568 Cultivation of Plants. 
The rainfall varies throughout these countries proportionate 
to their extent in the same ratio as in the British Islands, and 
according to local influences; but as we have records for a few 
localities only, we forbear giving them. 
One more observation should be made respecting the fore- 
going figures—that they must be treated as rough approxima- 
tions, both those relating to temperature and to latitude. And 
we may here repeat, that the cultivator’s special study should 
be the soil and climatal conditions of his own locality. 
§ 3. Sorts, turrr Natourp anp Composition. 
So much depends upon the nature of the soil affected by 
different plants, that we should like to devote much more 
space than we have at our disposal to the consideration of this 
question. Under the most favourable climatal conditions 
many plants have no chance of flourishing unless they are sup- 
plied with, or placed in, a suitable soil. It is true that a vast 
majority of plants will succeed in any ordinary, free, tolerably 
rich soil; but, on the other hand, there are others that prefer a 
light dry soil, a rich heavy moist soil, ora peaty soil, and so on. 
According to the composition of the soils, the greater or less 
will be their power of absorbing and radiating heat, and re- 
taining or discharging moisture. In other words, a soil may 
be either a good or bad conductor of heat; and evaporation 
and downward drainage of water will be either slow or rapid, 
in proportion to its density and depth. It is obvious, there- 
fore, that the extremes of these conditions—though both are 
suitable for certain classes of vegetation—are alike uncongenial 
to the majority of ornamental plants in cultivation. From 
observations in Scotland,’ over a period of nine years, the 
temperature at three inches below the surface has fallen to 
26°-5 in loose sandy soils, and at a depth of twelve inches the 
freezing point has only once been registered. In clayey soils, 
on the other hand, the lowest temperature at three inches was 
28°, whilst at twelve inches it frequently fell to the freezing 
point, and once even 32° was recorded at a depth of twenty-two 
inches. Hence it follows that a moderately light porous, 
sandy soil, being a feeble conductor of heat, and readily part- 
ing with its moisture by evaporation and drainage, is emi- 
nently adapted for tender shrubs, bulbous plants, &e. A heavy 
! Buchan, ‘Iandbook of Metcorology, 
