HEAT DEVELOPED IN THE SOLAR SYSTEM. 233 



thought, to make even a guess at the amount of heat to be 

 generated in this way. At present we can give definite 

 numerical values with certainty. 



Let us make this addition to our assumption ; that, at the 

 commencement, the density of the nebulous matter was a van- 

 ishing quantity, as compared with the present density of the 

 sun and planets ; we can then calculate how much work has 

 been performed by the condensation ; we can further calcu- 

 late how much of this work still exists in the form of mechani- 

 cal force, as attraction of the planets towards the sun, and as 

 vis viva of their motion, and find, by this, how much of the 

 force has been converted into heat. 



The result of this calculation is, that only about the 454th 

 part of the original mechanical force remains as such, and 

 that the remainder, converted into heat, would be sufficient to 

 raise a mass of water equal to the sun and planets taken to- 

 gether, not less than twenty-eight millions of degrees of the 

 centigrade scale. For the sake of comparison, I will mention 

 that the highest temperature which we can produce by the 

 oxyhydrogen blowpipe, which is sufficient to fuse and vapor- 

 ize even platina, and which but few bodies can endure, is 

 estimated at about two thousand centigrade degrees. Of the 

 action of a temperature of twenty-eight millions of such de- 

 grees we can form no notion. If the mass of our entire sys- 

 tem were pure coal, by the combustion of the whole of it only 

 the 3500th part of the above quantity would be generated. 

 This is also clear, that such a development of heat must have 

 presented the greatest obstacle to the speedy union of the 

 masses, that the larger part of the heat must have been 

 diffused by radiation into space, before the masses could form 

 bodies possessing the present density of the sun and planets, 

 and that these bodies must once have been in a state of fiery 

 fluidity. This notion is corroborated by the geological phe- 

 nomena of our planet ; and with regard to the other planetary 

 bodies, the flattened form of the sphere, which is the form of 



