Simbol for the S

Hi, all,

I've only recently began to read some XVIII century books, and I've noticed that, in English as in French, they used in that time two different simbols for the letter 's', one as we're used to it and the other similar to a "f".

Does anybody knows where it came from and what was the rule for using one or another?

Just found it: http://en.wikipedia.org/wiki/Long_s

That's the "long s" - you can read (probably more than you want to) about it at:
http://typefoundry.blogspot.com/2008/01/long-s.html

The wikipedia page (http://en.wikipedia.org/wiki/Long_s) isn't bad either.