70 IN STARRY REALMS. 



We must remember that the materials destined to 

 form the pair oi allied planets did not then form 

 two solid bodies as they do at present ; they were both, 

 in all probability, incandescent masses glowing with 

 fervour, and soft, if not actually molten, or incohe- 

 rent, or even gaseous. These aggregations were close 

 together, and one of them was whirling around the other 

 in a period of a few hours, the duration of that period 

 being equal to the time in which the larger mass revolved 

 on its axis. In fact, the two objects, even though distinct, 

 seem to have revolved the one around the other as if they 

 had been bound together by rigid bonds. The rapid rota- 

 tion with which they were animated suggests a cause for 

 this state of things. It is well known that a fly-wheel, 

 when driven at an unduly high speeed, is liable to break 

 asunder in consequence of its rapid motion. If a grind- 

 stone be urged around with excessive velocity the force 

 tending to rend the stone into fragments may overcome 

 its cohesion, and it will fly into pieces, often projected with 

 such violence that fearful accidents have been the conse- 

 quence. 



Viewing the earth as a rotating body, it must be sub- 

 ject to the law that there is a speed which cannot be ex- 

 ceeded with safety. With the present period of rotation 

 of once in every twenty-four hours the tendency to dis- 

 ruption is but small and consequently the earth retains its 

 integrity, though no doubt the protuberance at the equator 

 is the result of the accommodation of the shape of the globe 

 to the circumstances attending its revolution. But let us 

 suppose that the length of the day was greatly diminished, 

 or, what comes to the same *hing, that the speed with 



