nomy. But, at prefent, the direct contrary is the cafe; for the Fictions of Aftronomy are introduced into, and have corrupted Philofophy; and the Speculations of Philofophers about the celeftial Bodies please none but themfelves; and in a manner run off from Aftronomy; as regarding only the Heavens in general, without at all reaching to the particular Phenomena and their Causes. Therefore, as both thefe Sciences, in their prefent State, are but light and tottering things; their Foundations fhould, by all means, be stronger fix'd; and in fuch a manner, as if the two, which, by reason of the School Ufes made of them, and the Narrowness of Mens Comprehenfions, have, for fo many Ages, been feparated and disjoined, were but one and the fame thing, to be wrought up together into a fingle Corps Question of Science, under the Title of Philofophical Aftronomy. are of the. (1.) 2. Let, the first QUESTION, therefore, be this. Is the Subftance of Whether the celeftial Bodies the celeflial Bodies of a different nature from that of the terrestrial? For the rafh and difputatious Temper of Aristotle, has given us an imaginary Hea- fame Nature. ven, made of the Quinta Effentia, that is not fubject to Alteration, or with the ter even to Heat. But to drop, for the prefent, fpeaking of the four Ele-restrial ? ments, which this Quinta Effentia fuppofes; it was certainly a very confident Attempt, entirely to cut off all relation betwixt the elementary and celeftial Bodies; whilft two of the Elements, viz. Air and Fire, have fo great an Agreement with Ether, and the Stars: But it was the practice of that That the terPhilofopher to abuse his own Genius, make himself Work, and affect reftrial and Obfcurities. There is, however, no doubt, that the Regions both below celeftial Bodies and above the Moon, together with the Bodies they contain, differ from may differ in Properties, one another in many and great refpects: But 'tis no lefs certain, that the and not in Bodies of both thefe Regions have numerous Properties, Tendencies, and Effence. Motions, in common; fo that we should rather distinguish betwixt, than rend them afunder: as being, at the bottom, of the fame nature. 3. As to that Opinion of their Heterogeniety, which makes the celeftial That the inBodies eternal, and the terreftrial perishable; it seems fallacious on both ternal parts fides: For the Heavens have not that Conftancy, nor the Earth that Mu-of the Earth tability which is coined by the Favourers of this Notion. Whoever immutable as may be as would form a true judgment of the Earth, can only do it from fuch parts the Heavens. thereof as have been feen; but all the terrestrial Bodies hitherto obferved by Men, have fcarcely been dug, or thrown up, from a greater depth than that of three Miles from the Surface; which is nothing in comparifon of the Earth's Semidiameter, and the whole Contents of the Globe :: And therefore the internal parts of the Earth may, for any thing that has hitherto appeared, be as durable as the Heavens. 4. And if the Earth did fuffer Changes at greater depths; the Confe- And its quences thereof muft neceffarily produce greater Accidents, than appear Changes on reach not below its more Superficial Which the prefent Age has feen fuccefsfully promoted by Sir Ifaac Newton. Sect. I. 2. Parts. See Mr. Boyle, of the Subterraneal Regions. . on the Surface: But in all the Changes we perceive towards the fuperficial parts, there is almost conftantly fome other manifeft Cause of them derivable from above; as difference of the Seafons, Rains, Droughts, Heats,&c. fo that the Earth of itself, and its own proper Force, feems to afford no Caufe of any confiderable Change. And allowing, what is probable, that not only the celeftial Bodies, but alfo the Earth, acts upon the Regions of the Air; either by breathing out Cold, difcharging Winds, or the like; yet all this Variety may happen in thofe Regions of the Earth which lie near the Surface; and where no one can doubt but there are numerous Changes and Revolutions. That Earth 5. But of all the Phænomena of the Earth; Earthquakes, and Acciquakes, . dents of the like kind, must be allowed to penetrate by far the deepest; happen only near the Sur- as the Eruption of Water, the Eructation of Fire and Flames, Chafms, face. and falling in of the Earth, &c. and yet thefe do not happen at any great Depth; as most of them ufually affect but fome little fpace on the furface of the Earth, without fpreading far: For the wider an Earthquake, or the like, fhould fpread upon the Earth's Surface, the deeper its Origin must be conceived, and vice verfa. Earthquakes 6. 'Tis true, there fometimes happen fuch Earthquakes, as fhake very in the Earth large and fpacious Countries; tho thefe are not frequent, but extraordifet against Comets in the nary Cafes; and may therefore be, pertinently, compared to the Comets, which alfo appear but feldom: For the bufinefs here is not to maintain the Immutability of the Earth; but only to fhew there is no great difference betwixt the Heavens and the Earth in point of Conftancy and Change. Heavens. That poffibly 7. And further; that the internal parts of the Earth are not more subthe internal ject to Corruption than the Heavens themfelves, may be argued from parts of the hence; that things ufually decay and perifh, where they may be recruited Earth fuffer no Lofs, and and renewed. For as Showers and other falling Meteors, which renew the want no Re- face of the Earth, can, by no means, penetrate to its internal parts; which, pair. nevertheless, maintain their bulk, and quantities; it fhould feem to follow, that nothing is there loft; as there is nothing at hand to repair any lofsa. 