UTILIZING THE SUN'S ENERGY." 



By Robert H. Thurston, EL. P.. Dr. Eng., 



Direetor of Sibley College, Cornell University. 



Men of science, familiar with the resources of our globe in the 

 domain of power production and utilization, and especially all who 

 have considered the origin, extent, and rate of extinction of the quan- 

 tities of energA T available for the purposes of civilized humanity, have, 

 for many years, concerned themselves seriously with the question, 

 "When and how shall we reach and pass the critical period at which 

 the stores of now available latent energy of fossil fuel shall have 

 become exhausted ? " 



While this problem is not immediately pressing, it can not be long, 

 time being gauged by the periods of the historian — it is still more 

 limited in the view of the geologist — before our stock of coal will be 

 so far depleted as to make serious trouble in our whole social system. 

 Professor Leslie, when State geologist of Pennsylvania, and the late 

 Mr. Eckley B. Cox, estimated the probable life of the coal supplies of 

 that State, at the present rate of consumption and acceleration, to be 

 something like a century, and the close of the twentieth century will 

 be very likely to see an end of such manufactures in that State as 

 depend upon cheap fuel and proximity to the coal deposits. In Great 

 Britain the case is probably vastly more serious than in the United 

 States, for there the coal beds are far more restricted in area, and in 

 many localities are already extensively depleted, with prices rising as 

 a consequence. The same is to be said, in perhaps somewhat less 

 degree, of the fuels of the continent of Europe — and France, and 

 particularly Germany, may ere long feel the effect of a stringency in 

 the fuel market. 



Enormous deposits of coal remain untouched in other sections of 

 the globe, and China can probably supply the world for many years; 

 but a time must come, and that within a few generations at most, when 

 sonic other energy than that of combustion of fuel must be relied 

 upon to do a fair share of the work of the civilized world, and this 

 will probably by that time mean the whole of the world. 



Water power, which is the next most important source of energy in 



"Reprinted, by permission, from Cassier's Magazine, New York, August, 1901. 



263 



