I wonder why there is any set increment. Our lips can make minute changes, so why only by a fifth? There must be some physics involved with the design of the intrument that causes the incremental jump.

>You made me dig bag about 50 years for this one <g>
>
>If I remember correctly, lips can do a 5th.
>
>C 000 D 103 E 120 F100 G 000 A 023? B ??? C 000
>
>Could be completely wrong in remembering but I do remember than with no valves you could play a bugle call, so that means not just octaves.
>
>>There are only 8 possible valve combinations. How do you play the full 12 notes with sharps and flats? The lips are a variable that can change the note values for a combination, but I thought only by an octave.
>>
>>000
>>100
>>020
>>003
>>120
>>023
>>123
>>103