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Of the Figure of the Terraqueous Globe.
THIS I suppose I may take for granted to be Spherical, or nearly so (a). And this must be allowed to be the most commodious, apt Figure for a World on many Accounts; as it is most capacious, as its Surface is equi-distant from the Center,
(a) Although the Terraqueous Globe be of an orbicular Figure, yet it Is not strictly so, r. On account of its Hills and Vallies. But these are inconsiderable to the Earth"s Semidiameter; for they are but as the Dust upon a common Globe. But, z. Our modern Astronomers assign a much greater Variation from a globous Form, namely, that of a prolate Sphæroid, making the Polar about 34 Miles stiorter than the Equatorial Diameter. The Cause of which they make to be the centrifugal Force of the diurnal Rotation of the Globe.
This Figure they imagine is in Jupiter, his Polar being to his Equatorial Diameter, as 39 } to 40-|-. But whether it be so or no, I confess I could never perceive, although I have often viewed that Planet through very good, and long Glasses, particularly a tolerable good one of 71 Feet in my Hands: And although by Reason of cloudy Weather, and (at present) Jupiter's Proximity to the Sun, I have not been of late aiile to take a review of that Planet; yet Saturn (so far as his Ring would permit,) and Mars appear perfectly round thro' Mr. Huygens's long Glass of 116 Feet, which by Will he bequeathed, with its whole Apparatus, to our R. S. by whose Favour it is now in my Hands. And moreover, I believe it difficult, next to impossible, to measure the two Diameters to a 40^ Part, by reason of the smallness of Jupiter's apparent Diameter, and by reason he is moving all the time of measuring him.
As to what is alledged from lengthening the Pendulums of Clocks, to make them keep the fame Time under the Equator, as they do in our Climes; I have shewn from the like Variations in the Air-Pump, that this may arise from the rarity of the Air there, more than here. V. Phil. Trans. N°. 2.94. But if the Degrees of a Meridian grow larger, the more we go towards the Line, (as Mr, Caftni affirms they do, by an 8oo=u
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not only of the Globe, but at least (nearly) of Gravity and Motion tpo, and as some have thought, of the central Heat and Waters. But these, and divers other Things I shall pass over, and insist only upon two or three other Benefits of thisglobous Figure of the Earth and Waters.
I. This Figure is the most commodious in regard of Heat, and 1 may add of Light also in some measure. For by this means, those two great Benefits are uniformly and equally imparted to the World; They come harmoniously and gradually on, and as gradually go off again. So that the daily and yearly Returns of Light and Darkness, Cold and Heat, Moist and Dry, are Regular and Workman-like, (we may fay,) which they would not be, especially the former, if the Mass of Earth and Waters were (as some fancied (b) it) a large Plain; or as others,
Part in every Degree, in Phil, Trans. N°. 178.) then there j$ £reat reason to conclude in behalf of this Sphæroidal Form.
The natural Cause of this Sphericity of our Globe, is Recording to Sir Isaac Kewton's Principles) that Attraction, which the infinite Creator hath stamp'd oh all the Matter of the Universe, whereby all Bodies, and all the Parts of Bodies mutually attract themselves and one another. By which means, as all the Parts of Bodies tend naturally to their Center, so they all betake themselves to a globpus Figure, unless some other more prevalent Cause interpose. Thus Drops of Quick-silver put on a spherical Form, the Parts thereof strongly attracting one another. So Drops of Water have the fame Form, when falling in the Air; but are Hemispherical only when they lie on a hard Body, by reason their Gravity doth so far over-power their selfVattracting Power, as to take off one half of their Sphericity. This Figure is.commonly attributed to the Pressure of the circumambient Air:. But that this can't he the cause, is manifest from the AirPump; the cafe being the very fame in an exhausted Receiver, as in the open Air, and not any the least Alteration of the Figure that I could perceive, in all the Trials J haye made.
(i) It would be frivolous as well as endless to reckon up the various Opinionsof the Ancients about the Figure of the Terraqueous Globe; some of them may be seen in varen. Geogr.
like a large Hill in the midst of the Ocean -, or of a multangular Figure j or such like.
2. This Figure is admirably adapted to the commodious and equal Distribution of the Waters in the Globe. For since, by the Laws of Gravity, the Waters will possess the lowest Place j therefore, if the Mais of the Earth was cubick, prismatick, or any other angular Figure, it would follow, that one (too vast a Part) would be drowned j and another be too dry. But being thus orbicular, the Waters arc equally andcommodiously distributed here and there, according as the Divine Providence saw roost fit; pf which I shall take notice by and by.
