"Penumbral Zone Residua of Past Impressions is intended for a large string orchestra, the ideal balance consisting of 24 violins, 18 violas, 18 'cellos, and 12 basses, each divided into 6 sections. It is in one continuous movement, but with several strongly constrasting sections. The beginning and ending sections change meter often, keeping a common eighth-note pulse, except where otherwise indicated. In two passages, mm. 352--389 and 398--445, I have called for the use of two contrasting meters, related by a ratio of 3:2, to be used simultaneously."