SALV. But when the Moon is oppoſite to the Sun, what
ference is there between the tract of the rayes of your ſight, and
that motion which the Suns rayes make?
ference is there between the tract of the rayes of your ſight, and
that motion which the Suns rayes make?
SIMPL. Now I underſtand you; for you would ſay, that the
rayes of the ſight and thoſe of the Sun, moving by the ſame lines,
we cannot perceive any of the obſcure valleys of the Moon. Be
pleaſed to change this your opinion, that I have either ſimulation
or diſſimulation in me; for I proteſt unto you, as I am a
man, that I did not gueſſe at this ſolution, nor ſhould I have
thought upon it, without your help, or without long ſtudy.
rayes of the ſight and thoſe of the Sun, moving by the ſame lines,
we cannot perceive any of the obſcure valleys of the Moon. Be
pleaſed to change this your opinion, that I have either ſimulation
or diſſimulation in me; for I proteſt unto you, as I am a
man, that I did not gueſſe at this ſolution, nor ſhould I have
thought upon it, without your help, or without long ſtudy.
SAGR. The reſolutions, which between you two have been
alledged touching this laſt doubt, hath, to ſpeak the truth,
ed me alſo. But at the ſame time this conſideration of the
fible rayes accompanying the rayes of the Sun, hath begotten in me
another ſcruple, about the other part, but I know not whether I
can expreſſe it right, or no: for it but juſt now comming into my
mind, I have not yet methodized it to my mind: but let us ſee if
we can, all together, make it intelligible. There is no queſtion,
but that the parts towards the circumference of that poliſh't, but not
burniſh't Hemiſphere, which is illuminated by the Sun, receiving the
rayes obliquely, receive much fewer thereof, than the
moſt parts, which receive them directly. And its poſſible, that a
tract or ſpace of v. g. twenty degrees in breadth, and which is
wards the extremity of the Hemiſphere, may not receive more rays
than another towards the middle parts, of but four degree broad:
ſo that that doubtleſs will be much more obſcure than this; and
ſuch it will appear to whoever ſhall behold them both in the face,
or (as I may ſay) in their full magnitude. But if the eye of the
beholder were conſtituted in ſuch a place, that the breadth of the
twenty degrees of the obſcure ſpace, appeared not to it longer
than one of four degrees, placed in the midſt of the Hemiſphere,
I hold it not impoſſible for it to appear to the ſaid beholder
qually clear and lucid with the other; becauſe, finally, between
two equal angles, to wit, of four degrees apiece, there come to
the eye the reflections of two equal numbers of rayes: namely,
thoſe which are reflected from the middlemoſt ſpace, four degrees
in breadth, and thoſe reflected from the other of twenty degrees,
but ſeen by compreſſion, under the quantity of four degrees: and
ſuch a ſituation ſhall the eye obtain, when it is placed between the
ſaid Hemiſphere, and the body which illuminates it; for then the
ſight and rayes move in the ſame lines. It ſeemeth not impoſſible
therefore, but that the Moon may be of a very equal ſuperficies;
and that nevertheleſſe, it may appear when it is at the full, no leſs
alledged touching this laſt doubt, hath, to ſpeak the truth,
ed me alſo. But at the ſame time this conſideration of the
fible rayes accompanying the rayes of the Sun, hath begotten in me
another ſcruple, about the other part, but I know not whether I
can expreſſe it right, or no: for it but juſt now comming into my
mind, I have not yet methodized it to my mind: but let us ſee if
we can, all together, make it intelligible. There is no queſtion,
but that the parts towards the circumference of that poliſh't, but not
burniſh't Hemiſphere, which is illuminated by the Sun, receiving the
rayes obliquely, receive much fewer thereof, than the
moſt parts, which receive them directly. And its poſſible, that a
tract or ſpace of v. g. twenty degrees in breadth, and which is
wards the extremity of the Hemiſphere, may not receive more rays
than another towards the middle parts, of but four degree broad:
ſo that that doubtleſs will be much more obſcure than this; and
ſuch it will appear to whoever ſhall behold them both in the face,
or (as I may ſay) in their full magnitude. But if the eye of the
beholder were conſtituted in ſuch a place, that the breadth of the
twenty degrees of the obſcure ſpace, appeared not to it longer
than one of four degrees, placed in the midſt of the Hemiſphere,
I hold it not impoſſible for it to appear to the ſaid beholder
qually clear and lucid with the other; becauſe, finally, between
two equal angles, to wit, of four degrees apiece, there come to
the eye the reflections of two equal numbers of rayes: namely,
thoſe which are reflected from the middlemoſt ſpace, four degrees
in breadth, and thoſe reflected from the other of twenty degrees,
but ſeen by compreſſion, under the quantity of four degrees: and
ſuch a ſituation ſhall the eye obtain, when it is placed between the
ſaid Hemiſphere, and the body which illuminates it; for then the
ſight and rayes move in the ſame lines. It ſeemeth not impoſſible
therefore, but that the Moon may be of a very equal ſuperficies;
and that nevertheleſſe, it may appear when it is at the full, no leſs