distant from the Earth: By
this _Penumbra_, say they, the Moon is Eclipsed, for it alwayes passes
between the lines 12, and 34.

To which I say, That if the Air be such, as I have newly shewn it to be,
and consequently cause such an inflection of the Rays that fall into it,
those dark _Penumbra's_ FYZQ, HXVT, and ORPS, will all vanish. For if we
suppose the Air indefinitely extended, and to be no where bounded with a
determinate refracting surface, as I have shewn it uncapable of having,
from the nature of it; it will follow, that the Moon will no where be
totally obscured, but when it is below the Apex N, of the dark blunt Cone
of the Earth's shadow: Now, from the supposition, that the Sun is distant
about seven thousand Diameters, the point N, according to calculation,
being not above twenty five terrestrial Semidiameters from the Center of
the Earth: It follows, that whensoever the Moon eclipsed is totally
darkned, without affording any kind of light, it must be within twenty five
Semidiameters of the Earth, and consequently much lower then any
Astronomers have hitherto put it.

This will seem much more consonant to the rest of the secundary Planets;
for the highest of _Jupiter's_ Moons is between twenty and thirty _Jovial
Semidiameters_ distant from the Center of _Jupiter_; and the Moons of
_Saturn_ much about the same number of _Saturnial Semidiameters_ from the
Center of that Planet.

But these are but conjectures also, and must be determin'd by such kind of
Observations as I have newly mention'd.

Nor will it be difficult, by this _Hypothesis_, to salve all the
appearances of Eclipses of the Moon, for in this _Hypothesis_ also, there
will be on each side of the shadow of the Earth, a _Penumbra_, not caus'd
by the Refraction of the Air, as in the _Hypothesis_ of _Kepler_; but by
the faint inlightning of it by the Sun: For if, in the sixth Figure, we
suppose ESQ, and GSR, to be the Rays that terminate the shadow from either
side of the Earth; ESQ coming from the upper limb of the Sun, and GSR from
the under; it will follow, that the shadow of the Earth, within those Rays,
that is, the Cone GSE, will be totally dark. But the Sun being not a point,
but a large _area_ of light, there will be a secondary dark Cone of shadow
EPG, which will be caus'd by the earth's hindring part of the Rays of the
Sun from falling on the parts GPR, and EPQ, of which halved shadow, or
_Penumbra_, that part will appear brightest which