IMPROVEMENTS IN APPARATUS FOR REGU- APPARA FOR REGULATING THE SUPPLY OF AIR TO FURNACES
Year: 1857

page_text: LETTERS PATENT to Thomas Symes Prideaux, of 32, Charing Cross,
Engineer, for the Invention of "IMPROVEMENTS IN APPARATUS FOR REGU-
"
Sealed the 13th April 1858, and dated the 30th October 1857.
PROVISIONAL SPECIFICATION left by the said Thomas Symes Prideaux
at the Office of the Commissioners of Patents, with his Petition, on
the 30th October 1857.
I, THOMAS SYMES PRIDEAUX, of 32, Charing Cross, Engineer, do hereby
declare the nature of the Invention for "IMPROVEMENTS IN APPARATUS FOR
REGULATING THE SUPPLY OF AIR TO FURNACES," to be as follows:-
The object of this Invention is to provide furnaces with an extra supply of
air after coaling by apparatus which shall (automatically) gradually diminish,
and finally shut off altogether this extra supply by such time as the coking of
the coal may be judged to be complete.
In furnaces where the products of combustion travel horizontally from the
mouth to the back it is undesirable that the bars should be more than 5 or
6 feet long, and where they exceed this length a better result will be obtained
by admitting a portion of the extra air required after coaling at the back.
Thus in a furnace 8 feet long, by admitting about 6 parts of air at the door
and about 2 parts at the bridge, the whole of the smoke may be burned with
the admission of a smaller quantity of air than would be sufficient if the whole

page_text: supply be admitted at the mouth of the furnace. To effect this object, instead
of causing the valve box to enter within the furnace (as shown in my Patent
dated 27th December 1853), I cause it to shut against the margin of the
furnace so that its lower edge may meet a channel running beneath the dead
plate and communicating with the back of the furnace.
Where furnaces have a surplus draft power regulated by a damper in the
chimney, instead of the sliding damper now generally used, the damper is hung
on an axle so weighted and arranged as by.its own gravity. to settle into the
position to give the average draft required, and the increased but gradually
diminishing supply of air demanded after coaling is obtained by setting the
damper wider open, and causing it to close gradually to its former position (in
any desirable period) by means of self-acting apparatus adjusted to regulate
the time of closing.
In some cases where no surplus draft exists in the chimney (or where from
other causes this adjustment by damper is not desirable), the supply of air
is regulated by the use of a steam jet, the pipe supplying which is opened after
coaling, and is made to close gradually by self-acting mechanism. Where
the discharge of steam through the chimney is continuously employed for the
production of draft, the increased supply of air required after coaling is
obtained either by increasing the size of the supply aperture, or where (as in
locomotives) the whole of the used steam from the cylinders is transmitted
by the flue by contracting the orifice for exit; the average condition of draft
demanded being gradually restored in any. required period of time by the
action of self-acting apparatus. When for kilns used in the manufacture
of pottery, I regulate the admission of air to the furnace by means of a self-
acting valve in communication with an air chamber at the sides of the fire-
places.
The self-acting apparatus used in combination with the apparatus above.
explained may be varied, but those preferred are as follows:-A wheel having
a hollow periphery to contain fluid, and divided radially by partitions each
baving a small hole, such partitions temporarily arresting the flow of the fluid
and prolonging the time of its descent. On one side there is a well into.
which all the fluid ultimately arrives when the extent of closing of: the air
regulating apparatus has been obtained. There is a passage between the well
and the opposite side or diameter of the wheel through which (on turning the
wheel so as to bring the well above the horizontal-position) the fluid runs to
the opposite side of the axis, when the fluid will only again reach the well by
passing through the series of partitions in the hollow periphery as the wheel.
moves on its axis in a direction to bring the well below the axis of motion

page_text: of the wheel; by this arrangement the self-acting apparatus may be adjusted to:
any requirement. Or, in place of the above apparatus acting by gravity, the
principle of immersion of the float may be employed, and the fluid placed in a
vessel having two cisterns, the tops of which are connected by a wide passage:
and the bottoms by a narrow one: Two floats or plunges are so adjusted with
reference to the two cisterns, that by altering the relative level of the ends"
by causing either the floats or the cistern vessel partially to revolve on an axis,
that when the plunger or float on one side shall be at the bottom of the
cistern, the plunger or float on the other side shall be at the top of its cistern.
By causing the plunger to descend to the bottom of the cistern the fluid is:
forced out and caused to run along the higher level passage into the other
cistern, there supporting the float or resisting the immersion of the float on
that side, it allows it gradually to approach the bottom of the cistern as the:
fluid gradually escapes through the small or lower level passage. Or the fluid:
used in the self-acting apparatus may be moved by the action of a flexible or
bag piston in place of a solid one, the flexible or bag piston driving the fluid
through a small passage; by thus using flexible or bag pistons the fluid is.
prevented evaporating or oxydating by reason of its being closed within a
chamber impervious to air.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed.
by the said Thomas Symes Prideaux in the Great Seal Patent Office on
the 30th April 1858.
. TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS:
SYMES PRIDEAUX, of 32, Charing Cross, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters:
Patent, bearing date the Thirtieth day of October, in the year of our Lord'
One thousand eight hundred and fifty-seven, in the twenty-first year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Thomas Symes Prideaux, Her special licence that I, the said
Thomas Symes. Prideaux, my executors, administrators, and assigns, or such
others as I, the said Thomas Symės Prideaux, my executors, adininistrators, 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 APPARATUS FOR REGULATING THE SUPPLY OF AIR TO FUR-

