364 BTTREATT OF AMERICAN ETHNOT.OGY [BrLL. 28 



roboration through Forstemann's researches respecting the Maya 

 manuscript of the Royal Public Library at Dresden. As Forste- 

 mann has proved in his elucidation of this manuscript published 

 in the year 1886 the apparent revolution of Venus, which is made 

 in 584 days (exactly, 583 days and 22 hours), is represented five 

 times in succession on the remarkable pages 46 to 50, and each time 

 divided into periods of 90, 250, 8, and 230 days. These 90, 250, 8, and 

 236 days are sioecified on each of the pages by days named accord- 

 ing to the tonalamatl system having these intervals between them, 

 by month dates, and lastly by rows of numerals. Forstemann's 

 Iiypothesis is that thereby the 90 days are reckoned as the period of the 

 planet's invisibility during its superior conjunction, the 250 days as 

 the period of its appearance in eastern elongation (as the evening 

 star), the 8 days as the period of its invisibility during inferior 

 conjunction, and the 236 days as the period of its visibility in west- 

 ern elongation (as the morning star). The difference between the 

 period of invisibility during inferior and superior conjunctions is ex- 

 plained by the fact that in superior conjunction Venus passes behind 

 the sun ; hence, owing to the parallel movement of the two heavenly 

 bodies, a far longer period is required than in inferior conjunction. 

 Under the assumption that the planet is invisible during the entire 

 period in which it is distant less than 10 degrees from the sun, 

 Forstemann computed the duration of its invisibility in inferior 

 conjunction at about 12 days, in superior conjunction at from 77 

 to 80 days. He goes on to say that at the time of superior conjunc- 

 tion Venus is seven times farther away from the earth than at the 

 time of inferior conjunction, and the remoteness from the time of 

 its greatest brillianc}' is also much greater than at the latter period; 

 hence it would be necessary to allow more than 10 degrees distance 

 from the sun for it to be again clearly visible. Thus the assump- 

 tion of 90 days for its invisibilitj^ during superior conjunction would 

 be warranted. The assumption of 8 days for its invisibilty during 

 inferior conjunction, which is shorter by 4 days than the computed 

 period of invisibility, Forstemann believes can be defended by ref- 

 erence to the clear sky of Yucatan and the sudden coming on of night. 

 The difference in the periods of visibility, which are generally 

 accepted as 243 days each, but need not, of course, be exactly equal, 

 Forstemann says he is unable to explain more definitely. 



Let me say at the outset that I have not yet found these de- 

 tailed accounts of the periods of visibility and invisibility specified 

 in Mexican picture writings, but the passage from the Anales de 

 Quauhtitlan, which I translated above, contains the definite statement 

 of a period of 8 days from the time of the planet's disappearance as 

 the evening star until it appears as the morning star. At the time 

 when the ulanet (as the evening star) was visible in the sky Quetzal- 



