Why do harmonics ring out as to a note on the guitar?

Question

I was just playing around on my guitar and relized that the sound from a harmonic ring out even if your finger isnt on the fret as compared to a regualr note you have to hold it down for the sound to stay, why is that

Answer 1

Your finger in contact with the string creates a dead spot.

The whole string cannot vibrate along its length, so it vibrates in

a 'mode' that allows that spot to remain still.

When you touch the center, the string 'splits' in two, when you

touch at one third the length, in three, and so on.

Answer 2

because it is a harmonic vibration.  the regular notes are made in essence by shortening the length of the string.  

this page describes it in very good detail.

http://www.harmony-central.com/Guitar/ha...