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tue bdged in certain Sides both of the Kays,<br />
and of the Particles of the Cq7ital. F’os were<br />
it not for foine kind of Difpoiition of Virtue<br />
lodged in Come Sides of the Particles of the<br />
Ckyihl, and not in their other Sides, and which<br />
inclines and bends the Rays toivards the Coait<br />
of unuf~~l Refra&ion, the Rays w!lich Ml pcrjxndicularly<br />
on the Cryitill, would not be’ rc-<br />
CaBted towat.ds that Goait rather than towards<br />
any other CoaJt, both af: their Incidence and at<br />
their Emergence, fo as to to emerge peqxndi-<br />
~&arly by a contrary Situation of the Coait of<br />
unn-fi~al Refix8ion at the fecond Surf&x ; the<br />
Cq4nl a&ing. upon the Rays afi-er they have<br />
pafs’d through it, and are emerging into the<br />
Air ; of, if you pleaTee, into a V&z~rn. And<br />
jince the CryfZal by this IMpoGtion or Virtue<br />
does not aA upon the Rays, unlefs when one<br />
of their Sides of ~mufu'ual RefinCtion looks towards<br />
that Goa& this argues a k?stue ‘01<br />
goiition in thok Sides of the Rays, whicl<br />
fwers to :md fjmpnthizes with that Virtue or<br />
i$ofition of the Cryftal, as the Poles of two<br />
Ma+gnets anfwer to one another. And as P&qnetlfm<br />
may be intended and remitted, and ;s<br />
found only in the Magnet an”d in Iron: So this<br />
Virtue of refra&ing the perpendicular Rays is<br />
.*reater in Ifland Cryital, lefs in Crvfial of the<br />
ffock, and is not yet found in otheiI3odies. I.<br />
do: not fay that-this Virtue is” magnetical I It’<br />
feems to be of another kind. I only fky, that:,<br />
what ever it be, it’s diffkult to conceive how<br />
the Rays of Ljght, unle1s they be Bodies, can<br />
have a permanent Virtue in ttio of their Sides<br />
which
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