Opticks 1717 - Up

j2di-attion be made
into kvater, the
Sine of Incidence of the red Light-is to the Sine
pfits IXefraCtion as 4 to 3;. If out of Air into Glafs,,
the Sines are as 17 to 11. In Light of other
CoTours the Sines have other .Proportions : hut
t&i &&ye&x is f~ little that !t peed feldom be
&niid&ed I ’
Snppofe therefore, that R S [in Fig. I .I’ reprefents
the Surface of fkgnating Water, and that C
ence in which anyRay coming
ln the Line A c is refleCted or
ould know whither this Ray
exion ‘of Refra&ion : I ere&
e of the Water fi-om the; point
e Perpendicular @ I? and produce
o Q, an&concIudc by the fir@
e Ray after Reflexion and R.eS’
fra&ion, filall be found fomewhere in the Plane
of the Angle of Incidekc A C P produced. I let
fall therefore upqn the Perpendicular C P the
Sine of Ipeidence AD 8 and if the refleCted
?‘kay be defired? I produce AD to’ B f~ that
.bB be equal to A.Dj and draw
il,iile C B ihall be the rei-leAed W
irpf Reflexion BCP and its Sin
gual to the Angle and Sine of Incidence
ought to be by the fecond Axiom. I3
iefiaAei1 Ray be d&red, ‘I produce A
fo that I3 II may be tcr AD as the Sine of Ike-:
@$‘i.jo~~ tcp &e Sine wf Incidence, that is. (if the
.&,g$$; ;;z)gs 3 to 4 ; ~n(l about the ,Center
ane 4 & I? wrth the Radms G A
$zfcpil$g a Circle A H9 E I draw Parallel to’the
Z$erpendq@ C.P Q, the r,ilr,” II E, ctatting tl$
.:
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