which
precedes the other, must necessarily be somwhat more _obtunded_, or
_impeded_ by the resistance of the transparent _medium_, than the other
part or end of it which is subsequent, whose way is, as it were, prepared
by the other; especially if the adjacent _medium_ be not in the same manner
enlightned or agitated. And therefore (in the fourth _Figure_ of the sixth
_Iconism_) the Ray AAAHB will have its side HH more deadned by the
resistance of the dark or quiet _medium_ PPP, Whence there will be a kind
of deadness superinduc'd on the side HHH, which will continually increase
from B, and strike deeper and deeper into the Ray by the line BR; Whence
all the parts of the triangle, RBHO will be of a dead _Blue_ colour, and so
much the deeper, by how much the nearer they lie to the line BHH, which is
most deaded or impeded, and so much the more _dilute_, by how much the
nearer it approaches the line BR. Next on the other side of the Ray AAN,
the end A of the pulse AH will be promoted, or made stronger, having its
passage already prepar'd as 'twere by the other parts preceding, and so its
impression wil be stronger; And because of its _obliquity_ to the Ray,
there will be propagated a kind of faint motion into QQ the adjacent dark
or quiet _medium_, which faint motion will spread further and further into
QQ as the Ray is propagated further and further from A, namely, as far as
the line MA, whence all the triangle MAN will be ting'd with a _Red_, and
that _Red_ will be the deeper the nearer it approaches the line MA, and the
_paler_ or _yellower_ the nearer it is the line NA. And if the Ray be
continued, so that the lines AN and BR (which are the bounds of the _Red_
and _Blue diluted_) do meet and cross each other, there will be beyond that
intersection generated all kinds of _Greens_.

Now, these being the proprieties of every single refracted Ray of light, it
will be easie enough to consider what must be the result of very many such
Rays collateral: As if we suppose infinite such Rays _interjacent_ between
AKSB and ANOB, which arc the terminating: For in this case the Ray AKSB
will have its _Red_ triangle intire, as lying next to the dark or quiet
_medium_, but the other side of it BS will have no _Blue_, because the
_medium adjacent_ to it SBO, is mov'd or enlightned, and consequently that
light does destroy the colour. So likewise will the Ray ANOB lose its
_Red_, because the _adjacent medium_ is mov'd or enlightned, but