Mobility Ahead of Its Time: A Fifteenth-Century Austrian Pocket Sundial as a Trailblazing Instrument for Time Measurement on Travels

Abstract

Recent excavations in the late medieval castle of Grafendorf in Austria revealed an equatorial sundial, consisting of a brass hour ring with engraved Arabic numerals and a revolvable gnomon. Epigraphic analogies suggest a dating around 1450, which is remarkably early, as the equatorial sundial was first described in 1431. Iconographic analogies not only support this dating but along with some complete museum pieces also reveal that the Grafendorf find was without a doubt part of a composite instrument of the following makeup: a closable box containing a compass, a retractable equatorial sundial, and a nocturnal. These parts added up to a highly functional, portable 3-in-1 instrument that was ideal for journeys and allowed its user to measure the correct time day and night, 365 days a year and even on wide travels. This certainly was a feat for the second half of the fifteenth century, where the majority of people still relied on modestly exact church clocks.

The Austrian pocket sundial is the only one of its type found in the course of an archaeological excavation. The historical background of Grafendorf castle around 1500 offers two owners of international format, who traveled through major parts of Europe and can therefore be considered perfect customers for such a groundbreaking timekeeping device. While it could have been used in Grafendorf for various reasons, this instrument nonetheless exemplifies the changing sense of time and the increasing need for precise individual timekeeping even abroad on the eve of the Late Middle Ages.