On The Edge was written for the Delta Saxophone Quartet and its primary research aim was to explore new melodic shapes through the use of quartertones and to modify my use of progressive chromatic tonality to accommodate quartertones. Quartertones are primarily used to inflect melodic shapes and as intermediate points of progression between fixed harmonic landmarks. A further research aim was to explore spatial separation through the creation of a variety of ensembles and sub-groupings within the quartet. These small-scale hierarchical changes are reflected by movement of players during the performance and through spatial separation in the recording process. The use of spatial movement is something I first explored in ‘Four Quartets’ (1981)...