g, I suppose, sufficient power to traverse
the atmosphere, communicates heat to it.

MRS. B.

Your inference is extremely well drawn, Emily; but the foundation on
which it rests is not sound; for the fact is, that terrestrial or
culinary heat, though it cannot pass through the denser transparent
mediums, such as glass or water, without loss, traverses the atmosphere
completely: so that all the heat which the earth radiates, unless it
meet with clouds or any foreign body to intercept its passage, passes
into the distant regions of the universe.

CAROLINE.

What a pity that so much heat should be wasted!

MRS. B.

Before you are tempted to object to any law of nature, reflect whether
it may not prove to be one of the numberless dispensations of Providence
for our good. If all the heat which the earth has received from the sun,
since the creation had been accumulated in it, its temperature by this
time would, no doubt, have been more elevated than any human being could
have borne.

CAROLINE.

I spoke indeed very inconsiderately. But, Mrs. B., though the earth, at
such a high temperature, might have scorched our feet, we should always
have had a cool refreshing air to breathe, since the radiation of the
earth does not heat the atmosphere.

EMILY.

The cool air would have afforded but very insufficient refreshment,
whilst our bodies were exposed to the burning radiation of the earth.

MRS. B.

Nor should we have breathed a cool air; for though it is true that heat
is not communicated to the atmosphere by radiation, yet the air is
warmed by contact with heated bodies, in the same manner as solids or
liquids. The stratum of air which is immediately in contact with the
earth is heated by it; it becomes specifically lighter and rises, making
way for another stratum of air which is in its turn heated and carried
upwards; and thus each successive stratum of air is warmed by coming in
contact with the earth. You may perceive this effect in a sultry day, if
you attentively observe the strata of air near the surface of the earth;
they appear in constant agitation, for though it is true the air is
itself invisible, yet the sun shining on the vapours floating in it,
render them visible, like the amber dust in the water. The temperature
of the surface of the earth is therefore the source from whence the
atmosphere derives its heat, though it is communicated neither by
radiation, nor transmitted from one particle of it t