When was the sundial first invented?

The story of the sundial

As early as 5000 BC, the Egyptians Chr. Sundials used as an instrument for measuring time. The Chinese have been using sundials for around 5000 years. The Aztecs, Mayas and Incas presumably used sundials and solar calendars in connection with cultic purposes, and in India around 1700 solar observatories were created on a massive scale. The sundial is the first time measuring instrument in all cultures.

The gnomon is an even older instrument than the sundial. This device used by the Babylonians, Chinese, Incas and Greeks to measure the height of the sun, a vertically standing, shadow-casting stick, is the forerunner of the sundial. The shadow of the gnomon point wanders along a different hyperbola line across the ground every day. When the sun is lower in winter, this line is further away from the gnomon than in summer. Initially in ancient times one could only read off the days of the solstices, the equinoxes and the equinoxes as well as the noon on each day using such line systems. Only later was it possible to read the hours of the day.

How the ancient division of time worked we can no longer emotionally grasp today. Both the day and the night were divided into twelve hours each. However, depending on the season and the geographical latitude, these had a different duration on each day. They are therefore called the hours of unequal length. According to today's calculation, the sun rises around 4 a.m. in June / July and around 8 a.m. in December. The day - and thus also the ancient hour - is up to twice as long in summer than in winter. In ancient times, water clocks were used to determine the time in cloudy weather and at night. Their running was checked by constant comparison with sundials. The first wheel clocks with weight drive and "escapement" did not appear until around 1300. This was a spindle that engaged in the climbing wheel. As a result, the sequence of movements was divided into even time segments. Due to their large dimensions, however, these clocks were only suitable for public buildings. [Dohrn - van Rossum, Gerhard. The story of the hour. 1992.]

Thus, the sundials have been further developed and numerous variants have appeared over the next centuries. Another recent invention is the globe sundial. Approaches to this can already be found in the Rococo.