What is a sundial

Sundials - documents of the art of timekeeping

Shortly before 1500 there was a significant innovation in sundial construction. From now on, a rod that is aligned with the celestial pole (near Pole Star) served as a shadow thrower.

Fig. 1: Folding sundial (pocket watch), popular for time measurement in the 17th and 18th centuries.

The angle of the inclined pole (polo) always corresponds to the geographical latitude of the location concerned (Essen: 51.5 ° N). The pole rod, which ran parallel to the earth's axis, offered a much better way of reading the time, regardless of the date and the height of the sun in the seasons. Each hour line applies to a certain time, the shadow direction now only depends on the time of day. The date is no longer important for the time reading.

It is understandable that this new and much more convenient way of displaying the time quickly spread, and a huge boom in the construction of sundials began. The commercial metropolises of Nuremberg, Augsburg, Paris, Antwerp and others offered favorable economic conditions for this. Well-known scholars and artists dealt with it, Albrecht Dürer provided the classic design for the construction of several types of sundials, which is still used today. During this time, numerous small, portable sundials were created that required a compass for alignment, which is why the manufacturers were referred to as compass makers (compasts).

The foldable pocket sundials, which, in contrast to the mechanical pocket watches, were much cheaper (Fig. 1), were much in demand. These could also be used in different geographical latitudes and certainly met the requirements of the time. It is known of Goethe that he carried folding sundials with him on his trips to Italy.

As a special gag they had come up with a small cannon that fires a shot at the time of true noon, when the sun is in the south. The transportable sundials in museums and collections, which were in great demand at the time, testify to great craftsmanship and a sense of art.

Vertical sundials were built everywhere on churches, town halls and houses of wealthy citizens, which not only served to display the time, but also served as a decoration for the building. The historic sundial with the solarium and the Arachne from 1550 at the old Ratsapotheke zu Görlitz are a sight to see. Cities like Nuremberg, Ellwangen and Dresden have real treasures to offer.

In addition to the straight hour lines, the curved zodiac lines (date or declination lines) are increasingly found, which enable a variety of displays, such as date, length of day and night, height and azimuth of the sun, Babylonian and Italic hours as well as astrological information (planetary hours, Houses). The sundial thus became a calendar work of art.

The construction of sundials experienced a heyday from 1500 to 1800 and one can rightly speak of the "three golden centuries" of gnomonic. A high point was the Baroque era. Large and extremely artistic artistic ones were created on the magnificent facades of castles, churches and monasteries Independence and beauty: the south of Germany and Austria are rich in sundials from this period.