The Music Stem / The Musician's Library / Composer's Handbook / Hemiola
Composer's Handbook
A hemiola regroups six beats as three groups of two where the meter implies two groups of three.
In 3/4, write three half notes across two bars.
Two bars of 3/4 hold six quarter beats. Grouped 2+2+2 as three half notes, they sound like one bar of 3/2.
Schumann, Symphony No. 3 (Rhenish), first movement