Of thefe Obfervations the Reader fhould have met with many more (and I believe fome of my 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 fuch an height, as to fee the Heavenly Bodies above the thick Vapours; which much obfcure all Objects near the Horizon, especially when viewed with fuch long and good Glaffes. 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 fuch Obfervations, especially at fuch Seasons of the Night and Weather, as are fitteft for viewing the Heavenly Bodies.

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And

And therefore if I have not fufficiently answered the expectations of fome of my learned and ingenious Friends, I hope they will excufe me, and believe it to be more my Calamity than Fault that I have done no more; especially among fuch Planets as have advantageously prefented themselves, as Saturn particularly hath, whofe 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 Glaffes, I had not any good Views of those Planets before my Sickness, by reason of the too great diftance of Mars from the Earth, and the proximity of Venus to the Sun, and the cloudy Weather, and the fmall Altitude which Venus had a

bove

bove the Horizon about that time.

up

But however what is here wanting in my own, is fufficiently made from the Obfervations of others. Of which the learned World hath good Store, fince 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 fcene of those Works than the World before dreamt of, and afforded us a far more rational Syftem of the Heavens and the Univerfe, than was before entertained.

And forafmuch as I have frequent occafions in my following Book to speak of, and, according to fome or other of the Systems of the Heavens, it is neceffary I fhould, by way of Preface, give fome account of them, to enable fuch Perfons to understand my Book as are unacquainted with Aftronomical Matters.

Among all the various Systems, I need take notice only of three, the Ptolemaick, the Copernican, and the New Syftem. Of each of which in their Order.

Of the Ptolemaick System.

In the Ptolemaick. Syftem the Earth and Waters are fuppofed 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 laftly the Cœlum Empyreum, or Heaven of Heavens. All these maffy Orbs, and vaft Bodies born by them, are, in this System, supposed to move round

round the terraqueous Globe once in 24 Hours: and befides that, in fome other certain periodical Times. For the effecting of which Motions, they were forced to contrive fuch Circles as they called Eccentricks and Epycicles, croffing and interfering with one another; which I could not represent in so narrow a compals as Fig. 1. is, which is a Scheme of this Ptolemaick Syftem; which is univerfally maintained by the Peripatetick Philosophers.

Of the Copernican Syftem.

The next System is the Pythagorean or Copernican, being invented, as fome imagine, by Pythagoras himself. But Diogenes Laertius (a) exprefly faith, That Pythagoras's opinion was, That the World was

(a) Lib. 8. in Pythagorâ.

round,

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