"Philip Lewis" wrote in message
...
you could always use the "perfect ratio" rule.

the perfect ratio is about 1:1.62
the 9 foot needs to be divided into two zones...
one of unit 1, the other of 1.62.
9' / 2.62 = ~3.44 so about 3 foot 5.25 inches

For lack of any other considerations. sounds as good a height as
any...

Other folks might have opinions.... like standard chair rail height.

called the 'golden rule' or 'golden mean'

http://www.woodcentral.com/russ/russ2.shtml