SECTION II 



CHAPTER III 

 The Age of the Earth 



FEW subjects of research and speculation are more inter- 

 esting than this. An attempt to ascertain the age of the 

 earth, or rather to ascertain the length of time during which 

 the earth has been such as we now know it a solid globe 

 capable of supporting life brings us face to face with far- 

 reaching questions which cannot fail to impress the imagi- 

 nation. Although the solution of these questions will never 

 influence the use which each individual makes of his own 

 life, they nevertheless appear to be of fundamental impor- 

 tance to every one who seeks to bring the universe within 

 his mental grasp. The attempt to give a general idea of the 

 data which are available will afford us the opportunity of 

 illustrating the methods adopted by astronomers, physicists, 

 geologists and biologists in grappling with the problem. 



For how long have the conditions upon the surface of the 

 earth been such as to render Life possible? By life we 

 mean the existence of such organisms as now surround us 

 organisms which depend upon the possession of a nitroge- 

 nous compound, protoplasm, for the chemical changes by 

 which the phenomena of living are exhibited ; and upon 

 the presence in the atmosphere, or dissolved in water, of the 

 element oxygen with which their nitrogenous constituents 

 may combine. We cannot imagine any other kind of life. 



1&3) 



