Gentlemen,

A question has come up that needs an accurate answer.

Those of us making optical scanners for our roll playing use the
various reference books on hole spacing. One dimension seems to have
slipped into the cracks.

Various organ rolls like the Aeolian 116 note and Duo-Art use a
staggered tracker bar. The notes are 6 to the inch on each row of
holes, 12 to the inch total.

But... what is the center to center vertical spacing of the two rows of
holes?  Measuring several rolls gives a spacing of 0.225" Is this
correct?

Jim Crank