THE UTILIZATION OF SOLAR ENERGY.^ 



By A. S. E. ACKERMANN, 



B. 8c. (Engineering), yi. 0. d. J., M. Cons. E., A. M. Inst. C. E. 



[With 6 plates. 1 



As it has been justly said that the phiy of Hamlet without the 

 Prince of Denmark is somewhat dull, perhaps it will be well to devote 

 a few^ Avords to the principal actor in all schemes for the utilization 

 of solar energy, viz, the sun. He is no longer regarded as a monster 

 fire, burning in the manner of fires in our grates. Great as is his 

 mass, it Avould be comparatively rapidly consumed if such combustion 

 were taking place. Another reason Avhy this old idea was given up 

 is that the temperature of the sun has been determined by several 

 experimenters, and all agree that it is about 6,000° C. This is far too 

 high to permit of the formation of most chemical compounds, and 

 for the production of heat by combustion it is necessary for such com- 

 pounds to be formed. Briefly, such a temperature decomposes nearly 

 all compounds into their elements and prevents their reuniting and 

 the consequent production of heat. 



Scientists are b}^ no means certain how the sun's heat is produced, 

 but one theory is that it is due to radioactivity; and another, due 

 to Helmholtz, that the energy to keep up the radiation could be sup- 

 plied by a relatively microscopic contraction of the sun's volume, 

 though even this theory is not a complete success, as it implies that the 

 age of the sun is 17,000,000 years. Great as is this lapse of time, 

 geology indicates that our earth is considerably older; but as the 

 earth can not very well be older than the sun, we must conclude that 

 the sun is older than 17,000,000 years. 



As to Avhat the structure of the sun is there is also doubt; but the 

 inner portion is spoken of as the nucleus and the outer portion as the 

 atmosphere, and as the outer layers of the atmosphere get relatively 

 cooled they sink to a lower level, and their place is taken by hotter 

 layers. Thus there is a continual circulation of the sun's atmosphere. 



The specific gravity of the sun is only about a quarter of that of 

 the earth, whose specific gravity is 5.53. A cubic foot of Avater Aveighs 



1 Reprinted, by permission, from the Journal of the Roj'al Society of Arts. London, 

 April 30, 1915. 



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