Chap. I.] IiVEliTlOiV. 5 



of the ocean to the equatorial regions, there to rise and 

 return to the poles as surface water. Recent researches 

 have, however, practically refuted that theory.^ 



Neither of the foregoing causes has, however, at 

 any time obtained general acceptance among men 

 practically acquainted with the movements of the 



^ The above paragraph has been added to this edition, and 

 the manner in which the theory alluded to has already been 

 refuted by recent researches, may be judged of by the following 

 extracts : — 



' From the drift of this disrupted ice we have fair evidence of 

 a great bodily movement of the water northward ; for it must be 

 remembered that icebergs have been fallen in with in the entire 

 circumference of the Southern Seas, and that they are pushed in 

 the South Atlantic ocean as far as the 40th parallel of latitude; in 

 the South Indian to the 45th parallel; and in the South Pacific 

 to the 50th parallel. 



' In the discussion of oceanic circulation, it has been assumed 

 that water flows from Equatorial into Antarctic areas ; there is no 

 evidence, so far as I am aware, that warm surface water in the 

 sense implied is found south of the 45th parallel.' — Address to the 

 British Association, September 1876, by F. J. Evans, C.B., F.Il.S., 

 Captain R.N., and Her Majesty's Hydrographer. 



The motion of icebergs, above alluded to, from the pole to the 

 temperate zone is against the average direction of the winds. 



' I have never seen, whether in the Atlantic, the Southern 

 Sea, or the Pacific, the slightest ground for supposing that such a 

 thing exists as a general vertical circulation of the water of the 

 ocean depending upon difference of specific gravity,' — Professor 

 Sir Wyvilie Thompson's Report to the Admiralty, December 5, 

 1875. 



For further consideration of the above question see Chapter 

 VII. of The New Principles of Natural Philosophy . As heat 

 acts chiefly by creating differences of specific gravity, the above 

 quotation from Sir Wyvilie Thompson shows that the connection 

 between its action and the existing circulation is not easily to be 

 tiaced. 



