regions.

_The elevation of the counter-trade above the earth varies in the same
latitude with the variations in the phenomena of the weather._ An
attentive observation of the clouds of our climate will soon satisfy any
one of this, after he has become familiar with them, so as to distinguish
with certainty the clouds of the trade. Its range, in this country, is
from 3,000 feet, or less, to 12,000 feet above the earth, and its depth
with us probably, from 6,000 to 8,000 feet. Gay-Lussac, in his scientific
experimental balloon ascension, the first of _that character_ ever made,
except an imperfect one just previous, by himself and Biot, found it at
about 12,000 feet over Paris, and about 4,000 feet in depth. It is
detected by the thermometer when much elevated.

The atmosphere grows cool as it is ascended on mountains, or by balloons.
The rate of cooling is ordinarily about 1 deg. of Fahrenheit for every 300
feet. If it were not for the equatorial current, this progressive decrease
of temperature would doubtless be perfectly uniform. Of Gay-Lussac's
ascension, on this point it was said:

"At forty minutes after 9 o'clock, on the morning of the 15th
September, 1804, the scientific voyager ascended, as before, from the
garden of the repository of models. The barometer then stood at 30.66
English inches, the thermometer at 82 deg. Fahrenheit, and the hygrometer
at 57-1/2 deg.. The sky was unclouded, but misty.

"During the whole of this gradual ascent, he noticed, at short
intervals, the state of the barometer, the thermometer, and the
hygrometer. Of these observations, amounting in all to twenty-one, he
has given a tabular view. We regret, however, that he has neglected
to mark the times at which they were made, since the results appear
to have been very materially modified by the progress of the day. It
would likewise have been desirable to have compared them with a
register, noted every half hour, at the Observatory. From the surface
of the earth to the height of 12,125 feet, the temperature of the
atmosphere decreased regularly, from 82 deg. to 47 deg. 3' by Fahrenheit's
scale; _but afterward it increased again, and reached to 53 deg. 6' at
the altitude of 14,000 feet_; evidently owing to the influence of the
warm currents of air which, as the day advanced, rose continually
from the heated ground. From that point the tempera