COSMOGRAPHY. COSMOGRAPHY, in Greek Κοσμογραφία, is derived a Mundus; & γραφή; e. Scriptum, De fcription: So that COSMOGRAPHY is a Defcription of the World; confider'd under the Names of the Heavens, as the Cæleftial; and of the Earth and Water, as the Terrestrial Parts thereof. A true aud perfect Represention of both which, may be (and • usually is) described upon Two Round Bodies, called GLOBES: And therefore we shall first treat of them.. CHAP. Ι. Of a material Sphere or Globe; and of fuch Circles, Lines and Points, as are described upon it, and that are appendant to it. And how to rectifie the Globe, fitting it for the resolving of such Problems as are to be performed by it. 1. Of the Circles of the Sphere.. A Globe Sphere is an Artificial Representation of the Starry Fig. Heaven, or of the Earth and Water, under the Form or Fi- XXV. Fig. gure of Roundness, which they are supposed to have: Shewing XXV. in a just Proportion every particular Constellation in the Heavens: And luch a Globe is called [A Calestial Globe] and every particular Region or Country on the Earth, and Island in the Sea : And such a Globe is called [A Terrestrial Globe.] gure Upon the Convex Superficies of either of these Globes (befides the Constellations of the Stars, upon the Calestial; and the Countries, Kingdoms, Sea-Coafts, Islands, &c. upon the Terrestrial) there are defcribed several Circles; fome Great Circles, which divide the whole Body of the Globe into Two Equal Parts, and fome Leffer Circles, which divide the Body of the Globe into Two Unequal Parts. The Great Circles described upon the Body of either Globe are, The Leffer Circles are, The Two Tropicks; and, The Two Polar Circles. I. Of the EQUINOCTIAL. The Equinoctial is a Great Circle, dividing the Body of the Globe into Two Equal Parts, paffing through A and a; which Points are, each of them, equidistant from Pand S, the Two Poles of the World; and so the Line or Axis PAS paffing through the Body of the Globe, cutteth this Circle always at Right Angles. II. Of the ECLIPTICK and ZODIAСК. The Zodiack is a Great Circle, croffing both the Horizon and Equinoctial in A, the East and West Points of the Horizon at Oblique Angles, viz. the Horizon at an Angle equal to the Sun's greatest Meridian Altitude in any Latitude, but the Æquinoctial, always, at an Angle, equal to (23.5 Deg.) the Sun's greatest Declination. This Circle is supposed to have Breadth; for, through the middle of it, there passeth a Line, noted in the Figure with the Twelve Signs of the Zodiack, r8 II the upper Part, and with m 1 vs * on the lower Part; which Line is called the Ecliptick, or Via Solis, for that the Sun always keepeth in this Line. on ΠΙ. Of III. Of the Two COLURES. These are Two Great Circles, which pass through the Poles of Fig. the World, where they cut each other at Right Angles: One of XXV. these cutteth the Horizon in A, and the Equinoctial also in the Point, and is therefore called the Equinoctial Colure. The other Colure cutteth the Horizon in H and O, the North and South Points thereof, and also the Ecliptick in the Points and , and is therefore called the Solsticial Colure. In the Figure the Equinoctial Colure is noted with PAS (and is the fame with the Sixth Hour Circle.) the Solfticial Colure, with HPOS, and is the fame with the Meridian. IV. Of the TROPICK of CANCER. This is a Leffer Circle of the Sphere, described upon the Superficies of the Globe, parallel to the Equinoctial, on the North Side thereof, at 23.5 Deg. distant therefrom, equal to the Sun's greatest Declination. It is called the Northern Tropick, for that it lyeth towards the North Pole, and is represented in the Figure by the Small Circle, 5 6 5. V. Of the TROPICK of CAPRICORN. This is a Leffer Circle also, described upon the Globe, parallel to the Equinoctial on the South Side thereof, at the Distance of 23.5 Deg. towards the South Pole, and is called the Southern Tropick: It is noted in the Figure with w 6 พ. VI. Of the Two POLAR CIRCLES. These are Two Leffer Circles described about the Poles of the World, parallel to the Equinoctial and Tropicks, and so far distant from either Pole, (viz. 23.5 Deg.) as the Tropicks were from the Equinoctial: That described about the North Pole, noted with B 6 C, is called the Artick Circle, and the other, noted with G 6 E, described about the South Pole, is called the Antartick Circle. Besides these Circles, which are described upon the Convex Superficies of either Globe, there are others, which are framed without the Body of the Globe; and those are, principally, Two, Dd of Fig. of the Meridian, and the Horizon; the one of Brass, the other of XXV. Wood. -Circles, indeed they are not so properly called; for, in the rigorous Sense, no Line is supposed to have any Breadth, but both these have Breadıb allowed them; that such Things might be written, or engraven upon them, as might render them more ufeful in all Pofitions of the Globe: And therefore, (they being of a Circular Form) notwithstanding the Impropriety of Speech, we will have it fo; and we must call them, The Meridian and Horizontal Circles. The Meridian in the Figure, is noted with the Letters ZÆN a, and the Horizon with HAO. Unto this Brazen Meridian, there belong Two other Appendants, viz. An Hour-Circle, with its Index; and a Quadrant of Altitude. Through the Body of either Globe, there runs a ftrong Wyre; the Ends whereof are fo fixed in the Brazen Meridian, that the Body of the Globe may turn about together with the Wyre. -This Wyne is called the Axis of the World, and the Ends thereof, the Poles of the World, one the Artick or North Pole, noted with P; the other, the Antartick, or South Pole, noted with S.. Unto this Brass Meridian also, there belongs another Appendant, called A Quadrant of Altitude; which is a thin Plate, divided into 90 equal Parts or Degrees, and fitted with a Nut and a Screw, to move to any Degree upon the Meridian; but generally in the Vertical Point Z, the Zenith of any Place. II. Of the several Positions, that a Globe or Sphere, mag. be pofited in its Horizon. Here Here are are but but Three Positions, in which a Globe may be seated in its Horizon; viz. (1.) Direct. (2.) Parallel. (3.) Oblique. Of which, the Two first are Particular, the third more General. I. Of Direct Position. The Globe may be so placed in the Frame, that both the Poles thereof may reft upon (or lye directly in) the North and South Points of the Horizon, neither Pole having any Elevation: The Zenith Point being in the Æquinoctial Circle, and the Axis of the World in the Plain of the Horizon. And this is called Direlt Pofition. IL OF |