Thanks to everyone for the response.  I now understand how it works.
The organ I want to re-tune is a Wurlitzer 105, the second organ I've
built.  The first I built was tuned on pitch because of the trumpets
that I used from a Wurlitzer 125 that I built 40 years ago.  Since
then, using Bob Stanoszek's plans, he says the organ should be tuned
one note low.  So I wanted to try this new organ tuned to his plans.

Les Higger