This Treasure is paired with: Holst’s Planets (Influences of the planets)
Apian sought to make astronomy easy, in this lavish book for royal patrons. He reduced complex astronomical computation to simple mechanics with the aid of paper volvelles – those pictured are for Mars – adapted from the astrolabe. The discs enabled the casting of horoscopes (used by doctors to treat patients), and the forecasting of eclipses and comets. The reader was expected to know little more than the most basic mathematics.
This Treasure isn’t currently on display in the Weston Library.