Many thanks to the several readers, too numerous to list, who have
responded to my query for Caliola scale info, both privately and
via MMD postings [MMDigest 030910].  (But I will give special mention
to Robbie, who was especially helpful).

My reason for asking is to make Caliola arrangements, not
(unfortunately) to get an instrument working.

I enjoyed the various explanations of the "oddball" hole spacing.
And to answer my own question (though Robbie answered it), yes, the
lowest pipe is just F below Middle C.  I got a close look and listen
to the unique "Duplex" Caliola at the DeBence Museum in Franklin, PA.

While it has a lot of extra pipes (mostly reeds) added on to make a
full-size band organ, half buried in its guts are the large-scale open
wood pipes of a Caliola.  And the longest one, mitred back on itself,
looked to be about the 3 foot length of F below Middle C.  The
instrument plays APP rolls like a plain Caliola.

By the way, you don't want to be too close to this machine when it's
playing -- it's definitely built for the great outdoors!

Thanks again to all -- Mike Knudsen