art from the obvious fact on which the mistake is
usually based--the continued presence, namely, of snow on the summits of
high mountains even in the torrid zone--it had been shown shortly before
by Newton, that the light fleecy clouds seen sometimes even in the
hottest weather above the wool-pack or cumulus clouds are composed of
minute crystals of ice. Seeing that these tiny crystals can exist under
the direct rays of the sun in hot summer weather, many find it difficult
to understand how those rays can of themselves have any heating power.
Yet in reality the reasoning addressed by Swedenborg to his Mercurial
friends was entirely erroneous. If he could have adventured as far forth
into time as he did into space, and could have attended in the spirit
the lectures of one John Tyndall, a spirit of our earth, he would have
had this matter rightly explained to him. In reality the sun's heat is
as effective directly at the summit of the highest mountain as at the
sea-level. A thermometer exposed to the sun in the former position
indicates indeed a slightly higher temperature than one similarly
exposed to the sun (when at the same altitude) at the sea-level. But the
air does not get warmed to the same degree, simply because, owing to
its rarity and relative dryness, it fails to retain any portion of the
heat which passes through it.

It is interesting to notice how Swedenborg's scientific conceptions of
the result of the (relatively) airless condition of our moon suggested
peculiar fancies respecting the lunar inhabitants. Interesting, I mean,
psychologically: for it is curious to see scientific and fanciful
conceptions thus unconsciously intermingled. Of the conscious
intermingling of such conceptions instances are common enough. The
effects of the moon's airless condition have been often made the subject
of fanciful speculations. The reader will remember how Scheherazade, in
'The Poet at the Breakfast Table,' runs on about the moon. 'Her delight
was unbounded, and her curiosity insatiable. If there were any living
creatures there, what odd things they must be. They couldn't have any
lungs nor any hearts. What a pity! Did they ever die? How could they
expire if they didn't breathe? Burn up? No air to burn in. Tumble into
some of those horrid pits, perhaps, and break all to bits. She wondered
how the young people there liked it, or whether there were any young
people there. Perhaps nobody was young and nobody was old, but the