THE CAUSE OF THE EARTH'S HEAT 



PROF. ERNEST RUTHERFORD 

 contributes to Harper 's Magazine 

 for February'an intensely inter- 

 esting article on the cause of the earth's 

 heat, which he is inclined to believe is 

 radium. From his article we may draw 

 much comfort, for whereas Eord Kelvin 

 and later scientists have been arguing 

 that all of our descendants must become 

 extinct in about five million years, Prof. 

 Rutherford gives the hope that our race 

 may hold out for five hundred millions 

 of years, which is quite a bit longer. 

 All estimates, of course, are based on the 

 duration of the heat from the sun. Our 

 new knowledge of radium seems to show 

 that the sun's heat is diminishing much 

 more slowly than has been generally 

 supposed. 



After describing the heat inside the 

 earth and the various present theories 

 to account for this heat, Prof. Ruther- 

 ford proceeds to tell some of the remark- 

 able characteristics of radium. 



" In the course of a year one pound 

 of radium would emit as much heat as 

 that obtained from the combustion of 

 100 pounds of the best coal, but at the 

 end of that time the radium would ap- 

 parently be unchanged and would itself 

 give out heat at the old rate, and it 

 would emit heat at the above rate for 

 about one thousand years." 



The heat which radium gives off seems 

 to be caused by the breaking up of the 

 radium atom into tiny particles, which 

 fly away with tremendous velocity; but 

 notwithstanding their great speed, most 



From F. H. Newell, U. S. Geological Survey 



Four Coal Beds each 4 or 5 Feet Thick on Little Missouri River, near Mikkelson, 

 North Dakota. See preceding page 



