112 VOLCANOES; EARTHQUAKES. 



the sun a great quantity of heat, both of these influ- 

 ences together can only retard, not altogether stop, 

 the gradual escape of the inner heat, and its dissipa- 

 tion into space. For according to the laws which are 

 received as the true expressions of the movements 

 of heat, a spherical body, which has a higher tem- 

 perature within than at its surface, and which is 

 surrounded, as the earth is, by the sun and the 

 starry heavens, — by sources of heat, by whose mean 

 effect temperature as high as that of its mass 

 within cannot be produced at the surface, — must 

 at length be cooled down to the mean temperature 

 of the surrounding space. 



A time must therefore come when fiery moun- 

 tains shall no longer, on the one hand, stand in 

 awful contrast in the midst of the realms of ice, 

 nor on the other hand, with the earthquake's aid, 

 ravage lands the most fruitful and flourishing, nor 

 lay the hopes and labours of men in ruins, in a 

 moment, for years, or for ever. And the jets of 

 steam, and the hot springs, must at last lose their 

 power, with their heat ; and every spring must one 

 day flow with cold water only. This time must 

 indeed be far, very far off, since the temperature of 

 the earth does not seem to have undergone any 

 change during two thousand years. Many vol- 

 canoes, of which history records the activity, seem, 

 it is true, to have become extinct already; but 

 many other new ones have arisen. Regions, the 



