WINTER MANAGEMENT OF PLANTS IN FRAMES. 
231 
substance on which the plants stand, is by far the most prefer¬ 
able mode. As to all the ways of obtaining heat in a frame by 
means of fermentation there is one general objection: all plants 
placed in such a situation require air, that is, change of air for 
sweetening the effluvia of the compost; and many require change 
of air for their own health without any reference to injurious ef¬ 
fluvia in the frame. The usual and indeed almost the only way 
of giving this fresh air has been by opening the frame more or 
less, and keeping it open for a longer or shorter time according 
to the state of the weather and the habit of the plant. This air 
necessarily lowers the temperature and diminishes the capacity 
for heat in the air, immediately in contact with the plants, for 
the greater specific gravity of this colder air causes it to occupy 
the lower part of the frame, by which the plants generally are 
chilled and a sort of unwholesome dew formed upon them. This, 
to the full amount of the change produced, has the same effect 
as if the plants were changed from a warm and dry atmosphere 
to a cold and humid one, and there is a fresh chill when the 
frames are closed, and the dew thus formed is changed into 
vapour, and this second chill is as bad as the first. These tem¬ 
porary chills are not very injurious, if the plants are merely in 
the frames for repose and not for growth, or for ripening their 
stems or ligneous parts, though it is a little injurious in all 
cases. 
A great improvement in the ventilating and heating of frames 
and pits, which also applies to all other horticultural erections, 
is one made by Mr. Weeks, junior, of King’s Road, Chelsea ; 
both he and his father have paid much attention to the applica¬ 
tion of warm water for floricultural and horticultural purposes. 
The recent improvement, which is an important one, was made 
for forcing cucumbers in frames or pits, so that they might be 
ready for use in winter or very early in spring ; it is only appli¬ 
cable in conjunction with hot water pipes; with them it may be 
applied so as to give a temperature of T20°, or even considerably 
more; as great a temperature indeed as any plant can bear without 
injury ; and for many species from the hottest parts of tropical 
climates, it may be made more effective than any stove, as what¬ 
ever degree of humidity is required in the air may be obtained. 
If, on the other hand, great heat and dry air are required, they 
