# Leibniz Legible — https://leibnizlegible.com
# Page: https://leibnizlegible.com/page/1677894601:0261
# Permalink to this reading: https://leibnizlegible.com/page/1677894601:0261?run=74
# Title: Opticks: Or, A Treatise Of The Reflexions, Refractions, Inflexions and Colours Of Light (shelfmark Leibn. Marg. 193)
# Folio 85, page id 1677894601:0261
# Original at the GWLB: https://digitale-sammlungen.gwlb.de/resolve?id=1677894601&page=261
# Source image: https://digitale-sammlungen.gwlb.de/content/1677894601/jpgs/default/00000261.jpg
# Model: FoNDUE-GD_v2_ft_Leibniz, run 74, 2026-09-06T16:05:13Z — 29 lines, status machine
# Lines: 29 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.

P R OP. ZIX.
I any sort of rays fallins on the polite surface of any
pellucid medium be refected bacte, the fits of easus re-
fexion rehich they have at the point of reflexion, palt
stiu continue to return, and the returns sal be at di-
stances from the point of reflexion in the arithmetical
prooression of the numbers 2, 4, 6, 8, 10, 22, _C. and be-
treeen these fits the rays sai be in fits of easy trans-
mission.
FOT CinCe thC AES OF casy rellexion and easy tran-
mission are ot a returnins nature, there is no reason
rtr chele Ats, irhich continued till the cay arrired at
the reflectins medium, and there inclined the ray to
reflexion, Bould there cease. And it the cay at the
point ot reflexion ras in a ft ot casy resexion, the
progression oF the distances ot thele tuts trom that point
must besin From o, and (0 DC OF the numDerS O, 2,4,
6, 8, c. And theretore the prooression ot the di-
sances of the intermediate AIS oF casY tran(missIOn ZCC
koned From the lame point, must be in the progrestion
oF the odd numbers 1, 3, 5,7, 9, Dc. Contrary towrtrat
happens wrhen the Ats are propasated trom points et
retraction.
PROP. XZ.
The intervals of the fits of easy reflexion and easis
transmission, propasated from points of reflexion into any
medium, are equal to the intervals of the litee fits rehict
the same rays vould have, if refracteu into the same
medium