IMPROVEMENTS IN STEAM BOILERS
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by John Gillett at the Office of the
Commissioners of Patents, with his Petition, on the 19th December
1873.
I, JOHN GILLETT, of Melksham, in the County of Wilts, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
STEAM BOILERS," to be as follows:-
My Invention is applicable to boilers of the class styled egg-ended,
and also to boilers in which one or more flues are employed, but it is
more particularly adapted to the latter class of boilers.
i
In applying my Invention to a Cornish or single-flued boiler of about
the following dimensions, namely, 5 feet diameter, 20 feet length, with
one flue 2 feet 6 inches or 2 feet 7 inches diameter, I place inside the
flue of such boiler an auxiliary cylindrical vessel or generator of about
the following dimensions, namely, 16%, inches in diameter, and 10 feet
in length, made of wrought iron or steel, said generator to be fitted with
seven wrought-iron tubes of 4 inches internal diameter, and to reach

page_text: from end to end of the auxiliary generator. The said auxiliary generator
is suspended in the centre of the boiler flue, so that about 12 inches
project beyond the boiler at the back end.
The mode of suspending the generator in the boiler flue is accomplished
as follows: On the top of the generator cylinder (or barrel) are rivetted
two or more wrought-iron flanged pipes of about 7 inches internal
diameter; the ends of these pipes pass up through the top of the boiler
flue. A brass nut is screwed on each end, which fits down on a corre-
sponding flange rivetted to the boiler flue, with an india-rubber or other
suitable washer inserted between the surfaces.
This Invention may also be applied for heating the feed water, and to
aid the circulation of water in the boiler. In this case a wrought-iron
pipe of not less than 4 inches internal diameter (for the size of boiler
stated) is attached to the back end of the auxiliary generator, where it
projects beyond the boiler, and is carried the whole length of the boiler
under the bottom, and this pipe is then attached to the flange that is
usually put on at this point for the blow-off cock; and the pipe from
the injector or force pump is inserted about 2 feet into the large pipe
before stated:
$
It will be noticed that in the apparatus before described the heated
gases from the furnace pass through tubes surrounded by water; but in
some cases it would be advisable to set the tubes in two rings or circular
pipes, and in this arrangement the tubes would be full of water, and the
heated gases would act on the outside of them. This plan though not
quite so efficient can be attached to the top of the boiler flue as easily as
the plan before mentioned.
My plan of adapting the apparatus to egg-ended or cylindrical boilers
is as follows:-The auxiliary generators are suspended from the bottom
of the boiler or boilers in the flue space behind the bridge in precisely
the same manner as that described for flue boilers, unless when required
to be modified for boilers already at work.
In a boiler of this description, about 4 feet in diameter and 20 feet in
length, fitted with an auxiliary generator 12 feet in length and same size
of barrel and tubes as that before described for flued boilers, the gain in
heating surface would be nearly 100 per cent., as the effective surface of

page_text: the auxiliary generator nearly equals the whole surface of the boiler
acted on by the hot gases from the furnace.
I do not restrict myself to the sizes, number, or length of the tubes
so employed, as they together with the plan of attachment would
5 sometimes require to be modified to suit various flues of already existing
boilers.