3. The orbicular Figure of our Globe, is far the most beneficial to the Winds and Motions of the Atmosphere. It is not to be doubted, if the Earth was of some other, or indeed any other Figure, but that the Currents of Air would be much retarded, if not wholly stopped. We find by Experience what Influence large and high Mountains, Bays, Capes, and Head-lands have upon the Winds -, how they stop some, retard many, and divert and change (near the Shores) even the general and constant
1.1. c. 3. inlf. or Jonston's Thaumat. c. i. Artie. 3. But ijnong the variety of Opinions, one of the principal was, 'That the visible Horizon was the Bounds of the Earth, and the Ocean the Bourids of the Horizon, that the Heavens and Earth above this Ocean, was the whole visible Universe; and that all beneath the Ocean was Hades, or the invisible WorU. Hence, when the §un set, he was said tingere Jc Oceano; and when any went to Hades, they must first pass the Ocean. Qi thjs Opinion were not only the ancient Poets, and others among the Heathens, but some of the Christian Fathers too, particularly Lad am ha, St. Augustine, and others, who thought their Opinion was favoured by the Psalmist, in Pfal. xxiv. %. arid cjtx?si. 6. See»/. Ujher'i Anf.te A 3's. Chall. p. 366.
Winds (Y), that blow round the Globe in the Torrid Zone. And therefore, since this is the effect of such little Excrescences, which have but little Proportion to our Globe, what would be the Consequences of much vaster Angles, which would equal a Quarter, Tenth, or but an Hundredth Part of the Globe's Radius? Certainly these must be such a Barricade, as would greatly annoy, or rather absolutely stop the Currents of the Atmosphere, and thereby deprive the World of those salutiferous Gales that I have said keep it sweet and clean.
Thus the Figure of our Globe doth manifest it to be a Work of Contrivance, inasmuch as it is of the most commodious Figure j and all others would be liable to great and evident Inconveniences.
(c) Neither do these constant Trade-Winds usually blow near tot Shore, but only on the Ocean, at least 30 or 40 Leagues off at Sea, clear from any Land ; especially on the Weft Coast, or Side of any Continent: For indeed on the East Side, the Easterly Wind being the true Trade- Wind, blows almost home to the Share, so near as to receive a check from the Land-Wind. Dampier's Winds, Ch. 1.
And not only the general Trade-Winds, but also the constant coasting Trade-Winds, are in like manner affected by the Lands. Thus, for Instance, on the Coast of Angola and Peru. But this, faith the curious Captain Dampier, the Reader must take notice of, That the Trade-Winds that blow on any Coast, except the North Coast of Africa, whether they are constant, and blow all the Tear, or whether they are fluffing Winds, do never blow right in on the Shore, nor right along Shore, but go stanting, making an acute Angle of about iz Degrees. Therefore, as the Land tends more East or West, from North or South on the Coast; so the Winds do alter accordingly. Ibid. Ch. z.
THE next Thing remarkable in the Terraqueous Globe, is the prodigious Bulk thereof (a). A Mass of above 160 Thousand Million of Miles solid Content. A Work too grand for any thing less than a God to make. To which in the next Place we may add,
(4) It is not difficult to make a pretty near Computation of the Bulk of the Terraqueous Globe, from those accurate Observations of a Degree made by Mr. Norwood in England, and Mr. Picart, and Mr. Cajfmi in Trance. Whose Measures do in a surprizing manner agree. But Mr. Cajsmi's seeming to be the most accurate (as I have (hewn in my Astro-Theology, B. r. Ch. i. Note a.) 1 have there made use of his Determinations. According to which the Diameter of the Earth being 7967,71 Englijh Miles, its Ambit will be2.5031 - Miles; and (supposing it to be Spherical) itsSurface will be 199444110 Miles; which being multiplied into -J- of its Semidiameter, gives the Solid Content, viz.. z648j<5pooooo Miles.
The Motions of the Terraqueous Globe.
TH E Motions the Terraqueous Globe hath, arc round its own Axis, and round its Fountain of Light and Heat, the Sun (a). That so vast a Body as the Earth and Waters should be moved at
(<i) With the Copunicans, I take it here for granted, that the Diurnal and Annual Revolutions are the Motions of the Terraqueous Globe, not of the Sun, vc but for the Proof thereof I (hall refer the Reader to the Preface of my AstroTbtolofy, and B. 4. Chap. 3.