IMPROVEMENTS IN STEAM BOILERS
Year: 1865

page_text: LETTERS PATENT to Robert William Thomson, of Edinburgh, in
County of Mid Lothian, North Britain, Civil Engineer, for the Invention
of "IMPROVEMENTS IN STEAM BOILERS."
Sealed the 1st August 1865, and dated the 18th February 1865.
PROVISIONAL SPECIFICATION left by the said Robert William Thomson
at the Office of the Commissioners of Patents, with his Petition, on the
13th February 1865.
I, ROBERT WILLIAM THOMSON, of Edinburgh, in the County of Mid
Lothian, North Britain, Civil Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN STEAM BOILERS," to be as follows, that is
to say:-
This Invention relates more particularly to steam boilers of comparatively
small size, and its object is to render such boilers more efficient whilst
retaining simplicity in construction with facility for cleaning and repairing.
A boiler made with the improvements may be in the common form exter-
nally of a vertical cylinder; it is constructed with an internal fire-box, from
the top of which a number of tubes arranged in a circle convey the fire gases
to the uptake above. Within the circle of tubes an opening is made in the
top plate of the fire-box, and to the edges of this opening there is rivetted a
vessel, by preference of copper, and of a spherical or other convenient form, and

page_text: which occupies the upper part of the fire-box. This vessel furnishes very
efficient heating surface, the fire gases in rising towards the tubes above being
compelled to spread over the bottom of it and to pass between its sides and the
sides of the fire-box in a thin cylindrical sheet. A proper circulation through
or within the vessel may be provided for by fitting a pipe to the bottom of it,
with its other end communicating with the water space surrounding the fire-
box, or a funnel may be fitted in the vessel with its top projecting above the
mouth thereof, and serving to separate the downward current of water from
the upward current of steam.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert William Thomson in the Great Seal Patent Office
on the 10th August 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
WILLIAM THOMSON, of Edinburgh, in the County of Mid Lothian, North
Britain, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of February, in the year o
Lord One thousand eight hundred and sixty-five, in the twenty-eighth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Robert William Thomson, Her special licence that I, the
said Robert William Thomson, my executors, administrators, and assigns, or
such others as I, the said Robert William Thomson, my executors, adminis-
trators, 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 night 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 J, the said Robert William Thomson, my executors or adminis-
trators, 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 Robert William Thomson, 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

page_text: following statement in writing, reference being had to the accompanying
Drawings, that is to say :-
My said Invention relates more particularly to steam boilers of com-
paratively small size, and its object is to render such boilers more efficient,
whilst retaining simplicity in construction with facility for cleaning and
repairing.
And in order that my said Invention, and the manner of performing the
same may be properly understood, I have hereunto appended a Sheet of
explanatory Drawings, to be herein-after referred to, and representing a steam
boiler as constructed with my improvements.
Figures 1 and 2 are respectively a horizontal and a vertical section of the
boiler. The external shell 1 is in the common form of a vertical cylinder, and
an inner shell 2 of a slightly tapered form constitutes the sides of an internal
furnace 3, which is supplied with fuel by the door 4. To the top of the
furnace shell 2 there is rivetted a flanged annular top or crown plate 5, and a
number of tubes 6 arranged in a circle are fixed in this plate 5 and in the
top plate 7 of the boiler for the passage of the fire gases from the furnace 3 to
the uptake 8 above. Within the circle of tubes 6, and in the central opening
of the annular plate 5 there is rivetted a vessel 9, by preference of copper,
which occupies the upper part of the furnace 3 and which is of a spherical or
other convenient form, having its horizontal area more or less enlarged below
its attachment to the tube plate 5. This vessel 9 furnishes very efficient
beating surface, the fire gases in rising towards the tubes 6 being compelled
to spread over the bottom of it, and to pass between its sides and the sides 2
of the furnace in a comparatively thin cylindrical sheet, whilst the contraction
of the upper part conveniently affords space for fixing the tubes 6. Access
for cleaning the inside of the vessel 9 and the outsides of the tubes 6 is very
conveniently obtained by a manhole 10 in the top plate or upper tube plate 7,
whilst access to this manhole, and for cleaning the insides of the tubes 6 is
obtained by lifting off the shell 11 of the uptake 8. If found necessary or
desirable, circulation through or within the vessel 9 may be provided for by
fitting a pipe to the bottom of it with its other end communicating with the
water space between the outer shell 1 and the furnace shell 2, or a funnel
may be fitted in the vessel 9, with its top projecting above the mouth thereof,
and serving to separate the downward current of water from the upward
current of steam; or, again, one or more siphon pipes may be suspended each
with one leg reaching nearly to the bottom of the vessel 9, and with the other
carried down a short distance near the outer shell 1.
Having thus particularly described my said Invention, and the manner in

page_text: which the same is to be performed, I have to state that I do not restrict
myself to the precise details herein described or delineated; but that what I
believe to be novel and original, and claim as the Invention secured to me by
the herein-before in part recited Letters Patent is, the constructing of a steam
boiler with vertical fire-gas tubes arranged in a circle, and with a vessel pro-
jecting down into the furnace from within such tubes, substantially as herein-
before described.
In witness whereof, I, the said Robert William Thomson, have hereunto
set my hand and seal, this Eighth day of August, in the year of
our Lord One thousand eight bundred and sixty-five.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
R. W. THOMSON. (L.8.)