237 
THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, January 22, 1861. 
ventilator should he placed for the escape of the cold air 
in the pit, when the hot air was first lei in. 
In. the Polmaise system all the confined and conta¬ 
minated cold air in a pit or house has to be passed and 
burnt between hot plates of red hot iron, and returned to 
tfie same house in an endless stream, or current, back and 
round again and again as long as the heat is wanted. 
One does not like to ask many questions in social conver¬ 
sation, else I should have asked my friend why he advised 
the ventilator for my pit, seeing he had no provision for 
letting off the cold air from his conservatory. A venti¬ 
lator iu the end of my pit may, or may not, be necessary. 
No one, I believe, can positively prove that by inference, 
the plan must be put to the test of actual practice before 
a decided opinion can be given. No one could say before¬ 
hand that a rushing aud continuous flow of warm air 
could be passed into a large conservatory or other room 
without some opening on purpose to let out as much cold 
or cooled air ; but all the opening in his conservatory is 
that between the laps of the panes of glass in the roof— 
the front, being all glazed like windows, is just as air¬ 
tight as the windows of the best-built mansions. Still 
he must have thought my pit too much air-tight, for this 
mode of heating, without some such contrivance. 
Another thing occuring to me as essential to this mode 
of heating (which heating we must call after the inventor 
as soon as we have his name and consent), is that the 
extreme heating of the Polmaise, in passing through the 
furnace, must be altogether avoided. That was most 
certainly the main cause of the total failure of the true 
Polmaise. But in this mode there need be nothing of 
the kind. True, we must learn if the system will work 
on the level, and we must also learn every other parti¬ 
cular which is not already explained; but there is no 
question about the intensity of the heat which any one 
who is accustomed to hothouses and the requirements of 
plants may not settle at once, and before laying a brick. 
Take the heated conservatory and my pit as extreme 
examples, the largest and the smallest, the farthest off 
and the nearest to the hot-air chamber. The plants in 
both cases are of the same nature, and the same degree 
of heat is to be aimed at. The heat which rises into the 
conservatory through the two openings in the pathway 
at one end of the house would suit my plants and my pit 
to the same degree and nicety as it does there; but the 
heat in my air-chamber would need to be very different 
from that of the one to the conservatory, not on account 
of the difference of the sizes of the two plant-places, but 
owing to the difference of the distances the two air- 
chambers are, or would be, from the place to be heated. 
His air-chamber is, say, four yards from the escape of the 
hot air to the conservatory, and the distance of my air- 
chamber at the end of the pit is merely the thickness of 
the brickwork which forms the end of the pit. If the 
hot air in my air-chamber was as hot as that in his air- 
chamber, it would, probably, be too hot for my plants, as 
it could not get cooled in passing the short distance like 
that into the conservatory : therefore, and considering 
the smallness of the pit, the heat in the hot-air chamber 
for the pit need not have more than one-fourth of the heat 
in that for the conservatory; and, therefore, this mode 
of heating pits and small greenhouses I conceive to be as 
safe for the life and well-being of ornamental plants as 
the best system now in use. The heated air from a 
closed hot-water system must be as hot and as dry on 
leaving the surface of the pipes, and other ironwork, as it 
would need to be in leaving the air-chamber, or when it 
entered the pit or house. Then the rest of the difference 
would be as that between a baker’s oven and a hot-water 
apparatus. If the oven is too hot, or not sufficiently hot 
for the purpose, Avork the ventilators or the fire before 
you let the heat go to the greenhouse. Fresh air is con¬ 
stantly warmed, but must not be baked or roasted in the 
oven on its passage to the plants: therefore, and for all 
very small places, it would bo necessary to have control 
over the hot-air channel between the oven or hot-air 
chamber and the entrance to the house or pit. That could 
be done by a common “ damper ” or slide, to stop the 
current if it happened to get too hot. 
For all small or moderate houses I would shun metal. 
No more iron than the fire-bars and furnace-doors 
would I allow, as far as I can see through it at pre¬ 
sent. The air-chamber I should make more safe than 
the head and neck of the best flue now in use, and 
use fire-brick and fire-mortar between the top of the 
fireplace and the bottom of the air-chamber, or, say, 
the flame would and could touch none but firebricks. 
The air-chamber I would make much larger in pro¬ 
portion than the fireplace, so as to have the air not so 
hot. The idea of appropriating the heat in the ash-pit 
when it is half full of hot ashes is new, but not so econo¬ 
mical in one sense as it might seem. Part of it is ex¬ 
pended on the air which passes over it to the bottom of 
the fire through the fire-bars, but a good portion of it is 
lost in the side brickwork ; and when I shall make the air- 
chamber to my pit I shall have it all in one completely 
surrounding the ash-pit and fireplace ; and when this mass 
of brickwork is well heated, but not a fierce heat, as from 
heated metal, a great source of heat is obtained and is in 
reserve even if the fire is let out, but by a smouldering 
and banked-up fire, as is usually done the last thing at 
night, the source of heat is kept up for a whole night, 
and it seems to me a very feasible scheme at a com¬ 
paratively small cost and trouble. 
Turning to the universal topic of bedding plants, I am 
pleased to hear that the “Doctor’s Boy ” lias kept his 
nice seedling Geranium, of which he had sent me two 
plants—which I lost, however, with the early frost of 1859. 
It is of the Lucia rosea breed, and is more compact than 
even Mr. Kinghorn’s Christine. The Variegated Arabia 
which was first recommended by the “Yorkshire 
Clergyman,” and last week by Mr. Hobson, is the true 
Arahis alhida, which is a month earlier than alpina, but 
in other respects is hardly to be distinguished from 
Arabis alpina by common observers, and caucasica was 
an old name for the same plant, though never applied to 
it out of old books. It must have been the reason why 
this excellent edging plant has not been discussed long 
since, that no one was quite sure what name to apply to 
it; but now, to avoid confusion, the old name by which 
it has been known for an age, is the best to retain in 
popular works, and that name is Arabis alpina variegata, 
or better, merely Arabis variegata. Arahis lucida is a 
more dwarf plant, and is of a different and closer habit, 
besides being very slow of growth, and difficult to keep 
even as an alpine plant in pots and in cold frames in 
winter. From what is here brought to light, I have 
altered my opinion of the value of discussing all the 
known kinds of variegated plants in one lump, as was 
lately proposed by one of our correspondents ; then if any 
one of them which is in use within our influence is 
omitted, some one will be sure to step in and let us hear 
of it. 
I recollect when the Variegated Mint was first brought 
before us by the same clergyman who first mentioned the 
Variegated Arabis, that soon afterwards lots of it were 
sent to the Experimental Garden from -Trentham, and 
from Shrubland Park, and at that time the borders of the 
Experimental were full of it. So that it must have been 
then getting fast into use ; but a hitch in the name, or 
whether it was a Balm or a Mint, caused a stoppage in 
circulating it, through the press. 
Mr. Eobson will be pleased to hear that his mode of 
giving life in winter to his great oval flower-bed is to be 
adopted bj^ Mr. Nesfield, the great designer of terrace- 
gardening at the new garden for the Eoyal Horticultural 
Society at Kensington Gore, where large compartments 
are set apart for coloured gravels, or such like. They 
say that that fashion is prevalent in Italy where the heat 
spoils their grass, and where flowers are not so profusely 
