This question is funny. I did ask some of my friend who are expert in music but they do not have answer also.
while searching internet for answer, this is what I get here. And it is interesting.
http://www.uk-piano.org/history/compass.html
God bless
I found the NET(New English Translation) Bible is very useful for my bible study reference. And oen good thing is IT IS FREE to download. you may just get it from their website now
www.bible.org
God bless
Now Hear and Play from Jermaine Griggs is having digital download. You no longer need to use conventional way to buy DVD and wait for long shipping time and possible being TAXED by logistic custom (I got TAXED before 
).
Go here and get more info…..it is almost 40% price slashed from original price now.
Hear & Play digital download