Méridienne de Gueberschwihr

Historically, the men have sought to identify as accurately as possible the middle of the day, that "noon" associated with the time of the break, at mealtime. The "meridian" is a solar clock that makes it possible to determine this midday moment, the "true midday", the "solar midday", the one that effectively divides the day into two parts of equal length, from sunrise to sunset. This instant corresponds to the highest position of the Sun in the sky (its culmination) and thus to its passage due south. Such a meridian is thus a sundial giving only the time of "noon". In fact, these meridians, which are still found on some buildings, were only used to adjust the mechanical clocks of bell towers, town halls and other public buildings, clocks whose mechanisms were still unreliable with irregular movements. In Alsace, there were two types: the "Ungerer" type meridians found mainly in the Bas-Rhin region and the "U.Adam" type meridians built by the watchmaker Urbain Adam of Colmar. The most famous meridian is the one created by J.B. Schwilgué and installed at the south portal of the cathedral of Strasbourg for the adjustment of the famous astronomical clock. The meridian is fixed on the facade of the church.