Year: 1888

page_text: JAMES JOHNSTON, Civil Engineer, 10, Balloon Street, Manchester, in the County
of Lancaster do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
Hitherto this kind of hot air stove has been made by joining a sheet iron cylinder
with a cast base and head. The base without a grating is covered with a slab of
refractory material, and to the interior of the cylinder is fitted a lining, also of
refractory material.
It is in the interior thus fitted that combustion takes place, in such a manner that
the upper part receives directly the action of the heat. These arrangements prevent
any decoration of the stove, either by enamels or by galvanic plating, so that the
casting is obliged to be left in its natural condition, consequently articles cannot
be made in this manner having a neat appearance, for warming apartments. I have
remedied this inconvenience, thus making a new arrangement by means of the
important improvements I have effected.
•
First Interior of the hot air stove. I have arranged a feeding chamber for com-
bustion with removable grate at the place of the basis of refractory material, in this
manner the lower part of the hot air stove does not get overheated to such an extent
as to impair the decoration, whether it be enamel or galvanic plating. Moreover
by giving to the combustion column the same height as before the heating surface is
increased by the whole height of the ash pan.
Figures 1 and 2, and 2b represent a cylindrical hot air stove; 3, 4, 4, 5, 6, 7, 8,

page_text: 9, 10 represent cylindrical hot air stoves fitted with a removable grate with cast iron
fire place.
Fireplace. "The employment of the cast iron vessel or box F is for the purpose of
preventing the grate getting dirty, and to allow the apparatus to be easily cleaned.
Removable Grate:The Grate G is circular, Figures 5 and 11 and has in the
centre a pivot which rests in the socket or notch of the support. This circular
support His fixed at the side I to the cast iron box F by means of a hinge J which
permits it to be lowered or raised again and at the side K by a movable little latch L
placed on the fore part of the cast iron box, and which being drawn towards the door
of the ash pan allows the grate and its support to fall into the ash pan.
The opening thus obtained permits the fireplace to be emptied for cleaning.
In order to recharge the apparatus with fuel, care must be taken to raise again the
support of the grate which mechanically catches in the movable latch.
To this grafe is fitted.a screw ring M, figures 5 and 11, to which a rod N is
fastened by a joint, and which comes through to the outside, terminating in a ring 0,
figure 8:
To clean the grate a "push and pull" movement is given to this rod, which is
communicated to the grate, causing a rotary alternative motion round the pivot.
The arrangement of this grate therefore gives facilities for freeing it from the ashes
and cinders which choke it up, and to completely empty the fire place for cleaning,
It has also the object of keeping the fire away from the door of the ash pan, and
consequently prevents it from becoming heated, which permits having a door with an
even surface applied to a part with a similar surface and neither losing their shape by
the heat; figures 5 and 6. This hermetical closing permitting perfect regulation of
the combustion can only be really effective provided that no air can get in, beneath the
grating, a condition which is never realised, for the numerous joints of the different
parts of the basement always allows air to pass in. I have therefore obviated this
inconvenience by doing away with all joints.
I have constructed in the interior of the base, figures 5, 6, 7, a cast iron box P, cast
in one piece. This box itself receives the straightened (or flattened) door which fits
upon a frame, also straight.
The bottom of the sheet iron shaft of the hot air stove is fitted with an internal ring,
and is fixed immediately over the box, in a circular groove, which is packed with
amianthus, or cement, before tightening the screws a a, which fasten it to the
box, figures 5 and 6.
The grate rests on the circular ring bbb", and the rod N of the movable grid
passes through the box by a hole Q, of a diameter exactly the size of itself.
When the grate is let down to empty the hot air stove the rod N slides in its
passage and turns around the point O as shewn in figure 8, in dotted lines.
Through these arrangements a single joint only is required, and considering the
shape of the circular groove there would not even be need of any joint.
The hermetical closing is therefore secured & air can only pass through the door.
The advantages of these improvements are detailed further on.
Secondly. Improvements made in the upper part. For the reason that it was
necessary to withdraw the base & door from the action of the heat in order to decorate
them, it has been necessary to do the same thing for the upper part:
As shown by figures 1, 2, 3 & 4 I have placed on the combustion cylinder a cast
iron cover containing a pad of refractory material. This cover is independent of the
top of the stove. The refractory material, & the space which exists between the
cover & the top are sufficient to prevent the top from getting hot.
For hot air stoves of large size which would necessitate a slab of refractory material
relatively unweildy & consequently difficult to manage, I have obviated this incon-
venience by substituting for the pad of refractory material a special cover consisting
of a double cast iron pad, the edge of which R, is buried in a bed of sand.
This special cover is made in the following manner.
The part S is fixed to the part T by a screw U. It is intended to prevent the
part $ from getting hot by the radiation of the fire.

