54 POPULAR LECTURES AND ADDRESSES. 



and if we could apply the test deep enough, we 

 ^should, no doubt, find it very warm. Suppose you 

 should have here before you a globe of sandstone, 

 and boring into it found it warm, boring into 

 another place found it warm, and so on, would it 

 be reasonable to say that that globe of sandstone 

 has been just as it is for a thousand days ? You 

 would say, " No ; that sandstone has been in the 

 fire, and heated not many hours ago." It would 

 be just as reasonable to take a hot water jar, such 

 as is used in carriages, and say that that bottle has 

 been as it is for ever as it was for Playfair to 

 assert that the earth could have been for ever as it 

 is now, and that it shows no traces of a beginning, 

 no progress towards an end. 



26. There have been feeble attempts to reason 

 away the argument from under-ground heat. The 

 geologists, to whose theory I object, do at the 

 same time, I believe, admit that the temperature 

 increases downwards, wherever observations have 

 been made. They have hitherto taken a some- 

 what supine view of the subject. Admitting that 

 there is in many places evidence of an increase 



