Re: [HM] Snell, Fermat, light rays, and all that
Roger Cooke (cooke@emba.uvm.edu)
Sun, 18 Oct 1998 23:08:23 -0400 (EDT)
At the time (17th century) I'm not sure, though I believe Descartes has
some claim to this law also. Refraction was studied by Ptolemy, who gave
a table of angles of refraction for a few media. However, the tables give
the angle of refraction as a strictly quadratic function of the angle of
incidence, which is very close to Snell's law, but not exact.
It would be interesting to know how Ptolemy decided to give these values,
since he didn't have the concept of a quadratic function, of course. I
suspect he DID have the concept of equal second differences, however, as
(I think) did the Chinese about the same time.
Roger Cooke