THE MAYAN CIVILIZATION 111 
is reason to believe that a marginal subtraction amount- 
ing to two days in 25 revolutions was made. 
On Stela K at Quirigua (a cast of this monument is 
exhibited in the American Museum) we find what ap- 
pears to be an effort to calculate the errors of the differ- 
ent calendars. The introducing glyph contains the sym- 
bol of Venus and it is not unlikely that the calculations 
deal in part with the movements of this planet. The 
initial series records the end of an even 5 tun period 
(9-18-15-0-0) in the notation system but the number 
(1,431,000 days) equals 3920 years of 365 days each plus 
200 days. On the basis of ‘‘five to eight’’ the 3920 solar 
calendar years equal 2950 revolutions of Venus and allow- 
ing an error of .08 of a day per revolution the total error 
amounts to 196 days. This very nearly equals the 200 
days counted in advance of the 3920 solar calendar 
years. The Mayan scholars seem to have observed the 
fact that counting from the original 4 Ahau 8 Cumhu up 
to their own times, the actual position of Venus practi- 
cally coincided with the end of a 5 tun period when it 
should have coincided with the end of 3920 solar calendar 
years. ‘This supposition is made more credible by evi- 
dence that the error in the solar calendar from the same 
beginning day was also calculated here. From the 
Initial Series date, which leads to 3 Ahau 3 Yax, 10 uinals 
and 10 kins (210 days) are subtracted and the day 1 Oc 
18 Kayab is reached. Then follows the Supplementary 
Series which doubtless refers to the lunar count and im- 
mediately after this comes the unusual number 0 uinals 
0 kins—that is, nothing. Next the day 3 Ahau3 Yax is 
repeated, thus:— 
9-18-15-— 0O- 0 3 Ahau 3 Yax 
10-10 backward 
9—-18-14— 7-10 1 Oc 18 Kayab 
0O- 0 forward 
9-18-15- 0- 0 3 Ahau 3 Yax 
