408 SKETCHES OF CREATION. 



CHAPTER XXXVIIL 



THE SUN COOLING OFF. 



WE are not driven to the necessity of summoning ex- 

 aggerated and imaginary agencies to the destruc- 

 tion of the earth. There are hostile powers reserved for 

 the final conflict that will not be content with directing 

 toward us merely " Quaker guns." 



The sun, we say, affords us thirty-nine fortieths of all the 

 warmth which we enjoy, and we feel quite unconcerned 

 about the alleged slow cooling of the earth. To the sun 

 we owe the numberless activities of the organic and inor- 

 ganic worlds, and we feel quite independent of the wan- 

 ing temperature of this dying ember which we call the 

 earth. 



The amount of heat dispensed by our solar orb is truly 

 something the contemplation of which overpowers the im- 

 agination. The rays which fall upon a common burning- 

 glass, converged to a focus, speedily ignite a piece of wood. 

 The heat which is received by a space often yards square 

 is sufficient, as Ericsson states, to drive a nine-horse power 

 engine. The amount of heat which falls upon half a Swe- 

 dish square mile is sufficient to actuate 64,800 engines, each 

 of 100 horse power. The total amount of heat received 

 annually by the earth would melt a layer of ice one hun- 

 dred feet thick. As the solar heat is radiated equally in 

 all directions, it is easily calculated that the total emission 

 of heat from the sun is 2300 millions of times the whole 

 amount which reaches our earth. 



Such an enormous expenditure of heat is sufficient to re- 



