THE ORIGIN OF SOLAR HEAT 



one whole, one macrocosm, revealing to our sense of 

 sight on the one hand, the intimate structure of all 

 organic bodies by means of the microscope, though 

 not the atoms or even the molecules of ultimate mat- 

 ter ; while, on the other hand, it teaches us that there 

 are innumerable worlds governed apparently by the 

 same physical laws as our own world, but almost in- 

 finitely distant. As Proctor has said of the stars : 

 " Beyond the limits of the highest power of the tele- 

 scope lie thousands of millions more." 



The vibrations of the material atoms of the sun 

 transmit to us through the vibrations of the ether 

 the energy of light, of heat, and of elecricity ; but 

 what causes the vibrations of the atoms composing 

 the sun's matter? The photosphere is evidently 

 intensely hot; but whence arises the heat? Com- 

 bustion, or the results of chemical action, has been 

 shown by calculation to be utterly inadequate to pro- 

 duce and maintain its emission of heat. " If the 

 whole mass of the sun was composed of coal, it would 

 all be consumed in 6000 years." (Barker.) 



The conversion of the motion of aerolites into 

 heat by their fall into and impact upon the sun prob- 

 ably contributes a small but an insignificant and in- 

 adequate portion. The generally accepted theory is, 

 that the solar heat is due to the condensation of the 

 originally diffused nebulous matter of the sun's 



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