Wilkins, John, A discovery of a new world : or a discourse tending to prove, that 'tis probable there may be another Habitable World in the Moon ; with a discourse concerning the Probability of a Passage thither; unto which is added, a discourse concerning a New Planet, tending to prove, that 'tis probable our earth is one of the Planets

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166154That the Moon may be a World. Vertical point. Or, which is the more eaſie
Geog. l. 3.
prop. 3.
way, when a man ſhall chooſe ſuch a Station,
where he may at ſome diſtance, diſcern the
place on which the Cloud does caſt its ſhadow,
and withal does obſerve, how much both the
Cloud and the Sun decline from the Vertical
From which he may eaſily conclude
the true Altitude of it, as you may more plain-
ly conceive, by this following Diagram.
7[Figure 7]
Where A B is a perpendicular from the cloud,
G the Station of him that meaſures, D the place
where the ſhadow of the Cloud doth fall.
The inſtrument being directed from the Sta-
tion G, to the Cloud at A, the perpendicular
will ſhew the Angle B A G.
Then letting the
Sun ſhine through the ſights of your Inſtru-
ment, the perpendicular of it will give the
Angle B A D.
After wards having meaſured
22Pitiſc. Tri-
the diſtance G D by paces, you may, according
to the common Rules, find the height B A.
But if without making the Obſervation, you
would know of what Altitude the higheſt of
33Subt. l.
theſe are found by Obſervation;
Gardan an- ſwers, not above two miles; Keplar, not 44Epit. Co-
per. l. 1. p. 3.
1600 Paces, or thereabouts.

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