OF GEOLOGICAL DYNAMICS. 107 



ance, of the chapter in which this hypothesis is set 

 forth. But I earnestly beg Professor Huxley, and 

 those in whose name he speaks, to reconsider their 

 opinion ( 4 above), that the secular cooling of the 

 earth and of the sun " has made no practical 

 " difference to the earth during the period of 

 " which a record is preserved in stratified deposits." 

 There is, surely, good ground for Sir Roderick 

 Murchison's opinion that metamorphic causes have 

 been more active in ancient times than at present, 

 because of more rapid augmentation of tempera- 

 ture downwards below the earth's surface ; and 

 it cannot be reasonably urged that a hotter sun 

 is not a probable explanation of the supposed 

 warmer climate of the palaeozoic ages. 



25. The "grave charge of opposition to the 

 principles of Natural Philosophy," which Professor 

 Huxley so earnestly repudiates, was carefully 

 limited by the words in which I expressed it, to 

 certain clearly specified points ; and it was only 

 because of the prominent and fundamental position 

 given to those points in many of our standard 

 works, that I brought that charge against " British 



