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THE Grecian Stadium* or Furlong, is supposed to be 600 of their Feet, which make 625 Romant or Rbinland, Feet; their Foot being a little larger than the Roman.
AGERMJN Mle (15 of which Geographers allow to a Degree) contains 22800 Rbinland Feet, and is accounted 4000 Paces, or 32 Furlongs. It is in Proportion to the Rbinland Mile, as 19 to 15.
THE Italian or Roman Mile is 1000 Paces, which is equal to 4000 Rbinland Feet. Note, The Romans used to call their Mile Lapis, because a Stone was erected at the end of every Mile; especially in Places adjacent to the City.
A G E 0 METRICAL Pace is exactly 5 Feet; and a Fatbom 6 Feet; which is thought by some to have been the Pace of the Grecians.
A CUB IT is supposed to be a Foot and a half.
THE Parafange, or Persian Mile, is thought to be 30 Furlongs, or 3000 Persian Paces.
THE Schcenus, or Ægyptian Mile, according to Herodotus, contains 60 Furlongs, tho* only 40 according to Pliny. Perhaps their Length differed in divers Places, or the Furlongs of the Authors might be unequal: Or very likely their Books are corrupted.
-THE French League is in Proportion to the Rbinlandijh Mile, as 19 to 25; and the Spanish League is to the fame Mile, as 19 to 27*: But because in several Parts of France and Spain their League is found to differ, we cannot be well assured of the Length of these Measures.
THE English Mile is in Proportion to the Rbinlandijh, as 19 to 55, of as 19 to 60 (r). But
(r) The least Part of English and well dryed; whereof 3 in Measure is a Barley-Corn, taken Length make an Inch, as out of the middle of the Ear in the following Table.
there are three forts of English Miles, whereof 275 'of the longest, 50 of the middle Kind, and 60 of • the shortest, make a Degree or 19 Dutch Miles.
THE Banish and Swedish Mile is to the Rhinlandijh Mile as 19 to 10; tho' in some Places they use the German Mile.
THE Forest, or Ruffian, Mile is as 19 to 80.
THE Turkish League or Mile is said to be equal to the Italian Mile; of which 60 make a Degree.
THE Arabian League was formerly accounted the twenty fifth Part of a Degree, or 19 Holland Miles: but they now use another of which 56 make a Degree.
AHUNDRED Indian Miles are thought to equal a Degree. Tho' the Indians commonly describe Distances by a Day, or an Hour's Journey.
THE Inhabitants of Cambaya and Guzarat, use a Measure which they call Cojsa, of which 30 make a Degree.
THE Chinese observe three Measures in their Journies, which they call Li, Pu, and Uchan. Li is the Distance at which a Man's loud Voice may be heard on a Plain, in a calm Air ; which is accounted 300 Geometrical Paces. Their Pu contains jo Li's j
so that 20 Pa's make a Degree. And 10 Pa's make an Uchan, or 30000 Paces j which they account a day's Journey.
Note, A Square Rhinland Mile consists of Square Feet, and a Cubic Mile of Cubic Feet. Also a Mile multiplyed into itself makes a Square Mile j and that again by a Mile makes a Cubic Mile. The fame is to be understood of a Square and Cubic Foot,
Containing some general and absolute Properties of the Earthy in five Chapters.
Of the Figure of the Earth.
TH E first and noblest Property of the Earth (as exceeding the rest in being more useful and neceslary) is it's Figure; without the Knowledge of which there can be nothing well Understood or demonstrated in this Science •, and all the following Propositions almost entirely depend on, or immediately flow, from this; which for that Reason ought to be first treated of.
