SCIENCE IN THE ANCIENT WORLD 23 



tion of cereals and other annual plants makes a 

 calendar almost a necessity, and Chaldean art shows 

 that the use of the plough was well understood. 

 It is to Babylon that we owe the division of the 

 year into months, days, hours, minutes and seconds, 

 and the invention of the sundial to mark the 

 passing hours. The Babylonian year was one of 

 360 days ; the necessary adjustments being made 

 from time to time by the interposition of extra 

 months. 



The movement of the sun and planets among the 

 fixed stars was known, the journey of the sun across 

 the sky being mapped out into twelve divisions ac- 

 cording to the months. Each division was named 

 from some Babylonian god, and represented by the 

 symbol of that deity. Thus arose the association of 

 parts of the sky with the crab, the scorpion and other 

 beasts, which afterwards came to be connected with 

 the definite groups of stars which we still know by the 

 names of the signs of the zodiac. 



Astronomical observation appears in the Babylonian 

 records more than twenty centuries before the Christian 

 era. From these early dates the Chaldean priests 

 had recorded on their clay tablets the aspect of the 

 heavens night after night, the brilliancy of the atmo- 

 sphere and the skill of long practice helping their 

 natural keenness of vision. Gradually the period- 

 icity of astronomical events was revealed to them, 

 till the prediction of eclipses of the moon became 

 possible. 



On this basis of definite knowledge, a fantastic 

 scheme of astrology was built up, and, indeed, regarded 

 by the Chaldeans as the chief and most worthy object 



