WILLIAM SIEMENS, F.K.S. 425 



simple transfer of heat from the interior of a fluid sun to the 

 surface by means of convection currents, which latter hypothesis 

 appears at the present time to be also supported by Professor 

 Stokes and other leading physicists. 



But if either of these hypotheses could be proved, we should 

 only have the satisfaction of knowing that the solar waste of 

 energy by dissipation into space was not dependent entirely upon 

 loss of his sensible heat, but that his existence as a luminary 

 would be prolonged by calling into requisition a limited, though 

 may be large, store of energy in the form of separated matter. 

 The true solution of the problem will be furnished by a theory, 

 according to which radiant energy which is now supposed to be 

 dissipated into space and irrecoverably lost to our solar system, 

 could be arrested, wholly or partly, and brought back in another form 

 to the sun himself, there to continue the work of solar radiation. 



Some years ago it occurred to me that such a solution of the 

 solar problem might not lie beyond the bounds of possibility, and 

 although I cannot claim intimate acquaintance with the intricacies 

 of solar physics, I have watched its progress, and have engaged 

 also in some physical experiments bearing upon the question, all 

 of which have served to strengthen my confidence and ripened in 

 me the determination to submit my views, not without some mis- 

 giving, to the touchstone of scientific criticism. 



For the purposes of my theory, stellar space is supposed to be 

 filled with highly rarefied gaseous matter, including probably 

 hydrogen, oxygen, nitrogen, carbon, and their compounds, besides 

 solid materials in the form of dust. This being the case, each 

 planetary body would attract to itself an atmosphere depending 

 for its density upon its relative attractive importance, and it 

 would not seem unreasonable to suppose that the heavier and less 

 diffusible gases would form the staple of these atmospheres ; that, 

 in fact, they would consist mostly of nitrogen, oxygen, and 

 carbonic anhydride, whilst hydrogen and its compounds would 

 predominate in space. 



But the planetary system, as a whole, would exercise an at- 

 tractive influence upon the gaseous matter diffused through space, 

 and would therefore be enveloped in an atmosphere, holding an 

 intermediate position between the individual planetary atmospheres 

 and the extremely rarefied atmosphere of the stellar space. 



