of rain, and the southern extra-tropical
one, and never be covered by either; but the volume of N. E. trades from
the Atlantic, although from the make of the land not concentrated to so
great an extent as the volume of S. E. trade on the north, and therefore
not so liable to hurricanes and other violent storms, is yet sufficiently
so to carry the southern line of the equinoctial rainy belt down in winter
to the summer line of extra-tropical rains, and give a supply of rain to
all the continent--leaving no strictly rainless region south of the
equatorial rainy belt and east of the Andes. Those mountains, however,
present a barrier to its south-western progress which it doubtless passes
to some extent, but deprived of its moisture, and unable to supply the
rainless coast region of Peru, Bolivia, and Northern Chili. There is,
therefore, a portion of this rainless line of coast which is within the
region of extra-tropical rains, over which a portion of the N. E. trades
of the Atlantic, as a counter-trade, should or do, curve, and where there
should therefore be extra-tropical rains. It is washed by the Pacific, an
evaporating surface, and westerly and south-west breezes are drawn in from
that ocean over it. Why then is it rainless? The only reason which can be
assigned why rain does not fall there is that the high mountain ranges of
the Andes intercept and perhaps in part divert the counter-trade, and
deprive that portion of it which passes them, of its moisture, by that
reciprocal action of opposite polarities which takes place whenever and
wherever the trade approaches so near the earth; and it curves over the
narrow line of coast with the feeble condensation, and imperfect forms,
and varied coloring which mark so peculiarly the rainless clouds of that
region. (See Stewart's Journal of a Voyage to the Sandwich Islands, page
72.)

Again, it is estimated, and on reliable data, that twelve perpendicular
feet of water are annually evaporated from the surface of the Red Sea,
between Nubia on one side, and Arabia on the other; yet they are both
rainless countries, except so far as the inter-tropical belt of rains
extends up on to a small portion of them. The moisture of evaporation,
floated up from a surface covered by the surface-trade is invariably so
combined as to remain uncondensed till it has passed south into the
equatorial rainy belt, and over to the opposite hemisphere, and been
exposed to the currents of an opposite ma