Science History: the Babylonians and Egyptians

Sumerian god Enki, with characteristic symbols: bird, goat and water flows

The early Sumerians and Babylonians have contributed to later generations important units for the measurement of time and of angles. Babylonian in origin is the week of seven days, also the division of the day and of the night into twelve hours each. The Babylonians made quite extensive use of the sexagesimal scale in writing integral numbers and fractions; using the same scale, they divided the hour into 60 minutes and the minute into 60 seconds. The circle was subdivided into 360 degrees, the degree into 60 minutes of are, and the minute into 60 seconds. The most humble worker of the present day measures the time of work by the hour, as did the Babylonians of perhaps 5000 years ago. The most noted engineer and the most distinguished astronomer of the present time measure angles in degrees, minutes and seconds, much as did the astronomers at the Euphrates and Tigris eons ago. Early Babylonian astronomical records indicate a surprising precision. An achievement of the first magnitude was the discovery of that slow motion of the equinoctial points on the ecliptic called the precession of the equinoxes. This was done by the Babylonian astronomer Cidenas, who directed an astronomical school at Sippra, on the Euphrates, about 343 B.C.

Primitive sun-dials and water-clocks served for measuring time. For finding the angular altitude of the sun (at noon time), they used the gnomon which consisted essentially of a vertical rod of known length. The length and direction of its solar shadow afforded the necessary data. The beam-balance served for weighing medicine and precious articles. The medical recipes described in the Egyptian papyrus Ebers indicate the use of weights as small as 0.71 grams.