to correct the mistakes into which we
may fall respecting the heavenly bodies.

(57) See above, Essay XXI.

The result of the uncertainty which adheres to all astronomical
observations is such as might have been expected. Common readers
are only informed of the latest adjustment of the question, and are
therefore unavoidably led to believe that the distance of the sun
from the earth, ever since astronomy became entitled to the name of
a science, has by universal consent been recognised as ninety-five
millions of miles, or, as near as may be, twenty-four thousand
semi-diameters of the earth. But how does the case really stand?
Copernicus and Tycho Brahe held the distance to be twelve hundred
semi-diameters; Kepler, who is received to have been perhaps the
greatest astronomer that any age has produced, puts it down as three
thousand five hundred semi-diameters; since his time, Riccioli as seven
thousand; Hevelius as five thousand two hundred and fifty(58); some
later astronomers, mentioned by Halley, as fourteen thousand; and Halley
himself as sixteen thousand five hundred(59).

(58) They were about thirty and forty years younger than Kepler
respectively.

(59) Halley, apud Philosophical Transactions, Vol. XXIX, p. 455.

The doctrine of fluxions is likewise called in by the astronomers in
their attempts to ascertain the distance and magnitude of the different
celestial bodies which compose the solar system; and in this way their
conclusions become subject to all the difficulties which Berkeley has
alleged against that doctrine.

Kepler has also supplied us with another mode of arriving at the
distance and size of the sun and the planets: he has hazarded a
conjecture, that the squares of the times of the revolution of the earth
and the other planets are in proportion to the cubes of their distances
from the sun, their common centre; and, as by observation we can
arrive with tolerable certainty at a knowledge of the times of their
revolutions, we may from hence proceed to the other matters we are
desirous to ascertain. And that which Kepler seemed, as by a divine
inspiration, to hazard in the way of conjecture, Newton professes to
have demonstratively established. But the demonstration of Newton has
not been considered as satisfactory by all men of science since his
time.

Thus far however we proceed as we may, respecting our propositions on
the subject of the solar system. But, beyond this, all