This article describes the Equinoctial Armilla, built by Egnazio Danti in 1573 on the Santa Maria Novella basilica in Florence. Its purpose was to determine the Equinox time and tropical year length, contributing to calendar reform. The article discusses its historical context, Danti's observations, chronological discrepancies, measurement errors due to the armilla's size, and the instrument's features.
Mathematics of Dialling,
Historical Dials,
Dials: Armillary Sphere