This book lists 2,770 strong chords and 96 scales that are playable on piano style keyboard instruments that are tuned to the Eagle 53 musical tuning. Some notes are higher than usual and others are lower. Some chords are more out of tune but many are more *in* tune. Also some new and exotic chords and scales occur that you won’t find in the regular Western tuning: 12 Tone Equal Temperament (12 TET). The 7/4, 7/5, 7/6, 8/7, 9/7, 10/7 and 12/7 intervals occur in Eagle 53 within 8.5 cents accuracy. You won’t find these intervals in 12 TET within 8.5 cents accuracy. There is some theory and mathematical background here as well and a chapter on composing in Eagle 53.