On the Agency of Water in Volcanic Eruptions. 173 



The lost of terrestrial heat by radiation is now exceedingly small. 

 But small as this loss is, it cannot take place without producing con- 

 traction, and Cordier long since calculated that supposing five volcanic 

 eruptions to take place annually, it would take a century to eject so 

 much lava as would shorten the radius of the earth to the extent of 

 1 mm., or about ¥ x j inch. 



I therefore conclude that the hypothesis originally propounded, 

 namely, that volcanic phenomena are dependent on the effect of 

 secular refrigeration is, with certain modifications, the one that best 

 meets the necessities of the problem. 



