a compound central flue therein
by the use of the parallel tubes; these tubes may be formed by flattening
drawn tubes, or of plates rivetted, welded, or brazed together at their edges.
Within the tubes at given distances apart I insert longitudinal stays, which
may be countersunk at given distances to receive protuberances formed in the
flat sides of the tubes for holding the stays in place, or ribs may be rolled on
the plates used to form the tubes, and the ribs of two plates being brought
together will form stays requiring no connection or attachment. The tubes,
however made, I so arrange that when laid together, whether in a vertical or
horizontal position, their extremities will form inclines, and while in this posi-
tion the ends of the adjacent tubes are rivetted together so as to close the ends
of the water spaces left between the tubes; the tubes thus connected are then
secured to the tube plates. In the horizontal land boiler these tube plates
will close the ends of the shell, and the mouths of the tubes will be presented
at the requisite angle to admit of the ascending flames and heated gases from
the fire-place turning easily into and passing along the horizontal flues. In
order to increase the circulation of the water I cant the horizontal flues so that
the water spaces between them being transversely on the incline will facilitate
the escape of the steam from the raised side. The angle best suited for the
turning in of the flame and heated gases to the flues at one end and their
escape at the other gives access also to the lines of rivets by which I secure
the tubes the one to the other, and when any tube is burned out it can readily
be removed by cutting away the rivet beads and replaced. To facilitate the
removal of the compound tubular flues I make in the horizontal boiler a door
in the brickwork opposite the tubes, and of sufficient size to allow of their
being taken out in a body, and in the vertical boiler I make the upper part of
the shell detachable for the like purpose. For cleaning this boiler. I provide
small doors on the opposite sides of the shell. For improving the evaporating
power of marine boilers of the ordinary construction I propose to fill the
ordinary flue space with tubes arranged as described with respect to the
horizontal land boiler.
Another arrangement of marine boiler which I propose to employ is one
in which the flue chambers are secured directly to the top of the furnace; one
side only of the chambers is open, and a division is made in them extending
to about one-half their depth. The chambers are set up in a vertical plane
and are canted so as to present their open mouths at an incline to the flame.
A bridge forming the roof of the front part of the furnace extends to the divi-
sion in the flue chambers, and the flame and gases are thus caused to pass into

page_text: the chambers and turn over the divisions therein and escape on the other side
of the bridge. The lips of the chambers are provided with flanges, by which
(through lines of rivets they are connected together, and the division in the
chambers is formed either by indenting the metal of the adjacent plates or
inserting a stay bar therein. For securing the series of chambers in place tie
rods may be used, and the flanges of the end chambers are rivetted directly to
the top of the fire chamber. To allow of the removal of the chambers from
the boiler the bridge, which is hollow and connected at its opposite sides to
the water spaces, is made removeable, it being supported in its place on angle
irons.
'
In constructing locomotive boilers I incline the tube plates towards the top
of the fire chamber, and fill the space between the tube plates with the
flattened tube flues. These tube flues I place horizontally and connect them
together by lines of rivets, as in the above-described land boilers. I also cant
them on one side to increase the circulation, and I connect them to the tube
plates by forming lips or flanges on the tube plates to embrace the tubes -
to receive rivets, which are passed through the sides of the tubes. At t
of the furnace I provide a series of vertical flue chambers open only at bottom
which project upwards into the steam space, and afford an increased heating
surface to the water, while they serve also to superheat the steam in the
steam space.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Holt in the Great Seal Patent Office on the
10th December 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
HOLT, of Trieste, in the Empire of Austria, but now residing at the Terminus
Hotel, in the Borough of Southwark, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of June, 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
Thomas Holt, Her special licence that I, the said Thomas Holt, my executors,
administrators, and assigns, or such others as I, the said Thomas Holt, 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

