IMPROVEMENTS IN THE CONSTRUCTION OF STEAM BOLLERS
Year: 1866

page_text: LETTERS PATENT to Thomas Holt, of Trieste, in the Empire of
Austria, but now of 66, Chancery Lane, in the County of Middlesex,
for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF STEAM
BOLLERS."
Sealed the 4th September 1866, and dated the 14th May 1866.
PROVISIONAL SPECIFICATION left by the said Thomas Holt' at the
Office of the Commissioners of Patents, with his Petition, on the 14th
May 1866.
I, THOMAS HOLT, of Trieste, in the Empire of Austria, but now of 66,
Chancery Lane, in the County of Middlesex, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF STEAM
BOILERS," to be as follows:-
This Invention consists in giving to marine and other steam boilers a large
increase of heating surface over and near the fire, so that the size of the
boiler may be materially diminished, whereby not only is fuel greatly
economized, but a great evaporative power is attained. The Invention can
be applied to the various descriptions of marine and land boilers.
The mode of applying the Invention and adapting it to the construction of

page_text: boilers is as follows:-Instead of conducting the currents of heat and smoke
from over the bridge at the back of the grate direct into the flues, as is usual,
a series of narrow hollow disc-shaped or oblate spheroidal chambers are
arranged around the tubular flue or space of the boiler which contains the
furnaces, so that the heated gases will rise into these spaces or chambers through-
out the entire length of the boiler before passing into the external flues, thus
by retaining the gases and holding them back for a time, giving a more perfect
combustion of the fuel and gases and insuring a much greater evaporation of
the water by allowing the water time to absorb the caloric from the heated
gases. A suitable provision is made for the admission of a sufficient quantity
of air to ensure perfect combustion in the various chambers (forined by the
discs or concave sides as above mentioned) by the introduction of curved air
supply pipes which are placed inside the air chambers and communicate
either with a longitudinal pipe which runs from the back of the boiler to the
bridge, or with any other suitable channel whereby the external air may be
admitted. If required, the disc-shaped or convex air chambers may be made
to project above the water line in the boiler, and their heated surfaces will
thus form very efficient means for drying and superheating the steam.
The construction, arrangement, and position of the disc-shaped or convex
hot-air chambers may be varied, as also their form, so as to render them
suitable for the various purposes to which the Invention may be applied.
The hot-air chambers are by preference formed of convex discs rivetted
together at their edges, thereby giving great strength to resist the pressure of
the steam. Less thickness of metal will be required by constructing the
chambers with convex sides, and a greater amount of heat will be transmitted
to the water than in boilers of the present construction. In order to increase
the heating surface of the discs they may be corrugated, or protuberances may
be made thereon or made to project from the convex sides. These hot-air
chambers may be arranged in any convenient manner, such as vertically in a
horizontal row with their axes in the same line and the tubular flue running
through the whole series.
In locomotive and some other boilers it may be found convenient to
employ two or more sets of chambers which (to save room) may be made to
interlock with each other.
In vertical boilers the air chambers may be placed horizontally and
arranged in a vertical series, or one above the other, with the flue running up
the centre, to which flue either solid or hollow deflectors are adapted for the
purpose of directing the heated gases into the horizontal hot-air chambers.
As a modification of this arrangement instead of horizontal disc-shaped or

page_text: convex chambers the hot-air spaces may be made of a star shape in section
with a central water space, and additional hot-air flues may be arranged
between the arms of the star-shaped chamber for the purpose of still further
increasing the heating surface. By this form of hot-air chamber a very large
heating surface will be obtained. This star-shaped hot-air chamber, or a
modification of the same may be placed horizontally, if preferred, and stops or
bridges may be introduced for the purpose of keeping back the hot air until
the water in the boiler has absorbed the heat therefrom.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Holt in the Great Seal Patent Office on the 14th
November 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
HOLT, of Trieste, in the Empire of Austria, but now of 66, Chancery Lane,
in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of May, in the year of our Lord
One thousand eight hundred and sixty-six, in the twenty-ninth year of Her
reign,did,for Herself, Her heirs and successors, give and grantunto me, the said
Thomas Holt, Her special license that I, the said Thomas Holt, my executors,
administrators, and assigns, or such others us 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 aud 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 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 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 Thomas Holt, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Drawings hereunto annexed, and to
the letters and figures marked thereon (that is to say): -

