I.J T1IK ICAIUATlnN.x OF UiMTKD IJODIKS. QJ 



Our estimate of the age of the earth, as deduced from 

 the cooling she has undergone, must therefore, in vit-u 

 of these considerations, be diminished a result insi.-tcd 

 upon by many recent authors. Too much weight must, 

 however, not be given to this conclusion, since it ought 

 to be borne in mind that the cooling was not taking 

 place by radiation into space from the earth alone as a 

 solitary body. She was in presence of a high extrane- 

 ous temperature, which diminished her speed of cooling, 

 and correspondingly increased the time. 



Though the problem of the age of the earth, as inves- 

 tigated through the changes of her temperature, may not 

 at present be capable of exact solution, it must be ad- 

 mitted that the time required to bring her heat to its 

 present degree must have been inconceivably long. 



