The necessity of applying water, of a temperature equal to that of the soil, is rendered evident by a reference to the natural conditions by which the soil is watered. In a small and nearly globular form, the water gathered up by the action of the sun, and forming the clouds above us, is precipitated through the atmosphere, and there its temperature becomes equalized or assimilated with that of the medium through which it has been passing; and although in our own latitude, we perhaps fail to discover any material degree of warmth in the drops of rain as they fall, yet in eastern climes, we cannot but imagine, that after having been submitted in the thin strata of the clouds to the action of the sun, they must previously to entering the soil, have imbibed some portion of heat. Moreover, the importance of maintaining a gentle bottom heat, at the roots of forced plants, renders it necessary to avoid any application, which may tend to lesson its effect, and submit the roots to any chilling influence. The temperature of the soil is naturally above that of the atmosphere, and as the application of moisture by exciting evaporation, has an abstract tendency to lower the temperature, it should therefore, when applied, be in a slight degree warmed, so as thus to increase rather than diminish the heat contained in the soil. As some moisture in the soil is necessary to render the food contained therein, soluble, and available to the spongioles of the roots, so moisture in the atmosphere is essentially necessary to assist in applying the gaseous elements of that elastic compound fluid, to the nutrition of plants by the action of the leaves: without moisture in the atmosphere, the leaves and outer covering of plants would become dessicated, and the stomatas shrivelled up and closed, so that neither the exhaling nor the imbibing functions of the plants could then be carried on. The moisture of the atmosphere, then must not be neglected; not only because the healthy action of the vital organs of the plants depends on a proper hygrometrical state of the atmosphere, but, inasmuch as it is the readiest means both of avoiding, and when unhappily, they are present, of destroying, many of the most destructive and troublesome insect enemies, to whose depredations, plants are subject.