PORTION OF THE COSMOS. THE PLANETS. 309 



condense towards different points of predominating attrac- 

 tion, it must have passed through an almost infinite succes- 

 sion of states in order to form some simple and other 

 intersecting orbits ; and planets varying so greatly in mag- 

 nitude, ellipticity, and density, some accompanied by, and 

 others destitute of moons, and even in one case a series of 

 satellites united in a solid ring. The present form of 

 things, and the exact numerical determination of their mu- 

 tual relations, have not as yet conducted us to a knowledge 

 of the states previously passed through, nor to a clear insight 

 into the conditions under which they have arisen. Yet 

 these conditions are not therefore to be termed accidental, 

 as man is prone to call all which he cannot yet explain gene- 

 tically. 



3. Absolute and apparent magnitudes, and external 

 figure. The diameter of the largest of all the planets, Jupi- 

 ter, is 30 times as great as that of Mercury (the smallest of all 

 the planets having securely measurable disks), and almost 1 1 

 times as great as that of the Earth : as compared with the Sun, 

 its diameter is nearly as 1 : 10 a ratio nearly similar, in- 

 versely, to that between it and the Earth. It has been stated, 

 perhaps erroneously, that the difference of size between 

 meteoric stones, which many are inclined to regard as small 

 planetary bodies and Yesta, which, according to a measure- 

 ment of Madler's, has a diameter of 264* geographical 

 miles (320f geographical miles less than the diameter of 

 Pallas, according to Lamont) is not more considerable 

 than the difference of size between Vesta and the Sun. 

 According to these proportions, there should be meteoric 



* 66 German geographical miles, 

 f 80 German geographical miles. 



