bēru

BAY-roo

babylonian: bēru (DANNA)

Definition

The bēru (Akkadian; Sumerian DANNA) is a Mesopotamian unit that measures both arc in the sky and time. It equals 30 UŠ — roughly 30° of arc, or about two hours of time, in the later schematic astronomy. A full day's circle is twelve bēru (12 × 30 = 360 UŠ), and the unit divides downward into smaller units, the UŠ and the NINDA, in steps of sixty. The same word also served as a unit of distance on the ground (about 10.8 km on the standard reckoning).

In Tradition

Hunger and Pingree describe the bēru as one of the standard conventional units of Babylonian schematic astronomy: "30 UŠ = 1 bēru" (Hunger-Pingree 1999, p. 50). The unit runs through the daylight-and-nighttime tables of EAE Tablet 14, the shadow table of MUL.APIN, the Hilprecht-Text problem on the Moon's distance from the stars, and the water-clock weight schemes that lie beneath the Three-Paths picture of the sky.

In Practice

When you read a Babylonian astronomical procedure text or a modern edition of one, read bēru as either time (about 2 hours) or arc (about 30°), depending on context. In EAE Tablet 14 Table A, the night at the equinox is 6 bēru = 3,0 UŠ. In the MUL.APIN shadow scheme, the longest day at the latitude of Babylon is 7;12 bēru and the shortest is 4;48 bēru — a 3:2 ratio. In the Ivory Prism BM 123340 and the Seasonal Hours report K 2077+, daylight runs from 8 bēru at the summer solstice down to 4 bēru at the winter solstice, an idealised 2:1 scheme. Modern scholars reconstruct the Babylonian schematic day as twelve equal bēru, a twelve-part time scheme that parallels the later Greek twelve-hour daylight division but is built on counting by sixties.

Historical Origin

The bēru is attested across the Babylonian astronomical corpus from the Old Babylonian period — in the BM 17175+17284 daylight-nighttime scheme — through to the Late Babylonian ACT ephemerides. It is used in EAE Tablet 14 (assembled in the late 2nd millennium BCE), MUL.APIN (composed around 1000 BCE), and the Neo-Assyrian Reports and Letters. Modern critical treatments: Hunger-Pingree, *Astral Sciences in Mesopotamia* (1999); Hunger-Steele, *The Babylonian Astronomical Compendium MUL.APIN* (2019); Neugebauer, *A History of Ancient Mathematical Astronomy* (1975).

Further Reading

  • Hermann Hunger & David Pingree, Astral Sciences in Mesopotamia
  • Hermann Hunger & John Steele, The Babylonian Astronomical Compendium MUL.APIN
  • Otto Neugebauer, A History of Ancient Mathematical Astronomy