8. Laftly, 2 This, tho probable, may require to be better confirm'd; because the Force that was great at first, and exerted on the central Parts, might be fufpected to diminish near the Surface; fo as not there to produce any very confiderable Effect. a This Conjecture may receive fome Light from the Converse thereof, which is intimated by Sir Ifaac Newton in his Principia, upon better grounds, perhaps, than he there expreffes; viz. that as the Sea is abfolutely neceffary to the Conftitution of the Earth, in order to afford a fufficient quantity of Vapour, which is raised by the Sun; and being either condenfed into Clouds, falls back again in Rain, to water and fupply the Earth, for the production of Vegetables; or elfe being condenfed upon the cold tops of Mountains, runs down into Springs and Rivers; fo, Comets feem neceffary for fupplying the Seas, and proper Moisture in the Planets; that what Liquors are there confumed in Vegetation and Putrefaction, and converted into dry Earth, may be feafonably recruited and made good, by the Exhalations and Vapours of the Comets. For all Vegetables wholly receive their Growth from Liquids; and afterwards turn, by Putrefaction, in great meafure, to dry Earth. Whence the bulk of dry Earth is perpetually upon the increafe, and Liquids, unless otherwife fupplied, perpetually upon the decreafe, fo as to fail at laft. Princip. Lib. III. pag. 473. external 8. Laftly, the Mutability obferved in the more external parts of the The Mutabi Earth, feems only accidental: For the thin outside Cruft, which appears lity of the to reach but a few Miles downwards, and to contain the two wonderful Earth acciLaboratories of Plants and Minerals, would receive little Variety, much less dental. produce fuch beautiful and elaborate Works, without feeling the Influences and perpetual Animation of the celeftial Bodies. To imagine that the heat and active powers of the Sun, and other celeftial Bodies, may ftrike quite thro the entire Body of the terreftrial Globe, must be a strange degree of Superftition and Enthufiafm; whilft it plainly appears how fmall an Object is fufficient to check and reftrain them. vifible. 9. No fure Argument for the immutability of the Heavens, can be drawn The Argufrom hence; that the Effects thereof are not vifible: for the Sight is fru- ments for the ftrated as well by Distance, excefs, or defect of Light, as the fubtilty or Immutability of the Heaminutenefs of the Object: So an Eye placed in the Moon could not difcover vens not conthe changes which happen here upon the Earth's Surface; fuch as Inundations, clufive; as no Earthquakes, and the like; for these are but as Atoms at fo great a distance. Change is Nor is it fafe, because the interftellar Heaven appears transparent, and the fixed Stars, on clear Nights, appear the fame, both in Number and Complexion, to pronounce from thence, that the entire body of the Æther is clear, pure, and unchangeable: For the Air receives numberlefs varieties of Heat, Cold, Odours, and Mixtures, of all kinds, in fubtile Vapours, and Effluvia; and yet appears tranfparent. So likewife the clear face of the Heavens is no Proof of their Purity, Homogeneity, and Incorruptibility. For if those huge maffes of Clouds, which fometimes overfpread the Heavens, and, by reason of their nearness to us, hide the Sun and Stars from our fight, were to float in the higher parts of the Heavens; they would not at all fully or obfcure the clearnefs thereof: As themselves could neither be seen, on account of their distance, nor darken the Stars, on account of the fmallness of their Body, with regard to the Body of the Stars fo near them c. Even the Body of the Moon does not alter the face of the Heavens, except on that half which receives the Sun's Light; fo that, were it not for that Light, even fuch a vaft Body as the Moon would be perfectly hid from us. the Heavens. 10. On the other hand, it plainly appears from thofe maffes of Bodies, Visible Chanwhich by their bulk and fize fupply their want of nearnefs; and which, ges found in by means of their luminous Matter, brifkly ftrike the Eye; that there are ftrange and extraordinary Changes in the Heavens. Thus the higher Comets, feen in the form of Stars, without their Tails, are not only by the Doctrine of the Parallax, demonftrated to be above the Moon, but have also been found to preferve their own Figures, Stations, and Conftancy, for fome time, like the fixed Stars; without wandering in the manner of Planets. And fuch Comets have more than once appeared in our Time: First b That is owing to Caufes from without. Compare this with Sir Ifaac Newton's Doctrine of the Tails of Comets. Princip,. Lib. III. pag. 466, 467, 468, Or. d See Newton, Princip. Lib. III. Lem. IV. Stars. First in Caffiopeia, and again in Ophiucus. That this Conftancy of the The Appear- Ghanges in the Sun. Alterations in Venus. 