THE COTTAGE GARDENER. 
[March 28 . 
850 
boiler, as shewn in Jig. 4. The same fire will do 
for one or both : care being taken that both fuel-pipe 
and boiler are directly over the furnace-bars. My 
boiler holds about 3 quarts, or rather less. It is a 
great mistake to suppose that a large boiler is re¬ 
quired. It is a loss of fuel to heat more water than 
the diameter of the flow-pipe will allow to go into 
circulation at the same time. In mine, warmth is 
perceptible as soon as the fire is lighted. My green¬ 
house is 18 by 15 feet; and being built with its back 
adjoining a sitting-room, I am obliged to adopt the 
following arrangement, which others would vary 
according to circumstances. 
Eig. 5 represents the whole complete, put together, 
and set in brickwork :—m is the flow-pipe conveying 
the hot water from the boiler; n is the brass union- 
joint connecting it with the tank in the greenhouse; 
o is the return-pipe, bringing the water back from the 
tank; h is the flue, through the wall k, into the 
chimney l; and i is a damper. 
As soon as the fire is lighted, the lieated air ascends 
from the plate to a low ceiling (p, in fig. 6), in a porch 
-if -' P 
<tvA-;d 
rm 
nil 
P 
Fig. 6. 
at the north end of the greenhouse, into which there 
is a door (r) from the porch. Over this glass door a 
head-light of one pane, (s) swings upon pivots, and 
lets the warm air into the greenhouse. Under the 
threshold of this door is a cast iron grating, (t) com¬ 
municating with an air drain under the floor of the 
house. This drain has a regular fall of several 
inches: thus a circulation of warm air is kept up on 
the Polmaise principle. 
Very little fuel is consumed : less than a bushel of 
coke in 24 hours, at a cost of about 4d. It requires 
very little attention; when the fuel-pipe is filled to 
the top with coke, and the lid put on, the contents of 
the pipe b will last from 12 to 24 hours without re¬ 
plenishing : according to the heat required, and the 
draught given by means of the damper and ventilator. 
The flue is a four-inch iron pipe, with a nicely-made 
damper fitted into it. There is a double door to the 
furnace and ash-pit. In the outer door is a circular 
brass ventilator or regulator. The short iron pipe- 
flue must pass into a brick chimney—this is indispens¬ 
able. By means of the damper and ventilator the nicest 
possible regulation of draught may be maintained. 
The atmosphere of the house is never quiescent: an 
undulation of the vine-leaves is always perceptible. 
I have now tried it for two years; it has never failed 
to do all that I wish. The fire never goes out, night 
or day (if the coke is broken small enough), unless 
designedly put out; or through any gross mismanage¬ 
ment, when under the care of one who does not un¬ 
derstand its principle. 
The coke is broken into pieces of a size varying 
from that of a hazel-nut to a walnut; the residue is 
sifted, and also burned; the very smallest dust only 
being thrown away. 
I do not keep a regular entry of my self-registering 
thermometer; but, during this severe winter, my 
lowest temperatures have been about the following:— 
Greenhouse, night temperature, 40 u or 45° to 50° or 
55°. Among pines, over tank, night, 50° or 55° to 
60°—never below 50 u . 
Temperature, on floor level, 40“ or 45°, generally. 
The apparatus is perfectly clean, free from dust, 
and without the smallest escape of coke-gas. The 
whole can be taken down in five minutes, without the 
aid of any workman, cleaned, and replaced ; for when 
once the brick-work is complete, no unsetting or re¬ 
setting is required. The little copper boiler is made 
of the thickest metal that can be procured. By 
using copper, instead of iron, there is never any 
sediment in the pipes or tank. I have some shallow 
zinc pans, which I place on plate a at pleasure, for 
evaporation. I have also means of preserving suffi¬ 
cient moisture by the tank in the house. 
This is a simple and effectual plan for procuring 
the Polmaise circulation of warm air, and the tank 
circulation of warm water, by means of one and the 
same fire. Either of them can be shut off at plea¬ 
sure when not required. It can never fail. I had a 
model made in wood, under my own direction, which 
I then sent to the nearest foundry to be cast. 
You will like to have a little guidance as to the 
first expense:— 
The cast iron plate a, with fuel-pipe Z>,) 
cover, flange, handles, &c., complete, L 3 12 0 
as shewn .j 
Copper boiler, with branches and unions 1 15 0 
415 7 0 
The furnace-bars and ash-pit door I had by me 
before. I have not included the brick-work—the in¬ 
terior of which is lined with Ramsay’s fire-bricks. 
Of course, for any house of larger dimensions than 
mine, an apparatus upon a proportionately larger 
scale would be required. If I were to make a 
second, and did not require a boiler, &c., for hot 
water, I should think of having the casting in a 
dome-shape instead of a flat plate, which would give 
a larger warming surface of iron : such, as I believe, 
is usually known as the cocWe-shape; but this would 
be matter of experiment. 
Bo accurately does this work, that if the damper is 
