93. Part of the Paths of three Comets are delineated in the Scheme of
the Solar System, and the years marked in which they made their
appearance. It is believed, that there are at least 21 Comets belonging
to our System, moving in all sorts of directions: and all those which
have been observed, have moved through the ethereal Regions and the
Orbits of the Planets without suffering the least sensible resistance in
their motions; which plainly proves that the Planets do not move in
solid Orbs. Of all the Comets, the Periods of the above-mentioned three
only are known with any degree of certainty. The first of these Comets
appeared in the years 1531, 1607, and 1682; and is expected to appear
again in the year 1758, and every 75th year afterwards. The second of
them appeared in 1532 and 1661, and may be expected to return in 1789
and every 129th year afterwards. The third, having last appeared in
1680, and it’s Period being no less than 575 years, cannot return until
the year 2225. This Comet, at it’s greatest distance, is about 11
thousand two hundred millions of miles from the Sun; and at it’s least
distance from the Sun’s center, which is 490,000 miles, is within less
than a third part of the Sun’s semi-diameter from his surface. In that
part of it’s Orbit which is nearest the Sun, it flies with the amazing
swiftness of 880,000 miles in an hour; and the Sun, as seen from it,
appears an hundred degrees in breadth; consequently, 40 thousand times
as large as he appears to us. The astonishing length that this Comet
runs out into empty Space, suggests to our minds an idea of the vast
distance between the Sun and the nearest fixed Stars; of whose
Attractions all the Comets must keep clear, to return periodically, and
go round the Sun; and it shews us also, that the nearest Stars, which
are probably those that seem the largest, are as big as our Sun, and of
the same nature with him; otherwise, they could not appear so large and
bright to us as they do at such an immense distance.
[Sidenote: Inferences drawn from the above phenomena.]
94. The extreme heat, the dense atmosphere, the gross vapours, the
chaotic state of the Comets, seem at first sight to indicate them
altogether unfit for the purposes of animal life, and a most miserable
habitation for rational beings: and therefore [17]some are of opinion
that they are so many hells for tormenting the damned with perpetual
vicissitudes of heat and cold. But, when we consider, on the other hand,
the infinite power and goodness of the Deity; the latter inclining, and
the former enabling him to make creatures suited to all states and
circumstances; that matter exists only for the sake of intelligence; and
that wherever we find it, we always find it pregnant with life, or
necessarily subservient thereto; the numberless species, the astonishing
diversity of animals in earth, air, water, and even on other animals;
every blade of grass, every tender leaf, every natural fluid, swarming
with life; and every one of these enjoying such gratifications as the
nature and state of each requires: when we reflect moreover that some
centuries ago, till experience undeceived us, a great part of the Earth
was judged uninhabitable; the Torrid Zone by reason of excessive heat,
and the two Frigid Zones because of their intollerable cold; it seems
highly probable, that such numerous and large masses of durable matter
as the Comets are, however unlike they be to our Earth, are not
destitute of beings capable of contemplating with wonder, and
acknowledging with gratitude the wisdom, symmetry, and beauty of the
Creation; which is more plainly to be observed in their extensive Tour
through the Heavens, than in our more confined Circuit. If farther
conjecture is permitted, may we not suppose them instrumental in
recruiting the expended fuel of the Sun; and supplying the exhausted
moisture of the Planets? However difficult it may be, circumstanced as
we are, to find out their particular destination, this is an undoubted
truth, that wherever the Deity exerts his power, there he also manifests
his wisdom and goodness.
[Sidenote: This System very ancient, and demonstrable.]
95. THE SOLAR SYSTEM here described is not a late invention; for it was
known and taught by the wise _Samian_ philosopher PYTHAGORAS, and others
among the ancients; but in latter times was lost, ’till the 15th
century, when it was again restored by the famous _Polish_ philosopher
NICHOLAUS COPERNICUS, who was born at _Thorn_ in the year 1473. In this,
he was followed by the greatest mathematicians and philosophers that
have since lived; as KEPLER, GALILEO, DESCARTES, GASSENDUS, and Sir
ISAAC NEWTON; the last of whom has established this System on such an
everlasting foundation of mathematical and physical demonstration, as
can never be shaken: and none who understand him can hesitate about it.
[Sidenote: The Ptolemean System absurd.]
96. In the _Ptolemean System_ the Earth was supposed to be fixed in the
Center of the Universe; and that the Moon, Mercury, Venus, the Sun,
Mars, Jupiter, and Saturn moved round the Earth: above the Planets, this
Hypothesis placed the Firmament of Stars, and then the two Crystalline
Spheres; all which were included in and received motion from the _Primum
Mobile_, which constantly revolved about the Earth in 24 hours, from
East to West. But as this rude Scheme was found incapable to stand the
test of art and observation, it was soon rejected by all true
philosophers; notwithstanding the opposition and violence of blind and
zealous bigots.
[Sidenote: The Tychonic System, partly true and partly false.]
97. The _Tychonic System_ succeeded the _Ptolemean_, but was never so
generally received. In this the Earth was supposed to stand still in the
Center of the Universe or Firmament of Stars, and the Sun to revolve
about it every 24 hours; the Planets, Mercury, Venus, Mars, Jupiter, and
Saturn, going round the Sun in the times already mentioned. But some of
TYCHO’s disciples supposed the Earth to have a diurnal motion round it’s
Axis, and the Sun with all the above Planets to go round the Earth in a
year; the Planets moving round the Sun in the foresaid times. This
hypothesis, being partly true and partly false, was embraced by few; and
soon gave way to the only true and rational System, restored by
COPERNICUS and demonstrated by Sir ISAAC NEWTON.
98. To bring the foregoing particulars at once in view, with several
others which follow, concerning the Periods, Distances, Bulks, _&c._ of
the Planets, the following Table is inserted.