258 LIGHT SCIENCE FOR LEISURE HOURS. 



alliance, so far as his special views are concerned. So 

 far as I know, all the continental students of science 

 who share our common views as to vertical circulation, 

 reject the wind theory as solely sufficing to account for 

 the Gulf Stream. Again, he sets Sir J. Herschel's 

 opinion (thirty years ago) that ' the Gulf Stream is 

 entirely due to the trade winds ' as almost conclusive 

 against me. It is, at least, not new to me, since it 

 is cited in every paper I have written on the subject. 

 But is there no evidence to show that Sir J. Herschel 

 abandoned the view he formerly entertained ? I would 

 ask what Sir John Herschel implies when, in his letter 

 to Dr. Carpenter, he writes, * The action of the trade 

 and counter-trade winds, in like manner, cannot be 

 ignored ; and henceforward the question of ocean cur- 

 rents will have to be considered under a twofold point 

 of view.' The word 6 henceforward ' implies very dis- 

 tinctly that Sir J. Herschel was entertaining a new 

 opinion that is, an opinion new to him ; and I think 

 Dr. Carpenter would find it difficult to demonstrate that 

 this new opinion would not have enforced the omission 

 of the word entirely from the sentence quoted by Dr. 

 Carpenter. 



I need hardly say that I do not agree with Captain 

 Maury, whose theory of oceanic circulation appears to 

 me to be wholly untenable. Nor do I for a moment 

 assert that the winds play no part in producing oceanic 

 circulation. I may have been mistaken in attaching 

 so much weight as I have to Maury's evidence as to the 

 trade wind zones, though it is known that science owes 

 more to him than to any man for our present knowledge 