page_text: NACES," upon the condition (amongst others) that I, the said Thomas Symes
Prideaux, 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 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 Thomas Symes Prideaux, 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 thereof, that is to say :-
The object of this Invention is to provide furnaces with an extra supply of
air after coaling by apparatus which shall (automatically) gradually diminish
and finally shut off altogether this extra supply by such time as the coking of
the coal may be judged to be complete.
In furnaces where the products of combustion travel horizontally from the
mouth to the back, it is undesirable that the bars should be more than five
or six feet long, and where they exceed this length a better result will be
obtained by admitting a portion of the extra air required after coaling at the
back. Thus in a furnace eight feet long, by admitting about six parts of air
at the door and about two parts at the bridge, the whole of the smoke may be
burned with the admission of a smaller quantity of air there would be sufficient
if the whole supply be admitted at the month of the furnace. To effect this
object, instead of causing the valve box to enter within the furnace (as shown
in my Patent dated 27th December 1853), I cause it to shut against the
margin of the furnace, so that its lower edge may meet the lower edge of a
channel running beneath the dead plate and communicating with the back of
the furnace as shown in Figure 1, where a is the dead plate, 6 the channel
beneath communicating with a perforated bridge or air chamber at the back
of the furnace, and c the lower edge of the valve box.
· Where furnaces have a surplus draft power regulated by a damper in the
chimney, instead of the sliding damper now generally used, the damper is
hung on an axle so weighted and arranged as by its own gravity to settle into
the position to give the average draft required, and the increased but gradually
diminishing supply of air demanded after coaling is obtained by setting the
damper wider open, and causing it to close gradually to its former position (in
any desirable period) by means of self-acting apparatus adjusted to regulate
the time of closing, see Figure 2, which represents the section of a chimney
where a is the damper shown as just thrown wide open, 6 a weighted lever

page_text: fixed to the axle of the damper, and c a self-acting apparatus adjusted to
regulate the time of closing.
In some cases where no surplus draft exists in the chimney (or where from
other causes this adjustment by damper is not desirable), the supply of air is
regulated by the use of a steam jet, the pipe supplying which is opened after
coaling, and is made to close gradually by self-acting mechanism. Figure 2
may be referred to as illustrating this and the following Invention, the
chimney being regarded as a steam pipe, and the damper as a throttle valve.
Where the discharge of steam through the chimney is continuously employed
for the production of draft, the increased supply of air required after coaling
is obtained either by increasing the size of the supply aperture, or where (as
in locomotives) the whole of the used steam from the cylinders is transmitted
by the flue by contracting the orifice for exit. The average condition of draft
demanded being gradually restored in any required period of time by the
action of self-acting apparatus, see Figure 3, which represents a section of
the chimney of a locomotive. a is the blast pipe, having side apertures b, and
fitted with a sliding ring c, which has attached to it on each side a rack-
work d, worked on each side by a toothed wheel e, the axle of which on one
side is carried through the chimney and connected with the weighted lever f,
the descent of which is regulated. by raising the self-acting. apparatus g. By
raising the lever the ring rises and shuts up the side apertures, thus increasing
the keenness of the draft, which gradually diminishes to the average standard
as the lever descends.
When for kilns used in the manufactory of pottery, I regulate the admis-
sion of air to the furnace by means of a self-acting valve in communication
with an air chamber at the sides of the fire-places, see Figure 4, where à is
an air channel, capable of being closed or opened to the atmosphere by the
damper b, which swings on an axle, to which is attach the self-closing
apparatus c (shewn in a front view in Figure 4). The air chamber a leads
to the perforated air chambers & at the sides of the fire-place, and the
requisite air, after each coaling, is admitted by putting the self-acting appa-
ratus into the position shown in the Figures, when it gradually clowses.
itself.
The time of closing apparatus for regulating the supply of air to
furnaces is most conveniently regulated by the time occupied by the passage
of a given quantity of fluid through an orifice of a given size, and this
measure of time is susceptible of mechanical application on three different
principles :-
First, that of equilibrium or the balance, wherein à vessel, moving freely

