Again, on a part of a doorway in El Cayo, on C D 3 we find 13 Cimi 19 Zotz; on H 3 G 4 is a number which seems to be 8.18.6. Counting forward we reach 9 Eb 20 Uo, if the month begins with 1, or 9 Eb 0 or 20 Zip, if the months begin with 0 or 20. Although the glyphs for Uo and Zip resemble each other, yet the date on I J 1 is clearly 9 Eb 0 or 20 Zip. It should be said, however, that the number on H 3 G 4 is somewhat effaced and very unusual, in showing 18 uinals, and that there is another date 5 ? 3 Yaxkin on E F 3.
On the other hand the inscription of the Temple of the Cross shows us on D 3 C 4, 4 Ahau 8 Cumhu, and on D 5 C 6, is 1.9.2., which is equal to 1 year 177 days. Counting forward this number of days from 4 Ahau 8 Cumhu we reach 13 Ik 20 Mol, if the month begins with 1, or 0 or 20 Chen, if the month begins with 0 or 20. On C D 9 we find 13 Ik ? Mol. However, on D 13 to C 15 we have the long number 1.18.3.12.0., which counted forward from 13 Ik 20 Mol brings us to 9 Ik 15 Zac, which is not found anywhere near by. But if we count forward this number from 13 Ik 0 or 20 Chen, we should reach 9 Ik 15 Ceh, which is found on E F 1. It would seem, therefore, that the glyph for Mol had been carved in error for that of Chen.
Other cases where 0 or 20 probably occur before the month sign are the following:
Copan, Altar U, 1 to 2 2 Caban 0 or 20 Pop. " " U, 51 to 52 3 Eb 0 or 20 Pop. Temple of the Cross, Q 2 P 3 11 Caban 0 or 20 Pop. " " " " F 12 E 13 9 Ik 0 or 20 Chen (J.T.G.) " " " " E F 9 9 Ik 0 or 20 Yax or Zac.
The month glyph of the last example looks like Zac. If it is Yax it proves Goodman's theory by calculation.
Thus we see that in three out of four cases in the Dresden Codex and in three cases out of four in the Inscriptions where the context is such as to throw light on the question, the evidence is in favor of concluding that the months began with a day 0 or 20 and not with a day 1. Moreover in the single case in the Codex which tends to prove the contrary, it is interesting to see that the month glyph, Xul, is somewhat different from the other Xul glyphs, while in the doubtful case in the inscriptions, if the month glyph had been Chen and not Mol, it would have agreed with the dates before and after it. In other words, the calculations both before and after the date in question would be quite accurate if the month were Chen and if, therefore, the beginning day were 0 or 20, while the glyph of Mol makes the calculation after that date inaccurate.