114 On the Distribution of Rain in the Temperate Zone. 
vapor into rain as it did when covered with forests? We do not 
know: but are not the new ars supplying many opportunities: 
of answering this question? For the Tropics, we well know the” 
extensive influence of that Semciisinnz systens, called land eultiva= 
tion. The Cape Verde Islands and ‘the Canaries, when the pri- 
meval forests fell before the axe of European settlers, or were 
burnt.as on the Azores, became more and more like here rocks ; 
fer with the destruction ‘of the woods which clothed them and 
shaded their soil, those rains that fed the earth either disappeared 
or very much diminished. From. similar causes, as Boussing- 
ault explains, in South America, the springs in the neighberhoo 
of colonies of rapid growth gradually dry up. But as the long : 
contests which followed the liberation of the colonies from Spain, 
frightened away colonists, the forests won back the ground that 
they had hefore lost, and since that time. the old wealth of wa- 
ters is returned, aud just in proportion, the rains have rif be- 
come frequent, 
The natural inference from all this is, that with increased cul- 
tivation of the country, when all material for combustion has to } 
be sought under the earth, the continually increasing population 
of the earth, in its effort to maintain itself, will plant in natnre the 
germ of a period of death, when vapors shonld no more condense 
into clouds over the treeless earth, aud even the seed in the soil re 
freshed only by dew would lose its syst of a: or if it shoul 
shoot up, would slowly wither and die. But the world as well - 
and s ied tp abbas If the sun sand over the southern het 
sphere with its broad waters, there will then be a greater ext 
touched by the warmth thus created, than if it beam in northe 
limits over a broad solid surface. The vapors with whieh the 4 
mospliere becomes charged in excess between the autumn all 
the spring = in the southern hemisphere, return i 0 
other half year ack to the earth in the shape of snow ne 
and in excess eae the northern hemisphere. 
