Alsatian Horology (Strasbourg Astronomical Clock Tradition)

Alsace, and Strasbourg in particular, is best known in horological history for its succession of monumental astronomical clocks in Strasbourg Cathedral: a first mechanism built in the mid-fourteenth century, a substantially new second astronomical clock completed in 1574 (associated with mathematicians Conrad Dasypodius and the Habrecht brothers, Isaac and Josias Habrecht, as builders), and the current, largely rebuilt third astronomical clock completed in 1843 by Jean-Baptiste Schwilgué, incorporating an early mechanical computer-like system of gearing to calculate and display the date of Easter and other calendrical data.

Beyond the cathedral clock tradition, the Alsace region (straddling French and German cultural influence and changing sovereignty between France and Germany across this period) supported a broader regional clock and instrument-making trade, though it did not develop a distinct large-scale industrial watch manufacturing sector comparable to nearby Switzerland or the German Glashütte and Black Forest traditions.

Jean-Baptiste Schwilgué's nineteenth-century work on the third Strasbourg astronomical clock is particularly significant in the history of complex calendrical mechanisms, since his solution to mechanising the moving Easter-date calculation (the computus) is among the most celebrated attempts to build such a mechanism, and is well documented compared with most other historical computus-mechanism efforts (see Easter Computus Indicator).