page_text: This Invention consists in giving to marine and other steam boilers a large
increase of heating surface over and near the fire, so that without detracting
from the evaporative power of the boiler its dimensions may be materially
diminished, whereby not only is fuel greatly economised, but a greatly in-
creased evaporative power is attained. The Invention can be applied to
the various descriptions of marine and land boilers.
The mode of applying the Invention and adapting it to various constructions
of boilers is shewn in the accompanying Drawings, and is as follows:-
Instead of conducting the currents of heat and smoke from the fire over the
bridge at the back of the grate direct into the flues as is usual, a series of
narrow hollow dis-shaped or oblate sphoroidal chambers are arranged around
the tubular flue or space of the boiler which contains the furnaces, so that
the heated gases will rise into these spaces or chambers throughout the
entire length of the boiler before passing into the exit flues. By thus
retaining the heated gases and holding them back for a time a more perfect
combustion of the fuel and gases is obtained and a much greater evaporation
of the water is insured by allowing the water time to absorb the caloric
from the heated gases. A suitable provision is made for the admission of a
sufficient quantity of air to insure perfect combustion in the various chambers
formed by the disc or concave sides as above mentioned. This may be
effected by the introduction of curved air supply pipes placed inside the air
chambers and communicating either with a longitudinal pipe which runs
from the back of the boiler to the bridge or with any other suitable chanuel
whereby the external air may be admitted. If required, the disc-shaped or
convex air chambers may be made to project above the water line in the
boiler, and their heated surfaces will thus form very efficient means for drying
and superheating the steam in the upper part of the boiler.
The construction, arrangement, and position of the dish-shaped or convex
hot air chambers may be varied, as also their form, so as to render them
suitable for the various purposes to which the Invention may be applied.
The hot air chambers are by preference formed of convex discs rivetted
together at their edges or flanges, thereby giving great strength to resist the
pressure of the steam. If preferred, the hot air chambers may be made with
straight and parallel sides, but less thickness of metal will be required by
constructing the chambers with convex sides, and a greater amount of heat
will be transmitted to the water than in boilers of the present construction.
In order to increase the heating surface of the discs they may be corrugated
or protuberances may be made thereon or made to project from the convex
sides. These hot air chambers may be arranged in any convenient manner

page_text: such as vertically in a horizontal row with their axes in the same horizontal
line, and the tubular flue running through the whole series, or they may be
arranged in a vertical series with the flue placed vertically.
In locomotive and some other boilers it may be found convenient to employ
two or more sets of chambers, which (to save 100m) may be made to interlock
with each other.
In vertical boilers theair chambers may be placed horizontally and arranged
in a vertical series or one above the other with the flue running up the centre,
to which flue either solid or hollow deflectors are adapted for the purpose of
directing the heated gases into the horizontal hot air chambers.
In the accompanying Drawings I have shewn various forms and arrange-
ments of boilers constructed on my improved principle. Fig. 1, Sheet 1., is
a longitudinal vertical section of a fixed cylindrical boiler mounted in masonry;
Fig. 2 is a transverse vertical section of the same. a, a, is the outer skin of
the boiler; b, b, b, are a series of dish shaped chambers composed of two
hollow discs rivetted together at their flanges. A few of these chambers are
shewn detached in perspective at Fig. 3. It will bo seen that each of the
discs 61 has an outer flange 1 whereby the two discs are connected together
to form one chamber b, and an inner flange 2 whereby two adjoining
chambers 6 are connected together. It will now be understood on referring
to Fig. 1 that the internal heating surface of the boiler is composed of a
number of these chambers b, b, arranged or rivetted together by their iuner
flanges 2 so as to leave a long cylindrical space for the fire-place or furnace c.
This s space for the fire-place and flue is, however, placed excentrically so as to
leave a number of crescent shaped spaces 63, Fig. 2 above, into which the
heated gases and flame from the fire rise and licat the sides of the chambers
b, b, and thus transmit heat to the water in the boiler. By this arrangement
of crescent shaped spaces 62 the heated gases are kept in contact with the
beating surfaces of the boiler and prevented from passing away too rapidly.
When the gases ultimately escape from the central flue at the back of the
bridge d into the exit flues e, c, arranged on both sides of the boiler, as seen
at Figures 1 and 2, they will have been deprived of a very large portion of
their caloric which will have been absorbed by the water in the boiler. In
order to admit air to the chambers 6 to support the combustion of the gases
therein each of the chambers is provided with a curved air supply pipe f,f,
(shown by dots in Fig. 2) which communicates with a longitudinal supply
pipe g, whereby the external air may be admitted.
Fig. 4, Sheet II., is a sectional plan view, and Fig. 5 a longitudinal
vertical section of a.marine boiler constructed on the improved plan; Fig. 6