12. Nor is it abfolutely true, that the ancient Stars remain perfectly the fame, and unchangeable; whilft only thofe of late date are subject to alteration: For, not to mention the Arcadian Fables about the first appearance of the Moon; there are in Hiftory, and the faithful Records of things, certain examples to our purpose. The Sun has three feveral times changed his Face, for many days together; whilft the Air remained clear and ferene, without any Eclipfe, or interpofition of Clouds. At one of these times his Light was little; and at the two others brownish. This happen'd in the year 790, for seventeen days together; again, in the time of Juftinian, for half a year; and, after the Death of Julius Cæfar, for feveral days fucceffively. Virgil bears a remarkable Teftimony of the Darknefs that happen'd upon the Death of Julius Cæfars. 13. The Account of Varro, a Man extremely well versed in Antiquity, found in St. Auftin, concerning the Planet Venus, might feem incredible; had not the like thing happen'd again in the year 1578: For Varro fays, that in the time of King Ögyges, Venus changed both her Colour, her Magnitude, and her Figure: But in our own time, there was, for a whole year together, a most remarkable alteration in the fame Planet; when she' appear'd of an unusual Magnitude, and Splendor; exceeded even Mars in Disappear- rednefs; and frequently changed her figure. And that ancient Star which ance of Stars. Ariftotle declares himself to have feen in Coxa canicula, bearded fomewhat like a Comet; and vibrating its Beard, efpecially upon a tranfient viewi; now seems changed, and to have loft its Beard: For it no where appears at prefent. We may add, that numerous alterations in the celeftial Bodies, but See the Author laft mention'd. Princip. Lib. III. pag. 455, &c. and Wolf. Elem. Aftron. pag. 594. See Wolfi Elementa Aftronomia, pag. 594. & Ille etiam extincto miferatus Cafare Romam, Cum caput obfcura nitidum ferrugine texit. n See Wolfii Elementa Aftronomia, p. 473, 474. i Compare this with Dr. Hook's Difcourfe of Comets, Sir Ifaac Newton's Princip. Lib. II. P. 467. and with Wolfius's Doctrine of Comets. Element. Aftronom. p. 595, &c. but especially in the fmaller Stars, may eafily be loft to us; or, thro neglect, and want of Curiofity, escape our Obfervation *. 14. If any one fhould attribute thefe apparent Changes to the interpofi- Thefe Chantion of Vapours, and the difpofition of the Medium; we anfwer, Thatges not juftiy affigned to fuch Changes as are conftantly, equally, and for a long time together, the Air. found in the Body of a Star, and revolve along with it, muft neceffarily be either in the Star itself, or in the Ether adjacent thereto; and not in the lower Region of the Air. And 'tis a Confirmation hereof, that such Changes happen but feldom, and at long periods; whereas the Changes that happen in the Air, from the interpofition of Vapours, are frequent. 15. Again, if any one fhall judge from the Order of the Heavens, and Order and the Equability of their Motion, that they are immutable; and take the exact Motion, no Argument exactness of their Periods and Revolutions, as a certain fign of their Conftancy, because such a conftancy of Motion may seem unfuitable to a cor- bility in the ruptible Substance; he fhould confider a little more attentively, that these Heavens. regular Returns and fixed Periods are alfo found in fome things upon the Earth; particularly in the ebbing and flowing of the Sea: And that the fmaller Differences which there may be in the celestial Bodies, their Periods and Revolutions, escape our Sight and Calculation'. 16. No more can the circular Motion of the Heavens, be brought as an Circular Motion no ArguArgument of their Immutability; as if because a circular Motion has no ment of EterEnd, it should be adapted to an ever durable Subftance: For even the lower nity in the Comets defcend below the Moon; and that from a Force of their own; Heavens. unless any one had rather give into that idle Fiction of Ariftotle, of their being tied to a Star. And if Men would argue for the Eternity of the celeftial Bodies, from their circular Motion; the Argument fhould be applied to the whole Expanse of the Heavens, and not to their Parts: For the Air, the Sea, and the Earth, are eternal in their entire Maffes; but perishable in their Parts. On the contrary; fuppofing the Rotation of the Heavens, their Eternity cannot be thence collected; for their Motion is not perfectly circular, or fuch as restores itself exactly, in a Circle; but has its Declinations, Curvatures, and Spirals ". 17. Again, if any one fhould retort our own Argument, which afferts Whether the the Changes happening in the Earth to be accidental, or proceeding from Earth be caabove; and maintain the Cafe to be otherwife in the Heavens; which can pable of af Heavens. by no means fuffer, in like manner, from the Earth; whofe Influences fecting the must all fall short, without reaching to the celestial Bodies; fo that, probably, the Heavens, being exempted from all hoftile Violence, are capable of Eternity; as not liable to Injury, or difturbed from any oppofite Nature: We acknowledge the Force of the Objection; for we pay no deference to For an Account of fuch Stars, fee the Philofophical Tranfactions, and Wolfius's Elementa Aftronomia, pag. 593, 594, 595. The late Improvements made in Telescopes, and other Optical Inftruments, have enabled Aftronomers to difcover fuch fmaller Objects and Variations in the Heavens, as without fuch Improvements, must have been ftill unknown. See Wolfii Elem. Aftronom. paffim. m But in the Hypothefis of the Earth's Motion, things appear much more fimple; tho this, as was before obferved, is no Proof of the Truth of that Hypothefis. F VOL. II. the |