Mar 4, 2019
LJS 487 - [Treatises on astronomical instruments]
This is an anonymous treatise on constructing and using a horologium diei et noctis (combined sun dial and nocturnal). The uses include telling the time of day and night, determining the times of sunrise and sunset and the precession of equinoxes and solstices, and measuring the height of stars. It was written in France in the 16th century.
Click here if you want to know more, or here if you want to see the facsimile!