82 
RETROSPECT OF THE LATE WINTER. 
cooled in Spain and India by being put into porous earthen vessels ; and, secondly, 
by exhausting the vegetative powers of the plant. Yegetables also have the power 
of absorbing moisture from the atmosphere, and must consequently suffer in propor- 
tion as this is in an arid state. Those three considerations show the great import- 
ance of a vaporous atmosphere in hothouses raised by keeping the floor of the 
house and surface of the flues continually wet." 
Mr. Knight was also a great advocate for an absolutely saturated state of 
vaporisation, that is, when high temperature was kept up ; and now, having 
appealed to the authority of past years, we may with more propriety cite the 
evidence of recent facts accruing under a much improved method of heating, and 
during a winter unusually sombre and of protracted severity. 
"We have said that some writers have lately expressed their opinions of the risk 
that must have been incurred by those gardeners who had to depend on fire-flues 
only during the late black winter. A very few years have elapsed since there were 
no other appliances of heat than such flues ; and winters of equal rigour have 
repeatedly occurred without producing any disastrous results. We happen to 
possess opportunities of comparing the progress and effects of the two methods of 
heating, carried on pretty extensively, and can therefore assert that we never saw 
a large greenhouse, filled with the finest specimens of Camellia, Epacris, Acacia, 
and other hard-wooded species, with a liberal admission of Cyclamens, Mimulus, 
Cinerarias, and the more succulent tribes, in a higher state of health, perfect foliage, 
and brilliant flowers ; and this greenhouse was heated by a fire-flue only, running 
abreast of the front wall, though not quite in contact with it. The aspect is east- 
by-north, and, therefore, without sun from November to mid February. These 
facts may tend to calm the anxiety of those who are over-solicitous concerning the 
absence of the direct solar ray. 
Again, we see a beautiful crop of grapes, with noble foliage, in a stove, heated 
by broad, expansive, water channels, the clusters stoned and nearly ready to acquire 
colour in the second week of April. 
A flower -house is in two compartments ; the one excited by a gutter-tank, from 
which are continued a double course of six inch by four channels, the other, by a 
single course of the same, admitted from, and returning to, the former, through 
openings made in the partition wall. Now, in all these houses, wherein of course 
there has existed a great difference in temperature, from 50° to 73°, every plant 
has prospered. 
The moisture has been considerable, in the tank department particularly, 
wherein a great number of Gardenias are, and have been, in rich verdure, 
while almost every cutting of this plant has taken root, and is growing after 
transplantation into small pots. 
Darkness — fog of dense character — absence of sun for weeks, may have 
retarded, but they have done no injury. Even Hibiscus rosa sinensis, young 
plants of spring cuttings, have not lost a leaf : thus we have ample evidence, that 
