33(i AIDS TO THE STUDY OF THE MAYA CODICES. 



Adding tlie difference, 1, 0, 4, 0, to the final result of the preceding 

 addition we obtain the figures of the riglit hand column (fifth column, 

 Plate 71) of this series: 



6 10 



7 1 10 



To obtain the figures of the fourth column this difference must be 

 doubled, thus: 



7 1 10 



2 8 



9 2 



To obtain the black numbers of the next (third) column, the lower 

 cipher symbol of which is wanting, we add the former difference: 



9 2 



10 2 4 



This decrease in the difference is unusual and indicates some error. 

 This idea seems to be confirmed in the following way : In order to 

 obtain the numbers of the next (second) column it is necessary to 

 add three times the former difference, thus: 

 10 2 4 



13 2 1() Second column, Plate 71. 



If the increased difference, 3, 0, 8, 0, were retained after its appear- 

 ance the result would be as follows: 



7 1 10 Fifth column. Plate 71. 



Fourth column. Plate 71. 



Tliird column. Plate ' 



13 2 16 Second column, Plate 71. 



2 8 



l.'j 3 6 Fir.st column. Plate 71. 



Adding the difference, 3, 0, 8, 0, to the third column. Plate 71, thus: 



10 2 4 



2 S 



we obtain the red numerals inserted in the third column. It is prob- 

 able that the original or some subsequent scribe, observing an error at 



