] Since the few conduct books that I have acess to do not have anyhting to say on the subject of napkins...

Hmm, I haven't looked into conduct books, but right the other day I was looking through "The Illustrated History of Britain", and there was a mention of napkins in Tudor times - also with an advice not to wipe fingers on the tablecloth.

And then - Susan Price, nearing Mansfield Park, "was meditating much upon silver forks, napkins and finger-glasses."