the celestial globes. The
variations of the moon are a necessary consequence of those laws.
Moreover, the reason is evidently seen why the nodes of the moon perform
their revolutions in nineteen years, and those of the earth in about
twenty-six thousand. The several appearances observed in the tides are
also a very simple effect of this attraction. The proximity of the moon,
when at the full, and when it is new, and its distance in the quadratures
or quarters, combined with the action of the sun, exhibit a sensible
reason why the ocean swells and sinks.

After having shown by his sublime theory the course and inequalities of
the planets, he subjects comets to the same law. The orbit of these
fires (unknown for so great a series of years), which was the terror of
mankind and the rock against which philosophy split, placed by Aristotle
below the moon, and sent back by Descartes above the sphere of Saturn, is
at last placed in its proper seat by Sir Isaac Newton.

He proves that comets are solid bodies which move in the sphere of the
sun's activity, and that they describe an ellipsis so very eccentric, and
so near to parabolas, that certain comets must take up above five hundred
years in their revolution.

The learned Dr. Halley is of opinion that the comet seen in 1680 is the
same which appeared in Julius Caesar's time. This shows more than any
other that comets are hard, opaque bodies; for it descended so near to
the sun, as to come within a sixth part of the diameter of this planet
from it, and consequently might have contracted a degree of heat two
thousand times stronger than that of red-hot iron; and would have been
soon dispersed in vapour, had it not been a firm, dense body. The
guessing the course of comets began then to be very much in vogue. The
celebrated Bernoulli concluded by his system that the famous comet of
1680 would appear again the 17th of May, 1719. Not a single astronomer
in Europe went to bed that night. However, they needed not to have broke
their rest, for the famous comet never appeared. There is at least more
cunning, if not more certainty, in fixing its return to so remote a
distance as five hundred and seventy-five years. As to Mr. Whiston, he
affirmed very seriously that in the time of the Deluge a comet overflowed
the terrestrial globe. And he was so unreasonable as to wonder that
people laughed at him for making such an assertion. The ancients were
almost in the same way of t