ARITHMETIC AND GEOMETRY
Conspicuous advance took place in the exact sciences. The leading operations of arithmetic were known. A Babylonian tablet gives a table of squares and cubes correctly calculated from 1 to 60. The number 12 was the basis of all reckonings. The division of the circle into degrees, minutes, and seconds (360°, 60', 60") was an invention of the Babylonians which illustrates this duodecimal system A start was made in geometry. One of the oldest of Egyptian books contains a dozen geometrical problems. This knowledge was afterwards developed into a true science by the Greeks.
ASTRONOMY
In both Egypt and Babylonia the cloudless skies and still, warm nights early led to astronomical research. At a remote period, perhaps before 4000 B.C., the Egyptians framed a solar calendar, [19] consisting of twelve months, each thirty days in length, with five extra days at the end of the year. This calendar was taken over by the Romans, [20] who added the system of leap years. The Babylonians made noteworthy progress in some branches of astronomy. They were able to trace the course of the sun through the twelve constellations of the zodiac and to distinguish five of the planets from the fixed stars. The successful prediction of eclipses formed another Babylonian achievement. Such astronomical discoveries must have required much patient and accurate observation.
GEOGRAPHY
Geographical ideas for a long time were very crude. An ancient map, scratched on clay, indicates that about eight centuries before Christ the Babylonians had gained some knowledge, not only of their own land, but even of regions beyond the Mediterranean. The chief increase in man's knowledge of the world in ancient times was due to the Phoenicians. [21]
PRACTICAL SCIENCES
The skill of Oriental peoples as mechanics and engineers is proved by their success as builders. The great pyramids exactly face the points of the compass. The principle of the round arch was known in Babylonia at a remote period The transportation of colossal stone monuments exhibits a knowledge of the lever, pulley, and inclined plane. [22] Babylonian inventions were the sundial and the water clock, the one to register the passage of the hours by day, the other by night. The Egyptians and Babylonians also made some progress in the practice of medicine.
[Illustration: A BABYLONIAN MAP OF THE WORLD A tablet of dark brown clay, much injured, dating from the 8th or 7th century B.C. The two large concentric circles indicate the ocean or, as it is called in the cuneiform writing between the circles, the 'Briny Flood.' Beyond the ocean are seven successive projections of land, represented by triangles. Perhaps they refer to the countries existing beyond the Black Sea and the Red Sea. The two parallel lines within the inner circle represent the Euphrates. The little rings stand for the Babylonian cities in this region.]