1893.] -t)d [Brinton. 



Dr. Forstemann is of opinion that the 13-clay period arose 

 from an effort to divide tlie vague solar year, counted as 364 

 days, into equal parts, thus making 13 X 28 = 364. * 



Another theory, especially urged by the able Mexican anti- 

 quary, Paso y Troncoso, is that the period of 260 days and the 

 number 13 owe their selection to astronomical observations of 

 the planet Yenus. He points out that 5 synodical revolutions 

 of Yenus equal 8 solar years; and that after 13 periods of 8 

 years, forming a cycle of 104 years, on the initial day of the 

 next cycle the relative positions of Yenxis and the sun would be 

 the same as at the commencement of the first C3'cle.f 



An entirely different explanation of the selection of the num- 

 ber 13 is that which traces it to certain widespread terrestrial 

 and mythical connections. 



Whether these mythical relations were adopted from the Cal- 

 endar or whether they gave rise to it, they certainly were pres- 

 ent in marked prominence among these nations. According to 

 Aztec mythology the heavens were 13 in number, and 13 divini- 

 ties ruled over the under world. The Quiches and Cakchiquels 

 believed that 13 was the number of the first ancestors of the 

 human race, so they divided their tribes into 13 divisions or 

 gentes. And other instances could be quoted of the sacredness 

 of this number. 



Whence did it derive this mythical character ? 



A possible explanation has been suggested to me by M)-. 

 Frank H. Gushing, based on his observations among the Zunis. 



In the ceremonies of this nation the complete terrestrial 

 sphere is symbolized by pointing or blowing the smoke to the 

 four cardinal points, to the zenith and the nadir, the indi- 

 vidual himself making the seventh number. When the celestial 

 is also to be symbolized only the six directions are added to 

 this seven, because the individual remains the same. So that 

 the number typifying the whole universe, terrestrial and celes- 

 tial, becomes 13. 



When, on the other hand, in their ceremonies the rite requires 

 the officiant to typify the. supra- and the infra-terrestrial spheres, 



* " Die Zahl 364 scheint den Anlass gegeben zu haben das Jahr in Perioden von je 13 

 Tagen zu teilen. Denn die Natur scheint die Zahl 13 nicht geliefert zu haben." Globus, 

 Bd. 03, No. 2. 1892. 



t See his lengthy and careful study in the Analcs del Museo Nacional de Mexico, Tomo ii, 

 pp. 350, seq. 



