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[[page number]]168[[/page number]]

unmovable, while some Stars, or the Sun, or the Moon, or some other Planet, or a Comet, may seem to pass behind the Earth: Any one of their visible points describing its proper curve BKKB, or DKKD, or DD, or GG, or AECIA, &c.
17. In all the Space which is without the [[underline]]Cone formed[[/underline]] by the infinite Tangent HL or HL (of the refracting Atmosphere) and [[underline]]having[[/underline]] H for Vertex, and HC for Axis; the heavenly Motions observed from the Point H will seem the very same, and to have the same Swiftness, as if the Earth had no Atmosphere.
18. And whereas, because of the Interposition of the Earth, no Lucid Point in the Heavens, contained within the Circle whose Radius is CP or CP, can be seen directly from H; but only by the Refraction made in our Atmosphere: Therefore no such Points whatsoever, were it even a Part of the Surface of the Sun, can appear within the Apparent Limb of the Earth, but only upon or near this very Limb; and that with a very small Breadth or Thickness.
19. Thus from whatsoever Place, called here H, the Globe of the Earth be seen, as suppose from the fixed Stars, or from the Moon, or from the Sun, or from Venus, or Mars, or from a Comet, &c. it may be said;
As the Distance CH; Is to the Semediameter CQ of the Globe of the Earth: So is the Radius of the Tables; to the Sine of the mathematical Apparent Semidiameter of the Earth as seen from the Point H.
And as CH; Is to CP or CP perpendicular to HX or Hx: So is the Radius of the Tables; to the Sine of

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