86 THE OCEAN. [Booe: III. 



variance with it, of what avail is it to oppose it with 

 ideas which, though asserted to be laws of motion, 

 are merely theoretical, for they are not corroborated 

 by phenomena observed in nature. The more clearly 

 those so-called laws are shown to be at variance 

 with the theory substantiated by natural phenomena 

 throughout the visible universe, the more certain and 

 complete must be their destruction. 



According; to the above-mentioned laws the 

 moon's orbital motion is maintained by its inherent 

 tendency to keep itself in motion — that motion having 

 been communicated to it at some unknown period, 

 by some unknown cause : and then the force which 

 resists the earth's gravitation is said to be the ten- 

 dency of that motion to carry it onwards at a tangent 

 from its orbit, like a stone from a sling. Whereas, 

 according to the arguments in the foregoing Chapters 

 of this Book, the earth's gravitation is the motive 

 force which draws the moon onwards in its orbit, and 

 the centripetal and centrifugal forces, which by their 

 opposing action keep it at its mean distance from the 

 earth, are — the former terrestrial and the latter astral 

 gravitation. These centripetal and centrifugal forces 

 are of a very different nature from those in the case 

 of a stone swung round in a sling. Let us consider 

 what the diiference is. 



As regards the centripetal force : the string hold- 

 mg the stone in its course has been compared to the 

 earth's sjravitation holding the moon in its course. 



