ANCILLA MATHEMATICA. VEL, Spa T Trigonometria Practica. SECTION II. OF COSMOGRAPHY. OSMOGRAPHY, in Greek Koopoygapla, is derived a Kocu; i. e. Mundus; & yeaq; i. e. Scriptum, the Defcription: So that COSMOGRAPHY is a Defcription of the World; confider'd under the Names of the Heavens, as the Caleftial, and of the Earth and Water, as the Terreftrial Parts thereof. A true aud perfect Reprefention of both which, may be (and ufually is) defcribed upon Two Round Bodies, called GLOBES: And therefore we fhall firft treat of them.. CHA P. I. Of a material Sphere or Globe; and of fuch Circles, Lines and Points, as are defcribed upon it, and that are appendant to it. And how to rectifie the Globe, fitting it for the refolving of fuch Problems as are to be performed by it. I. Of the Circles of the Sphere.. Fig. Globe or Sphere is an Artificial Reprefentation of the Starry A Heaven, Prof or gure Fig. gure of Roundness, which they are fuppofed to have: Shewing XXV. in a juft Proportion every particular Conftellation in the Heavens: And fuch a Globe is called [A Cæleftial Globe and every particular Region or Country on the Earth, and Island in the Sea: And fuch a Globe is called [A Terrestrial Globe.] Upon the Convex Superficies of either of thefe Globes (befides the Conftellations of the Stars, upon the Cæleftial; and the Countries, Kingdoms, Sea-Coafts, Ilands, &c. upon the Terreftrial) there are defcribed feveral 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 defcribed upon the Body of either Globe are, The Equinoctial 2 { The Equinoctial & Colure. The Ecliptick The Solftitial The Leffer Circles are, The Two Tropicks; and, The Two Polar Circles. 1. Of the EQUINOCTIAL The Equinoctial is a Great Circle, dividing the Body of the Globe into Two Equal Parts, paffing through and a; which Points are, each of them, equidiftant from P and S, the Two Poles of the World; and fo the Line or Axis P A S paffing through the Body of the Globe, cutteth this Circle always at Right Angles. II. Of the ECLIPTICK and ZODIACK. The Zodiack is a Great Circle, croffing both the Horizon and Equinoctial in A, the East and Weft Points of the Horizon at Oblique Angles, viz. the Horizon at an Angle equal to the Sun's greateft Meridian Altitude in any Latitude, but the Equinoctial, always, at an Angle, equal to (23.5 Deg.) the Sun's greatest Declination. This Circle is fuppofed to have Breadth; for, through the middle of it, there paffeth a Line, noted in the Figure with the Twelve Signs of the Zodiack, r8 пon the upper Part, and with won the lower Part; which Line is called the Ecliptick, or Via Solis, for that the Sun always keepeth in this Line. III. Of the Two COLURES. "Thefe are Two Great Circles, which pafs through the Poles of Fig. the World, where they cut each other at Right Angles: One of XXV. thefe cutteth the Horizon in A, and the Equinoctial alfo 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 alfo the Ecliptick in the Points and w, and is therefore called the Solfticial Colure. In the Figure the Equinoctial Colure is noted with PAS (and is the fame with the Sixth Hour Circle.) the Solfticial Colure, with H POS, and is the fame with the Meridian. IV. Of the TROPICK of CANCER. This is a Lefler Circle of the Sphere, defcribed upon the Superficies of the Globe, parallel to the Equinoctial, on the North Side thereof, at 23.5 Deg. diftant 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, 6. V. Of the TROPICK of CAPRICORN. This is a Leffer Circle alfo, defcribed 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 w. VI. Of the Two POLAR CIRCLES. Thefe are Two Leffer Circles defcribed about the Poles of the World, parallel to the Equinoctial and Tropicks, and fo far diftant from either Pole, (viz. 23.5 Deg.) as the Tropicks were from the Equinoctial: That defcribed about the North Pole, noted with B 6 C, is called the Artick Circle; and the other, noted with G 6 E, defcribed about the South Pole, is called the Antartick Circle. Befides thefe Circles, which are defcribed upon the Convex Superficies of either Globe, there are cthers, which are framed without the Body of the Globe; and thofe are, principally, Two, 1 |