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 by the Terms Zenith and Nadir, the former of which Words I have often met with in Books, but never knew the Meaning of it.

' an Arabick Word, said I, Madam, and signifies that Point in the Heavens that is directly over your Head, as Nadir doth the opposite one in the lower Hemisphere, at the opposite End of a Diameter of the Earth: And this Brazen Circle is called the Meridian, because, whenever the Sun comes to the Meridian of any Place on the Earth, in his daily Course, 'tis then, what the Latins called Meridies, i.e. Mid Day, or exactly Noon there.

O! Sir, said she, this Astronomy is mighty instructive; I now understand the just Meaning of such Expressions, as these,

But pray let me know the Use of this Circle here on the Globes.

I shew'd you just now, said I, Madam, That on the Terrestrial Globe it shewed the Latitude of all Places, which, by being brought successively to it, as the