IMPROVEMENTS IN THE CONSTRUCTION OF SMITHS' HEARTHS
Year: 1882

page_text: LETTERS PATENT to Percival Everitt, of Queen Victoria Street, in the City of
London, Engineer, for an invention of "IMPROVEMENTS IN THE CONSTRUCTION
OF SMITHS' HEARTHS."
PROVISIONAL SPECIFICATION left by the said Percival Everitt at the
Office of the Commissioners of Patents on the 6th March 1882.
PERCIVAL EVERITT of Queen Victoria Street in the City of London, Engineer,
"IMPROVEMENTS IN THE CONSTRUCTION OF SMITHS' HEARTHS."
The object of this invention is to increase the efficiency of Smiths Hearths and
to facilitate the discharge of slag therefrom. The Hearth proper or the surface
which carries the fuel I make dish-shaped with a hole in the centre thereof. This
dish-shaped piece forms a cover for an annular air chamber in connection with a
fan or blower. The internal arrangement of this air chamber may vary so long as
it is made to retain the air forced into it by the blower a sufficient time to enable
its temperature to be raised considerably by contact with the under surface of the
cover while moving towards the escape opening at the centre of the chamber.
This escape opening I make by preference annular so that the air as it leaves the
heating chamber will rise freely and distribute itself through the centre of the
overlying fuel. The central opening through the air heating chamber I fit with a
plug which may be removed from time to time to permit of the discharge of the
molten slag from the Hearth. Or instead of a plug I may close the central
opening through the air heating chamber by a weighted valve which on being
depressed will allow of the discharge of the molten slag and will on pressure being
removed from the lever which carries the valve rise automatically to its seat. My
improved Smith's Hearth I propose to make of cast iron and to connect together
the several parts into which it is divided for the convenience of the moulder, by
means of luting.
To provide for an intense hot-blast when that is desired I control the exit
opening for the air by means of a valve or cock which when closed or partly closed
will ensure the compression and rise of the temperature of the air in the heating
chamber.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Percival Everitt in the Great Seal Patent Office on the 6th September
1882.
PERCIVAL EVERITT of Queen Victoria Street in the City of London Engineer
"IMPROVEMENTS IN THE CONSTRUCTION OF SMITH'S HEARTHS"
The object of this invention is to increase the efficiency of Smiths Hearths and
to facilitate the discharge of slag therefrom. The Hearth proper or the surface
which carries the fuel I make dish-shaped with a hole in the centre thereof.-This
dish shaped piece forms a cover for an annular air chamber in connection with a
fan or blower. The internal arrangement of this air chamber may vary so long as
it is made to retain the air forced into it by the blower a sufficiently long time to
enable its temperature to be raised considerably by contact with the under surface
of the cover, while moving towards the escape opening at the centre of the chamber.
This escape opening I make by preference annular so that the air as it leaves the
heating chamber will rise freely and distribute itself through the centre of the
overlying fuel. The central opening through the air-heating chamber I fit with a
plug which may be removed from time to time to permit of the discharge of the
molten slag from the hearth. Or instead of a plug I may close the central opening
through the air heating chamber by a weighted valve which on being depressed
will allow of the discharge of the molten slag and will on pressure being removed
from the lever which carries the valve rise automatically to its seat. My
improved Smiths heath I propose to make of cast iron and to connect together the
several parts into which it is divided for the convenience of the moulder, and to
facilitate the renewal of any worn part, by means of luting.
To provide for an intense hot blast when that is desired I control the exit
opening for the air by means of a valve or cock which when closed or partly closed
will ensure the compression and rise of temperature of the air in the heating
chamber:-
In the accompanying drawings Fig: 1 is a side elevation and Fig: 2 a sectional
elevation (taken on the line 1. 2. Fig: 1) of a Smiths Hearth constructed according
to my Invention.
In these Figures A is the dish shaped hearth proper having a central aperture a.-
B is the annular air heating chamber connected with a fan or blower (not shewn
in the Drawings) by an air trunk C and provided with an escape opening 6 for the
passage of the heated air to the fuel.
B is a valve for regulating the omission of the heated air from the chamber B.
This valve B¹ is situate on the opposite side of the air chamber to the point of
junction between the air chamber and the air trunk so that the air has to travel
on each side round one half the circumference of the air chamber before it is able
to escape by the valve B¹.
D is a valve or trap serving to close the bottom of the central aperture a and
carried by a weighted lever E or its equivalent.
The valve D allows of the molten slag being discharged from the hearth when
necessary.
The hearth proper it will be seen is of dish shape built up as shown of annular
sections of cast iron, say three in number the joints of the several sections being
luted together.
The lowermost a¹ of these annular castings having a hole a in its centre rests on
a suitable flanged support and forms the bottom and outer side of the air
chamber B. The uppermost annular casting a² forms the sloping top and inner
side of the air chamber B and rests upon the casting a¹ an annular rib q³ or its

