IMPROVE- MENTS IN STEAM BOILERS
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Thomas Lishman at the Office of
the Commissioners of Patents, with his Petition, on the 6th July
1866.
I, THOMAS LISHMAN, of Stockton-on-Tees, in the County of Durham,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN STEAM BOILERS," to be as follows:-
My Invention consists in the general arrangement or construction of boilers,
as hereafter described, by which great strength is obtained, and the numerous
stays required in other boilers rendered unnecessary; also in the employment,
as hereafter described, of large tubes leading from one fire-box to the other, or
in the case of boilers for locomotive and other engines where there is only one
fire-box of large tubes, leading from the fire-box to the receiver or smoke box;
also in the construction and employment, as hereafter described, of wells for
receiving the accumulations. The general principle upon which I construct my
boilers is that I form as many of the parts as may be circular or cylin-
drical with the view of obtaining great strength and dispensing with stays.
In constructing boilers for marine purposes I erect at each end of a hori-
zontal boiler, which is formed externally of a cylindrical shell, a vertical fire-box
of circular form; this fire-box consists of an inner casing or fire-box proper,
surmounted by a dome, and of an outer shell or casing, also surmounted by a
dome; an annular water space exists between the fire-box proper and the
outer shell, and there is also a water space between the two domes; these

page_text: water spaces are in communication with the horizontal boiler between the two
fire-boxes. At or about the middle of the boiler I construct a receiver or
smoke box, to the top of which a chimney or uptake is rivetted; this
chimney passes through the top of the boiler, and is surrounded by a super-
heater, that is to say, a jacket is fitted round it so as to leave an annular
space, which is in communication with the boiler. Between each fire-box
and the receiver or smoke box I place one or several large tubes (for small
classes of marine engines one large tube may be sufficient, and I prefer to
place it at an angle with the horizontal plane of the boiler); these tubes are
rivetted at one end to the fire-box, and at the other end to the receiver; they
convey the flame and heat to the receiver, which thus acts as an expansion
chamber or disc. Below the boiler I construct one or more wells (by preference
two) of cylindrical or other form; these wells receive the accumulations from
the boiler, which easily circulate through the other parts owing to the absence
of small tubes; each well is fitted with a blow-off cock. When required
I employ cross tubes in the fire-boxes in connection with the boilers, and I
flange the plates wherever practicable.
For locomotive and stationary engines I construct boilers with only one
fire-box, which is formed as before explained, and I lead one large tube or
continuation of the fire-box along the boiler; at the opposite end of this tube
or continuation I rivet the end of 4 or other convenient number of smaller
tubes, the other ends of which are rivetted to the receiver or smoko box, from
which the chimney is carried up through the top of the boiler. At the
entrance of the large tube or continuation I place a bridge or cross tube.