« AnteriorContinuar »
Stars, is not so perfectly deterinined, for want of Certainty in their Parallaxes. Also in the Copernican System the Distance varieth, not only from the Motion of the Planets; but also from the Motion of the Earth itself.
THE Reason for either Opinion, (viz. of the Ptolemaic and Copernican) about the Situation of the Earth, are much the same with those we difcussed in the preceeding Chapter about the Earth's Motion. For this Dispute is of great Affinity with the former. Because, if the Sun hath an annual Motion, then the Earth and not the Sun possesses the middle Place : But if the Earth so move, the Sun and not the Earth will certainly be in the Center.
THE following Arguments favour the Copernican Hypothesis.
1. THE Sun is not only the glorious Fountain of Light, which like a clear shining Torch, illuminates the Earth, Moon, Venus, and, without doubt, the rest of the Planets ; but is also the Focus of Heat, and the Source of vital Spirits ; whereby the whole Universe is subsisted and nourished: and therefore very probably pofsefleth the Center about which they all revolve.
2, IT is more likely that the Earth, with the rest of the Planets, should revolve bout the Sun, when they receive Light and Heat from him ; than that the Sun should move about the Earth, when he receives nothing from it.
3. THERE are many Causes why the Sun should possess the middle Place, and the rest of the Planets revolve round him, (especially if we embrace the Hypothesis of Kepler concerning the Motion of the Planets) the chief of which is, that the Sun, being a vast Body, is moved about it's Axis, and by a strong [Vectory] Force exciteth the
Earth and the rest of the Planets to a circular Motion (c).
4. THIS Rotation of the Sun about it's Axis is proved from the Observations of the Spots upon it's Surface by Galileo.(d), Scheiner, &c. and we may reasonably presume, it is owing to this common Cause that the rest of the Planets revolve about theirs ; but we cannot perceive a likelihood of any Motion in this Luminary (e).
. 5. IF
(c) The fagacious Kepler Phases of Saturn; the Increase · was the Founder of the New- and Decrease of the Light of
tonian Philofophy: it was he Venus; the mountainous and that first found out the true uncertain Surface of the Moon ; System of the World, and the the Spots of the Sun; and the Laws which the celestial Bodies Revolution of the Sun about observe in their Motions; it was it's own Axis : all which were he that determined the true first discovered and observed by Path of the Earth, and the this great Philofopher. Keill's rest of the Planets about the Astron. Lect. Pref. Pag. 11. Sun, and discovered the har- (e) From the later Obsermonic Proportions and Concin- vations of Astronomers it is nities of their Distances and manifest to our Sight, that alMotions : and tho' he did not so every Heavenly Body we demonstrate (and shew a Reason have any good Views of, is for the necessity of) such Laws turned round some principal and Proportions ; yet he gave a Point, and also it's own Axis, Hint, and laid a Foundation viz. hath the like Annual for that Prince of Geometers Revolutions, and Diurnal MoSir IS AAC NEWTON, to tions as those are which we demonstrate an absolute Necef- ascribe to the Earth ; yea even fity of these Laws; and that the more maffy Globes of Sa. without a total Subversion of turn and Jupiter, which seem the Laws of Nature, no other not in their own Nature more Rule could take place in the fitted for such Rotations. Revolutions of the heavenly Bo- Wherefore we may certainly dies. .
conclude, that it is as poslible, (d) He was the first that and as probable, that this our applied a Telescope to the Hea- leser Globe, should perform vens, and by it's means disco- it’s Revolutions according to the vered a great may new furn fame Law which is observed prising Phænomena; as the in the rest of the Planets, Moons or Satellites of Jupiter, whereby the beautiful Order and their Motions; the various and Harmony of Morions is VOL. I.
5. IF we suppose the Earth placed betwixt Mars and Venus, and also place the Sun in the Center of the System ; the Motion of each of the Planets will be exactly in Proportion to their several Distances from that Center : But this will not hold in the Ptolemaic Hypothesis, as is manifest by comparing the Motion of the Sun, Venus, Mercury, &c. (f).
