Favorite diagrams from music theory texts

Iacobus de Ispania: Speculum musicae Walter O'Connell: Tone Spaces Marin Mersenne: Harmonie universelle Paul Erlich: The Forms of Tonality Ian Quinn: General Equal-Tempered Harmony Athanasius Kircher: Musurgia Universalis Erv Wilson: Hebdomekontany Marin Mersenne: Harmonie universelle Winchester and Portsmouth Guild of Church Bellringers on twitter Jan Haluska: The Mathematical Theory of Tone Systems Robert Gross: Music Theory Nerd Fight II Walter O'Connell: Tone Spaces Marin Mersenne: Harmonie universelle Iacobus de Ispania: Speculum musicae Athanasius Kircher: Musurgia Universalis Ian Quinn: Listening to Similarity Relations Bernard Gates: A Pitch-Class Set Space Odyssey Miles Okazaki: Musician's Visual Reference