1MPROVE- MENTS IN THE FIRE BRIDGES AND TUBES OF STEAM BOILERS, AND IN THE MANNER OF APPLYING THE SAME
Year: 1861

page_text: PROVISIONAL SPECIFICATION left by the said Robert Harlow at
the Office of the Commissioners of Patents, with his Petition, on the
7th June 1861.
I, ROBERT HARLOW, of Heaton Norris, in the County of Lancashire,
Engineer, do hereby declare the nature of the said Invention for "1MPROVE-
MENTS IN THE FIRE BRIDGES AND TUBES OF STEAM BOILERS, AND IN THE MANNER
OF APPLYING THE SAME," to be as follows:-
My improvements in the construction of the fire bridges of steam boilers
consist in making the same with fire tubes passing through them arranged
as in a multitubular boiler. The form of a fire bridge so constructed, in
ordinary cases, is that of a short semicircular vessel, and when in position it
occupies the space (at the back of the furnace) between the furnace bars and
the sides of the flue; the said fire bridge rests upon cross bearers supported
by a screw jack, the base of which is shaped to fit the bottom of the fluc. By
means of the said jack the top of the fire bridge is screwed up tight against a
thick washer inserted between it and the top of the flue, and is thus held in
position. Through the said washer a water communication is opened between
the top of the boiler and the interior of the fire bridge, which by means of a
pipe passing from the under side of the said bridge through the said screw
jack is continued into the water space at the bottom of the boiler. The said
[Price Sd.]

page_text: washer is also the means of preserving an open space above the fire bridge for
the passage of the flames.
My improvements in the construction of tubes for steam boilers consist in
making them shaped at one end with a short neck like a bottle, the opposite
end being rounded and tapped to receive a screwed tube. The bottle-shaped
tubes are to be used as water tubes for placing across boiler flues, and are
applied as follows:-The short neck of the said tube is inserted-in the boiler
through a hole made in the flue, and the tapped hole in the opposite end of
the said tube is fitted with a small screwed tube, the outer end of which bears
against a thick washer, and communicates through a hole in the same (con-
tinued through the flue) with the inside of the boiler on the side of the flue
opposite-lo. which the short neck is inserted. The said tube is then fixed by
tightening up the said screwed tube: which acts as a jack, as herein-before
described, and retains it in position.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Harlow in the Great Seal Patent Office on the
6th December 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
HARLOW, of Heaton Norris, in the County of Lancaster, Engineer, send
greeting.
WHEREAS ller most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of June, in the year of our Lord One
thousand eight hundred and sixty-one, in the twenty-fourth year of Her reign,
did, for Herself. Her heirs and successors, give and grant unto me, the said
Robert Harlow, Her special licence that 1. the said Robert Harlow, my
executors, administrators, and assigns, or such others as 1, the said Robert
Harlow, 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 United Kingdom of Great Britain and Ireland. the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN FIRE BRIDGES
AND TUBES OF STEAM BOILERS, AND IN THE MANNER OF APPLYING THE SAME," upon
the condition (amongst others) that I, the said Robert Harlow, 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

page_text: 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 Harlow, 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;
My improvements in the construction of the fire bridges of steam boilers
consists in the substitution for the ordinary fire-brick bridge, of a hollow vessel
constructed of wrought iron welded up into the form of a segment of a cylinder
(or other convenient shape to suit the figure of the flue to which it is to be
applied). This vessel is provided with a series of thin steel tubes, the size and
number of which are regulated by the dimensions of the bridge, and which are
fixed and applied in the manner and after the fashion of a multitubular boiler.
This vessel, when in use, is kept constantly filled with water, in manner here-
after explained. The bridge is put into position, and supported by a footing,
the base of which is shaped to suit the lower side of the flue. The footing is
provided with a gland and a pair of elevating screws for the purpose of sup-
porting the bridge, and by means of which the top of the fire bridge is pressed
tightly against a thick washer inserted between it and the top of the flue, and
is held thereby. Through the washer a communication is opened between the
upper part of the boiler and the interior of the bridge, which by means of a
pipe passing from the under side of the said bridge and through the gland of
the footing, is continued into the water space at the lower part of the boiler.
The before-named washer is also the means of preserving an open space above
the fire bridge for the purpose of additional heating surface, and making good
the area for the passage of the products of combustion which is deficient in
the tubes.
My improvements in the construction and application of tubes for steam
boilers consist in placing two or more removable cylindrical tubes, one beyond
another, and in such position that each tube makes with its fellow an angle
or in the line of tubes shewn as an X-like figure seen in the transverse section
of boiler.
I prefer to construct these tubes of a diameter of about 6 inch, and of a
length suitable to the diameter of the flue. They are formed of steel, of a
thickness equivalent to the strength of boiler, and thin enough to present
the least obstacle to the passage of heat. I prefer to make the tube with
hemispherical ends (although other forms may be used), one end of which
rests in a cup-shaped washer, and the other is maintained by a ferrule, upon
which is formed a right and left hand screw thread, by means of which it is

page_text: screwed tightly against the washer, and when brought into position is held
there by locking the jam nuts. The tension thus put upon the flues by the
pressure required to make the joint, converts the tubes into a series of hollow
props or pillars, giving the boiler great strength to resist collapse, and at the
same time opening a communication between the upper and lower bodies of
water, a considerable portion of the heat passing through the flue, (and which
would without this contrivance be wasted), impinges upon these tubes, and is
transmitted to the water contained therein, which becoming rarefied rises into
the upper portion of the boiler, the colder or heavier portions rushing to supply
its place. Thus the temperature is equalized, and altogether a better result
produced.
My-improvements being more particularly applicable to the class of boilers
known as the Cornish" or "internal-flued cylindrical boiler."
full size; Figures 8 and 9, on a scale of 3 inches to one foot; but it is
obvious that the size of the several parts must be adapted to the power of the
boiler to be constructed.
Fig. 1 is a sectional elevation of a steam boiler, shewing one of the
movable tubes in section, where A, A, is the boiler; A', A', the internal flues;
a', a', a', manner of applying the tubes; a, a, tube in section; ', ', commu-
nication with upper and lower portion of boiler.
Fig. 2 is a longitudinal section of the boiler A, A, shewing the furnace bars
fire bridge b', and the series of removable tubes a, a, a, in section, cut
through the middle of the flue A¹, A'.
Fig. 3 is a half-section and half-elevation. A, A, boiler; b', fire bridge; b³,
washer; b, footing; b', tube connecting boiler with bridge; 65, 66, elevating
screws.
Fig. 4 is a sectional plan of boiler A, A, with two internal flues A', A¹; the
upper flue has the tubes a. a, a, and the communication a, a, and the
bridge band washer shewn entire and in plan; the lower flue A'. A', shews
the tubes a,, and the bridge b', with its fire tubes b, b, in sectional plan.
Fig. 5 is a transverse section of an egg-ended boiler B, B, with my improved
bridge b', b', applied.
Fig. 6 is a longitudinal section of same. B, B, boiler; b', b', is the bridge;
b, . fire tubes. In this case the junction between the bridge and under side
of boiler can be made like an ordinary flanged steam or water joint. B'. B¹, a
wrought-iron circulating tube used for bringing the cooler water from the