IMPROVEMENTS IN APPARATUS FOR REGULATING THE SUPPLY OF AIR TO FURNACES
Year: 1872

page_text: LETTERS PATENT to Thomas Symes Prideaux, of 7, Eardley Crescent,
West Brompton, in the County of Middlesex, for the Invention of
“IMPROVEMENTS IN APPARATUS FOR REGULATING THE SUPPLY OF AIR TO
FURNACES.'
"
PROVISIONAL SPECIFICATION left by the said Thomas Symes Prideaux
at the Office of the Commissioners of Patents, with his Petition,
on the 24th December 1872.
I, THOMAS SYMES PRIDEAUX, of 7, Eardley Crescent, West Brompton,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN APPARATUS FOR REGULATING THE SUPPLY OF
AIR TO FURNACES," to be as follows :-
The object of this Invention is to effect certain improvements in the
apparatus for regulating the supply of air to furnaces patented by me on
the 11th of August 1870, No. 2227. This apparatus had for its object
"to afford furnaces an additional supply of air after coaling, which

page_text: supply should gradually diminish and eventuaдy cease after a certain
definite period of time by the action of an automatic apparatus, thus
securing the cutting off of the additional supply of air when no longer
required, independently of the attention of the fireman."
These improvements consist,-
1st. Of a means for varying the size of the neck of the air chamber
to enable the quantity of air supplied to be varied according to the
character of the fuel. This is effected by fixing a flap moving on an
axle in the throat of the air chamber, when according to the angle its
surface makes with the axis of the line of draft will be the amount
of impediment it will offer to the inflow of air. The right position being
attained it is to be made fast with a jam nut.
2d. Of certain modifications in and additions to the motor regulator
designed, first, to adapt it for working in a confined space above the lid
of the air chamber (as for example, between the smoke box and furnace
mouth in steam vessels), and also to prevent the access of dust or steam
to the interior; second, to enable it to support a heavier weight, thus
lessening its liability to derangement, and at the same time affording the
means of varying within certain limits the time occupied in its descent;
third, to prevent its rusting.
To attain the first mentioned objects I alter the proportions of the
cylinder, and shorten it greatly by attaching the cistern rod nearer to the
axis of the lid of the air chamber. I also construct a closed channel on
each side of the exterior of the cylinder, extending throughout its length
for the passage of the side rods from the cross head. The cross head
itself being covered with a hood or cap, the lower edge of which is placed
in apposition with the upper faces of the lateral channels, by which the
entry of dust or steam is effectually prevented. An alternative plan for
excluding the entrance of dust or steam more compact and elegant in
appearance, but entailing slightly more friction, and requiring greater
delicacy and accuracy in workmanship, is to construct the cistern rod
hollow, so as to enable it to contain within it and travel freely upon a
small tube securely tapped into the bottom of the cylinder. This tube
must be of such a size as to allow of the traverse within it of a small rod
attached at its upper end to the top of the cistern rod (or rather tube) by.
a pin joint, and at its lower to the lid of the air chamber in the same
mode. .
:

page_text: To attain the second mentioned objects I apportion the depth of the
plunger cistern and cylinder so that the cistern when at the bottom of
the cylinder considerably overlaps the edge of the plunger. As the
velocity with which the quicksilver traverses through the orifice and
enters the cistern cncreases with the pressure, the wider the range of
pressure available, the greater the power of varying at pleasure by means
of variable weights the time of the descent of the cistern and the closure
of the air valve.
To attain the third mentioned object, viz., to prevent the cylinder and
its appendages rusting, I heat the cylinder in detached pieces to a tem-
perature of about 6 or 700°, and then plunge it into warm linseed oil,
after which it is carefully wiped, and then washed with benzoline.
Finally, I may observe that I have simplified the construction of the
motor regulator by substituting for the vertical grooves on the interior
of the cylinder, and on the exterior of the plunger, a wider circum-
ferential interstice.
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 23rd June 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
SYMES PRIDEAUX, of 4, Granville Place, Blackheath, in the County of
Kent, late of 7, Eardley Crescent, West Brompton, in the County of
Middlesex, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of December, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth ycar 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 Symes Prideaux, 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,
aud vend, within the United Kingdom of Great Britain and Ireland,

page_text: Finally, I may observe that I have simplified the construction of the
motor regulator by substituting for the vertical grooves on the interior
of the cylinder and on the exterior of the plunger a wider circumferential
interstice.
Fig. I. shews a front elevation of an apparatus (to be applied to the.
mouth of a furnace) constructed according to my Invention; Fig. 2 is
a cross section of the same through the line A, B; Fig. 3 is an end
elevation; Fig. 4, a longitudinal section through the line C, D; Fig. 5, a
horizontal section through the line E, F; and Fig. 6, a back elevation.
The same letters indicate the same parts in all the Figures..
•
a, shows the exterior air case divided into three chambers or passages;
b, the cover connected by a link or pin joint to the connecting rod
attached to the cistern rod of the motor regulator or cylinder g. The
cover of the air chamber b may either be opened by the fireman when
he closes the door after coaling or made self-opening by the aid of the
segment of a screw y formed on the hinge of the furnace door, which
raises a lifting bar z, upon the door being opened; C is the grating for
heating and finely dividing the air on its passage into the furnace, and
at the same time assisting in conjunction with the plates of sheet iron t
(having vertical slits or openings so placed that the intervals shall not
correspond), to prevent the passage of the radiant heat outwards; p is.
the flap, the office of which is to vary the size of the neck of the air
chamber; w¹, a moveable weight suspended from the tip of the link
which attaches the connecting rod to the cover of the air chamber, and
which is furnished with a small hole for the purpose.
Fig. 7 shews a vertical section of the motor regulator with a hollow
cistern rod; Fig. 8 is a horizontal section of the same. g is the cylinder,
d, the cup or cistern; h is the plunger which displaces the mercury and
causes it to flow over the rim of the cistern into the cylinder when the
cover of the air chamber is raised; f is the hollow cistern rod; e, the
orifice for the passage of the mercury; u the tube tapped into the bottom
of the cylinder; w, a weight advantageously placed to assist by its gravity
in overcoming any friction opposing the closing of the apparatus; o, the
hood or cap for excluding dust and steam; and m, tlie connecting rod;
and i its pin joint.

page_text: Fig. 9 shews a vertical section of the motor regulator with a cross
head and closed channels for the passage of the side rods; Fig. 10 is a
view of the same, seen from above, showing the hood or cap, and the
channels for the passage of the side rods; g is the cylinder; d the cup
or cistern; /, the plunger; f, the cistern rod; e, the orifice for the passage
of the mercury; o, the hood or cap for excluding dust and steam; k, the
cross head; s, the side rods; and 7, the channels for the passage of the
side rods.
I have now described the nature of my Invention and the mode in
which it is to be accomplished, I do not however confine myself to the
precise mechanical details provided the principles be carried out.
In witness whereof, I, the said Thomas Symes Prideaux, have here-
unto set my hand and seal, this Twenty-third day of June, in
the year of our Lord One thousand eight hundred and seventy-
three.
T. SYMES PRIDEAUX. (L.S.)