page_text: equivalent on the latter, serving to hold it securely in place. The third and
central section of cast iron a is formed with an aperture corresponding with the
central aperture a in the lower casting a¹ above referred to. This central casting
rests on a flange of the casting a2 and its lower edge is rounded and does not quito
extend to the level of the bottom casting a' thus leaving an escape opening b
(preferably annular) by which the air which has been retained and heated in the
chamber B may rise freely and distribute itself into the centre of the overlying
fuel, the lower part of the opening a being at this time closed by the trap or
valve D.
The air chamber B is fitted as indicated in Figures 1 and 2 by dotted lines with
a plug or valve B', operated by a lever handle B-by which arrangement the air
from the blower entering the chamber at a point opposite to the valve B¹ may be
retained and compressed within the chamber until sufficiently heated by contact
with the undersurface of the sloping cover forming part of the hearth and be then
discharged from the air chamber B filling the annular space beneath the central
casting and passing by the rounded lip or annular escape opening b at a steady
pressure into the centre of the mass of fuel on the hearth. Means may be provided
if necessary for retaining the lever handle B in any desired position.
When it is desired to discharge the molten slag the weighted lever E or its
equivalent will be raised by the pull, handle F thereby lowering the trap or
valve D and opening the aperture a.
It will be seen that the castings are so constructed and arranged as to constitute
a hearth with a smooth sloping upper surface like a shallow funnel and having an
air chamber situate within the castings and around the central aperture of the said
funnel.
In Figures 3 and 4 I have shewn a modified arrangement of the valves for
regulating the emission of heated air to the hearth and for discharging the slag
through the central aperture a; Fig: 3 being a side elevation of the hearth centre
and Fig: 4 a sectional elevation taken on the line 1. 2 Fig: 3.
Instead of operating the valve B' for regulating the compression and emission of
heated air as described with reference to Figures 1 and 2, I key the lever B2 upon
a shaft or axle B³ to which a short lever arin B is also keyed. This short lever
arm B is loosely connected with the spindle B5 of the valve B¹ and when the
lever B is raised the shaft B³ will be partially rotated and the lever arm B' will
pull down the valve spindle B; and draw the valve B¹ off its seat.
To enable the slag to be discharged when required and at the same time to
allow a considerable quantity of slag to accumulate without impeding the working
of the hearth or the free passage of heated air into the fuel I provide the following
arrangement.
To the underside of the lower casting a¹ and immediately below the central
aperture a. I attach by screw bolts or otherwise a box pot or receptacle G having
the shape of a frustum or a vessel swelling towards its base. This box or receptacle
is closed at bottom by a trap or valve H supported by a bell crank lever I
pivotted in brackets or lugs attached to or formed in one with the receptacle G.
On rocking this bell crank lever I on its fulcrum pin the valve H will be opened
and the slag discharged. The slag accumulating in this broad based receptacle will
spread out as it falls and not cake into a solid mass difficult to be removed.
In order to regulate with greater nicety the supply of heated air I in some cases
in addition to the valve B¹ above described, interpose a valve between the fan or
blower and the air chamber B.
This additional valve K is shown in Fig: 5 and it is operated by the motion of
a short lever arm keyed on a shaft L' the valve being so constructed that a slight
backward movement of the valve will allow a plentiful supply of air to pass
around it from the main air trunk C to the box or casing C in connection with
the air chamber B. The box or casing O' I attach by screw bolts C³. and C³.
whereby it may be easily removed for the inspection, cleaning, or repair of the
valve K.

page_text: Moreover by slackening the screw bolts C and C³ I am enabled to swing round
the hearth with the box or casing C¹ attached, upon the bolt C as a centre, and
thus shift the hearth to one side or the other, as may be required to suit the work
in hand.
Having now set forth the nature of my said Invention of "Improvements in the
construction of Smiths Hearths" and explained in what manner the same may be
carried into practical effect I wish it to be understood that I claim.
First A Smiths hearth having an annular air heating chamber in communi-
cation with an air supply on the one hand and with a central escape opening or
openings on the other, such hearth being provided with a valve or valves for
regulating the retention or emission of the heated air and with a trap or valve for
the discharge of the molten slag substantially as described with reference to the
drawings.
Secondly-The adaptation to smiths hearths of a centrally disposed trap or
valve for the discharge of the slag and means for actuating the same as described
with reference to the drawings or any mere modification thereof.
In witness whereof I the said Percival Everitt have hereunto set my hand
and seal the fifth day of September in the year of our Lord one thousand
eight hundred and eighty two.
PERCIVAL EVERITT. (L.S.)