6. THE Celestial Phenomena, mentioned in the former Chapter, to prove the annual Motion of the Earth, do likewise as effectually prove that this is the right place in which it ought to be moved, viz. The Retrograde Motion, and seeming Immobility of the Planets ; the admirable apparent Motion [and Pbases] of Venus and Mercury, &c (8). For since the annual Motion of the Earth is presupposed in this Place, or in some other very near it ;
every where preserved thro' gument that the Sun is as much the frame of Nature.
the Center of the Earth and of Sir Isaac Newton's De- Planets about him, as the Earth monstration, That the Squares is of the Moon. of the Planets Revolutions (8) These Observations, are as the Cubes of their Din which utterly overthrow the Atances, every where takes place, Ptolemaic Hypothefis, are ow‘if the Sun be supposed the ing to later Astronomers. For Center of the Planets about they, by their Glasses, have him ; but does not hold at all found out that the spherical Fi'in Relation to the Earth; for gure of Venus and Mercury, if the Moon revolve round the seen from the Earth, will be Earth in (273 Days) a Perio altered, and have the same vadical Month, as it certainly docs, riety of Phases as the Moon the Sun, as being at a greater hath, viz. will appear opake, Distance, will take no less than horned, bisected, gibbous, and 54700 Years, according to the full, at proper Distances from áforesaid Law, to make his Re- the Sun, as explained upon volution about the Earth. But the Copernican Hypothefis ; since this Law, is found to be which certainly establishes and observed not only in the prin confirms that Order and Situamary Planet's about the Sun, tion, namely that Venus and but also in the Secondaries a- Mercury revolve about the Sun bout Jupiter, Saturn, and the in Orbits that are included Earıb, it is an incontestable Ar- within the Earth's Orbit.
this Argument, in my Opinion, is the best to defend it by į since this situation of the Earth cannot be proved immediately from it's diurnal Motion : Because it might poffefs the Center of the Universe, and have a diurnal Motion, tho it wanted the annual; as Origanus fuppofed.
7. BY this Hypotbefis likewise, the Variation of the Distances of the Planets from the Earth is accounted for.
THE Ptolemaics, on the other hand, oppose the Pytbagorean Opinion, and endeavour to prove that the True Plače of the Eartb is in the Center of the World, by the following Arguments. 1. That heavy Bodies are all naturally carried towards the Center, but that the Earth is more ponderous than the reft, therefore it ought to reside in the Center (b). -2. Heavy Bodies would recede from the Earth towards the Center of the World, if the Earth itself was not in the Center. 3. The Center is the basest Place, and the Earth the ignobleft Part of the Creation į therefore it ought to be placed in the Center. 4. If the Earth was placed out of the Center of the World, and was not the Center of the Stars and Planets Motion, then would the Stars and Constellations at fome Seasons of the Year appear greater than at others (i). 5. The Medium of the Heavens could not always be perceptible, nor would Taurus rise when Scorpio sets. 6. Neither would there be Equinoxes. 7. Nor would the Moon set, nor be eclipsed when the Sun was rising. 8. Neither could an equal Number of
(5) This Assertion is falle : far greater in the middle of See the Note at the end of this their Regresses than in the Chapter 7
middle of their Progresses, be(i) Tho' this does not hold cause the Earth, in their Rein the fixed Stars, because of gresses, comes nearer chese · their immense Distance ; yet Planets an entire Diameter of all the superior Planet's fécm 'the Orbis Magnus,
Miles on the Earth answer to each Degree in the Heavens.
THE Copernicans easily refute these Arguments of the Aristotelians. For the first and second is rejected, because the Motion of heavy Bodies is not towards the Center of the Universe, but towards the Earth, a homogeneous Body; as is proved from the Parts of the Sun and Moon, and of the Loadstone. In the third both the Assumptions are false ; For the Center is an Honourable Place; and the Earth is no ways dishonourable. The rest of the Arguments are easily disproved by a Description of the System; it being first presupposed that tho' the Earth's Distance from the Sun be very great, yet if compared with the Distance of the fixed Stars, it is so small, that it hath no Proportion to it ; which seems to some a great Poftulatum in the Copernican Astronomy (k). . .
(k) To find this Variation Skill, determine any sensible of the Distance of the fixed Parallax at all (only they difStars (arising from the annual covered a seeming new Motion Motion of the Earth, and cal- of the fixed Stars, which (alled their annual Parallax) hath lowing the progressive Motibeen often attempted by the on of Light) does in some MeaCopernican Astronomers ; be sure demonstrate the annual cause that the annual Motion Motion of the Earth). There of the Earth would thereby be appearing therefore, after all, not only inade probable, but no sensible Parallax in the fix. certainly demonstrated. This, ed Stars, the Anti-Copernicans I say, was attempted without have still room, on that AcSuccess, 'till Dr Hook and count, to object against the MoMr Flamsized, by new inven- tion of the Earth. And the - ted accurate Instruments, seem- Copernicans are still obliged to
ed to have found out this an- hold, that the Orbis Magnus nual Parallax to be at least as is but as a Point in Comparimuch again as the double of son of the Distance of the nearthe Sun's diurnal Parallax, viz. est fixed Stars; which is cer. 47 Seconds. But Mr Moly- tainly (as our Author observeth) neaux and Mr Bradley, by a great Blot in the Copernican · their late accurate Observati. Astronomy, left to be wiped ens, could 1106, with all their out by future Ages.