he fleecy cumuli and the
commencement of rain, while the lower atmosphere is comparatively dry,
and during the approach of thunder storms. The appearance of the
cumulo-stratus, among ranges of hills, presents some interesting
phenomena. It appears like a curtain dropping among them and enveloping
their summits; the hills reminding the spectator of the massy Egyptian
columns which support the flat-roofed temples of Thebes. But when a
whole sky is crowded with these clouds, and the cumulus rises behind
them, and is seen through the interstices, the whole, as it passes off in
the distant horizon, presents to the fancy mountains covered with snow,
intersected with darker ridges, lakes of water, rocks and towers.
Shakspeare seems to have referred to this modification in the well-known
lines:--

"Sometimes we see a cloud that's dragonish;
A vapour, sometimes, like a bear or lion,
A towered citadel, a pendent rock,
A forked mountain, a blue promontory,
With trees upon 't that nod unto the world,
And mock our eyes with air.--
That which is now a horse, even with a thought
The rack dislimns, and makes it indistinct
As water is in water.

The _distinct_ cumulo-stratus is formed in the interval between the first
appearance of the fleecy _cumulus_ and the commencement of rain, while
the lower atmosphere is yet dry; also during the approach of thunder
storms when it has frequently a reddish appearance. Its _indistinct_
appearance is chiefly in the longer or shorter intervals of showers of
rain, snow, or hail.

THE CUMULO-CIRRO-STRATUS; NIMBUS OR RAIN-CLOUD.

Clouds, in any one of the preceding forms, at the same degree of
elevation, or two or more of these forms at different elevations, may
increase and become so dense as completely to obscure the sky; this, to
an inexperienced observer, would seem to indicate the speedy commencement
of rain. But Mr. Howard is of opinion that clouds, while in any of the
states above described, never let fall rain.

Before rain the clouds always undergo a change of appearance,
sufficiently remarkable to give them a distinct character. This
appearance, when the rain happens overhead, is but imperfectly seen; but
from the observations of aeronauts, it appears that whenever a fall of
rain occurs, and the sky is at the same time entirely overcast with
clouds, there will be found to exist another stratum of clouds at a
certain elevation above the fo