Skip to content
The Encyclopedia of Horology

Astronomical clock with mechanical automata and perpetual calendar work · France (Strasbourg Cathedral)

Strasbourg Astronomical Clock

Verified

The present clock is the third built at Strasbourg Cathedral; Schwilgué incorporated a mechanical computer capable of calculating moveable feasts (including Easter) and functioning correctly through the Gregorian calendar's leap-year exceptions.

Technical facts

Calendar computation
Mechanical computus mechanism for moveable feasts, accounting for the Gregorian leap-year rule
Automata
Procession of the Apostles and a mechanical rooster that crows at noon
Astronomical display
Orrery-style display of planetary positions known at the time of construction

Historical significance

  • The present clock is the third built at Strasbourg Cathedral; Schwilgué incorporated a mechanical computer capable of calculating moveable feasts (including Easter) and functioning correctly through the Gregorian calendar's leap-year exceptions.
  • A celebrated example of pre-electronic mechanical computation applied to calendar astronomy, distinct from being merely a large decorative clock.
  • Because three successive clocks have occupied the site, researchers should always specify which clock (1354, 1574 or 1842) a given claim or fact refers to.

Photographs

Strasbourg Astronomical Clock (museum replica)
Strasbourg Astronomical Clock (museum replica) — Museumsfotografierer, Public domain. Wikimedia Commons file page
Strasbourg Astronomical clock Equations
Strasbourg Astronomical clock Equations — Tangopaso, Public domain. Wikimedia Commons file page
Strasbourg Cathedral Astronomical Clock - Diliff
Strasbourg Cathedral Astronomical Clock - Diliff — Diliff, CC BY-SA 3.0. Wikimedia Commons file page

Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.

Sources & references

  1. Strasbourg Cathedral, published horloge astronomique visitor materials
  2. Antiquarian Horological Society, comparative articles on astronomical clocks

Where sources disagree, the disagreement is stated rather than resolved silently.