THE MAI W CIVILIZATION 97 



human group has failed to notice. Longer periods than 

 those included within the memory of the oldest men 

 presenting an imperfect reflection of the memory of 

 men still older) are found only in those favored centers 

 where a serviceable system of counting has been de- 

 veloped. Mythology has a content of history but 

 hardly of chronology. Tradition, when organized by 

 the priesthood, may he reasonably dependable for per- 

 haps two hundred years. 



The year and the month are the basis of all primitive 

 time systems, the former depending on the recurring 

 seasons, the latter on recurring moons. Both of these 

 are expressed in days. Unfortunately, the day is not 

 contained evenly in either the month or the year, nor 

 do these larger time measures jshow any simple relation 

 to each other as regards length. The history of the 

 calendar is one of compromise and correction. 



The Mayan calendars were made possible by: first, 

 the knowledge of astronomical time periods ; second, the 

 possession of a suitable notation system; third, the dis- 

 covery of a permutation system of names and numbers. 



Elements of the Day Count. There is reason to 



believe that the Mayas had first a lunar-solar calendar of 

 twelve months of thirty days each, making a year of 

 360 days, and that they reduced the number of days in 

 the formal month to 20 and raised the number of months 

 in the year from 12 to 18. These changes permitted a 

 close adjustment of the units of time with their 

 vigesimal system of counting. With a truer knowledge 

 of the length of the year an extra five day month was 

 added to make a year of 365 days. Beyond this the 

 "leap year" error was calculated but not interpolated. 

 A- proof that the lunar month of thirty days preceded 

 the formal month of twenty days, it need only be 

 pointed out that the name for this period, uiinil. seems 



