163-164.
If, in forming a thermic scale of different kinds of cultivation,* we begin
with those plants which require the hottest climate, as the vanilla, the
cacao, banana, and cocoa-nut, and proceed to the pine-apples, the
sugar-cane, coffee, fruit-bearing date-trees, the cotton-tree, citrons,
olives, edible chestnuts, and fines producing potable wine, an exact
geographical consideration of the limits of cultivation, both on plains and
on the declivities of mountains, will teach us that other climatic relations
besides those of mean annual temperature are involved in these phenomena.
[footnote] *Humboldt, op. cit., p. 156-161; Meyen, in his 'Grundriss der
Pflanzengeographie', 1836 s. 379-467; Boussingault, 'Economie Rurale', t.
ii., p. 675.
Taking an example, for instance, from the cultivation of the vine, we find
that, in order to procure 'potable' wine,* it is requisite that the mean
annual heat should exceed 49 degrees, that the winter temperature upward of
64 degrees.
[footnote] *the following table illustrates the cultivation of the vine in
Europe, and also the depreciation of its produce according to climatic
relations. See my 'Asie Centrale', t. iii., p. 159. The examples quoted in
the text for Bordeaux and Potsdam are, in respect of numerical relation,
alike applicable to the countries of the Rhine and Maine (48 degrees 35' to
40 degrees 7' N.
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