194 SEE— TEMPERATURE, SECULAR COOLING [April 20, 



approximately its present dimensions. This conclusion was essen- 

 tially independent of the encrustation, and rested primarily on the 

 resistance to the supposed convection movements caused by the 

 pressure, which is so great as to make all the matter in the deeper 

 portions of the globe behave as an aeolotropic elastic solid. The 

 matter thus made effectively rigid by pressure, could cool only by 

 conduction, and that process is so excessively slow and the heat 

 transferred by it so small in amount as to render it of little effect 

 in the postulated contraction of the earth. 



In the former paper arguments were adduced to show that earth- 

 quakes and mountain formation depend principally on the secular 

 leakage of the ocean bottoms, and not on the shrinkage of the globe. 

 An attempt was made to justify this inference by an appeal to the 

 observed lay of the mountains parallel to the sea coasts, and the 

 recognized connection between volcanoes, earthquakes and mountain 

 formation. Mention was also made of the inadequacy of the con- 

 traction theory to account for the height of mountains, and their 

 congested distribution; and of various other considerations, such 

 as the observed elevation of the sea coasts by earthquakes and the 

 sinking of the adjacent sea bottom shown by the accompanying 

 seismic sea waves. We shall now examine more at length the phys- 

 ical questions connected with the temperature of the earth, and this 

 will afford a basis for judging of the validity of current theories, as 

 well as of certain conclusions respecting seismological problems 

 reached in the former paper. 

 § 2. The Probable Law of Temperature within the Earth. 



The exact process by which the matter of the earth was gathered 

 together and formed into the spheroid which we now inhabit is quite 

 unknown, and one can conceive of what probably took place only 

 by means of dynamical principles applied to ideal conditions offering 

 by analogy a greater or less degree of probability. In this way well 

 guided imaginative conceptions may enable us to approximate the 

 former physical conditions of our planet. For example, it is not 

 likely that the earth as we now find it was formed very suddenly, 

 all the material being brought together so rapidly that but little of 

 the heat of condensation escaped into space. Neither is it probable 

 that the process of agglomeration was so excessively slow that nearly 