page_text: !nited Kingdom of Great Britain and Ireland, the Channel Islands, and Isle
of Man, an Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF STEAM
BOILERS," upon the condition (amongst others) that I, the said Thomas Holt,
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 per-
formed, and cause the same to be filed in the Great Seal Patent Oilice within
six calendar months next and immediately after the date of the said Letters
Patent..
NOW KNOW YE, that I, the said Thomas Holt, 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 statement,
reference being had to the Drawing hereunto annexed, and to the letters and
figures marked thereon (that is to say) :-
The object of this Invention is to obtain an increased heating surface in
stationary, marine, and locomotive steam boilers, and at the same time to
simplify the construction of such boilers. This end I obtain by the use of a
novel arrangement of flattened tubes or chambers which form the passages or
flues, for the flame and heated gases to pass through while the water circulates,
freely between them. The tubes. or chambers are set parallel to each other,
and in such relative positions that an easy access to the rivets used for con-
necting the tubes or chambers together will be provided, and the surfaces of
the tubes or chambers by contracting and expanding under variations of
temperature will tend to prevent the adhesion of scale or deposit.
In the accompanying Drawings 1 have shewn five different arrangements of
boilers with my Invention applied thereto for the purpose of illustrating the
adaptability of the Invention to very varying circumstances.
In constructing. a high-pressure land boiler I use by preference a cylindrical
shell, either vertical as shewn in Fig. I. or horizontal as shewn in Figs. 8 & 9,
and I form a compound central flue therein by the use of the parallel tubes.
In the Drawing Fig. 1 shews in central section a vertical bigh-pressure land
boiler, and Fig. 2 is a transverse section of the same.
. A is a cylindrical shell closed at top by an inverted cone, which is made
removable to allow of the withdrawal of the parallel tubes in a body for
repairs. At bottom the shell A is extended by a slightly conical continuation ;
B, B', are the tube plates set parallel to each other, but at an incline for
the purpose, to be presently explained. The lower tube plate B' forms the
top of the fire chamber C, the fire-bars of which are shown at D.
space of the boiler extends down to a level with the fire-bars, and
The water
it is to the

page_text: inner casing A¹ forming the perimeter of the fire chamber that the tube
plate B' is secured; E, are the flattened tubes set vertically in the middle of
the shell of the boiler, and forming flues for the passage upwards of the gases
of combustion, while they present a large heating surface around and over
which the water is free to circulate. The construction of these tubes admits
of modification, but in all cases the tubes when rivetted together at their
opposite ends must allow of a free passage between them for the circulation.
of water over the greater portion of their length. Fig. 3 shews detached and
in perspective the form of tube which I generally prefer to employ, the tube.
having expanded ends; Fig. 4 is a cross section of the same, showing an
arrangement for preventing the buckling or retaining the parallelism of the
sides; Fig. 5 is a perspective view of two tubes rivetted together; these tubes
have also expanded ends, but different means for preventing the buckling
inwards of the sides of the tubes; Fig. 6 shows; in perspective two tubes made
parallel from end to end, and yet rivetted together so as to provide for the
free circulation of water between them. The tubes E may be formed by flat-
tening drawn tubes, or of plates rivetted, welded, or brazed together at their
edges. Figures 3 and 4 shew the tubes composed of plates rivetted to side
pieces. Within the tubes at given distances apart I insert stays which may
be longitudinal, as shown at Figures 5 and 6, or simply balls placed in cups
formed at given distances apart by indents made in the flat sides of the tubes,
and intended for holding the stays in position. Ribs may also if preferred be
rolled on the plates used to form the tubes, and the ribs of two. plates being
brought together will form stays requiring no connection or attachment. This..
form of stay is illustrated by Fig. 7, which will hereafter be more particularly
referred to. The tubes, however made, are so arranged with respect to each
other that their extremities will form when connected together inclines, the
ends of the tubes from the first to the last, being advanced the one beyond the
other so as to expose and give access to the lines of rivets by which the adjacent
tubes are secured rivetted together, and caused to close the ends of the water.
spaces left between the tubes, as shewn at Fig. 1; the group of tubes thus
formed are then secured to the tube plates which are properly shaped to receive
the group. The form of the group itself will be determined by the space
allowed for it in the shell, it being understood; that the water must circulate
around the group as well as, between the individual, tubes.
In Figs. 8 and 9, which illustrate the horizontal land boiler, Fig. 8 is a
longitudinal section of the boiler, and Fig. 9 shews in partial front view and
in partial transverse, section a pair of horizontal land boilers. In this arrange-
ment the tube plates form the ends of the cylindrical shell A, and the mouths

