_That exactly under the Æquator is always the hottest Climate on the
Globe._
This Error by no Means ought to be called a vulgar one; because it is a
Course of Philosophical Study, joined to a Want of Experience, which gives
Occasion to it. It is the Result of a Knowledge of the general Cause of
Heat and Cold, in different Degrees of Latitude upon the Surface of the
Earth; which Knowledge is apt to apply the Rules of Astronomy, that explain
the Phoenomena of Nature in general, to every Purpose that offers itself,
in all Cases, without being able to search into the individual Parts of a
System, on Account of the Distance of the Objects which are the Subjects of
Enquiry. For though, as has been said before, for a just Astronomical
Reason, the Position will hold good, that those Inhabitants who are under
the Line, live in the hottest Climate in general, yet it is proved by the
Experience of Navigators, that in several Parts under the Æquator there is
a fine, mild, soft Climate, even excelling any of those in the temperate
Zones; so happily are Things disposed for the Purposes of Animal Life, by
the Author of Nature.
This is a Truth which we are constrained to believe, as we have so many
living Witnesses in our own Country, who are ready to assert it.
We have one accurate Account in Anson's Voyage, where the Author reasons
very Philosophically upon the Subject. This Author tells us, that the Crew
of the Centurion were in some Uneasiness about the Heat of the Climate,
which they expected they were to undergo, when they came to that Part of
the Æquator which is near the American Coast, upon the South Sea; but that
when they came under the Line, instead of those scalding Winds which
sometimes blow in immensely hot Climates, they were agreeably surprized
with the softest Zephyrs imaginable; and that, instead of being scorched by
the perpendicular Rays of the Sun, they had a fine Covering of thin grey
Clouds over their Heads, and just enough of them to serve for a Screen,
without looking dark and disagreeable. Many other Beauties of the Climate
the Author describes, which need not be mentioned here, as it is easy to
see the Book.
He accounts for the extraordinary Mildness of the Climate in Words to this
Purpose:
"There are Mountains on the Sea Coast of this Latitude, of an enormous
Height and great Extent, called the Andes, the Tops and Sides of which are
covered with everlasting Snow. These Mountains cast a Shade and Coolness
round them, for several Leagues, and by their Influence it is, that the
Climate is so temperate under that Part of the Line. But, says the Author,
when we had sailed beyond the Æquator, into four or five Degrees of North
Latitude, and were got out of the Influence of those Mountains covered with
Snow, we then began to feel that we were near the Line, and the Climate was
as hot as we could have expected to have found it at the Æquator itself."
There can be no Doubt of the Truth of this Account: No Man would have made
such Assertions as these, if they had not been true, when there were so
many living Witnesses to have contradicted such an idle, needless Falshood
as this would have been. And indeed the Appearance of wise Design in the
Author of Nature is no where more conspicuous than in these Instances of
his Care for the Preservation of the animal System. What could we have
expected more than Mountains of Snow in Greenland? And even in those frozen
Regions we have as great Instances of the same Providence: When the Springs
are all frozen up, in that severe Climate, they have sometimes, even in the
middle of Winter, such mild South Winds as serve to thaw the Snow, so as to
cause Water to settle in the Valleys, and to run under the Ice in
Quantities large enough to serve the Purposes of animal Life; not to
mention the great Quantities of Timber which the Surf of the Sea brings
upon that Coast, from other Countries; without which the Inhabitants would
have no Firing, nor Timber for their Huts, nor Shafts for their Arrows, as
there are no Trees in that Country.
And now I hope it will not be thought too bold an Analogy if we presume to
say, that as, contrary to all Expectation, at the Æquator (where
intolerable Heat might be expected) the Inhabitants are provided with
Mountains covered with Snow, to qualify their Atmosphere; why may not we
suppose, that at the very Poles themselves there may be some Cause, unknown
to us, which may render the Climate serene and mild, even in that supposed
uninhabitable Part of the Globe? Why may there not be hot, burning Minerals
in the Earth at the Poles, as well as snowy Mountains at the Æquator?
We have Reason to think that the Composition of the Earth, at that Part of
the Globe, is of an extraordinary Nature; as the magnetic Quality of it is
to be apprehended, from it's immediate Attraction of the Needle. We are
entirely ignorant of the Soil, of the Place, and of the Constitution of the
Inhabitants, if there are any. We are certain that, near Greenland, there
are Sands of so extraordinary a Nature, that the Wind will carry great
Clouds of them several Leagues to Sea, and they will fall into the Eyes and
Mouths of Navigators, who are sailing past the Coast, at a great Distance.
