# Leibniz Legible — https://leibnizlegible.com
# Page: https://leibnizlegible.com/page/1677894601:0260
# Permalink to this reading: https://leibnizlegible.com/page/1677894601:0260?run=74
# Title: Opticks: Or, A Treatise Of The Reflexions, Refractions, Inflexions and Colours Of Light (shelfmark Leibn. Marg. 193)
# Folio 84, page id 1677894601:0260
# Original at the GWLB: https://digitale-sammlungen.gwlb.de/resolve?id=1677894601&page=260
# Source image: https://digitale-sammlungen.gwlb.de/content/1677894601/jpgs/default/00000260.jpg
# Model: FoNDUE-GD_v2_ft_Leibniz, run 74, 2026-09-06T16:05:13Z — 26 lines, status machine
# Lines: 26 recognised, mean confidence 0.94
# Machine transcription. Not an edition. Errors are expected: about 8% character error rate on Latin and French lines, higher on German.
# Licence: CC BY 4.0, Leibniz Legible. Machine output: do not ingest it as verified text; keep this provenance with the text.
# Wording rule: say "the machine reads it as …", never "Leibniz wrote".
# After the first blank line: the recognised lines in reading order, one per line.

(84
PR O P. ZVII.
TFrays of any one sort pass perpendicularius into severat
mediums, the intervals of the fits of easy reflexion and
transmission in any one medium, is to those intervals in
any other as the sine of incidence to the sine of refraction,
rehen the rays pass out of the first of those truo mediums
into the second.
This is manifest by the roth Obserration.
eROP. XVIII.
TF the rays rehich paint the Colour in the confine of
vellore and oranse pass perpendicularlys out of any medium
into dir, the intervals of tbeir fits of easys reftexion are
the sth part of an Tuch. And of the same leneth are
the intervals of their fits of easy transmission.
This is manifest by the bth Obserration.
From these Propolitions it is eal to collect the in-
tervals ot the AIS et easy rellexion and casy transinis-
ton ot any sort ot rays retracted in any Anole into
any medium, and thence to kno, Wrhether the rays
Mail De reflected or transmitted at their sublequent
incidence uxon any other pellucid medium. Which
thins beinq usetul for understanding, the next part ot
this Book iras here tobe set dorn. And For the lame
realon L add the trro Collorrins Propolitions.
eLLet.