10 



THE J&ODIES OF SPAClfc. 



than half; Jupiter, l 2 l 4 ; IVflfrs, 3* ; Earth, 4} 5 Vemsa-, 

 53 1 ; Mercury, 9^, or about the weight of lead. Th^n 

 the distances are curiously relative. It has been found 

 that if we place the following line of numbers — 



3 6 12 24 48 _ 96 192, 

 and add 4 to each we shall have a series denoting the 

 respective distances of the planets from the sun. It will 

 stand thus — 



4 7 10 16 28 52 100 196 

 Merc. Venus. Eartl*. Mars. Jupiter. Saturn. Uranus 



It will be observed that the first row of figures goes on 

 from the second on the left hand in a succession of dupli- 

 cations, or multiplications by 2. Surely there is here a 

 most surprising proof of the unity which I am claiming 

 for the solar system. It was remarked when this curious 

 relation was first detected, that there was the want of a 

 planet corresponding to 28 ; the difficulty was afterwards 

 considered as in a great measure overcome, by the dis- 

 covery of four small planets revolving at nearly one mean 

 distance from the sun, between Mars and Jupiter. The 

 distances bear an equally interesting mathematical relation 

 to the times of the revolutions round the sun. It has been 

 found that, with respect to any two planets, the squares o* 

 the times of revolutions are to each other in the same pro- 

 portion as the cubes of their mean distances — a most surpri- 

 sing result, for the discovery of which the world was in- 

 debted to the illustrious Kepler. Sir John Herschel truly 

 observes " When we contemplate the constituents of the 

 planetary system from the point of view which this rela- 

 tion affords us, it is no longer mere analogy which strikes 

 us, no longer a general resemblance among them, as indi- 

 viduals independent of each other, and circulating about 

 the sun, each according to his own peculiar nature, and 

 connected with it by its own peculiar tie. The resem- 

 blance is now perceived to be a true family likeness ; they 

 are bound up in one chain,interwoven in one web of mutual 

 relation and harmonious agreement, subjected to one per- 

 vading influence, which extends from the centre to the far- 

 thest limits of that great system, of which all of them, the 

 Earth included, must henceforth be regarded as members.* 

 Connecting what has been observed of the series of 

 nebulous stars with this wonderful relationship seen to 



* Astronomy, Lardner's Cyclopaedia. 



