t, in showers, with thunder and
lightning, as with us in summer, although among the mountains the rain
sometimes falls in the night also. The precipitation in the heat of the
day is obviously induced by the action of the sun, although it is by no
means certain that the friction of the opposing surfaces does not assist
in the operation.

I am well aware that the lines of magnetic force curve upward and carry
the trades with them, and that, therefore, precipitation by condensation
from the mere cold of the upper stratum of the atmosphere is possible.
But, there are three reasons why I do not believe such to be the fact.

1st. Precipitation takes place in the day time mainly, and in sudden,
isolated, heavy showers and not in steady continuous rain. Nor is there
condensation or continual mist at other hours of the day.

2d. They occur at a time of day when the sun is affecting the magnetic
currents most powerfully, _viz._, between ten o'clock A. M. and sunset,
and mainly at the time of greatest heat.

3d. The counter-trades _do not precipitate_ after they leave the rainy
belt, although at a great elevation, until they reach the outward limits
of the trades; and they _do precipitate again_, although they gradually
descend _nearer the earth_, as soon as they become subject to the action
of the currents of an opposite magnetism. Their precipitation is partial
too, even then, and they carry a portion of their moisture through an
atmosphere of the coldest temperature up to the geographical poles.

A similar result attends the action of the sun in the extra-tropical
regions. Cumuli commence forming in the counter-trade, or at the line
between that and the surface current, at the same time of day that the
diurnal motion of the magnetic needle commences, or the rain clouds form
in the tropics; they continue to enlarge here as there, till about the
same hour of the day that the _needle_ obtains its maximum diurnal
variations; and when the influence of the sun upon the needle ceases, and
it returns to its original status, the cumuli disappear. Hail storms too,
it is said, always, or generally occur in the day time.

In like manner the sea-breezes and other fair-weather surface winds, rise
in the forenoon with the influence of the sun upon the magnetic currents
and the needle, and die away at nightfall when the influence ceases.

There are other electro-magnetic, or to speak more correctly,
magneto-electric, effects of the sun's