page_text: is a front view of the same, shewn partly in section; Figures 7, 8, and 9, are
detached views, drawn on an enlarged scale, ofa portion of a marine boilersuch
as that shewn at Figures 4, 5, and 6. In this construction of boiler three sets
of dish shaped chambers and three furnaces or fire-places are employed, in
this instance the hot air chambers or spaces 6, b, are formed by the vertical
plates being arranged near together, leaving very narrow spaces between
them for the circulation of the hot air, gases, and flame from the fire below. In
order to keep these vertical plates-in their proper place, and to prevent them
from being bulged out by the internal pressure of the steam, protuberances
are formed on the plates at intervals, as shewn at 1, 1, Fig. 8, and by bring-
ing the protuberances of two adjoining plates together they will mutually
support each other and greatly strengthen the boiler. To prevent the outer
skin from giving way under pressure the sides are strengthened by tie rods
or bolts r, 1, Figures 5 and 6. The flame and heated gases from the fire
ascend up the narrow spaces b, b, between the plates, and in so doing impart
their caloric to the water in the narrow water spaces s, s, and then pass off
into the exit flue e above.
Figures 10 and 10ª, Sheet III., are sectional elevations, and Fig. 11 is a
longitudinal section of another form of marine boiler having three furnaces or
fire-places. The flame and heated gases from the fire-places pass into a
flue e, and ascend up and pass along return flues ex, ex, formed in a second
series of dish shaped chambers 6, 6, above, and constructed precisely like
the lower set, but of smaller dimensions, but instead of only one set of
chambers there are two, as will be seen in the sectional elevations
Figures 10 and 10. The chambers b, b, may be provided with air supply
pipes, as in the former instance.
Fig. 12, Sheet I., is a longitudinal vertical section, and Fig. 13 an end
elevation and partial section of a locomotive boiler constructed on my
improved system. If desired, two series of chambers b, b, may be arranged
side by side, and having flues or air passages through them, but communi-
cating at the rear with a common cast flue or chimney. The rest of the
parts are so similar to those already described that no further explanation
will be needed.
Fig. 14, Sheet III., is a vertical section of an upright cylindrical boiler;
Fig. 15 is a horizontal section or plan view of the same. In this instance the
dish-shaped chambers bare arranged in a vertical series, one above the other,
but the flue is made concentric with the circular chambers instead of excentric
as in the horizontal boilers. The fire-place is below, but up the middle of
the central flue passes a long tubular water space h, which communicates at

page_text: top and bottom with the water space surrounding the chambers 6,6. In order
to cause the flames and heated gases from the fire to pass into the spaces b, b,
deflectors i, i, are attached to the central cylindrical water space h, the effect
of which will be that the heated gases as they ascend the annular flue will
strike against the deflectors i, i, and be directed laterally into the spaces b, b,
in which before they ultimately escape they will give up a portion of their
caloric to the water.
Fig. 16 is a vertical section, and Fig. 17 a horizontal or sectional plan view
of another form of vertical boiler; Fig. 18 is another horizontal section of the
same taken at a higher level. The central water space is retained, but
instead of employing a series of oblate disb-shaped air spaces or chambers, as
in the former instances, the extended heating surface is obtained by forming
the surfaces of a star shape, as seen best in the plan or sectional views,
Figures 17 and 18. The spaces b, b, form a series of vertical flues of the
shape shewn at Figures 17 and 18, and in addition there are other vertical
flues j,j, of a cylindrical form, which communicate by the branch pipes j', j¹,
Figures 16 and 18, above with the central annular flue, and thus increase
the evaporative power of the boiler. The furnace or fire-place and ash-pit
are placed in the star-shaped air space, so that the flame and heated gases
therefroin may rise into the radial air spaces and give off their caloric to the
water in the boiler. Stops or bridges may be placed in those air spaces for the
purpose of keeping back the heat and allowing the water time to absorb it.
Fig. 19, Sheet IV., is a longitudinal vertical section; and Fig. 20 is a
sectional elevation of a stationary boiler constructed without masonryand with
the hot-air chambers b, b, formed upon the plan shown in detail at Figures 7,
8, and 9, Sheet II.
Fig. 21 is a longitudinal vertical section, and Fig. 22 a sectional elevation
of a locomotive boiler constructed upon the same plan. In order to avoid
useless repetition the same letters of reference are marked upon corresponding
parts in these Figures as in Figures 4, 5, 6, 7, 8, 9, Sheet II., so that by
reference to the description of the latter Figures, and comparing it with the
Figures shewn in Sheet IV., the construction of the boilers shewn at Figs.
19, 20, 21, and 22 will be fully understood.
Figures 23, 24, 25, 26, 27, 28, 29, 30, and 31, Sheet IV., are perspective
views of various nodifications of boilers constructed according to my Invention.
These Figures are only intended as diagrams to give a general idea of the
form and arrangement of the parts. The details and mode of carrying out
these forms will be understood by referring to the more detailed Figures
shewn in the other Sheets.

page_text: Having now described my Invention of "Improvements in the Construction
of Steam Boilers," and having explained the manner of carrying the same
into effect, I claim as the Invention secured to me by Letters Patent as
aforesaid,―
First, constructing boilers or steam generators with a series of narrow
chambers, such as those shown at b, b, in the Drawings, for the circulation of
the flame and gases, and through which hot-air chambers passes a flue for the
purpose of conveying the heated gases from the fire-place or furnace to the
air chambers b, b, in which the caloric will be abstracted from the heated
gases by the surrounding water. I claim the use and application of such
narrow hot-air chambers, whether arranged horizontally or vertically, as berein
set forth.
Second, I claim constructing hoilers, as shewn in Figures 16, 17, and 18,
with the heating surfaces arranged in a star form as herein set forth.
In witness whereof, I, the said Thomas Holt, have hereunto set myhand
and seal, the Third day of November, in the year of our Lord
One thousand eight hundred and sixty-six.
THOMAS HOLT. (L.S.)

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