Page:Cyclopaedia, Chambers - Volume 1.djvu/629

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the 'Phenomena, both of the Heavens and Earth, refpond to and confefs this fpherical Figure.

What the Earth lofes of its Sphericity by Mountains and Vallies, is nothing confiderable ; the highefl Eminence be- ing fcarce Equivalent to the minuteft Protuberance on the Surface of a Lemon .- What it lofcs by the Swelling of the Equatorial Parts is more fenfible. See Mountain.

Sir JJaac Newton makes the greatest Diameter 34 Miles bigger than the lefs, fixing the Ratio, as ffj 2 to CS8. If the Earth were in a fluid State, its Revolution round its Axis would neceffanly make it put on fuch a Figure, by Reafon the Centrifugal Force being greatest towards the Equator, the Fluid would there rife, and fwell moil : and that it fhould be fo now, fcems neceffary to keep the Sea in the Equinoctial Regions from overflowing the Earth thereabouts. Add, that Experiments made on Pendulums, which muft be of different Lengths, to fwing equal Times here and at the Equator, evince the fame Thing. See Pendulum.

Monfr. de la Hire and M. Derbam, indeed, have fliewn, in the Memoirs of the French Academy, and Philofoph. TranfsS. that this Divcrfity may arife either from the greater Heat, or the greater Rarity of the Air there than here; as having obferved a like Variation between Pen- dulums when heated and cold, and when in Vacuo and open Air. Bur, befide that Sir Ifaac Newton and Monf. Bernoulli, have fct afide thefe Caufes as infufficicnt ; Monf Caffmi has found, that the Degrees of a Meridian grow larger, the further we go towards the Line by one Eight hun- dredth Part or every Degree ; which puts the Spheroidifm of the Earth paft Question.

The Antients had various Opinions as to the Figure of the Earth : Some, as Auaximmider, held it Cylindrical ; and others, zsLeucipfus, in Form of a Drum. But the prin- cipal Opinion was, that it was flat; that the vilible Horizon was the Bounds of the Earth, and the Ocean the Bounds of the Horizon ; that the Heavens and Earth above this Ocean ■was the whole vifiblc Univerfe ; and that all beneath the Ocean was Hades. Of which Opinion were not only divers of the ancient Poets and Philofophers, but alfo fome of the Chriilian Fathers, as ZaSantius, St. Augyftine, &c.

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From the former we derive the T>W*rG,"«* c if ,, -i Day: See Night and Day. A nd^™ /f'^' & f Viciflitudes of Seafons, Spring, Summer Tc s V' the Spring, Summer, Water, \Sc. ' &e SeASON >

See the Motion of the Earth proved under the Article Earth in Ajlronomy. Article

In the Terraqueous Globe we diftinguifh three Parts ot Regions, viz,. 1. The External Part, or Cruft, which is

4' f L° m whicl1 Vt 'S etables arift > antl Animals are nourilhed 2. Tthe Middle, or intermediate Parr, which is poffclfed by extending further than human Labour ever yet pe- 3. The Internal, or Central Part, which is un-

Foffil, netrated.

known to us, tho' by many Authors fuppofed of a magnetic JNature^ by others, a Mafs, or Sphere of Fire ; by others an Abyfs, or Colkaion of Waters, furrounded by the Strata ot Earth ; and by others, a hollow, empty Space, inhabited By Animals, who have their Sun, Moon, Plants, and other ^onvemencies within the fame.

Others divide the Body of the Globe into two Farts. viz. the External Part, which they call the Cortex, including the whole Depth or Mafs of the Strata of the Earth : An3 the Internal, which they call the Nucleus, being of a different JNature from the former, and poffcfs'd by Fire, Water, or the

£;, Cortex and Nucleus.

™ ! External Part of the Globe either exhibits Inequa- as Mountains and Vallies ; or it is plain and level ;

litics,

Fa. Tacquet draws fome pretty Conclusions from the Spherical Figure of the Earth ; as, 1. That if any Part of the Surface of the Earth were quite plain; a Man cou'd no more walk uprighr thereon, than on the Side of a Mountain : 2. That the Traveller's Head goes a greater Space than his Feet ; and a Horfeman than a Footman, as moving equal Arches of greater Circles : 3. That a VefTel full ol Water being rais'd perpendicularly, fome of the Water will be continually flowing out, yet the Veffel ftill remain lull ; and on the contrary, if a Veffel full of Water be let perpendicularly down, tho' nothing flow out, yet it will cealc to be full : Confequently there is more Water con- tain'd in the fame Veffel at tfje Foot of a Mountain, than on the Top; by Reafon the Surface of the Water is com-

prefs'd into a Segment of a lefs Sphere below than above, precipitated to the Bottom, * *and that, according "I, acq. Aftronom. L. I. C. 2.

The Magnitude of the Earth, and the Number of Miles its Diameter contains, has been varioufly determined by va- rious Authors, ancient and modern. The Way to arrive at it, is, by finding the Quantity of a Degree of a great Circle of the Earth. But this Degree is found very different, ac- cording to the different Methods and Inftruments made ufe of, as well as the different Obfervers. See Degree.

