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PROPOSITION II. 
1 . 
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refraBtng Circle and its refraBing ^ower he^ 
ing given, the Ray is given in Rojition, which, faf- 
fing parallel to a given RDiameter of the Circle, after 
its RefraBion, is fo refleBed from the farther Sur- 
face of the Circle, as to be inclined to its incident 
Courfe in a given Angle. 
Let A B C D be the given Circle ; let A C be the 
given Diameter, E F the incident Ray parallel to it, 
which being refracited into the Line F G lhall lb be re- 
fled:ed from the Point G in the Line G H, that E F 
and FI G being produced, till they meet in I, the 
Angle under E I FI fhall be given. 
Let K be the Center of the Circle, and K F, K G be 
joined ; let the Semidiameter L K be parallel to the 
S reb:a(%ed 
