On this page of Marcel Tournier's Vers la source dans le bois, one sees S.H. in the 8th bar. What does this mean?
"S.H." stands for "sons harmoniques" (harmonic sounds). The circle above the note provides the same information.
The harmonic is a popular effect in harp music. Although the octave harmonic is the most common harmonic in the harp repertoire, fifth, double octave and third harmonics can also be produced. On some strings, even more harmonics can be produced. Harmonics can be used in combination with normal notes as well as with other harmonics. On the harp, as many as four harmonics can be produced simultaneously.