THE PHILOSOPHY AND USES OF BOTTOM-HEAT. 
161 
advocate. The question is, would they not be improved by the treatment we 
prescribe ? And if they would, — as, we think, no one will deny, — it would be 
difficult to justify indifference to such superiority. 
Far beyond the limits of stove-plants, however, will the principle extend which 
we have sought to establish. It will hold good of all plants, that keeping the 
roots adequately warm is indispensable to their perfection. And a strong case in 
favour of thorough drainage, as well as of keeping the roots of greenhouse species, 
and of plants in the open border, within the influences of the sun, will thus be 
made out. Stagnant or superfluous water always entails additional coldness ; and 
a great rule is frustrated thereby. We have not space to enter more largely 
into this subject, and can therefore only throw out these brief hints as a kind of 
indicator of the direction in which inquiry would be profitable. 
To go back to stove-plants, we must state that the period at which we would 
recommend the application of bottom-heat is simply during the spring, summer, 
and early autumn. The temperature of a bark or other bed should be suffered to 
die away gradually in the autumn ; and if the plants are left plunged in it through 
the winter, they will need scarcely any water. Perhaps it would be the wisest 
plan to take them out in the autumn, level the bed, and place them on the surface, 
with pieces of slate, stone, or brick beneath them. 
There is yet a material, however, of which we have not yet spoken, and which 
may be applied advantageously as a means of providing bottom-heat in stoves. This 
is the leaves of trees ; which, if collected towards the end of the winter, and 
placed in the pit of the house about the middle or end of February, will furnish 
an excellent heat for two or three months. This will also be a good mode of 
facilitating the decay of the leaves, in order to form leaf-soil. They must be well 
watered at the time of being introduced, and the pots should not be plunged in 
them at first, lest the heat prove too violent. When this has become more 
moderate, they may be slightly turned over, and the pots may be inserted to the 
rim in them, as in bark. 
Should the use of either leaves or bark be considered unsightly in an ornamental 
house, their surface may be readily covered over with a thin layer of bark, in a 
state of almost thorough decay, or of leaf-mould, or any light soil. This need not 
be employed so extensively as to render its mixture with the heating material at 
all objectionable, when the latter has to be stirred or turned over. 
In every instance where bottom-heat is supplied, it is msot essential that it 
should never be allowed to become too strong, or to exceed the general temperature 
of the house. It is also indispensable that it be kept from getting into a dry 
burning condition, by frequent waterings on the surface. With leaves, especially, 
these states have to be vigilantly guarded against. Too powerful a temperature 
to the roots of plants would, when dry, have a highly prejudicial effect ; and, if 
duly moist, the influence would be a kind of forcing, which is by no means to be 
desired, as it would entail general weakness and superfluity of growth. 
vol. x. — no. cxv. Y 
