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Of these Observations the Reader should have met with many more (and I believe some of
ingenious Friends do expect more) but that I lie under two inconveniences : One the want of an open free Horizon, my Habitation being furrounded much with Trees. The other, and indeed the chief, the want of a long Pole of 100 or more Feet, to raise my long Glass to such an height, as to see the Heavenly Bodies above the thick Vapours; which much obscure all Objects near the Horizon, especially when viewed with such long and good Glasses. But fince that, two very dangerous fits of Sickness, and the increase of my Age, (both which have much impaired my Sight) have render'd me uncapable of such Observations, especially at such Seasons of the Night and Weather, as are fittest for viewing the Heavenly Bodies.
And therefore if I have not sufficiently answered the expectations of some of my learned and ingenious Friends, I hope they will excuse me, and believe it to be more my Calamity than Fault that I have done no more ; especially among such Planets as have advantageously presented themselves, was Saturn particularly hath, whose. 5 or more Satellites it
may be expected I have seen ; but I could never reach but three of them, and they only when there were but few Vapours. And as for the Spots in Mars and Venus, and their Motion round their own Axes, after I had a good Furniture of excellent Glasses, I had not any good Views of those Planets before
my Sickness, by reason of the too great distance of Mars from the Earth, and the proximity of Venus to the Sun, and the cloudy Weather, and the small Altitude which Venus had a
bove the Horizon about that time.
But however what is here wanting in my own, is sufficiently made up from the Observations of others. Of which the learned World hath good Store, since the Invention of the Telescope ; which as it hath made ample discoveries of the Works of God, so hath laid open a new, and a far more grand and noble scene of those Works than the World before dreamt of, and afforded us a far more rational System of the Heavens and the Universe, than was before entertained.
And forasmuch as I have frequent occasions in my following Book to speak of, and, according to some or other of the Systems of the Heavens, it is necessary I should, by way of Preface, give some account of them, to enable such Persons to understand
Book as are unacquainted with Astronomical Matters,
Among all the various Systems, I need take notice only of three, the Ptolemaick, the Copernican, and the New System. Of each of which in their Order.
Of the Ptolemaick System.
In the Ptolemaick System the Earth and Waters are supposed to be in the Center of the Universe; next to which is the Element of Air, and next above that is the Element of Fire ; next that the Orb of Mercury, then that of Venus, then that of the Sun; and above the Sun's Orb, those of Mars, Jupiter, and Saturn; and above them all, the Firmament or Orb of the Fixt Stars; then the Crystalline Orbs; and lastly the Cælum Empyreum, or Heaven of Heavens.
All these massy Orbs, and vast Bodies born by them, are, in this System, supposed to move
round the terráqueous Globe once in 24 Hours : and besides that, in some other certain periodical Times. For the effecting of which Motions, they were forced to contrive such Circles as they called Eccentricks and Epycicles, crossing and interfering with one another; which I could not represent in so nårrow a compass as Fig. 1. is, which is a Scheme of this Ptolemaick System; which is universally maintained by the Peripatetick Philosophers.
Of the Copernican System.
The next System is the Pythagorean or Copernican, being invented, as some imaginé, by Pythagoras himself
. But Diogenes Laertius (a) expresly faith, That Pythagoras's opinion was, That the World was
(a) Lib. 8. in Pythagorâ.