page_text: The rod X which supports the non-conducting cover, slides in a perforated cover V.
This cover can be decorated in any manner, for the double pad prevents it getting
hot. The management of it is also very easy for it rises at the same time as the pad.
In the replacement, at the moment of the closing of the hot air stove, the cover
immediately takes its place on the cornice whilst the hilt Y, figures 9 & 10, permits
the double pad to be tuned so that its edge, like a knife, penetrates into the bed
of sand.
It is seen that the cornice rests upon the stove, & I actually only raise the cover,
which is the lightest (or least awkard).
I have represented, figures 5 & 6, the rod of the double pad, fitted with a support
of four handles, between which is inserted a cast enamelled vessel which is filled with
water, the evaporation of which keeps the air suitably moist.
The vessel is fitted with an inner rod c causing a handle to raise it.'
A flat surface on the lower part enables it to rest on the ground when it is full of
water so that the special cover can be more easily attended to.
My hot air stoves may or may not be surrounded by an envelope. If an envelope
is used it may be formed either of cast iron open panels or with a frame fitted
with ceramic squares.
If an envelope is used the cover being separated from the cylinder is perforated,
so as to permit the free escape of the hot air arising from the circulation which
is created around the cylinder.
I have shown figs. 5 & 6, a hot air stove with the envelope made entirely in
perforated cast iron. The plan figure 7, shows the passages d, d¹, d", d¹, d¹v, dv,
arranged in the base to establish a current of ascending air.
These cylindrical hot air stoves can be perfectly constructed without a covering,
with the base & head decorated as shown in fig. 10.
The improvements adopted have the same effect.as in those described above.
The hot air stove such as shown by figs. 5, 6 & 7 present the following advantages;
First. Grate not getting dirty, through the addition to the cylindrical hearth fire
place of a cast iron box receiving the grate.
Second. The ease with which the grate can be removed & consequently of increasing,
more or less, the combustion.
Third. The case with which the hot air stove can be emptied to clean it, by means.
of a rocking grate.
Fourth. No air let in through the joints in the base, since the inside box is in
one piece, whence results an absolute regulation of the combustion, by means of the
lateral displacement of the door.
the
The hot air stove drawn in figs. 5 & 6 contains 13 to 16 pounds of coke ;
duration of combustion is twenty-four hours for regulating it in a proper manner.
Fifth. The ease with which the stove can be extinguished. When in full com-
bustion, if the door is closed entirely it is extinguished at once.
Sixth. The ease with which the covering, the base & the upper part can be
decorated on account of the distance which separates them from the centre of com-
bustion & the air which circulates from all parts of the interior.
Seventh. The ease with which the cover is worked & hermetical closing obtained.
Eighth. The ease with which these hot air stoves can be constructed so that they
can be placed under a chimney piece by fitting it with a flat flue between the shaft
& the envelope as shown in fig. 9 by dotted lines.
This flat cast iron flue is rivetted with a hermetical joint on the shaft itself of
the apparatus.
The hot gases descend again
from the ground.
to escape by the cylindrical opening at about 17 inches

page_text: Having now particulary described & ascertained the nature of my said Inven-
tion & in what manner the same is to be performed, I declare that what I
claim is :
First. The slow combustion hot air stove represented in figures 5, 6, 7 & 9, with
the removable grate above described, & the interior box made in a single piece
allowing absolute regulation.
Second. The arrangements so as to be able to decorate the base, upper part
& covering by means of cooling by the interior air space.
Third. The double pad with its cover & saturater, the arrangement for fixing the
flue higher or lower, & covering with ceramic squares.