Re: The symbol for index of refraction

[Ludwik Kowalski <kowalskiL@MAIL.MONTCLAIR.EDU>]

Leigh Palmer wrote:

> Can anyone direct me to an appropriate source of information on
> the origin of the use of "n" (by American physicists) and "mu"
> (by the Brits) as symbols representing the index of refraction?

I do not about the origin of these symbols but a source of
information is probably the History of Physics library. It used
be in New York City and I recall its very old books, often
first editions. Unfortunately, the library is now at Maryland,
near the AAPT offices.

Let me speculate. I suppose that n was was not introduced as
the ratio of c/v but as the ratio of the angle of refraction over
the angle of incidence (Kepler believed, I read somewhere,
that this ratio is constant; this was before Snell's law was
introduced by Descartes.) It would be interesting to know
what words and symbols were used by Kepler, Snell and
Descartes. Those who know Arabic may tell us about names
and symbols used by Al Hazan (Sp?) who is said to know
about Snell's law long before Snell. Welcome back Leigh.
Ludwik Kowalski