Downward reed curvature!?

[Nidalap :D~ <nidalap@xxxxxxxxxx>]

  Hello folks,

  I've learned from some harp customizing gurus that adjusting reed
  curvatures help inprove performance. All the information I got say
  the curve has to be a upward one, that is, bent down from the rivet,
  then up somewhere near the middle or end of the reed.

  Recently I borrowed a book from libray, which explains the physics
  of  musical instruments. I'm quite confused when I read the part about
  free reed instrments, a figure displays a typical harmonium reed,
  which has a downward curve.

  The book pointed out the curvature, but didn't seem to explain it.
  I am very curious why a downward curve is applied, could somebody
  please help me find out the answer? thanx!

  I uploaded an excerpt at 
    http://harmonica.cc.ccu.edu.tw/pic/reed_curvature.jpg

  Regards,
  Nidalap :D~

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