470 THE UNFINISHED BOOK. [1858. 



inferred that they had not been brought as ballast. Is this 

 not beautiful ? 



The water-cure has done me some good, but I [am] noth- 

 ing to boast of to-day, so good-bye. 



My dear friend, yours, 



C. D. 



C. Darwin to C. Lyell. 



Moor Park, Farnham, April 26th [1858]. 



My dear Lyell, — I have come here for a fortnight's 

 hydropathy, as my stomach had got, from steady work, into a 

 horrid state. I am extremely much obliged to you for send- 

 ing me Hartung's interesting letter. The erratic boulders are 

 splendid. It is a grand case of floating ice versus glaciers. 

 He ought to have compared the northern and southern shores 

 of the islands. It is eminently interesting to me, for I have 

 written a very long chapter on the subject, collecting briefly 

 all the geological evidence of glacial action in different parts 

 of the world, and then at great length (on the theory of spe- 

 cies changing) I have discussed the migration and modifica- 

 tion of plants and animals, in sea and land, over a large part 

 of the world. To my mind, it throws a flood of light on the 

 whole subject of distribution, if combined with the modifica- 

 tion of species. Indeed, I venture to speak with some little 

 confidence on this, for Hooker, about a year ago, kindly read 

 over my chapter, and though he then demurred gravely to 

 the general conclusion, I was delighted to hear a week or two 

 ago that he was inclined to come round pretty strongly to my 

 views of distribution and change during the glacial period. I 

 had a letter from Thompson, of Calcutta, the other day, 

 which helps me much, as he is making out for me what heat 

 our temperate plants can endure. But it is too long a sub- 

 ject for a note ; and I have written thus only because Har- 

 tung's note has set the whole subject afloat in my mind 

 again. But I will write no more, for my object here is to 

 think about nothing, bathe much, walk much, eat much, and 



