This article examines a horizontal sundial described in Manuscript Rivipullensi 225, a 10th-century compilation from Ripoll monastery. The manuscript provides didactic instructions for laying out the dial with concentric circles for months and temporary hour divisions. The author reconstructs two versions, discussing its function, orientation, and unique characteristics, suggesting Latin or Ripollan origins distinct from Arabic sundials of the period.
Historical Dials,
Mathematics of Dialling,
Sundial Design & Layout