THERE have been, and are to this Day, several Opinions about the Figure of the Earth for the Vulgar that understand not Geography, imagine it to be extended into a vast Plain bounded with a Circular Line 5 except where Mountains and Vallies interpose. Of this strange Opinion was Laftantius and others of the Fathers, who strenuously argued that the Earth was extended infinitely downwards, wards, and established upon several Foundations (a). This they were inclined to think from some Places of Scripture which they either ill understood or wrong interpreted. Heraclitus, that ancient Philosopher, is said to have been of their Opinion: tho' others fay, he supposed the Earth to be in the Shape of a Skiff or Canoo, very much hollowed. But what is more strange Francis Patricius (a modern Philosopher of no small Repute in the last Age) strenuously endeavoured to prove, that the Earth was horizontally stretched out and plain under Foot. Anaximander is said by Peucerus to have supposed the Earth like a Cylinder; tho' that is not so probable, because he tried to measure it, and also invented a sort of a Dial at Lacedæmon, upon which the Top of the Gnomon by it's Shadow marked out the Days of the Equinoxes, and Solstices: which shewed him to have been tolerably skilled in Astronomy, considering the Time he lived in. Leucippus also thought the Earth to be in the Shape of a Drum. These with a great many other absurd Opinions, are by Aristotle and others attributed to the Antients: of which fee Aristotle Lib. ii. Cap. 13. de Cœlcr.
BUT the true and undoubted Opinion, which is defended by all Mathematicians, and almost all Philosophers, is, That the Earth is of a globular or spherical Figure (b).
(a) See Laflantius Lib. iii. Honour and Admiration in it; Cbap.z^.mAAuguftin L/Æ.xvi. that the true Figure of the Chap. 9. De Chit. Dei. They Earth, which Men have inhathought their Opinion was fa- bited for so many thousand voured by the Psalmist. Psal. Years, is but now begun to be xziv. 2. and cxxxvi. 6. known a few Years ago. For
(6) Among the many excel- that which all Men thought to lent and wonderful Inventions be globular and truly spherical, of the modern Philosophers, is now found to imitate rather this here is not certainly in the an oval Figure, or that of an last Place, nor hath the least Ellipsis revolved about it's lesser
Axis: So that those Diameters are longest which come nearest the Equator, and lessen as they become more remote, but the least Diameter of all is the Axis which joine.ii the two Poles. The Thing will perhaps be better understood if it be represented by a Figure.
Let <epqp (Fig. 4.) be a circular Section of the Earth made by the Meridian, such as it was thought to be formerly and p p the Axis or Diameter joining the Poles, and a q the Diameter of the Equator: then the oval Line Æ P QJ*, described upon the Diameters Æ Q_ and P P, will represent the Section or true Meridian Line, which for Distinction sake is made here to differ more from a Circle than it really ought to do; but in truth, the Proportion is as 692 to 689. So that the Line C Q_ measuring the Altitude of the Earth at the Equator, exceeds CP the Altitude at the Pole 8 5 zoo Paris Feet, or about 17 Miles.
This Affair is well worthy to be traced to it's Original, and to be backed by a Demonstration, so far as our Purpose will permit. See the History of the Royal Aeademy of Sciences by du Ham el. Fag. 110, 156, zo6. Also Hist, del" Acad. Roy. 1700, 1701.
The French made an Experiment about forty Years ago, (hewing that a Pendulum (which is a well known Instrument for measuring of Time) vibrates so much the flower, by how much the nearer it is brought to the Equator: that is, the Gravity, or Celerity of Descent of the Pendulum, and of all other Bo
dies, is less in Countries approaching the Equator than in Places near either Pole. The two famous' Philosophers Newton and Huygens being excited by the Novelty of the Thing, and seaerhing more narrowly into the Cause of it, found thereby that the Earth must have some other Figure than what was known; and also demonstrated that this Diminution of Weight doth naturally arise from the Rotation of the Earth round it** Axis; which Rotation, according to the Laws of circular Motion, repels all heavy Bodies from the Axis of Motion: fa that this Motion being swifter under the Equator than in Parts more remote, the Weight of Bodies must also be much led there than nearer the Poles. Therefore the Parts of theOcean under the Equator being made lighter, and according to the Nature of all Fluids, pressed and forced on either side by the Waters nearer the Poles, they must be raised up to a greater Height, that so they may better support and balance the greater Weight of the contiguous Waters. Which mutual Librarian is demonstrated upon Supposition of that Inequality of the Diameters which we mentioned above. The Figure of the Sea being resembled by the Lands ■ adjacent, which are every where raised above the Sea, the aforesaid Form must be attributed to the whole terraqueous Globe. They tha t would be more fully informed in this Matter may consult Newton't Principia Lib. iii. Prop. 19. or Huygeri's Treatise of the Cause of Gravity.