cted Rays CHK and GI; and the angle GHC shall be an acute, and so much
the more acute by how much the greater the refraction be, then which
nothing is more evident, for the sign of the inclination is to the sign of
refraction as GF to TC the distance between the point C and the
perpendicular from G on CK, which being as four to three, HC being longer
then GF is longer also then TC, therefore the angle GHC is less than GTC.
So that henceforth the parts of the pulses GH and IK are mov'd ascew, or
cut the Rays at _oblique_ angles.

It is not my business in this place to set down the reasons why this or
that body should impede the Rays more, others less: as why Water should
transmit the Rays more easily, though more weakly than air. Onely thus much
in general I shall hint, that I suppose the _medium_ MMM to have less of
the transparent undulating subtile matter, and that matter to be less
implicated by it, whereas LLL I suppose to contain a greater quantity of
the fluid undulating substance, and this to be more implicated with the
particles of that _medium_.

But to proceed, the same kind of _obliquity_ of the Pulses and Rays will
happen also when the refraction is made out of a more easie into a more
difficult _mediu_; as by the calculations of GQ & CSR which are refracted
from the perpendicular. In both which calculations 'tis _obvious_ to
observe, that always that part of the Ray towards which the refraction is
made has the end of the _orbicular pulse_ precedent to that of the other
side. And always, the oftner the refraction is made the same way, Or the
greater the single refraction is, the more is this unequal progress. So
that having found this odd propriety to be an inseparable concomitant of a
refracted Ray, not streightned by a contrary refraction, we will next
examine the refractions of the Sun-beams, as they are suffer'd onely to
pass through a small passage, _obliquely_ out of a more difficult, into a
more easie _medium_.

Let us suppose therefore ABC in the second Figure to represent a large
_Chimical Glass-body_ about two foot long, filled with very fair Water as
high as AB, and inclin'd in a convenient posture with B towards the Sun:
Let us further suppose the top of it to be cover'd with an _opacous_ body,
all but the hole ab, through which the Sun-beams are suffer'd to pass into
the Water, and are thereby refracted to cdef, against which part, if a
Paper be expanded on the outside, there will appear all th