CERTAIN IMPROVEMENTS IN STEAM BOILERS OR GENERATORS
Year: 1863

page_text: LETTERS PATENT to John Stewart, of Leigh, in the County of Lancaster,
Boiler Maker, for the Invention of "CERTAIN IMPROVEMENTS IN STEAM
BOILERS OR GENERATORS."
Sealed the 10th May 1864, and dated the 18th November 1863.
PROVISIONAL SPECIFICATION left by the said John Stewart at the
Office of the Commissioners of Patents, with his Petition, on the 18th
November 1868.
I, JOHN STEWART, of Leigh; in the County of Lancaster, Boiler Maker, do
hereby declare the nature of the said Invention for "CERTAIN IMPROVEMENTS
IN STEAM BOILERS OR GENERATORS," to be as follows:-
My Invention relates to that portion of steam boilers or generators called
the flues, and is designed to increase the heating surface, and also to strengthen
the flues.
The improvements consist, first, in forming depressions, arches, or corrugations
along the flues, and at right angles to their length, so as to prevent the
flame from passing along the upper portion of the flue only, and to cause it to
assume an undulating course, so as to impinge upon the lowest surface of the
flue at certain intervals. If preferred these arches may be formed at the
upper surface of the flue above, leaving the lower clear for cleaning purposes;
or they may be placed alternately above and below, and will be found to add
strength to the flues."

page_text: A second part of the Invention consists in the use of a tube to .convey air
from the outside of the boiler to a point just beyond the "bridge," which
effects the admixture of air with the flame and smoke, and assists in heating
the flue, and in mitigating the smoke arising from the fires.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Stewart in the Great Seal Patent Office on the
16th May 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
STEWART, of Leigh, in the County of Lancaster, Boiler Maker, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of November, in the year of our
Lord One thousand eight hundred and sixty-three, in the twenty-seventh year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said John Stewart, Her special license that I, the said
John Stewart, my executors, administrators, and assigns, or such others
as I, the said John Stewart, 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 "CERTAIN IMPROVEMENTS IN STEAM BOILERS OR GENERATORS," upon the
condition (amongst others) that I, the said John Stewart, 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 per-
formed, 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 John Stewart, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement and accompanying Drawings (that is to say):-
My Invention relates to that portion of steam boilers or generators called
the flues, and is designed to increase the heating surface, and also to strengthen
the flues.

page_text: The improvements consist, first, in forming depressions, arches, or corrugations
along the flues, and at right angles to the their length, so as to prevent the
flame from passing along the upper portion of the flue only, and to cause it to
assume an undulating course, so as to impinge upon the lowest surface of the
flue at certain intervals. If preferred these arches may be formed at the
upper surface of the flue alone, leaving the lower clear for cleaning purposes;
or they may be placed alternately above and below, and will be found to add
strength to the flues, also allowing a greater facility for expansion and con-
traction than has been hitherto obtained.
A second part of the Invention consists in the use of a tube to convey air
from the front end of the boiler to a point just beyond the bridge, which
effects the admixture of air with the flame and smoke, and assists in heating
the flue, and in mitigating the smoke arising from the fires.
In order that the Invention may be better understood and explained in
detail, I have hereunto attached a Sheet of Drawings made upon a scale of
about one inch and a half to the foot, similar letters of reference being marked
upon corresponding parts.
Fig. 1 represents a vertical section taken through a boiler at the line A, B,
in Fig. 2, such latter Figure being a longitudinal section of a boiler exhibiting
the depressions or corrugations formed in the flues at right angles to their
length, and shewing the lower surface of the flue without corrugations, for
the better cleaning thereof; Fig. 3 is also a longitudinal section, shewing the
lower surface of the flue also raised in arches or corrugated; Fig. 4 exhibits
the upper surface of the flue as having an undulating or waved surface. The
second part of the Invention, consisting of a tube to convey air from the
outside to a point just beyond the bridge, is shewn in all the Figures.
In Figs. 1, 2, 3, 4, a, a, is the boiler, and b, b, the flues, which are corrugated,
depressed, or. rendered otherwise uneven, to cause the flame to assume an
undulating course, and thereby to obtain a greater heating surface, and more
frequent contact with or impingement upon the flues than hitherto, and also
gives additional strength to the flues. The bridge c supporting the fire-place d
may also be formed as part of the flue, as shewn; e is the air tube supplying
air beyond the bridge c.
Having now described the nature of the said .Invention, together with the
method of carrying the same into practical effect, I wish it to be distinctly
understood that I claim,-
The employment and use of corrugated, undulating, or waved surfaces in
the flues of steam boilers, for the aforesaid purposes.

page_text: And, secondly, the application and use of the air tube e, as herein-before
described, set forth, and fully illustrated in the Drawings attached.
In witness whereof, I, the said John Stewart, have hereunto set my
hand and seal, this Thirteenth day of May, in the year of our Lord
One thousand eight hundred and sixty-four.
JOHN STEWART. (L.S.)