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# Title: Lexicon Technicum: Or, An Universal English Dictionary Of Arts And Sciences (shelfmarks Leibn. Marg. 71; ZEN Leibn. Marg. 71)
# Folio - , page id 806933011:0347
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I
dc
Demonstration.
Ter FalI the Perpendiculars P X, on the 
ron che siven Ray, and C Z on che retracted
Ray.
THen P F and O R are parallet by Constructi.
on, Whence che Frianeles  R C and PF C aC
similar.
And CR: OR:: CF: PK;
That is, C R: OP :: G F: PF.
NTOW C F : PF 5: C Z : P X ob s
Wtence CR: O P:: C Z : P 3
And CR: CZ :: OP: P X.
Again, CR: CO:: 25 che Sines oF Retracti.
on, by Construction: chat is, a5SEOr, OPY 1O 5;
andas CR: CL: : CD = = Or CR: or  C2
eO: P x.
BuE PO : Px 5: C567
Theretore C y = - OF, 6,23
That i5, C 7 : C2:: 25 che Sines oF Retca
ction,
Duc LC) Iis he diue ocihe f as  lunete
2. F. D.
vergins as cheyenter the Curre Surtace oF a Con
Dex Or Concave Lens, are for che Readers ease deli-
neaced in Fis. 1, 2, 3, 4: And che lite Cales ot
Emersins Rys, in F1B. 5, 6, 2, 8.
The sereral Cales oF Rays Divergins Ox Con-
F15. L.
2
5. 4