page_text: on a horizontal axle fluid, either gradually descends to a position less distant
from the line of support, or else passes out of the vessel.
Secondly, that of immersion or the. float where the supporting or resisting
surface of the fluid gradually sinks as the fluid escapes.
Thirdly, that of the piston, where the fluid being subjected to pressure in a
vessel provided with a small orifice, gradually yields to this pressure by
escaping, comprising three varieties, videlicet, first, the well-known piston
fitting cylinder; second, where a plunger enters a cylinder through a closely
fitting collar; third, the bag piston or flexible cylinder.
In my Patent for regulating the supply of air to furnaces, dated December
27th 1853, the mode of closing figured was a simple form of cataract. This,
though easily kept in order with a little attention (wanting only to be sup-
plied with water and kept clean), becomes in the hands of many stokers,
through neglect, often deranged, and having regard to the general character
of this class of men, it has been my aim to devise means of closing which
shall be altogether independent of their superintendence and co-operation.
The self-acting apparatus used in combination with the apparatus explained
in the present Patent, and in my Patent dated 27th December 1853, may be
varied, but those preferred are as follows:-A wheel, see Figure 5, having a
hollow periphery to contain fluid, and divided radially by partitions b, b, b,
each having a small hole c, such partitions temporarily arresting the flow of
the fluid and prolonging the time of its descent. On one side there is a
well d, into which all the fluid ultimately arrives within the extent of closing
of the air-regulating apparatus has been obtained. There is a passage e
between the well and, the opposite side or diameter of the wheel, through
which (on turning the wheel so as as to bring the well above the horizontal
position) the fluid runs to the opposite side of the axis, when the fluid will
only again reach the well by passing through the series of partitions in the
hollow periphery as the wheel moves on its axis in a direction to bring the
well below the axis of motion of the wheel; by this arrangement the self-
acting apparatus may be adjusted to any requirement.
Or in place of the above apparatus acting by gravity, the principle of
immersion of the float may be employed, and the fluid placed in a vessel,
Figure 6, having two cisterns a and b, the tops of which are connected-by a
wide passage c, and the bottoms by a narrow one d. Two floats or plungers
a¹ and 6', are so adjusted with reference to the two cisterns, that by altering
the relative level of the ends by causing either the floats or the cistern vessel
partially to revolve on an axis, when the plunger or float on one side shall be
at the bottom, of the cistern, the plunger or float on the other side shall be at

page_text: the top of its cistern. By causing the plunger a¹ to descend to the bottom of
the cistern, the fluid is forced up and caused to run along the higher level
passage c'into the other cistern b, there supporting the float, or resisting the
immersion of the floats on that side which would be otherwise caused by the
weight of the shutters or other apparatus attached to the bar e; it allows it
gradually to approach the bottom of the cistern as the fluid gradually escapes
through the small or lower level passage d, the size of which (and consequently
the time of descent) may be varied by the adjusting screw f.
Or the fluid used in the self-acting apparatus may be moved by the action
of a flexible or bag piston in place of a solid one, the flexible or bag piston
driving the fluid through a small passage. By thus using flexible or bag
pistons, the fluid is prevented evaporating or oxydating, by reason of its being
closed within a-chamber impervious to air. Figure 7 represents one form of
bag piston; the lever is supposed to be just raised, and the apparatus put into
action. a and 6 represents two flexible air-tight chambers, opening into each
other by the large passage c, and closed by the valve d, which has a small
aperture in it at e; the pressure of the fluid beneath, caused by the weight of
the lever, keeps the valve closed, and the fluid traverses slowly into the upper
chamber through the small aperture e, thus allowing the lever gradually
to sink.
The act of lifting the lever takes the pressure off the under side of the
valve, which opens and allows the fluid suddenly to descend into the lower
chamber, and the apparatus is again put into action.
Figure 8 represents another form of bag piston, and the same letters
indicate the same parts.
Having thus described the nature of my. Invention, and the manner in
which it is to be performed, what I claim is,-
First, the simultaneous introduction of air by a self-acting apparatus at the
mouth and back of the furnace, and the application of a self-closing valve to
the exterior of the furnace mouth, the edge of the valve box shutting against
the margin of the furnace instead of entering within it.
Second, the regulating the supply of air to furnaces with a surplus power
of draft, by connecting the damper with a gradually self-closing apparatus.
Third, the regulating the supply of air to furnaces where the draft is
assisted by a steam jet, by placing this jet under the control of an automatic
apparatus, which, upon increasing power being given to the jet after coaling,
shall gradually reduce this power to the average pitch demanded.
Fourth, the regulation of the supply of air to the kilns or furnaces used in

page_text: the manufacture of pottery, by means of a self-closing valve in communication
with air chambers at the sides of the fire-place."
Fifth, the employment in self-acting apparatus of the principle of the
balance, wherein a vessel, moving freely on a horizontal axis fluid, gradually
descends to a position less distant from the line of support by a series of steps,
as described with reference to Figure 5.
Sixth, the employment of the principle of immersion or the float, where the
cistern is a closed vessel entered by a closely fitting axle, as described with
reference to Figure 6.
Seventh, the application of flexible vessels in the construction of self-
regulating apparatus, described in reference to Figures 7 and 8.
In witness whereof, I, the said Thomas Symes Prideaux, have hereunto
set my hand and seal, this Thirtieth day of April, in the year of our
Lord One thousand eight hundred and fifty-eight.
Witness,
FRED HARRIS.
THOMAS SYMES PRIDEAUX. (L.S.)