e by the refraction in the _Cornea_, and some other parts of the
eye, the sides of each Ray, which before were almost parallel, are made to
_converge_ and meet in a point at the bottom of the eye, therefore that
side of the _pulse_ which preceded before these refractions, shall first
touch the _Retina_, and the other side last. And therefore according as
this or that side, or end of the pulse shall be impeded, accordingly will
the _impressions_ on the _Retina_ be varied; therefore by the Ray GACH
refracted by the _Cornea_ to D there shall be on that point a stroke or
impression confus'd, whose weakest end, namely, that by the line CD shall
precede, and the stronger, namely, that by the line AD shall follow. And by
the Ray KCAI refracted to F, there shall be on that part a confus'd stroke
or impression, whose strongest part, namely, that by the line CF shal
precede, and whose weakest or impeded, namely, that by the line AF shall
follow, and all the intermediate points between F and D will receive
impressions from the _converg'd_ Rays so much the more like the impressions
on F and D by how much the nearer they approach that or this.

From the consideration of the proprieties of which impressions, we may
collect these short definitions of Colours: That _Blue is an impression on
the Retina of an oblique and confus'd pulse of light, whose weakest part
precedes, and whose strongest follows._ And, that _Red is an impression on
the Retina of an oblique and confus'd pulse of light, whose strongest part
precedes, and whose weakest follows._

Which proprieties, as they have been already manifested, in the Prisme and
falling drops of Rain, to be the causes of the colours there generated, may
be easily found to be the efficients also of the colours appearing in thin
_laminated_ transparent bodies; for the explication of which, all this has
been premised.

And that this is so, a little closer examination of the _Phaenomena_ and
the _Figure_ of the body, by this _Hypothesis_ will make evident.

For first (as we have already observed) the _laminated_ body must be of a
determinate thickness, that is, it must not be thinner then such a
determinate quantity; for I have always observ'd, that neer the edges of
those which are exceeding thin, the colours disappear, and the part grows
white; nor must it be thicker then another determinate quantity; for I have
likewise observ'd, that beyond such a thickness, no colours appear'd, but
the Plat