"[Volvelle]", Apianus, Peter Bienewitz
Subject: Cartographic Miscellany
Period: 1584 (circa)
Color: Hand Color
5.3 x 5.3 inches
13.5 x 13.5 cm
This incredible paper instrument is a functioning lunar clock designed to determine the time at night. It consists of an engraved circle showing 24 hours into which two rotating discs are mounted. In use, the hour angle of the Moon is determined using an ordinary sundial. The inner disc of the instrument is set to show the current phase of the moon through the little window. The lunar dial is set to the hour angle determined with the sundial; this yields the position of the sun and thus indicates the time.
Splendid old color. Light foxing in blank margins. Hinge remnants on verso.