Page:Cyclopaedia, Chambers - Volume 1.djvu/887

 GEO

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GEO

difpofing its four Sounds as to Succeffion. See Tetra-

CHORD.

The Genera of Mufick were three, viz. the Enharmo- nick, Chroma tick, and Diatonick: The two laft whereof were varioufly fubdivided ; and even the firtt, though 'tis commonly reckon'd to be without any Species, yet different Authors have propos'd different Divifions under that Name, tho' without giving particular Karnes to the Species as was done to the other two. See Species.

For the Character, &c. of the fcveral Genera, fee En-

HARMONICK, ChROMATICK, and DlATCNICK.

The Parts, or Divifions of theDiatcffaron they cail'd the SDiaftems of the feveral Genera, upon which their Differences depend j and which in the Enharmonick are particularly cail'd the Diefis, and 'Dwniwi; in the Chromatic, the lie- mitonium, and Triemiton'mm ; and in the Diatonic, the He~ mitonium, or Ltmma, and the Tonus.

But under thefe general Names, which ditUnguifh the Genera, there are other different Intervals, or Ratio's which conftitute the Colores Gcnerum, or Species of Enharmonic, Chromatic, and Diatonic. Add, that what is a Diaftem in one Genus, is a Syftem in another. See Diastem, Sy- stem, Chroai ; fee alfo Diagramma.

Genus, in Rhetorick. Authors dillinguifh the Art of Rhetorick, as alfb Orations, or Difcourfes produced thereby, into three Genera, or Kinds, Demonflrativc, Deliberative, and Judiciary.

To the Demonfirative Kind belong Panegyricks, Geneth- liacons, Epithalamiums, Funeral Harangues, &c. See each under its Head, Panegyric, Epitiialamium, SyG.

To the Deliberative Kind belong Pcrfuafions, Dijfua- JJons, Commendations, &c. See Persuasion, &C.

To the Judiciary Kind belong Defences, and Accufa- tions. See Rhetoric, Oration,^.

GENUS, in Algebra. The antient Algebraitts diftri- buted that Art into twoGenera, or Kinds ; the Logiflic, and Specious. See Logistic, and Specious.

Genus, in Anatomy. The Genus nervofum, or nervous kind, cail'd alfo the nervous Syflem, is an Expreffion, pretty frequent among Authors; fignifying the Nerves, coniider'd as an Aflemblage or Syflem of limilar Parts, distributed throughout the Body. See Nerve, and Similar 'Part.

Tobacco contains a deal of iharp, cauftic Salt, proper to caafe Irritations in the nervous Kind : Vinegar, taken in too great Quantity, incommodes the nervous Kind.

GEOCENTRIC, in Agronomy, is applied to a Planet, or its Orbit, to denote it concentric with the Earth ; or, as having the Earth for its Centre, or the fame Centre with the Earth.

Thus we fay, that all the Planets are not geocentric. See Planet.

Geocentric Place of a Planet, is the Place wherein it appears to us, from the Earth ; fuppofing the Eye there fix'd : Or, it is a Point in'the Ecliptick, to which a Planet, feen from the Earth, is referr'd. See Place, and Helio- centric.

Geocentric latitude of a Planet, is its Latitude feen from the Earth ; or the Inclination ot a Line connecting the Planet and the Earth, to the Plane of the Earth's (or true) Ecliptick.

Otherwise, it is the Angle, which the aforefaid Line (connecting the Planet, and the Earth) makes with the Line which is drawn perpendicular to the Plane of the Ecliptick. See Latitude.

Thus, in Tab. Aftronomy, Fig. 40. the Angle £ Te is the Mealure of that Planet's Geocentric Latitude, when the Earth is in T, and the Angle e T 2, the Mcafure of it when the Earth is in t. Sec Latitude.

GEOD.&SIA, that Patt of Geometry, which contains the Doctrine, or Art of mcafuring Surfaces ; and finding the Contents of all kinds of plain Figures. See Surface; fee alio Measuring.

It is ulually called Surveying, when employ'd in meafur- ing of Lands, Grounds, Roads, Countries, Provinces, &c. See Surveying.

The Word is Greek, yitu-», terra, Earth, and y&wv, fCfiks, I write.

Geography makes a Branch of Mathcmaticks, of the mix'd kind ; in that it confiders the Earth, and its Affections, as depending on Quantity, and confequently mcafurable,^/^. its Figure, Place, Magnitude, Motion, cccleftial Appearances, $?c with the fcveral Circles imagin'd on its Surface. See Mathematick.s.

Geography is diftinguifh'd from Cofmcgraphy, as a Part from the W'holc: This latter considering the whole vifible World, both Heaven, and Earth. See Cosmography.