This Instance only serves to shew, that we may be quite ignorant of the
Nature of the Soil which is under the Pole; we cannot tell whether it
consists of Mountains or Caverns, fiery Volcanos or craggy Rocks, of Ice,
Land, or Water, cultivated Fields or barren Desarts.
What has been laid will seem less strange, if we look back into the Notions
which the Ancients had of the Torrid Zone. It is not long since it was
thought, that only the Temperate Zone on this Side the Æquator was
habitable; so far were they from attempting to find out another Temperate
Zone beyond the Æquator, that nobody dare approach near the Line, for Fear
of being roasted alive. This is the true State of the Case; and if it be so
that the Ancients were, for such a vast Number of Years, under a mistaken
Notion, concerning the Possibility of living under or near the Line, why
may not we, who are neither more daring nor more ingenious than the old
Romans, be likewise mistaken, or rather totally ignorant of the Climates at
the Pole?
And here I beg Leave to offer a Philosophical Reason, why it should not,
according to the Nature of Things, be any colder at the Poles themselves,
than ten Degrees on this Side of them. Not that I by any Means insist upon
the Truth of what I am going to say; I only just offer it as a Subject to
be discussed by those who are more learned, and are able to take more exact
Mensurations of the Phoenomena of Nature than myself.
What I would offer is, that there is no Reason to apprehend more Cold at
the Extremities of the Poles than ten Degrees on this Side of them, on
Account of the Figure of the Earth. The Figure of the Earth is found, by
Observations which have been made, upon the Difference of the Vibrations of
Pendulums at the Æquator and near the Poles, and by other Experiments, to
be not a Sphere, but a Spheroid; it is not exactly round, neither is it
oval, but (if I may make Use of the Comparison) more in the Shape of a
Turnip.
Now the Climate is hotter at the Æquator than in high Latitudes, on Account
of the Inclination of the Poles to the Sun, as has been said before: What I
would urge is, that the Surface of the Earth, at ten Degrees on this Side
of the Poles, is as much or nearly as much inclined to the Plain of the
Ecliptic as the Poles themselves.
If that is the Case, no Reason can be given why the Poles should be colder
than Greenland, where, if we may believe the Accounts of Navigators, though
in the Winter the Cold is so intense as to freeze Brandy, yet, in the
middle of Summer it is sometimes so hot, that People have been glad to
strip off their Cloaths, for an Hour or two in a Day, in order to go
through their Work. But to return to the Surmise, that the Poles are no
colder than ten Degrees on this Side of them, on Account of the
Spheroidical Figure of the Earth.
I must trouble the Reader with a very plain Figure, in order to illustrate
the Meaning of this.
[Illustration]
By this Figure we may observe, that any Rays of the Sun A, which fall upon
a Place situated ten Degrees on our Side of the Pole B, and Rays which fall
on the Pole itself, do not make so large an Angle, as they would if the
Form of the Earth was a Sphere; for if we extend the two Points B and C so
far as to make a compleat Sphere, we must be obliged likewise to move the
Line D along with it to the Point E, which would make a larger Angle, and
in that Case the Surface of the Earth at the Pole B would be more inclined
to the Plain of the Ecliptic than it is, and consequently it would be
colder, as the Cause of Heat and Cold in different Parts of the Globe is
owing to the Inclination of the Poles to the Plain of the Ecliptic, and not
to the Distance of the Sun from the Earth at the different Seasons of the
Year; for if that was the Case, we should have colder Weather in July than
we have in December, the Sun being rather nearer to us in Winter than in
Summer.
I hope that this little Philosophical Effort, which has been made here,
will not be looked upon as unseasonably introduced in this Place; and I
likewise hope, that while I gaze with Wonder on the stupendous Frame of the
Universe, I shall not be thought presumptuous in having taken a little
Survey of one of the Wheels which duly performs it's Revolutions in that
glorious Machine, the Solar System; the exact and regular Movements of
which inspire the curious Beholder with a more awful Idea of the Greatness
of the Fabricator, than it is possible for any one to conceive, who is
entirely ignorant of the Accuracy of the Construction.
* * * * *