[HM] integral around a closed path symbol

Jeff Miller (JeffM@sanctum.com)
Tue, 01 Sep 1998 17:50:07 EST

I received a phone call today from an individual who is extremely interested
in finding the origin of the symbol for an integral around a closed path
(integral symbol with a circle in the middle of it). He does not have
e-mail and I told him I would pose his question here and read any replies to
him.

The earliest use he has found is by Arnold Sommerfeld in Annalen der Physik
around 1916 or 1917. He says the symbol was not used by Gibbs in Vector
Analysis (around 1896) and was not used by E. B. Wilson in Advanced Calculus
(1911), although Wilson used an integral symbol with a circle beneath it
(where the C appears now).

The symbol is not mentioned by Cajori.

Thanks in advance!

Jeff Miller
http://members.aol.com/jeff570/mathsym.html