THOMAS] MAYA MKTHOD OF CALCULATION 289 



fi'Din the first to the 2Sth column; but here a change takes place; the 

 amount at this point, being 5-l-i », or 1,820 days, is doubled to form the 

 20th column, and is ;igain added to form the 30th. Here again occurs 

 an increase in the cotmter, in this case a large one, viz, to 1-5-5-0, or 

 9,100 days; but at the next step the added number to form the 3:!nd 

 column is only 1-0— t-O, or 7,280 days, just one-half of the 31st col- 

 umn/ This counter is used to the end of the series; however, the S in 

 the 3tith column is an evident mistake; it should be 7. 



The number 65 is a very common cotmter in this and other codices; 

 in this case 13 is the basal factor. In the other counters 260 is the 

 permanent factor. The first counter, which is just one-fourth of the 

 second, always reaches a day with the same number, though not the 

 same day — but repeating by .series of four. However, aside from these 

 questions, we have the fact of the increase of the counter in the proc- 

 ess, to show which was the object of calling attention to the series. 



Returning now to the series on plate xxiv (our plate Lxxii), to 

 which reference lias been made, I call attention to the ttnusual changes 

 in the counter or added number. The series in the fourth tier from 

 the l>ottom, given in the way adopted above, is as follows: 



follow; 



9,100 33.280 08,900 185.120 



It will be found by trial that the greatest common divisor of these 

 totals is 260, and that it is contained in the first total 35 times; in the 

 second, 126; in the third, 265, and the fourth, 712 times. Although 

 each step must have required long and tedious addition.s — no two 

 having a common added number or multiple thereof — and the reason 

 for thus varying the added ntimber is not apparent, yet it is evident 

 that the aboriginal scribe chose 260 as the factor to be used, and also 

 that the desired result could be I'cached by successive additions. In 

 fact, the series and the others we have noticed seem to be mere records 

 of the steps in the process of determining the lapse of time between 

 two widely separated dates. 



These examples are sufficient to show that all the series in the 

 codices and inscriptions could have been formed by the aboriginal 



22 ETH— 04 19 



