466 THE INSCRIPTIONS AT COPAN. 
of Christ, and this solely because of the extraordinarily exact character of the 
native Maya chronological system, which within itself is absolutely accurate. 
Having stated the problem, let us next examine the evidence upon which the 
correlation here suggested is based. During the Old Empire, Maya dates were 
recorded in terms of their corresponding Initial Series numbers; but, as we have 
already seen, even before the close of the Old Empire this method had begun to 
give way to Period Ending dating, which, however, was only a more abbreviated 
form of the same system. In Initial Series dating the total number of elapsed 
days from the starting-point to the day recorded is given, while in Period Ending 
dating only the positions of the periods, whose ending-dates are recorded in the 
periods next higher, are given. These two methods, however, are but different 
expressions of the same system, as noted above; and as the following example will 
show, they are interchangeable. 
- Thus, the Initial Series 10.2.0.0.0 3 Ahau 3 Chen may be expressed by the 
following Period-Ending date: 3 Ahau 3 Chen, End of Katun 2. Or, reversing this 
process, 3 Ahau 3 Chen, End of Katun 2 may be expressed by its corresponding 
Initial Series 10.2.0.0.0 3 Ahau 3 Chen. 
It will be noted in this reverse process that it is necessary to assume that the 
number of the current cycle was 10, but in the Old Empire the cycle-coefficient was 
always either 8, 9, or 10, and, as between these three, there is never any doubt on 
stylistic grounds as to which one was intended in a Period Ending date. Moreover, 
the record of the date upon which the specified katun ended renders it impossible for 
such a Period Ending to recur, fulfilling all the given conditions, until after a lapse 
of 18,980 katuns or about 374,153 years; so that for all practical purposes, as used 
in the Old Empire, Period Ending dating is as accurate as, and indeed is interchange- 
able with, Initial Series dating. 
Coming down to the New Empire, however, a very much less exact type of 
Period Ending is found, although even in these cases the Initial Series intended 
can usually be worked out. 
As used in the New Empire, in the few inscriptions that have come down to us 
(with but one exception),! only tun-ending dates appear to have been recorded. 
These, moreover, frequently lack the month-parts of their corresponding terminal 
dates, and consist only of the record of a specified tun, together with the day on 
which it ended. When the corresponding month-parts are not omitted, such tun- 
ending dates are accurate within a period of 18,980 tuns or about 18,707 years, but 
when they are omitted, as is usually the case, the resulting dates are only accurate 
within a period of 260 tuns or about 256 years.” 
A natural development out of the latter for use in the manuscripts, where long 
historical summaries had to be kept, but still only a further abbreviation of the 
original system, was the u kahlay katunob or sequence of the katuns, in which a 
katun was named after the day on which it ended, as 7 Ahau, 5 Ahau, 3 Ahau, for 
example, and no record was made of its corresponding month-part, or more im- 
portant still, of its position in the period next higher, that is the cycle. An example 
of this kind of count has already been given in Chapter I (page 43), where the 
u kahlay katunob will be seen to have consisted of nothing more than a series of 
the ending-days of the succeeding katuns accompanied by the record of the more 
important events, if any, which occurred in each. 
Finally, and this is most important of all in the present connection, the u kahlay 
katunob are more or less accurately correlated with Christian chronology by means 
of several events in them, the dates of which are given in terms of both chronologies. 
1The inscription on the capstone in the outer chamber of the East Range of the Monjas Quadrangle at Uxmal. 
(See figure 74.) 
*See Morley, 1918a, pp. 270-275. 
