Mr. J. Eric Thompson in his The Solar Year of the Mayas at Quirigua, Guatemala (1932) and the late Dr. J. E. Teeple in his Maya Astronomy (1930) have very fully developed the theory of determinants in the Maya inscriptions. It is sufficient to recall here that according to the theory a determinant date is one which shows what was the number of days required to correct the shifting Maya year at the date of the inscription in which the date occurs. Thompson has shown that two different bases of correction were used. One was 4 Ahau 8 Cumhu, the starting point of the Long Count, 13 August 3113 B.C., the other was 7-6-0-0-0 11 Ahau 8 Cumhu, 10 September 235 B.C., which is thought by both these writers to have been a probable date for the actual inauguration of the Long Count.