Vlll PHEFACE. 



ted the progress of geology. Without details of facts, it would have 

 been useless to the student; and, without reasoning these into evidence, 

 it would have merited the fate of the German cosmogonies. In my 

 own opinion, it is far too short: and it is the learner who shall judge 

 between us. I am sensible that the sketch of a Theory of the Earth 

 requires a volume, instead of a Chapter ; and further, that it can scarcely 

 be understood without that series of drawings, as a guide through a 

 perfect labyrinth of reflections, without which I could not even have 

 written it. It must remain for others to demand such a volume : and 

 if it is not less true that illustrations would have been most useful to 

 the whole work, as they had been prepared for it, there are few who 

 do not know where the obstruction lies, as it is they alone who ca;i 

 remove it. 



That this work abounds in defects, I know better than most of my 

 readers: but it is no very heavy crime to have failed in producing a 

 complete one from deficient elements. As to errors and omissions, 

 there is no fear that they will not be noted ; and long before they will 

 be corrected and supplied. Of mere hypothesis, I hope there is none : 

 while perfectly indifferent whence Truth comes, provided it comes at 

 all. And thus may I safely say with Cicero. " Nosque ipsos redargui 

 refellique patiamur ; quod ii ferunt animo iniquo qui certis quibusdam 

 destinatisque sententiis quasi addicti et consecrati sunt, eaque neces- 

 sitate constricti, ut etiam quae non probare soleant, ea cogantur constan- 

 tise causa defendere: nos qui sequimur probabilia, nee ultra quam id 

 quod verisimile occurrit progredi possumus, et refellere sine pertinacia 

 et refelli sine iracundia parati sumus." 



