greatest, does give nearly the vifible Altitude of the Moon's Center: But the true Altitude is nearly equal to the Altitude of the Center of the Shadow at that Time. Now we know the Altitude of the Center of the Shadow, because we know the Place of the Sun in the Ecliptic, and its Depreffion under the Horizon, which is equal to the Altitude of the oppofite Point of the Ecliptic, in which is the Center of the Shadow. And therefore we have the true Altitude of the Moon and the apparent Altitude, whofe Difference is the Parallax, which will therefore be known.

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CHA P. XI.

Of the Fixed Stars.

HAT the Fixed Stars are at a very great Distance from the Earth, may

be concluded from the North Pole of the Earth pointing as directly to the Pole Star*, when the Earth is at Aries, as when it is at Libra; though thofe two Points in the Earth's Orbit are at the Distance of 162,000,000 Miles from each other, which,

*The Pole Star is a Star of the fecond Magnitude, in the Tip of the Tail of the little Bear, and is very near the exact North Pole of the World.

Part II. it feems, amounts to no more than an insensible Point, in respect to the Distance of the fixed Stars.

The fixed Stars being visible to us at fuch a vast Distance, makes it highly probable that they are very large Bodies.

They are probably also at vast Distances from one another, which may be one Cause of their appearing of fuch different Magnitudes. They feem, by the Luftre of their Appearance, to emit Light like the Sun; and, indeed, if they only reflected Light, they could hardly be vifible to us at all at fo great a Distance.

Scarce 2000 Stars can be feen by the naked Eye; but ten, or, perhaps, twenty times more, may be difcerned by Telefcopes.

Thus, in the Pleiades, where only fix Stars are to be feen with the naked Eye, Dr. Hook counted 78 with a Twelve-foot Telescope; and with longer Telescopes he discovered a great many more. (See his Micography, p. 241.) And in the Conftellation Orion, where but 62 Stars can be counted with the naked Eye, 2000 have been numbered with the help of Telefcopes.

Can we think that God made these vast and numerous Bodies only to twinkle to us in the Night? Or is it not a more reafonable Conjecture that the fixed Stars are

all

all Suns with planetary Worlds moving round them, like our Sun? which, perhaps, is no other than one of the fixed Stars.

All the fixed Stars are like the Sun, immoveable in their Places, but all of them are not invariable as to the Luftre of their Appearance. Some of them appear and disappear periodically, as that in the Neck of the Whale, which is invifible for eight or nine Months in the Year; and in the other three or four Months of its Appearance, it is continually changing its Lufture and Brightness; which may, perhaps, be owing to the Star's being covered with dark Spots, fuch as we fee in the Sun, over the greatest Part of its Surface. And, supposing it to have a Rotation on its Axis, like our Sun, but flower; it prefents, at fome Times, its bright Part to our View, upon which it becomes vifible; at other Times it turns its dark Side to us, and then we cannot see it.

New Sars have alfo been obferved to appear, as one in the Swan's Breast, which was firft taken Notice of by Kepler, in the Year 1600. And old Stars have difappeared, and become invifible. For Inftance, one in the Pleiades, which were formerly feven Stars, and are called so still, though no more than fix have been visible to the naked Eye for feveral Ages paft. It I 4

feems

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seems the seventh was loft as long ago as Ovid's Time, by this Verfe in the third Book of his Fafti:

Quæ feptem dici, fex tamen effe folent.

And we are affured by the Catalogues of the fixed Stars, which were made by the ancient Aftronomers, and even fo late as by Tycho, that several Stars were observed by them, which are now become invisible. But whether these are periodical Stars, like that in the Whale's Neck, only with a flower Motion whether the new ones are new Creations; and whether the old ones, that have disappeared, are burnt out and extinguifhed; are Matters which furpass the Knowledge of the Philofophers of this World.

or ;

COROLLAR Y.

From this View of the fixed Stars, a probable Argument may be deduced for the Earth's diurnal Motion, viz. that fuch a Motion of the Earth is more probable, (as being more agreeable to the Wisdom of the divine Architect) than the diurnal Rotation of all the fixed Stars, as well as of the Sun and Planets round the Earth. To illuftrate this Argument, fuppofe but a hundred Men fitting round a great Room, attending on a Lecture of Geography, and

a com

a common Terrestrial Globe placed in the midst of them. Now which would be the. best Way to fhew all the Parts of the Globe to each Perfon fucceffively? Whether by turning the Globe round its Axis; or, by a vaft deal of Machinery and Wheelwork, to make the Room, and all the Seats in it, turn round the Globe? Which Way any wife and skilful Man would take, in this Cafe, is eafy to determine.

It is a further Probability on the Side of the Earth's diurnal Rotation, that Venus, Mars, and Jupiter, are certainly known to revolve on their Axes; and it is highly probable the Earth does fo too.

As for Saturn and Mercury, the one is so remote from us, the other fo near the Sun, that we have not been able to discover any Spots on the Surface of either of them, by which to judge whether they revolve on their Axes or no. Another and more certain Proof of the diurnal Rotation of the Earth is deduced from the Shape of it, which is an oblate Sphæroide, having its Diameter at the Equator above 30 Miles longer than from Pole to Pole. This, no doubt, arifes from a diurnal Rotation; as it is certain that such a Rotation of the Earth must neceffarily give it the fame sphæroidical Form which it is found in Fact to bear.

As

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