xxxiv Appendix. 



Such is an oiitliDe of what I propose to call the Herschel-Babbage theory, 

 after the two distinguished philosophers who originated it ; it has the advan- 

 tage over all other theories of the same nature of being capable of being proved 

 or disproved by observations in the field. When firmly established, as I 

 believe it will be, it will throw a new light on geology, for it gives significance 

 to the thickness and composition of every rock, and to its geographical position ; 

 it gives significance to every bend and fold in the strata, to every fault and 

 volcanic dyke ; and it will also be found to furnish us with a key that will 

 decypher many of the hitherto obscure passages in geological history. 



