AB to represent the sensible Horizon; CDEF, the body of the Sun
really below it; GHIK, the same appearing above it, elevated by the
inflection of the _Atmosphere_: For if, according to the best observation,
we make the visible Diameter of the Sun to be about three or four and
thirty minutes, and the Horizontal refraction according to _Ticho_ be
thereabout, or somewhat more, the lower limb of the Sun E, will be elevated
to I; but because, by his account, the point C will be elevated but 29.
minutes, as having not so great an inclination upon the inequality of the
Air, therefore IG, which will be the apparent refracted perpendicular
Diameter of the Sun, will be less then CG, which is but 29. minutes, and
consequently six or seven minutes shorter then the unrefracted apparent
Diameter. The parts, D and F, will be likewise elevated to H and K, whose
refraction, by reason of its inclination, will be bigger then that of the
point C, though less then that of E; therefore will the semidiameter IL, be
shorter then LG, and consequently the under side of the appearing Sun more
flat then the upper.

Now, because the Rays from the right and left sides of the Sun, &c. have
been observ'd by _Ricciolo_ and _Grimaldus_, to appear more distant one
from another then really they are, though (by very many Observations that I
have made for that purpose, with a very good _Telescope_, fitted with a
divided Ruler) I could never perceive any great alteration, yet there being
really some, it will not be amiss, to shew that this also proceeds from the
refraction or inflection of the _Atmosphere_; and this will be manifest, if
we consider the _Atmosphere_ as a transparent Globe, or at least a
transparent shell, encompassing an opacous Globe, which, being more dense
then the _medium_ encompassing it, refracts or inflects all the entring
parallel Rays into a point or focus, so that wheresoever the Observator is
plac'd within the _Atmosphere_, between the focus and the luminous body,
the _lateral_ Rays must necessarily be more converg'd towards his eye by
the refraction or inflection, then they would have been without it; and
therefore the Horizontal Diameter of the luminous body must necessarily be
augmented.

This might be more plainly manifest to the eye by the sixth _Figure_; but
because it would be somwhat tedious, and the thing being obvious enough to
be imagin'd by any one that attentively considers it, I shall rather omit
it, and proceed to s