28 plint's natueal histoet. [Book II. 



veils are rapidly carried about to the rights And althougli, 

 by tbe stars constantly revolving with immense velocity, 

 they are raised up, and hurried on to the part where they 

 set, yet they are all forced, by a motion of their own, in an 

 opposite direction^ ; and this is so ordered, lest the air, being 

 always moved in the same direction, by the constant whirling 

 of the lieavens, should accumulate into one mass, whereas 

 now it is divided and separated and beaten into small pieces, 

 by the opposite motion of the different stars. Saturn is a 

 star of a cold and rigid nature, while the orbit of Jupiter is 

 much lower, and is carried round in twelve years^ The next 

 star. Mars, which some persons call Hercules ^ is of a fiery 

 and burning nature, and from its nearness to the sun is carried 

 round in little less than two years ^ In consequence of 

 the excessive heat of this star and the rigidity of Saturn, 

 Jupiter, which is interposed between the two, is tempered 

 by both of them, and is thus rendered salutary. The path 

 of the Sun consists of 360 degrees; but, in order that the 

 shadow may return to the same point of the diaP, we are 

 obliged to add, in each year, five days and the fourth part of 

 a day. On this account an intercalary day is given to every 

 fifth year^, that the period of the seasons may agree with 

 that of the Sun. 



1 Our author supposes, that the spectator has his face directed towards 

 the south, as is the case with the modern observers. We are, however in- 

 formed by Hardouin, that tliis was not the uniform practice among the 

 ancients ; see the remarks of Alexandre in Lemaire, ii. 243,, and of Mar- 

 cus in Ajasson, ii. 269. 



2 The constant revolution refers to the apparent daUy motion ; the 

 opposite direction to their annual course through the zodiac. Ptolemy 

 gives an account of this double motion in his Magna Constructio, i. 7. 



3 For the exact period, according to Somerville and Herschel, see 

 note 3, p, 27. 



^ Aristotle informs us, that Mars was also called Hercules or Pyrosis ; 

 De Mundo, cap. ii. p. 602. See also Apuleius, De Mundo, § 710. Hy- 

 gmus is said by Hardouin to give the name of Hercules to the planet 

 Mars, but this appears to be an inaccuracy ; he describes the planet imder 

 its ordinary appellation ; hb. ii. p. 62 ; and ii. 78, 9. 



5 Cicero, speaking of the period of Mars, says, " Quatuor et vigiati 

 mensibus, sex, ut opinor, diebus minus ;" DeNat. Deor. For the exact 

 period, see note 3, p. 27. 



^ " Sed ut observatio umbrarum ejus redeat ad notas." Aocordmg to 

 the interpretation of Hardouin, " Ad easdem lineas in solari horologio." 

 Lemaire, ii. 243. 



7 This is an example of the mode of computation wliich we meet with 



