Explain this old one...

[Brendan McKay]

I was just poking around in the Beinecke Rare Book and Manuscript
Library Photonegatives Database here:  
   http://highway49.library.yale.edu/photonegatives/
and I came across something called Utriusque Cosmi Oppenheim
dated 1617 which contains the sequence 
  3 5 6 8 10 12 13 15 17 19 20 22 24.
Matches in OEIS are
  A022838 Beatty sequence for sqrt(3)
  A047329 Congruent to {1, 3, 5, 6} mod 7,
but I don't know if either of them is the correct sequence.

A direct link to the manuscript page is
  http://highway49.library.yale.edu/photonegatives/oneITEM.asp?pid=39002036242312&iid=3624231
(click the image for a close view).

Can anyone solve this?  I guess it is something musical.

Brendan.