1being ſuppoſed, and not granted, that ſome one being placed in the
Moon to obſerve the Earth, he would every day ſee the whole
Terreſtrial ſuperficies, by means of the Moons going about the
Earth in twenty four or twenty five hours; but we never ſee but
half of the Moon, ſince it revolves not in it ſelf, as it muſt do to
be ſeen in every part of it.
Moon to obſerve the Earth, he would every day ſee the whole
Terreſtrial ſuperficies, by means of the Moons going about the
Earth in twenty four or twenty five hours; but we never ſee but
half of the Moon, ſince it revolves not in it ſelf, as it muſt do to
be ſeen in every part of it.
SALV. So that this, befals not contrarily, namely, that her
volving in her ſelf, is the cauſe that we ſee not the other half of
her, for ſo it would be neceſſary it ſhould be, if ſhe had the
cle. But what other difference have you behind, to exchange for
this which you have named?
volving in her ſelf, is the cauſe that we ſee not the other half of
her, for ſo it would be neceſſary it ſhould be, if ſhe had the
cle. But what other difference have you behind, to exchange for
this which you have named?
SAGR. Let me ſee; Well for the preſent I cannot think of
any other.
any other.
SALV. And what if the Earth (as you have well noted) ſeeth
no more than half the Moon, whereas from the Moon one may ſee
all the Earth; and on the contrary, all the Earth ſeeth the Moon, and
but onely half of it ſeeth the Earth? For the inhabitants, to ſo ſpeak,
of the ſuperior Hemiſphere of the Moon, which is to us inviſible,
are deprived of the ſight of the Earth: and theſe haply are the
Anticthones. But here I remember a particular accident, newly
obſerved by our Academian, in the Moon, from whch are gathered
two neceſſary conſequences; one is, that we ſee ſomewhat more
than half of the Moon; and the other is, that the motion of the
Moon hath exact concentricity with the Earth: and thus he finds
the Phœnomenon and obſervation. When the Moon hath a
reſpondence and natural ſympathy with the Earth, towards which
it hath its aſpect in ſuch a determinate part, it is neceſſary that the
right line which conjoyns their centers, do paſſe ever by the ſame
point of the Moons ſuperficies; ſo that, who ſo ſhall from the
ter of the Earth behold the ſame, ſhall alwayes ſee the ſame
Diſcus or Face of the Moon punctually determined by one and
the ſame circumference; But if a man be placed upon the
ſtrial ſurface, the ray which from his eye paſſeth to the centre of the
Lunar Globe, will not paſs by the ſame point of its ſuperficies, by
which the line paſſeth that is drawn from the centre of the Earth
to that of the Moon, ſave onely when it is vertical to him: but
the Moon being placed in the Eaſt, or in the Weſt, the point of
incidence of the viſual ray, is higher than that of the line which
conjoyns the centres; and therefore the obſerver may diſcern
ſome part of the Lunar Hemiſphere towards the upper
rence, and alike part of the other is inviſible: they are
ble and undiſcernable, in reſpect of the Hemiſphere beheld from
the true centre of the Earth: and becauſe the part of the Moons
circumference, which is ſuperiour in its riſing, is nethermoſt in its
ſetting; therefore the difference of the ſaid ſuperiour and
no more than half the Moon, whereas from the Moon one may ſee
all the Earth; and on the contrary, all the Earth ſeeth the Moon, and
but onely half of it ſeeth the Earth? For the inhabitants, to ſo ſpeak,
of the ſuperior Hemiſphere of the Moon, which is to us inviſible,
are deprived of the ſight of the Earth: and theſe haply are the
Anticthones. But here I remember a particular accident, newly
obſerved by our Academian, in the Moon, from whch are gathered
two neceſſary conſequences; one is, that we ſee ſomewhat more
than half of the Moon; and the other is, that the motion of the
Moon hath exact concentricity with the Earth: and thus he finds
the Phœnomenon and obſervation. When the Moon hath a
reſpondence and natural ſympathy with the Earth, towards which
it hath its aſpect in ſuch a determinate part, it is neceſſary that the
right line which conjoyns their centers, do paſſe ever by the ſame
point of the Moons ſuperficies; ſo that, who ſo ſhall from the
ter of the Earth behold the ſame, ſhall alwayes ſee the ſame
Diſcus or Face of the Moon punctually determined by one and
the ſame circumference; But if a man be placed upon the
ſtrial ſurface, the ray which from his eye paſſeth to the centre of the
Lunar Globe, will not paſs by the ſame point of its ſuperficies, by
which the line paſſeth that is drawn from the centre of the Earth
to that of the Moon, ſave onely when it is vertical to him: but
the Moon being placed in the Eaſt, or in the Weſt, the point of
incidence of the viſual ray, is higher than that of the line which
conjoyns the centres; and therefore the obſerver may diſcern
ſome part of the Lunar Hemiſphere towards the upper
rence, and alike part of the other is inviſible: they are
ble and undiſcernable, in reſpect of the Hemiſphere beheld from
the true centre of the Earth: and becauſe the part of the Moons
circumference, which is ſuperiour in its riſing, is nethermoſt in its
ſetting; therefore the difference of the ſaid ſuperiour and
zoom in
zoom out
zoom area
full page
page width
set mark
remove mark
get reference
digilib