page_text: of the tubes are: presented at the requisite angle to admit of the ascending
flames and heated gases from the fire-place turning easily into the rear ends
of and passing along the horizontal flues to the front. In order to increase
the circulation of the water I give the horizontal flues a cant transversely as
shewn at Fig. 9, wherein the tubes are represented, the one half in cross
section and the other half in end view. The water spaces between the tubes
being thus transversely on the incline the escape of the steam from the raised
side will be greatly facilitated.. The angle best suited in this arrangement for
the turning in of the flame and heated gases to the flues at one end and
their escape at the other, gives access also to the line of rivets by which I
secure the tubes the one to the other, and when any tube is burned out it can
readily be removed by cutting away the rivet heads and replaced by a new
tube. To facilitate the removal of the compound tubular flues I make in the
brickwork opposite the tubes a door F, and of sufficient size to allow of their
being taken out in a body; I also avail myself of the escaping gases of com-
bustion to superheat the steam generated in the boiler by connecting with the
steam space a cylinder. G, and conducting the escaping gases through the flue
containing this chamber. The steam may be taken from this superheating
chamber at any convenient part thereof.
. For improving the evaporating. power of marine boilers of the ordinary con-
struction I propose to fill the ordinary flue space with tubes arranged as
described with respect to the horizontal land boiler. This arrangement is illus-
trated in Figs. 10 and 10*, and Figs. 11 and 11*, where Figs. 10 and 10* are
front elevations and partial transverse sections taken in two different planes of
the two forms of marine boiler, and Figs. 11 and 11* are longitudinal sections
of the same. The ordinary flue spaces it will be seen are filled with groups
of the flattened tubes E. The flame and heated gases enter at the rear ends
of the tubes, and make their exit at the front ends, as in Figs. 8 and 9, to the
escape flue.
An incidental advantage of this arrangement of flues is that the
transverse tie rods H may be passed at any required level through the water
spaces in the groups.
Another arrangement which I propose to employ in adapting my Invention
to marine boilers is shewn in Figs. 12 and 13, wherein the flattened metallic
parallel flues are modified in form, and are secured directly to the top of the
furnace. Fig. 12 shews the boiler and furnace in longitudinal section, and
Fig. 13 is a partial transverse section. Instead of the flues being open at
their opposite ends one side only of the flues E is open, and a division is made
in them as shewn at E, extending to about one-half their depth; this is most
conveniently effected by forming an indented line in corresponding positions

page_text: in their side plates, the, indents being sufficiently deep to ensure the raised
surfaces coming into contact and thus preventing the flame and heated
gases from passing between the plates at that part. Thus a bridge will be
formed in each flue or chamber E for the flames to play over, as shewn in the
Drawing. The chambers E are set up in a vertical plane, and are canted so
as to present their open mouths at an incline to the flame. A hollow .or
water bridge I forming the roof of the front part of the fire-place C extends
to the bridge or division E in the flue chambers E, and the flame and gases
are thus caused to pass into the chambers and turn over the divisions therein,
and escape on the other side of the bridge to the uptake flue. The lips of
the chambers are provided with flanges, by which (through lines of rivets)
they are connected together, as shewn in the detached view, Fig. 7, which
represents three such chambers rivetted together. The division in the chambers
instead of being formed by indenting the metal of the adjacent plates, as shewn
at Fig. 7, may be made by inserting a stay bar therein. For securing the
series of chambers in place tie rods K are used, and the flanges of the end
chambers are rivetted directly to the top of the fire chamber C. To allow of
the removal of the chambers from the boiler the bridge I (which being hollow
is connected at its opposite sides to the water spaces) is made removeable, it
being supported in its place on angle irons.
In applying my Invention to locomotive boilers I incline the tube plates
B, B', towards the top of the fire chamber, and fill the space between the
tube plates with the flattened tube flues E. These tube flues I place hori-
zontally, and connect them together by lines of rivets as in the above described
land boilers; I also cant them on one side to increase the circulation. This
arrangement is shewn in Figs. 14 and 15, Fig. 14 being a longitudinal section
of the locomotive boiler and furnace, and Fig. 15 a transverse section taken
in two different planes for the purpose of shewing the front ends of the tubes,
and also the tubes in section. I connect the tubular flues E to the tube
plates by forming lips or flanges on the tube plates to embrace the tubes
and to receive rivets which are passed through the sides of the tubes. At the
top of the fire-box or furnace C I provide a series of vertical flue chambers E*,
open only at bottom like those used in the marine arrangement, Figure 12.
These chambers E* project upwards through the water space into the steam
space, and afford an increased heating surface to the water, while they serve
also to superheat the steam in the steam space; these chambers are rivetted
by means of their flanges to the top plate of the fire-box, and they are further'
secured in position by rods K pendent from the crown of the steam chamber.

page_text: Access to the tubes E may be obtained in the usual way by a door in the
smoke box.
Having now explained the nature of my Invention, and the manner of
carrying the same into effect, I wish it to be understood that under the above
in part recited Letters Patent I claim, constructing compound metallic boiler
flues as above described, and applying them to stationary, marine, and loco-
motive boilers, substantially as and for the purpose above set forth.
In witness whereof 'I, the said Thomas Holt, have hereunto set my
hand and seal, the Second day of December, in the year of our Lord
One thousand eight hundred and sixty-seven:
THOMAS HOLT. (L.S.)