THE ANTIPODES--MORNING AND EVENING DEW.
It is a gratifying thing when popular prejudices are overcome by the
progress of public enlightenment. The existence of the antipodes was
formerly disbelieved. Before the spherical form of our globe was
ascertained, how was it possible to suppose that there existed human
beings under our feet standing with their head downwards?
Till the Newtonian theory was developed, it seemed impossible but that
persons so placed must fall into the realms of endless space. There is a
general disposition in human nature to believe all that is impossible as
well as to doubt every thing that really exists; and such was the
incredulity of the world with regard to the antipodes.
The ancients, who admitted many absurdities, denied the existence of the
antipodes. The Fathers of the Church followed in their steps; some indeed
pronounced it heresy to hold such a belief. St. Augustin expressly says,
"Take heed lest thou believe such a fable." In his treatise on the Acts
of the Apostles, there is an argument remarkable enough, considering that
the rotundity of the earth was then unknown. "Faith teaches us, that all
men are from Adam. But if there were other men under the earth, they could
not be of Adam. How could they have found their way to the antipodes? Not
by land, for the antipodes are cut off from our hemisphere by boundless
seas. Not by sea; for the most experienced pilot would not dare launch his
vessel in such boundless space. It is, therefore, evident that the
doctrine of the antipodes is false and heretical." Time and experience
have taught us the folly of deciding upon topics exceeding our
comprehension. Yet, perhaps, even now we deny a host of truths, which at
some time may give us an insight into futurity. In great as well as
trifling things, every day brings its tribute to the cause of truth. The
antipodes are admitted to exist. The earth revolves round the sun, though
once supposed to be stationary in its place in the heavens; while the dew,
which our ancestors believed to descend from heaven, is known to be an
emanation from the earth."
Such an error was pardonable enough. The dews are often made use of in
Holy Writ as a term of comparison; and the mercy of the Lord is implored
to descend upon his people like the dews from heaven. After many
experiments in elucidation of the origin of dew, a scientific observer
obtained the following results.
Having placed some plants under glass bells, he examined them the
following morning, and finding them to be covered with dew like those left
in the air, he cut shreds of flannel; and placing them at graduated
heights, found that those nearest the earth were first wet, and that the
dew gradually rose towards the highest. Upon weighing the shreds, he found
those below to be the most saturated. Lastly, upon examining plants grown
in green-houses, he felt convinced that they also imbibed abundant dew.
These experiments excited attention; and Muschembroek, the author, had
many imitators. Among others, Dufay, who placed a double ladder thirty-two
feet high, in the centre of a garden, suspending tablets of glass at
different altitudes; so that each was equally exposed to the action of the
atmosphere. He remained at the foot of the ladder to watch the progress of
the phenomenon, and found that the tablets nearest the earth were the
first moist, and that the humidity ascended gradually to the highest.
Several other men of science repeated the same experiment with similar
results.
The problem was thus solved, and proof obtained that dew ascended from the
earth. To the joy, however, of some, a doubt presented itself. By renewed
experiments it was found that this dew from the earth did not equally
affect all bodies, and was partial in its bearing. For instance, it
appeared to avoid gold, silver, metal, and polished marbles; while it
adhered to glass, oily and resinous substances.
Place a gold or plated vessel under a crystal vase in a garden during the
night, and in the morning you will find the edges perfectly dry, while the
crystal vase will be wet. The cause of this difference is not accounted
for. Reaumur supposes, but does not affirm, that the golden vessel,
containing more caloric than the crystal, repels the dew, while the latter
attracts it.
In confirmation of this supposition, Reaumur proposed the following
experiment. Place a china cup upon a stone within a hot-bed; and further
on, and beyond the influence of the hot-bed, another cup of similar form,
substance, and diameter; this will be charged with dew, the other will
remain dry. In explanation of this difference, it may be imagined that the
phenomenon of which they sought the solution, originated in electricity;
an opinion, however, which has no influence over the main discovery that
dews arise from the ground, instead of falling from the skies, as asserted
by the mythology of the ancients, and the tropes of Scripture.