From topography, and Chorography, it is diftinguifli'd as the whole from a Part. See Topography, and Choro- graphy.

Golnitz-ius confiders Geography as cither Exterior, or In- terior : But Varenius more juitly divides it into General? and Special ; or, Uuiverjal, and 'Particular.

Generator Univerfal Geography is that which confi- ders the Earth in General, without any Regard to particular Countries; or the Affections, common to the whole Globe, as its Figure, Magnitude, Motion, Land, Sea, £5^. See Globe.

Special, or Particular Geography, is that which confi- ders the Constitution of the feveral Regions, or Countries ; their Bounds, Figure, &c. with the Mountains, Forefls, Alines, Waters, Plants, Animals, &c. therein: As alio their Climates, Scafons, Heat, Weather, Diflaucc from the E- quator, &c. And their Inhabitants, Arts, Foods, Commodi- ties, Cufloms, Language, Religion, Policy, Cities, &c.

Geography is very antient ; at leaft the Special Part thereof: For the antient Writers fcarce went beyond the Dcfcription of Countries.

It was a Cuitom among the Romans, after they had con- (juer'd and fubdued any Province, to have a Map, or painted Representation thereof carried in Triumph, and cxpofed to the View of the Spectators. See Map.

Hifforians relate that the Remain Senate, about a hundred Years before Chrift, lent Geographers into divers Parts, to make an accurate Survey and Menluration of the whole Globe ; but they fcarce ever faw the twentieth Part thereof.

Before them, Ncco, King of Egypt, crder'd the Phccni- cians to make a Survey of the whole Coaft of Africa, which they accompli/h J d in three Years: Darius procured the E- thiopic Sea, and the Mouth of the Indus to be examin'd : And Pliny relates, that Alexander, in his Expedition into Afia, took two Geographers, Diognetns, and 'Beto, to mea- fure and defcribe the Roads; and that from their Itineraries the Writers of the following Ages took many Particulars. Indeed, this may be obferved, that whereas molt other Arts are Sufferers by War, Geography and Fortification alone are improved thereby.

The Art, however, mult need have been exceedingly de- fective; as a great Part of the Globe was then unknown; particularly all America, the Northern Parts of Europe, and Afia ; with the Terra Auftralis, and Magcllanica : And as they were ignorant of the Earth's being capable of being fail'd round, of the Torrid Zone's being habitable, &c.

The principal Writings on this Art, among the Antients, are Ptolomy's eight Books : Among the Moderns, Joha?i?2cs dc facro Sofco, Dc Spheera, with Clavius's Comment ; Big- ciolns's Geoqraphia, and Hydrographia Reformata ; Wei- gclhis's Speculum Terra ; Dc Chales's Geography, in his Mundus Mathematicus ; and above all, Varenizis's Gcogra- phia Generalis, with jfurins Additions: To which may be added Eiebknecht's Elementa Geographic Generalis ; Stur- mius's Compendium Geographicum ; and Wolfius's Geogra- phia, in his Eleme?ita Mathefcos. — •

GEOMANCY, Geomantia, a kind of Divination, per- form'd by means of a Number of little Points, or Dots, made on Paper, at random ; and considering the various Lines and Figures, which thofe Points prefent ; and thence forming a Judgment of Futurity and deciding any Question propofed. See Divination.

The Word is form'd of the Greek yv>, terra, Earth ; and ftuifitia., Divination ; it being the antient Cuitom to caft lit- tle Pebbles on the Ground, and thence to form their Con- jectures ; inftead of the Points now made ufc of.

Polydore Virgil defines Geomancy a. kind of Divination perform'd by means of Clefts or Chinks made in the Ground; and takes the Perfian Magi to have been the Inventors thereof. De Invent. Rcr. L. i.e. 23.

GEOMETRY, the Science, or Doctrine of ExtcntiGn, or extended things ; that is, Lines, Surfaces, and Solids, See Line, Surface, and Solid.

The Word is form'd of the Greek y», terra, Earth, and y.'.T^zif, metiri, to meafure ; it being the Necefuty of mea- furing the Earth, and the Parts and Places rhcrcof that gave the firfl: occafion to the Invention of the Principles and Rules of this Art, which has fince been extended and applied to numerous other Things; infomuch that Geometry with A- rithmetick, are now the general Foundation of all Mathe- maticks. See Matiiematicks.

Geometry is commonly divided into four Parts, or Branches, Planimetry, Altimetry, Longimetry, and Ste- reometry. See each under its proper Article, Planime- try, Altimetry, Longimetry, and Stereometry.

Geometry, again, is diftinguiJh'd into "Theoretical, or Speculative, and Practical.

The firft contemplates the Property of Continuity ; and demonnrates the Truths of General Proportions, cail'd Theorems. See Theorem.

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