SITE.--The selection of a suitable site for an orchard is a matter of no small moment to him who would be a successful grower of fine fruits. Without, at this time, pausing to inquire into the characters of the soil, let us examine more particularly the _aspect_ of the field to be appropriated to this important crop; for the orchard is a permanent investment, and so much depends upon the site, that we should make some sacrifice of our convenience, rather than commit any error in this particular. In the first place, then, let it be understood that the orchard should be well exposed to the sun and air. The least desirable positions for orchard planting are narrow valleys, particularly limestone valleys in a mountainous country, traversed by a small brook, or where the surface is _spouty_ from springs or subjacent water. Even if such depressions are considerably elevated, but surrounded by higher and abrupt elevations, they will be found obnoxious to late and early frosts in spring and fall, especially the former, which are often disastrous in such situations, after the fruit-buds have expanded in these sheltered nooks. Every one at all conversant with meteorological observations made in a broken country, is aware of the different range of temperature that will be indicated by instruments suspended at different elevations.[19] When the cooling influence of radiation has lowered the temperature of the surface of the earth and of objects near it, the stratum of air in immediate contact will be chilled, and growing heavier, will flow down into the most depressed situations, and, accumulating there, will cause a difference of several degrees of temperature. This, when near the freezing point, will be of the greatest consequence to tender vegetation, which may be preserved in perfect safety at forty degrees, but will be destroyed at thirty degrees, or even at a higher point, in some cases. The _frost line_ becomes a very important subject of inquiry in the selection of an orchard site, and in some countries we find that its position may be definitely settled within a limited range of elevation; not that a certain level can be indicated, above which there will always be an immunity from frost, while all below will suffer, but we may approximate, in certain situations, so nearly as to indicate that certain sites are safe or unsafe.