only in the passage of the Ray by the Body, and at a very small distance
from it. So soon as the Ray is past the Body, it goes right on.

[Sidenote: _Mais pour dire comment cela se fait, je n'ay rien trove
jusqu' ici qui me satisfasse._ C. H. de la lumiere, c. 5, p. 91.]

To explain the unusual Refraction of Island Crystal by Pression or
Motion propagated, has not hitherto been attempted (to my knowledge)