Danna (Mesopotamia)

Danna (erroneously named double hour ; also Beru as a measure of length ) is the original Sumerian name of a measure of length that was later used by the Babylonians as a unit of time . For the first time, the measure of length is Danna around 2400 BC. Occupied.

background

Original use and further development of the term

The Danna was used by the Sumerians as a measure of length and corresponded to 6 SAR to 3600 cubits of 51.85 cm, corresponding to almost 11.2 km. The fact that the Danna - with a deviation of 7 ‰ - again in a ratio of 1: to 3600 times around the world is, is still unclear, but may be seen as an indication that the amount of a determination of the astronomical width has been derived .

The Danna was first used as a unit of time by the Babylonians. They replaced the Danna measure of length with the Beru, which corresponded to about 10.5 km. From now on, 1 Danna was the time in which 1 Beru could be covered and was defined in such a way that 1 day was divided into 12 Danna ( equivalent hours ), each lasting 60 minutes. 1 Babylonian Danna therefore corresponded to 2 hours according to today's time measurement.

According to Roman measurements, a beru was about seven miles to 7000 double steps and measured about 10.8 km. Because of this analogy, the Danna was also called the time mile. In the first millennium BC The time mile was extended as an astronomical unit of time for the revolutions of the sky .

The term “ double hour ” used in modern literature is misleading, as the hour measure of 60 minutes that is valid today is used as the standard for the designation. Ancient historians did not know the term double hour and therefore used, for example, the term stadia , which had a distance of about 148.5 m. Seventy Stadia was the equivalent of seven miles.

Change in value

In Hellenistic times , with the introduction of the temporal hours , the Danna was halved and the number of hours of the day increased from twelve to 24. The conversion was based on the ancient Egyptian precursors of the 24 seasonal - äqualen hours. A 24-division of the day could not be proven in writing on Babylonian tablets until the present day , which is why the Babylonians cannot be used as the originator of the 24-hour division of the day .

literature

Friedrich Karl Ginzel : Handbook of mathematical and technical chronology . Volume 1: Calendar of the Babylonians, Egyptians, Mohammedans, Persians, Indians, Southeast Asians, Chinese, Japanese and Central Americans . German book export and import, Leipzig 1958 (Reprint Leipzig 1906)
Otto Neugebauer : Astronomy and history - Selected essays . Springer, New York et al. 1983, ISBN 0-387-90844-7 .
Otto Neugebauer: A history of ancient mathematical astronomy . 3 parts. Springer, Berlin et al. 1975, ISBN 3-540-06995-X , ( Studies in the history of mathematics and physical sciences 1).

Individual evidence

↑ Cf. François Thureau-Dangin: Textes de l'époque d'Agadé <Fouilles d'Ernest de Sarzec en 1895> - Inventaire des tablettes de Tello (part 1) - , Leroux, Paris 1910, 11, 1175; Otto Neugebauer: Astronomy and history - Selected essays - , Springer, New York 1983, p. 8.
↑ Cf. Friedrich-Karl Ginzel: Handbuch der Mathematischen und Technische Chronologie, Vol. 1 - Time calculation of the Babylonians, Egyptians, Mohammedans, Persians, Indians, Southeast Asians, Chinese, Japanese and Central Americans - , German book exports and imports, Leipzig 1958 (Reprinted in Leipzig 1906), p. 123.

[1] Cf. François Thureau-Dangin: Textes de l'époque d'Agadé <Fouilles d'Ernest de Sarzec en 1895> - Inventaire des tablettes de Tello (part 1) - , Leroux, Paris 1910, 11, 1175; Otto Neugebauer: Astronomy and history - Selected essays - , Springer, New York 1983, p. 8.

[2] Cf. Friedrich-Karl Ginzel: Handbuch der Mathematischen und Technische Chronologie, Vol. 1 - Time calculation of the Babylonians, Egyptians, Mohammedans, Persians, Indians, Southeast Asians, Chinese, Japanese and Central Americans - , German book exports and imports, Leipzig 1958 (Reprinted in Leipzig 1906), p. 123.