_Why do the Heavens appear blue?_

Because of our looking at the dark vacuity beyond our atmosphere
through an illuminated medium. Were there no atmosphere, it is
universally admitted the appearance would be perfectly black, except
in the particular direction of the sun, or some other of the heavenly
bodies, and since the atmosphere is transparent, this blackness (if
such an expression may be used) must be seen through it, only somewhat
modified by the rays of light reflected by the atmosphere to the eye,
from the direction in which we look. For this reason, the clearer or
more transparent the atmosphere is, the darker is the appearance of
the heavens, there being then less light reflected by the atmosphere
to the eye. In the zenith, the appearance is always darker than nearer
the horizon; and from the tops of high mountains, the heavens in
the zenith appear nearly black.--_Mr. B. Hallowell, in the American
Journal of Science and Arts._

_Why does the heat of temperature of different parts of the earth
vary?_

Because of the position of the place with respect to the equator, or
rather to the ecliptic, or, more strictly still, with respect to the
plane in which the earth revolves around the sun; for on this relation
depends the temperature of the place, so far as it is produced,
directly, by the influence of the sun. Maltebrun ascribes to it the
following influences: 1, the action of the sun upon the atmosphere: 2,
the interior temperature of the globe: 3, the elevation of the earth
above the level of the ocean: 4, the general inclination of the
surface, and its local exposure: 5, the position of its mountains
relatively to the cardinal points: 6, the neighbourhood of great seas,