atmosphere are rarely seen, never
extensive, or attaining any considerable altitude._ I have watched for
them thirty years. I have seen currents of air ascend, with their moisture
condensing as they ascended, and unite with the under surface of a highly
electrified cloud--the advance condensation of a thunder shower--but that
cloud was moving horizontally at a distance of from one to two thousand
feet above the surface of the earth, and did not rise. I have seen patches
of scud rising from the surface during the intervals of a showery and
highly electrified storm, toward, and uniting with, the clouds above, when
very low, as I have seen them approach and unite horizontally; and
doubtless there is a tendency upwards of the wind, created and attracted
by the summer shower, as may be seen in the ascending dust before the
rain, but I have never been able to detect an ascending current, except as
induced and attracted by a cloud above moving horizontally, in the hottest
day or dryest time. None of the clouds of our climate, even when the earth
is heated and parched by a two months' unbroken drought, can be detected
rising above the strata in which they form. I have watched the cumuli at
such periods when they filled the air, and can assert that they never
rise. The atmosphere moves, invariably, in horizontal strata, and the
whole theory of ascending currents is fallacious.

But let us look still further at the tropical currents. The true harmattan
of north-western Africa (for the term is sometimes misapplied), hot and
blistering, generated upon the sand of the desert--why does it blow from
Sahara horizontally, on or over cooler surfaces, following the belt of
rains as a N. E. trade? Why does it not ascend? The sirocco of north
Sahara, the kamsin or chamsin of eastern Sahara, and the simoon of Arabia,
which blow hot and suffocating from those deserts--why do they blow _from_
heated surfaces and _horizontally over_ cooler ones? Why do they not
ascend? Arabia is surrounded on three sides by seas and gulfs, from which
evaporation is rapid. Her interior deserts are extensive and intensely
hot--why are they rainless? Why do they not have a _vortex_, a _monsoon_,
or even a _shower_? Because there is no such law or action as this theory
supposes. Those winds blow horizontally in obedience to other laws, and
under the control of other and more powerful agents. But further still,
what heating and ascending process is it that makes the v