428 THE SCIENTIFIC PAPERS OF 



solar rotation would be widely different, if it was supposed to take 

 place within a medium of unbounded extension. In this case 

 pressures would be balanced all round, and the sun would act 

 mechanically upon the floating matter surrounding it in the 

 manner of a fan, drawing it towards itself upon the polar surfaces, 

 and projecting it outward in a continuous disc-like stream. 



By this fan action, hydrogen, hydrocarbons, and oxygen, are 

 supposed to be drawn in enormous quantities toward the polar 

 surfaces of the sun ; during their gradual approach, they will pass 

 from their condition of extreme attenuation and extreme cold, to 

 that of compression, accompanied with rise of temperature, until 

 on approaching the photosphere, they burst into flame, giving rise 

 to a great development of heat, and a temperature commensurate 

 with their point of dissociation at the solar density. The result 

 of their combustion will be aqueous vapour and carbonic anhydride 

 or oxide, according to the sufficiency or the insufficiency of oxygen 

 present to complete the combustion, and these products of combus- 

 tion in yielding to the influence of centrifugal force will flow 

 toward the solar equator, and be thence projected into space. 



The next question for consideration is : What would become of 

 these products of combustion when thus rendered back into space ? 

 Apparently they would gradually change the condition of stellar 

 material, rendering it more and more neutral, but I venture to 

 suggest the possibility, nay, the probability, that solar radiation 

 would, under these circumstances, step in to bring back the com- 

 bined materials to a condition of separation by a process of dis- 

 sociation carried into effect at the expense of that solar energy 

 which is now supposed to be lost to our planetary system. 



According to the law of dissociation as developed by Bunsen 

 and Sainte-Claire Deville, the point of dissociation of different 

 compounds depends upon the temperature on the one hand, and 

 upon the pressure on the other. According to Sainte-Claire 

 Deville, the dissociation tension of aqueous vapour of atmospheric 

 pressure and at 2800 C. is 0-5, or only half of the vapour can 

 exist as such, its remaining half being found as a mechanical mix- 

 ture of hydrogen and oxygen, but with the pressure, the tem- 

 perature of dissociation rises and falls as the temperature of 

 saturated steam rises and falls with its pressure. It is therefore 

 conceivable that the temperature of the solar photosphere may be 



