CX11 NOTES, 



mathematician of the fouith century, calls regent ov ruler ot each day of the 

 week the planet whose name falls to the first hour of that day. 



This mode of explanation of the names of the days of the week has been 

 hitherto very generally received as the correct one ; but Letronne grounds 

 upon the long neglected zodiacal circle of Bianchini (which is preserved in 

 the Louvre, and to which I myself, in the year 1812, recalled the attention of 

 antiquarians, on account of the remarkable combination of a Greek with a 

 Kirgiso-Tartar zodiac) the belief that a third mode of explanation corresponds 

 best to the distribution of every three planets to a sign of the zodiac. 

 (Letroune, "Observ. crit. et archeol. sur 1'objet des representations zodiacales," 

 1824, p. 9799.) This distribution of the planets among the thirty -six 

 decans of Dodecatomery is quite that which is described by Julius Firmicus 

 Maternus (ii. 4) as " signorum decani eorumque domini." If we distinguish 

 in each sign the planet which is the first of the three, we obtain the succes- 

 sion of the planetary days in the week. (In Virgo Sun, Venus, Mercury ; 

 in Libra Moon, Saturn, Jupiter ; in Scorpio Mars, Sun, Venus ; in Sagit- 

 tarius Mercury may here serve as instances of the first four days of 



the week : Dies Solis, Luna, Martis, Mercurii.) As, according to Diodorus, 

 the Chaldeans originally counted only five planets (the starry ones), not 

 seven, so all those combinations in which periodical series are formed of 

 more than five planets, appear to have not an ancient Chaldean, but rather 

 a very late astrological origin. (Letronue, sur 1'origine du zodiaque grec, 

 1840, p. 29.) 



Some of my readers may perhaps be pleased to find here a farther very 

 short explanation of the agreement between the order of succession of the 

 planets as days of the week, and their order of succession and distribution 

 among the decans in the zodiac of Bianchini. If, taking the so-called seven 

 planets in the order of succession in which they were arranged according to 

 tlis custom of the ancients, and assigning to each a letter (Saturn a, Jupiter 

 6, Mars c, Sun d, Venus e, Mercury/, Moon g) we make of these seven 

 members the periodical series 



a d c d e f g > abed ; 



then we obtain, 1st, by missing two members in the distribution among the 

 decans, each one of which contains three planets (of which the first in each 

 zodiaeil sign gives its name to the day of the week), the new periodical 



series, a d g c f b e, adgc 



i, e. Dies Saturni, Solis, Lunse, Martis, &c. ; and 2ndly, the same new 



series a d g c 



bj the method given by Dio Cassius of the twenty-four planetary hours, according 



