84 CELESTIAL PHENOMENA. 



ment) are less than twice the size of Prance, Madagascar, 

 or Borneo. Remarkable as is the small density of all the 

 colossal planets which are farthest from the sun, yet neither 

 in this respect can we recognise any regular succession ( 38 ). 

 Uranus, even if we assume as correct the small mass of 

 a4 ao5J assigned by Lamont ( 39 ), appears to be denser than 

 Saturn ; and (although the inner group of planets differ but 

 little from each other in this particular) we find both Venus 

 and Mars less dense than the Earth, which is situated between 

 them. The time of rotation decreases, on the whole, with 

 increasing solar distance, but yet it is greater in Mars than 

 in the Earth, and in Saturn than in Jupiter. Among all 

 the planets, the elliptic paths of Juno, Pallas, and Mercury, 

 have the greatest eccentricity; Venus and the Earth, 

 which immediately follow each other, have the least : while 

 Mercury and Venus (which are likewise neighbours) present, 

 in this respect, the same contrast as do the four smaller 

 planets, whose paths are so closely interwoven. The eccen- 

 tricities of Juno and Pallas are nearly equa], but are each 

 three times as great as those of Ceres and Vesta. Nor is 

 there more regularity in the inclination of the orbits of the 

 planets towards the plane of projection of the ecliptic, or in 

 the position of their axes of rotation, relatively to their 

 orbits; on which latter position the relations of climate, 

 seasons of the year, and length of the days depend, more 

 than on the eccentricity. It is in the planets which 

 have the most elongated ellipses Juno, Pallas, and Mer- 

 cury that we find, though not in equal proportion, the 

 greatest inclination of the orbits to the ecliptic. The path 

 of Pallas is almost comet-like, its inclination twenty-six 

 times greater than that of Jupiter; whilst, in the little 



