Hi guys, i think i get it now.
Fret 7 and 19 have the same string length ratio, just mirrored, they are the same distance from the center of the string , fret 7 and 19 have the same harmonic note. Fret 8 and 17 too have their same mirrored ratio and are also their same distance from the center of the string, 8 and 17 have their same respective harmonic note also.
The thing that i had trouble with was why was fret 7 low and fret 8 high,, why was fret 16 low and fret 17 high, why was there this sawtooth pattern of harmonics as you progress up the neck.
I understand now that it is the interaction of both frequencies produced by the different string length ratios that results in the strings final frequency, whether the two waves where in phase or out of phase, whether they were constructive to producing a higher frequency, in phase so to speak, or destructive, out of phase that results in a lower frequency.. Like two ripples in a pond colliding, the resultant wave is never the same as either ripple was before they collided, but depending on the ripples frequencies and time in the cycle of their collisions, the resultant ripple might be high, low, wide or sharp. At fret 7 the collision of the two frequencies results in a stretched waveform, a destructive effect, hence lower frequency, the bottom of the sawtooth. At fret 8 though the collision of the two frequencies have become constructive to produce a higher frequency, the peak of the next sawtooth, and so it goes on.
Its been interesting for me and i thank you George and Ken for your input.
I will sleep better tonight im sure,
Cheers all
Geoff