THEIR ARRANGEMENTS AND FORMATION. 11 



motion, and knowing in what various ways a motive power 

 may be applied, see, for a familiar example, the wheels of a 

 clock revolving under the influence of a weight, all difficulty 

 in supposing an actual origin of a natural kind for the motions 

 of the heavenly bodies vanishes, however obscure our notions 

 may remain as to the process concerned in the case. Thus 

 everything leads us to the belief that there was a previous 

 form of matter, the alteration of which into the present was 

 brought about in the manner of, though certainly not by any 

 self-dependent efficacy in, Natural Law. 



At this point we might rest, for in the general conclusion 

 that the orbs were formed and arranged in such a manner, 

 enough has been gained for the present object. It is worth 

 while, however, to touch slightly on the ideas which have 

 passed through certain great minds with respect to the births 

 of these bodies. 



The first idea of what has been called the nebular cos- 

 mogony arose with Sir William Herschel, in consequence of 

 the observations which he made regarding a class of heavenly 

 bodies, to which the appellation of nebula had been applied, 

 in reference to their cloud-like appearance. Some of these 

 bodies were ascertained, by a high telescopic power, to be 

 only astral systems like our own, placed at such a vast dis- 

 tance, that the individuality of the stars composing them was 

 lost to ordinary perceptions. Others resisted the highest 

 telescopic power which the astronomer applied, and, from 

 various considerations, he came to regard them as masses of 

 diffused luminous matter. In these he further discovered a 

 variety of appearances, marking what seemed a gradation of 

 characters, as if they had been in various degrees of conden- 

 sation ; and hence he was led to surmise that they were solar 

 systems in the process of being formed out of a previous con- 

 dition of matter. Laplace now stepped forward to show that, 

 if such a luminous matter existed, and if nuclei were esta- 

 blished in it, these might become centres of aggregation for 

 the neighbouring diffused matter ; on such centres a rotatory 

 motion would be established, wherever, as was the most likely 

 case, there was any obliquity in the lines of direction in 



