NATURAL HISTORY OF CREATION. 31 



more would be required to cause the whole to become 

 vaporiform, which we may consider as equivalent to its 

 being restored to its original nebulous state. He can 

 calculate with equal certainty what would be the effect 

 of a considerable diminution of the earth's temperature — 

 what changes would take place in each of its component 

 s\ibstances, and how much the whole would shrink in 

 bulk. 



The earth and all its various substances have at 

 present a certain volume in consequence of the tempera- 

 ture which actually exists. When, then, we find that 

 its matter and that of the associate planets was at one 

 time diffused throughout the whole space now circum- 

 scribed by the orbit of Uranus, Ave cannot doubt, after 

 what we know of the power of heat, that the nebulous 

 form of matter was attended by the condition of a very 

 high temperature. The ixebulous matter of space, pre- 

 viously to the formation of stellar and planetary bodies, 

 must have been a universal Fire Mist, an idea which we 

 can scarcely comprehend, though the reasons for arriving 

 at it seem irresistible. The formation of systems out of 

 this matter implies a change of some kind with regard 

 to the condition of the heat. Had this power continued 

 to act with its full original repulsive energy, the process 

 of agglomeration 1)y attraction could not have gone on. 

 We do not know enough of the laws of heat to enable 

 us to surmise how the necessary change in this respect 

 was brought about, but v.e can trace some of the steps 

 and consequences of the process. Uranus would be 

 formed at the time when the heat of our system's matter 

 was at the greatest, Saturn at the next, and so on. Now 

 this tallies perfectly with tlic exceeding diffuseness 

 of the matter of those elder planets, Saturn being not 

 more dense or heavy than the substance cork. It 



