THE COTTAGE GARDENER AND COUNTRY GENTLEMAN, Febkuahy 14, 18G0. 
301 
HEATING A GREENHOUSE BY HOT AIR 
FROM A DWELLING-HOUSE FIRE. 
Having- at the suggestion of a friend put up in my small 
greenhouse (fiteen feet by ten feet) an apparatus for heating, and 
which is answering very well, I am induced to send it to you, so 
that others may be benefited by adopting a plan at once re¬ 
markably cheap and effective, when only in winter a moderate 
heat is required. It can only be adopted when the greenhouse 
is attached to a chimney. An iron box is made, and which 
forms the back of the grate in the dwelling-house. No openings 
in the box are made on this side; but on the greenhouse side 
three holes are made at the bottom for the cold air to enter, and 
six at the top for the hot air to escape. In these upper holes 
pipes may be fitted to bring into the greenhouse. The box is 
made larger than the grate requirement, but opens to its full 
extent on the greenhouse side, and two small flues are made on 
the grate side leading to the chimney, so that the hot air may 
heat the iron box over its whole surface. 
This plan has answered admirably with me, with the exception 
of that terribly destructive night, when I had 4° of frost in, but 
which I am satisfied I should have avoided if I had put matting’ 
outside the glass on the exposed side.—X. L. 
THE SCIENCE OF GARDENING. 
(Continued from page 252.) 
We have said that the night temperature usually averages from 
ten to twenty degrees lower than the day temperature. That 
there are exceptions we are quite aware, but they are extreme 
exceptions ; and where these extremes prevail, the plants subject 
to them are peculiar and few in number. 
Eor example : We may quote the summers within the arctic 
circle, when for a few weeks the sun never sets ; yet even then a 
disparity of temperature exists. Thus, one example among many, 
we find under the date of June 30th, 1832, this entry in Sir J. 
Ross’s “Journal of a Second Yoyage to the Arctic Regions.” 
“ The sun had a great effect on the snow, and the aspect of the 
land was hourly changing. At noon the thermometer was at 
47°, and at midnight at 32°.” Again: July 9th—15th, he says, 
“ The temperature rose once to 50°; but was at the freezing- 
point at night on most days.” 
There are, however, climates with temperatures having vast 
differences between those of their days and nights at the same 
season. Such a climate is Affghanistan, where, in March, Mr. 
Atkinson found at mid-day the weather was oppressively hot; 
yet “ after midnight the servants made up a blazing fire, for the 
north wind blew bitterly cold.” Let the gardener remember that 
that is the native country of the most delicious Grapes and 
Melons. 
Next, for an illustration of widely differing day and night 
temperatures, let us turn to the climate of tropical Australia. 
Sir Thomas Mitchell, Surveyor-General of New South Wales, 
traversed the land for a twelvemonth, and an abstract of his 
memoranda will be found in the third volume of the “ Journal 
of the London Horticultural Society.” Those who cultivate 
New Holland Plants, will do well to refer to the facts there 
recorded more fully than in the following epitome :— 
“In the end of April (our October), in latitude 28° S., within 
41° of the Tropic, at an insignificant elevation, the thermometer 
stood at 26° at sunrise, and was as low as 43° at nine p.m., ; 
nevertheless, the country produced wild Indigo, Mimosas, Casua- 
rinas, arborescent Myrtleblooms, and Loranths. A degree nearer 
the Tropic in May (our November), the thermometer at sunrise 
marked 20°, 19°, 18°, 17°, 16°, 12°, and on two separate days 
even 11°! On the 22nd May, the river was frozen, and yet 
herbage was luxuriant, and the country produced Mimosas, 
Eucalypti, Acacias, the tropical Bottle-tree {Delabechea) , a Ca- 
landrinia, and even a Loranth. On the 23rd of May, the ther¬ 
mometer at sunrise marking 12°, Acacia conferta was coming 
into flower, and Eucalypti, with the usual Australian vegetation, 
were abundant. On the 30th of May, at the elevation of 1118 
feet, the almost tropical Delabechea was found growing, with the 
temperature at sunrise 22°, and at nine P.M. 31°, so that it must 
have been exposed to a night’s frost- gradually increasing through 
12°. And this was evidently the rule during the months of May, 
June, and July (our November, December, and January) ; in 
latitude 26° S., among Tristanias, Phebaliums, Zamias, Hoveas, 
Myoporums, and Acacias, the evening temperature was observed 
to be 29°, 22°, 37°, 29°, 25°, falling during the night to 26°, 21°, 
12°, 14°, 20° ; in latitude 25° S., the tents were frozen into boards 
at the elevation of 1421 feet; the thermometer, July 5, sunk 
during the night from 38° to 10°, and there grew Cryptandras, 
Acacias, Bursarias, Boronias, Stenochiles, and the like. Cgmbi - 
dium canaliculatum , the only orchidaceous epiphyte observed, 
was in flower under a night temperature of 33° and 34°; that by 
day not exceeding 86°. These facts throw quite a new light upon 
the nature of Australian vegetation. 
