IMPROVEMENTS IN FURNACES FOR APPLYING HEAT OF FUEL
Year: 1839

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
ANDREW CALDWELL, of Audley Square, in the County of Middlesex, Esquire,
send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Sixth day of June, in the second year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto me, the said Charles
Andrew Caldwell, Her especial licence, full power, sole privilege and authority,
that I, the said Charles Andrew Caldwell, my exors, adiñors, and assigns, or
such others as I, the said Charles Andrew Caldwell, my exors, adiiors, or
assigns, should at any time agree with, and no others, from time to time and
at all times during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the
Town of Berwick upon Tweed, the Invention of "IMPROVEMENTS IN FURNACES
FOR APPLYING HEAT OF FUEL," communicated to me by a certain foreigner
residing abroad; in which said Letters Patent is contained a proviso that I,
the said Charles Andrew Caldwell, shall cause a particular description of the
nature of the said Invention, and in what manner the same is to be performed,
to be inrolled in Her said Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part
recited Letters Patent, as in and by the same, reference being thereunto had,
will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Charles Andrew Caldwell, do hereby declare the nature of the said In-
vention, and the manner in which the same is to be performed, are fully
described and ascertained in and by the following statement thereof (that
is to say):
The Invention relates to a mode of applying a rotatory blower or fan wheel
to furnaces whereby inore advantageous results may be obtained from fuel
burned in such furnaces, and whereby that description of fuel called anthracite
coal may be burned. Before I proceed to describe the peculiar character of
this Invention, I would remark that I am aware the requisite supply of air to
furnaces has before been forced into a closed ash pit by means of blowing
apparatus, and Patents have been taken for various means and apparatus
for performing the same, but in such cases the exit of the vapours from the
flues have been permitted, yet retarded, by various contrivances, one of which
was by having a loaded valve, which had to be lifted by the force of the com-
pressed air and vapours in the flues; and other arrangement consisted in
inverting the ends of the flue in water, and in such case the vapours had to
overcome the pressure of the water by passing through the same; and another
mode was the contracting the flue or flues, towards the outlet, so as to retard,
the progress of the vapours from the fire-place of the furnace, whilst other
arrangements have simply had a blast of air into the ash pit, without any
means of retarding the progress of the heated vapours, the object in most
cases being to retain the heated vapours so long as they contained heat which
could be taken up by the water or other fluid to be heated or evaporated; but
none of these plans have come into general use, and I believe they have all
been abandoned. Now the objects of the present Invention is the same as
those above mentioned; but the mode pursued for obtaining the blast of air
with the requisite retardation are more under control of the fire man than
heretofore, and the Invention consists of the combination of three particulars
of construction of the instruments or apparatus employed.
First, a rotatory fan or blower to force air into a closed ash pit; secondly,
the placing of the fire.bars much closer together than heretofore practised
with large furnaces; and, thirdly, a moveable damper, by which the fireman
can regulate the speed of the outgoing heated vapours, and thus at all times
bave the means of retarding the outlet of the heated vapours according to the
varying nature of the fuel employed, and the varying result of evaporation he
is required to produce; and it has been found essential to observe these three
particulars in constructing furnaces where blast of air is used in place of the
natural draft of a chimney, in order to obtain the most advantageous results

page_text: from fuel; and it is supposed that for the want of having these three particu-
Jars combined together, that parties before working under somewhat..similar
circumstances have failed, and I would wish it to be understood that no claim
of invention is made in the present Patent to either of the three particulars
separately considered, nor to any two of them, the claim of Invention being
confined to the combined using of the three particulars above stated..
Having thus explained, the nature of the Invention,. I will proceed to
describe the, Drawing hereunto annexed.
DESCRIPTION OF THE DRAWING.
.
Figure 1 represents the section of a furnace arranged according to the.
Invention applied to a steam boiler... Figure 2 is a plan- of Figure 1, being
partly in section. Figure 3 is a front view in elevation of the furnace; and.
Figure 4 is a transverse section of the same. In each of these. Figures the
same letters indicate similar parts. a is an ordinary rotatory blower or fan;
and b, the air pipe leading therefrom into the closed ash pit c;. and it will be
seen that there is a sliding valve d to the air pipe c, by which the blast can be
stopped when the fire door is opened, and the valve d has at all times a
tendency to close if not held up by the bar or handle e of the fire door, such
bar or handle moving on an axis e¹, on the fire door, and enters two staples f, g.
When the door is closed, and the inner faces of those staples, being inclined
planes, the forcing of the handle at the lower end thercof towards the left
hand closes the fire door close, and the same being ground to the face of the
furnace, the opening into the fire will be thus closed air-tight, and in the act
of forcing the handle e towards the left hand it will come in contact with the
end of the rod h, moving through a guide i, the rod h. being connected to one
arm of the axis k, the other arm of the axis k being connected to the
sliding valve of the air pipe by a short connecting rod, as is shown in the
Drawing. By this arrangement it will be evident that whenever the fire door
is opened the slide of the air pipe will be closed, and when the fire door is
closed the slide of the air pipe will be open. m, m, are the fire bars, which
have exceedingly small or narrow spaces between them, and I have found that
three sixteenth to one quarter of an inch the best for consuming fuel of the
various kinds generally employed, as well as anthracite coal; but I do not
confine myself to such very narrow spaces; they may be very slightly encreased
without materially prejudicing the result; but I believe that every increase
will be found prejudicial. is the damper in the chimney; and I world
remark that small and short chimneys may be employed when this Invention
is used. The damper n moves on a hinge at the lower part, as is shown, and

page_text: although it is of importance to have moveable damper when blast is used,
there should at all times be a small opening to allow of a constant discharge
of the heat vapours from the furnace when the same is at work, and not to
have a valve or pressure to overcome, and further, from the variable circum-
stances under which such apparatus is used, it is of importance that the
opening should be capable of change with facility, in order to vary the size of
opening allowed for the continued passage of the heated vapours. o is a rod
attached by a pin joint to the valve or damper n, the other end of the rod o
being attached by a pin joint to the arm p of the axis q, and that axis 7 has.
another arm, having a connecting rod s communicating with the cranked
lever t; and v is a rod and handle passing through a guide u, there being a
series of holes in the rod by which the position of the damper may be regulated
at pleasure by a pin passing through the guide u and the rod v.
Having thus described the nature of the Invention, I would remark that
I do not confine myself to the precise arrangement of the parts here shewn
anil described, so long as the three particulars of apparatus or instruments are
combined, and it will be evident that relative placing of the parts and the
means of connection will necessarily require different modification under
different local circumstances.
In witness whereof, I, the said Charles Andrew Caldwell, have hereunto
set my hand and seal, this Sixth day of December, One thousand eight
C. A. CALDWELL. (L.S.)
AND BE IT REMEMBERED, that on the Sixth day of December, in
the year of our Lord 1839, the aforesaid Charles Andrew Caldwell came
before our said Lady the Queen in Her Chancery, and acknowledged the
Specification aforesaid, and all and everything therein contained and specified,
in form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.