io6 KANT'S UNIVERSAL NATURAL HISTORY 



have most moons. The earth, which is much smaller 

 than they are, has only acquired one ; and Mars, which 

 on account of its distance might have shared in this 

 advantage, goes empty away because its mass is so small. 1 

 It is a pleasure to see how this same attraction of the 

 planet, which procured the matter for the formation of 

 the moons and at the same time determined their move- 

 ment, extends to its own body and communicates to it, 

 by the same action through which it is formed, a rotation 

 around its axis in the general direction from west to 

 east. The particles of the primitive falling matter which, 

 as has been said, obtain a universal rotating movement 

 from west to east, mostly fall on the surface of the 

 planet and become mixed up with its mass, because they 

 have not the requisite degrees of velocity to maintain 

 themselves suspended freely in circular movements. 

 Entering now into the composition of the planet they 

 must, as parts of it, continue the same revolution in the 

 same direction which they had before they were united 

 with it. And it can be seen generally from what pre- 

 cedes, that the multitude of the particles which the want 

 of the required motion precipitates on the central body, 

 must very far exceed the number of the other particles 

 which may have acquired the requisite degrees of 

 velocity. And hence it is easy to understand why this 

 central body in its axial rotation will come far short of 

 having the velocity required to produce an equilibrium 

 between the gravitation on its surface and the centripetal 

 force ; and yet in planets of great mass and at a remote 

 distance, it will be more rapid than in near and small 

 planets. In fact Jupiter has the rapidest axial rotation 

 J But see note on p. 47. Tr. 



