But this constant condensation on the mountains would probably check the
deposit on the lowlands in the form of dew, because the continual
up-draught toward the higher slopes would withdraw almost the whole of
the vapour as it arose from the oceans, and other water-surfaces, and
thus leave the lower strata over the plains almost or quite dry. And if
this were the case there would be no vegetation, and therefore no animal
life, on the plains and lowlands, which would thus be all arid deserts
cut through by the great rivers formed by the meeting together of the
innumerable torrents from the mountains.
Now, although it may not be possible to determine with perfect accuracy
what would happen under the supposed condition of the atmosphere, it is
certain that the total absence of dust would so fundamentally change the
meteorology of our globe as, not improbably, to render it uninhabitable
by man, and equally unsuitable for the larger portion of its existing
animal and vegetable life.
Let us now briefly summarise what we owe to the universality of dust,
and especially to that most finely divided portion of it which is
constantly present in the atmosphere up to the height of many miles.
Pages:
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510