224 Description and XJse of the

A right sphere

214. Is that in which the inhabitants feeboth poles in their horizon, the equatorpassing through their zenith and nadir, andall the circles parallel to the equinoctial per-pendicular to their horizon.

These people live upon the terrestrialequator, consequently all the heavenly bo-dies will always rise and set perpendicularlyto them; and their days and nights willbe of an equal length throughout the year.

An oblique sphere

215. Hath one of the poles of the globeabove, the other under the horizon; theequator in all the cases of this sphere is halfabove, and half below the horizon, and allits parallel circles cut the horizon obliquely*

That arch of any parallel of declinationin the celestial, or of latitude in the ter-restrial sphere that is above the horizon, iscalled the diurnal arch. And

The remaining part of it, which is belowthe horizon, is called the nocturnal arch.

These