remedy consists in avoiding an irregular composition of the atmosphere, as
regards heat and moisture; and also an excess or deficiency of moisture in
the soil, so that each may be in a condition to exert its proper influence
on the constitution and developement of the plants. Canker, another
disease, to which Cucumbers are sometimes subject, appears to be produced
by too low a degree of temperature, accompanied by an excess of moisture,
both in the soil and the atmosphere, and it generally attacks those
particular parts, where any check or obstruction is offered to the flow of
the sap, such as that occasioned by a wound, or even the ramifications of
the stem: this suggests that its remedy, would consist in a due regulation
and balance of the constituents of the atmosphere, and the soil.

Moisture is generally applied to the soil by being poured directly on it,
and to the atmosphere, by means of the syringe, and the use of evaporation
troughs. When applied to the soil only from the upper surface, there is a
liability of its failing thoroughly to moisten it, and by reason of this,
together with the constant action of the heat from below, by whatever
means heat may be applied, the soil is frequently found to be dry beneath,
when the appearance of the surface might lead to the supposition that it
was sufficiently moistened.

By a reference to the sketch and description already given, it will be
seen, that a provision is there made, whereby water can be poured in
quantity _beneath the soil_, immediately on the top of the tank, whence in
the form of vapour it will rise among the soil, and thus render it
thoroughly moist; at the same time, it can be applied to the surface,
whenever it may become necessary to do so. The moistening of the
atmosphere will also be fully secured by the mode of ventilation which is
there proposed, for the air, at the same time that it is warmed, will
become charged with moisture in a ratio equal to its temperature, before
it enters the house. If it becomes requisite to admit moisture without
changing the volume of air, it can readily be effected by opening the
tubes or shafts inside the house, without opening the exterior
ventilators; and when dry heat may be required, it can be secured by
closing entirely the communication with this reservoir of moisture, and
the hot-water pipes will then radiate any quantity of dry heat that may be
required.

By means of a due application of these provisions, an