DESTEUCTION OF MIGRANTS 173 



all, in this particular connection. We should expect 

 fewer old birds to perish, and yet what a vast number do ! 



Referring to this destruction of birds at lightships, 

 Newton wrote : — 



It does not seem to me that the destruction of life is 

 due to the lightships. They only enable one to see it. 

 It would surely go on nearly the same if there were no 

 lights. The birds are evidently lost already, and they 

 only make for the light in the want of any other directive 

 impulse. Unless the weather cleared or something else 

 (one hardly knows what) happened, they would fly on 

 ainilessly till they fell from exhaustion, perhaps on land, 

 most likely into the sea. It is a dreadful problem, one 

 to keep one awake at night thinking upon it. 



In one way it is plain that Natural Selection does act. 

 The birds that migrate successfully, and so carry on the 

 species, must be of the best, any shortcoming must carry 

 a fatal penalty ; but what a lot of unlucky individuals 

 there must be ! * 



It was at Newton's suggestion that Mr. Eagle Clarke 

 decided to write his invaluable book on migration, and 

 he gave him help in a hundred ways in the task. Newton's 

 knowledge of the old writers on Natural History was 

 profound, and he was able to make many suggestions for 

 the chapter on the history of migration. 



January 5, 1905. 



My DEAR Clarke, 



Such an introduction to your book would be 

 most desirable if not necessary, and I am sure I will 

 gladly help you all I can. Nothing like it has, I think, 

 been attempted of late years, and the old attempts are 

 sure to be full of errors, because so much has turned up 

 since they were written. I have never gone regularly 

 into the business and I can't say off hand what Aristotle's 

 or Pliny's views on migration were ; but it will not be 



* Letter to W. Eagle Clarke, October 24, 1903. 



