338 LIFE AT DOWN. ^ETAT. 33~45- [1845. 



who like you, educate people's minds as well as teach them 

 special facts, can never, I should think, have full justice done 

 them except by posterity, for the mind thus insensibly im- 

 proved can hardly perceive its own upward ascent. I had 

 intended putting in the present acknowledgment in the third 

 part of my Geology, but its sale is so exceedingly small that I 

 should not have had the satisfaction of thinking that as far as 

 lay in my power I had owned, though imperfectly, my debt. 

 Pray do not think that I am so silly, as to suppose that my 

 dedication can any ways gratify you, except so far as I trust 

 you will receive it, as a most sincere mark of my gratitude and 

 friendship. I think I have improved this edition, especially 

 the second part, which I have just finished. I have added a 

 good deal about the Fuegians, and cut down into half the 

 mercilessly long discussion on climate and glaciers, &c. I do 

 not recollect anything added to the first part, long enough to 

 call your attention to ; there is a page of description of a very 

 curious breed of oxen in Banda Oriental. I should like you 

 to read the few last pages ; there is a little discussion on 

 extinction, which will not perhaps strike you as new, though 

 it has so struck me, and has placed in my mind all the 

 difficulties with respect to the causes of extinction, in the 

 same class with other difficulties which are generally quite 

 overlooked and undervalued by naturalists ; I ought, however, 

 to have made my discussion longer and shewn by facts, as I 

 easily could, how steadily every species must be checked in 

 its numbers. 



I received your Travels * yesterday ; and I like exceedingly 

 its external and internal appearance ; I read only about a 

 dozen pages last night (for I was tired with hay-making), but 

 I saw quite enough to perceive how very much it will interest 

 me, and how many passages will be scored. I am pleased to 

 find a good sprinkling of Natural History ; I shall be aston- 

 ished if it does not sell very largely. . . . 



* ' Travels in North America, 3 2 vols., 1845. 



