And because of this
Reflection of these Rays, say they, there is superinduc'd another shell of
a dark Cone FPH, whose Apex P is yet further 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.
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