Opticks 1717 - Up

3 f
iheir pafing OLIN of one Medium into another.
Alld thus may &ys and ~efia~tions be confider&l,
if Light be propagated in aii i&ant.
,?KGt by an Argument taken from the fEqu2~
tions of the times of the Eclipfes o~J;I!P~GP~?J
8~~eZli~es it Jeems that Light is propagated in
time, fpending i,n its pnflagc from the Sun fo us
about ieven IMinutes of time : And therefore 1
have chofen to define kq7s and RefraAions in
fuch g~ne~l terms as-anay agree to Light in both
CdiZS~
E i? I N. ” III.
Rej!&~xiBility cfPZ62y.f; is Lhe& Di@ffJtioft to de
rej%iTed& turnPd back? z'F2.h the fameMedium fvm
iaf~y other’ Medium upof z.GlJaJk Siwfhte they falX
Arzd Rays aYe mow 01’Jefs rej’exible; which are
returnid baclz more or Zefs eaJYy. As if’Ljght
pafs out of Glafs into Air, and by being iixhnec$
more atid more to the common Surface of the
Glafs and Air, begins tit length to be total1 refleAed
by that Surface; thofe forts of -Y Zaps
which at like Incidcnces are rcflekkd molt copioufly,
or by inclining the Rays begin faonedE
to be totally reReAed, are molt,ref-lexible.
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.DEFiN. ry. ‘. *