130 MEXICO AND CENTRAL AMERICA 



These repeated dates would seem to recall events of 

 special importance to the city in question. 



The running co-ordination between the apparent 

 order of the artistic styles and inscribed dates permits us 

 to measure very accurately the rate of change in art 

 which was rapid, indeed, at certain times. The style 

 of carving, on the other hand, enables us to put 

 into definite 52 year periods many of the calendar 

 round dates — if these are to be regarded as contempor- 

 aneous. The result is that for the First Empire, as it 

 has been called, there is an exceedingly accurate chron- 

 ology. After the fall and abandonment of the great 

 southern cities dates are rare and we have to fall back 

 upon remnants of history preserved after the coming of 

 the Spaniards. 



Books of Chilam Balam. The Books of Chilam 

 Balam are digests of ancient chronicles preserved in the 

 Mayan language, but in Spanish script. They cover a 

 continuous record of 68 katuns (periods of 7200 days) 

 before the coming of the Spaniards to Yucatan in 1517. 

 The events are recorded as occurring in such and such a 

 katun, these katuns being designated by a day Ahau 

 associated with a number 1-13, falling in the peculiar 

 sequence 13, 11, 9, 7, 5, 3, 1, 12, 10, 8, 6, 4, 2, after which 

 there is a repeat. Now this is exactly the sequence of 

 the numbers combined with the day Ahau on the termi- 

 nal days of the katuns in the Long Count, and we as- 

 sume that these katuns are actual round numbers in 

 the Long Count of days running from the original 4 

 Ahau 8 Cumhu. But the period instead of being called 

 by its serial number in the notation of days is called by 

 its terminal day. The Mayas, at all times, laid stress 

 on the period-ending days. This Short Count may be 

 compared to our own use of '22 for 1922, which is 



