ear, when passing through
them, and see how many of them it would require to form a large drop of
rain. The clouds are of a similar vesicular character, and rain does not
fall till the vesicles unite to form drops. Sudden and extreme cold is
indeed produced in the hail-storm, when, above, below, and around it, the
temperature is unaffected. Testu, Wise, and other aeronauts, have so found
it, and the hail tells us it is so. But it is idle to say it results from
radiation. All the phenomena of the sudden, violent hail-storms are
electric in an extraordinary degree. The electricity is disturbed and
separated--the associated heat continues with the negative, and leaves the
positive portion of the cloud, and a corresponding reduction of
temperature results. So Masson found in his eudiometrical analytical
experiments the _negative_ wire would heat to fusion, while the positive
was cold. (See London, Edinburgh, and Dublin Journal of Science for
December, 1853.) This disturbed electricity is diffused over the vesicles.
Listen to the thousand _crackling_ sounds which initiate the clap of
thunder, and may be heard when the lightning strikes near you; produced by
the gathering of the lightning from as many points of the cloud where it
was diffused, to unite in one current and produce the "clap" or
"peal"--and to the "pouring" of the rain, which follows the union of the
vesicles, after the excess of repelling electricity is discharged.

No _change_ of temperature is observed when fogs form, except the ordinary
change between night and day; and it seems perfectly obvious, in looking
at all the phenomena, that fogs form at a temperature of 70 deg. or 75 deg., in
consequence of the electric influence of the earth upon the adjoining
surface-atmosphere; and, when formed, they withstand the most intense
action of a summer sun, till the time of day arrives for the barometric
and electric tension to fall, condensation to take place in the
counter-trade above, and wind to be induced. Who that has noticed the
almost blistering force of the solar rays, as they break through a section
of high fog, about 10 A.M., can forget them.

Fogs form near the earth, during the night, when the atmosphere above is
loaded with moisture many degrees colder, and yet remains free from
condensation. On the other hand, during the heat of the day, and of the
hottest days, the heavy rains condense above--nay, they frequently fall at
a temperature of 75 deg. to 80