PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 713 



in wliich a temperature, many degrees higher than that required 

 here to gasify all matter, might be found, and where all would 

 again be restored into nebula ? 



Is not this in harmony with nature's laws as we see them dis- 

 played everywhere ? 



In an essay on heat. Grove says: " It is quite conceivable that 

 the whole solar system may pass through portions of space, having 

 different temperatures, as was suggested, I believe by Poisson ; 

 that, as we have a terrestrial summer and winter, so there may be 

 a solar or systematic summer and winter, in which case the heat 

 lost during the latter period might bo restored during the former." 



TJiis summer having resolved our sun and his attendant planets, 

 satallites, and comets into a nebula, let us trace the operation of 

 laws by which he would be restored to his present condition and 

 place. 



To be rational, an hypothesis in jpJujsical science can admit noth- 

 ing supernatural, in the common acceptation of that term. All 

 the phenomena pertaining to it must be in harmony with and obe- 

 dient to Nature's Laws — the laws of the Great First Cause — God. 



What would be the course of phenomena under laws well under- 

 stood ? 



Let us suppose our solar nebula to be some 10,000,000,000 of 

 miles in diameter, (this was probably not more than the truth, for 

 the orbit of Neptune is nearly 7,000,000,000 of miles)— balanced 

 in space, having no object within many millions of miles to dis- 

 tract it. It would be reasonable to infer that it hag carried with 

 it some of the impulses of rotation under which we see it movino- 

 now. But to illustrate the point intended to be made, we will 

 imagine it to be just at the point of maximum heat, where the 

 contracting force of gravitation and the expansive force of heat 

 are balanced. We may now suppose its mass in itself to be in a 

 state of quiescence; the heat which it radiates and that which it 

 receives are equal — it is neither expanding or contracting. But 

 such a state can continue only for an instant. The mass m5vin«- 

 in its orbit, is passing into a colder region, and radiates faster than 

 it receives. Gravitation is free to act — the mass is contractinir 

 and falling toward a common center. 



W^hat may we now expect to see? What do we see when fluid, 

 either elastic, or non-elastic is gathering toward a common center? 

 What do we see in the common funnel when we fill it with liquid 

 and let the liquid flow through it? Rotation : Not necessarily so, 