The Method obferved by Mr. Norwood, and the French Aftronomers Picard, Caffmi, &c. viz. by meafuring the pittance between two remote Places on the fame Meridian, is undoubtedly the beft ; and was performed with fuch exceeding Accuracy, efpecially by Monf. Caffmi, that hardly any thing further or better can be expected. According to that Author, the Ambit or Circumference of the Earth is 123750720 'Paris Feet; or, 134650777 Englifi Feet; or, 250317 of our Statute Miles : Whence, fuppofing the Earth fpherical, its Diameter mufl be 79117 Statute Miles ; and con- fequently its Radius, or Semi-diameter, may be taken in a round Number for 200000000 Feet : Its Surface Will be i!>9444 2 oS Miles; which being multiplied into I of its Semi- diameter, gives the folid Content of the Globe of the Earth 15485^000000 Cubic Miles.

On the Surface of the Earth are conceiv'd the fame Circles, as on the Surface of the Mundane Sphere already oefenbed ; viz. an Equator, Ecliptic, Tropicus, -"-"LAR-Gjrfei, Meridians, Horizon, Parallels, (yc. which See, as alfo Sphere and Globe.

The terraqueous Globe is now generally granted to have two Motions, the one ^Diurnal, around its own Axis, m the Space of 24 Hours, which constitutes the Natural Ua ih m Nycthemeron. See Diurnal-A&WW.

1 he other Annual, round the Sun, in an Elliptical Orbit, or track, in 365 Days 6 Hours, constituting the Year. See Annv A-L-Monon and Year.

The External Patt ot the Globe either exhibits Inequ as Mountains and Vallies ; or it is plain and leve. , or dug m Channels, Fiffures, Beds, XSc. for Rivers, Lakes, Seas &c. See River, Lake, Ocean, &c.

thefe Inequalities in the Face of the Earth, are by moft jNatural.fts luppofed to have arofe from a Rupture or Subversion of the Earth, by the Force either of the lub- terraneous Fires or Waters. The Earth in its Natural and Original State, Des Cartes, and after him 'Burner, Stem, Woodward, U 'hifton, and others, fuppofe to have been per- fectly round, fmooth, and equable ; and accounts for its prefent rude and irregular Form, principally from the great Deluge. See Deluge, Earthquake, iSc.

In the External, or Cortical Part of the Earth, we meet with various Strata, which are fuppofed to be the Sedi- ments of various Floods, the Waters whereof being replete with Matters of divers Kinds, as they dried up, or oozed through, deposited thefe different Matters, which in Time harden'd into Strata of Stone, Sand, Coal, Clay, tSc. See Strata, Coal, c£c.

Dr. Woodward has confider'd the Bufinefs of Strata with great Attention, viz. their Order, Number, Situation with refpeft to the Horizon, Depth, Interfeclions, Fiffures, Co- lour, Confluence, HSc. and afcribes the Origin and Forma- tion of them all, to the great Flood, or Cataclyfmus. At that terrible Revolution, he fuppofes all the terrestrial Bodies of all Kinds to have been diffolved and mix'd with the Waters, and fuflain'd therein, fo as only to conftitute one common Mafs therewith. This Mafs of terrestrial Particles, intermix'd with Water, he fuppofes to have been at length precipitated to the Bottom, and that, according to "ne Laws of Gravity; the heaviest linking* first, and the lighter in their Order. By fuch Means were the Strata tbrm'd, whereof the Earth consists, which attaining their Solidity ^! d /- H o r j ners by De g rees > have eontinu'd fo ever iincc. Thefe Sediments, he further concludes to have been at firtt all parallel and conccntricai, and the Surface of the Earth rorm\l thereby, perfectly fmooth and regular : But in Courfe ot lime, divers Changes happening from Earthquake* Vulcanos, &c. the Order and Regularity of the Strata was diffurbed and broke, and the Surface of the Earth, by fuch Means, brought to the irr.gular Form in which it now appears. See further Particulars under Fosssl, Volcano Spring, Atmosphere, &c.

Earth, in Astronomy, is one of the primary Plan-ts according to the Syftem of Copernicus. Its Character is &'. See Planet, iSc.

In the Hypothesis of Ptolomy, the Earth is the Centre of the Syftem. See System.

Whether the Earth move, or remain at Reft, i. e. Whe- ther it be fixed in the Centre, with the Sun Heavens and u tafS m0T,n g round the fame from Eaft to Weft; or whe- ther, the Heavens and Stars being at Reft, the Earth move f f om W ™ to Eaft, is the great Article that diltinguifhes the Ptolemaic from the Copemican System. See Copek- nican, and Ptolemaic Syftem.

Motion of the Earth. The happy Industry of the Astronomers of our Age, has put the Motion of the Earth beyond all rcafonable doubt : On which Account, the Names of Cofemicus, Gaffendus, Kefler, Hook, Flamftead, &c. will ever be mentioned with the highell Honour.

Indeed, the fame Motion had been held by many of the ancient Philofophers. Cicero, in his T'ufc. gtteft. allures us, that Nicetas of SyracuJ'e sirft difcover'd that the Earth had a diurnal Motion, by which it revolved round its Axis in the Space of 24 Hours : And Plutarch, de 'Placit.

Philofoph.