Ok, so after all that , we're playing the "99 Year Waltz" on a "C" accordion in the key of "C".
Irregardless of what the first note of the tune is ( BTW, I play the "C" just ahead of the "E" ), the fiddle will start off "bassing" a "C" behind the accordion .
Jude

jude is correct. Normally for most Cajun Dancehall style music, Fiddle starts bassing on the low octave or just playing key parts of the melody on the low octave till it comes time to take a fiddle ride, (usually but not always after the first verse) At that point, fiddle player does whatever the heck pleases him. Usually playing the melody on the upper octave.

Thanks to both Jude & Layne. That was what I needed to know. See the above site for real good tuning and key signature finger positions for a violin/fiddle. Can really only tune a violin correctly one way. Tuning down to F will work, but you really don't get the best hum out of the strings. Got to convince this kid, well, he's 20, but that's a kid to me, that wasting 10 years of violin lessons and a high-dollar Antonio Strand violin just because it ain't as macho as working on a car engine, is losing out on what could be a potential for a lifetime of fun. Like I told his Dad, the girls always take the fiddle player home.

JB