“ It may be supposed that so low a temperature must liavo 
been accompanied by extreme dryness, and such appears to have 
been usually the case. Nevertheless, it cannot have been always 
so ; for although wo have no hygrometrical observations for Juno 
and July, and only four for May, yet there is other evidence to 
show that the dryness cannot always have been remarkable. In 
May the hygrometer indicated ’764, '703, -934, or nearly satura¬ 
tion, and ’596; yet the sunrise temperature was on those occa¬ 
sions 25°, 28°, 30°, and 34°. On the 22nd of May, the grass was 
white with hoar frost, and then the thermometer was, at sunrise, 
20° under canvas, and 12° in the open air ; and on the 5th of 
July, when it rained all day and the tents were ‘frozen into 
boards,’ the thermometer sank during the night from 38° to 16°. 
“ It is probable that this power of resisting cold is connected 
with the very high temperature to which Australian vegetation is 
exposed at certain seasons, and this i3 horticulturally a most im¬ 
portant consideration. We find that in latitude 32° S., in 
January (our July), the thermometer stood eight days successively 
above 100°, and even reached 115° at noon; that it was even as 
high as 112° at four p.m. ; that in the latter part of February, one 
degree nearer the line, it was twice 105°, and once 110° ; that in 
March, one degree further northward, it frequently exceeded 
100°, and there was not much fall in this excessive temperature 
up to the end of April. This will be more evident from the 
following 
TABLE OP NOON-DAY TEMPEKATTJEES. 
Lat. 
Date. 
Average Temperature. 
Maximum 
Minimum 
deg. 
deg. 
deg. 
O 
T3 
29 S. 
Nov., Dee. 
Average of 3 Observ. 102 
103 
62 
32 S. 
Jan., Feb. 
115 
73 
31 S. 
Feb., March 
„ 17 „ . 90 
110 
80 
30 S. 
March . . 
„ 20 „ . 95 
105 
84 
“ At this time the dryness was also excessive. Even such 
heats as these do not, however, destroy the power of vegetation, 
for we find in the midst of them all sorts of trees in blossom, a 
few bulbs, and even here and there (in damp places, no doubt), 
such soft herbs as Goodenias, Trichiniums, Helichrysum, Didis¬ 
cus, Teucrium, Justicia, herbaceous Jasmines, Tobacco, and 
Amaranths. 
“During these heats the night temperature seldom remains 
high. Sometimes, indeed, the thermometer was observed as 
much as 88°, and once even 97° at sunrise, the average noon heat 
of the month being 97Uj but generally the temperature is lower. 
Thus :— 
Temperature 
occasionally at Sunrise. 
Nov. and Dec., . averaging 102 ° at noon . G2°, 5S°, 61°. 
Jan. and Feb. . ,, 97£° ,, . 01°, 60°, 59°, 47°, &c ; 
Feb. and March . ,, 90 0 ,, 61°, 59°, 54°, 48°, &c. 
March . „ 95 ° „ . 08°, 55°, 51°, 47°, &c.”- 
Intimately connected with the salutary alternations of day and 
night temperature, is the.proper matiu’ing of the shoots and other 
permanent growth of plants during the year. 
Mr. Barnes, one of the best practical gardeners of the day, has 
very justly observed that there is more judgment required in 
thoroughly ripening the wood of forced fruit trees than in ripen¬ 
ing their fruit. It is too generally an error to think that when 
the fruit is off no further trouble is required; that the wood has 
got to be hardened,—and that no other care is necessary until 
the times for pruning, forcing, &c., come round. This is a mis¬ 
take fraught with failure. When the fruit is off, the whole 
vegetative power of the tree is employed,- until the leaves begin 
to fall, in imbibing and elaborating the sap which is to be the 
source from whence next year’s growth and produce are to arise. 
The hurry some gardeners are in to expose the forced trees to the 
full influence of the air, and allowing them to remain without 
the shelter of glass at night, after the arrival of frosts, are all 
errors, sources of injury and loss. A far more judicious plan is 
