Chap. 13.] ACCOITNT OP THE WOELD. 43 



that of the zodiac, which is situated obliquely between them. 

 And all these things are made evident by the infallible results 

 which we obtain by the use of the compasses ^ Hence the 

 apsides of the planets have each of them different centres, and 

 consequently they have different orbits and motions, since it 

 necessarily loUows, that the interior apsides are the shortest. 



(16.) The apsides which are the highest from the centre 

 of the earth are, for Saturn, when he is in Scorpio, for Jupiter 

 in Virgo, for Mars in Leo, for the Sun in Gemini, for Venus 

 in Sagittarius, and for Mercury in Capricorn, each of them 

 in the middle of these signs ; while in the opposite signs, 

 they are the lowest and nearest to the centre of the earth'. 

 Hence it is that they appear to move more slowly when 

 they are carried along tne highest circuit ; not that their 

 actual motions are accelerated or retarded, these being fixed 

 and determinate for each of them ; but because it necessarily 

 follows, that liues drawn from the highest apsis must approach 

 nearer to each other at the centre, like the spokes of a wheel ; 

 and that the same motion seems to be at one time greater, 

 and at another time less, according to the distance from the 

 centre. 



Another cause of the altitudes of the planets is, that their 

 highest apsides, with relation to their own centres, are in 

 ditterent signs from those mentioned above^. Saturn is in 

 the 20th degree of Libra, Jupiter in the 15th of Cancer, 

 Mars in the 28th of Capricorn, the Sun in the 19th of Aries, 

 Venus in the 27th of Pisces, Mercury in the 15th of Virgo, 

 and the Moon in the 3rd of Taurus. 



The third cause of the altitude depends on the form of the 

 heavens, not on that of the orbits ; the stars appearing to 

 the eye to mount up and to descend through the depth of 

 the au*^. With this cause is connected that which depends 



' "ratione circini semper indubitata." 



* In consequence of the precession of the equinoxes these points are 

 continually advancing from W. to E., and are now about 30 degrees from 

 the situation they were in when the observations were first made by 

 the modem astronomers. 



* Our author here probably refers to the motions of the planets through 

 their epicycles or secondary circles, the centres of which were supposed 

 to be ia the peripheries of the primary circles. See Alexandre in Le- 

 maire, ii. 270. 



* It is to this visible appearance of convexity in the heavens that Ovid 



