Whilst bowing, with a finger of the left hand the player lightly touches the string at a nodal point. This produces a light, "fluted" sound. Notation: a small circle above the note. Natural harmonics are only obtainable at certain positions along each string - they are as follows:1/2 way along (gives an octave above open string), 1/3 (gives 8ve+5th above open string), 1/4 (gives 2x8ves above open string) and 1/5 (gives 2x8ves+maj3rd above open string). There are more natural harmonics, but these are relatively unreliable.
The string is stopped normally, and then fingered lightly (with the little finger) at a point a 4th or a 5th above the stopped note. Notation: Looking at the example opposite, the first will produce a note two octaves above the stopped note, the second an octave and a fifth above the stopped note. Sometimes flag (= flageolet) is written over the note. It is possible to add vibrato and to play melodic lines in artificial harmonics, but both techniques should be used with care. Two rarer artificial harmonics are: min 3rd above stop - produces two octaves + a 5th and maj 3rd above stop - produces two octaves + a maj 3rd.