596 



Dr. W. B. Carpenter on the 



[June 13, 



and thence passing southwards between the Gulf-stream and the Coast of 

 the United States, is regarded by Sir John Herschel as the return-current 

 of that portion of the N.E. Drift which passes onwards into the Arctic 

 basin, completing what (borrowing a term from Anatomy) I would call the 

 longer circulation, On the other hand, the southern deflection of a large 

 portion of the Gulf-stream to the east of the Azores, and its re-entrance 

 into the Equatorial current, complete the shorter circulation. 



93. As Sir John Herschel, when placing himself in antagonism to 

 the doctrine of Oceanic Circulation propounded by Capt. Maury, was 

 himself an adherent of the doctrine of the uniform Deep-sea temperature 

 of 39°, which had been propounded by Sir James Ross, on the basis 

 of observations now proved to have been vitiated by the imperfection 

 of his Thermometers, his repudiation of Capt. Maury's views must be un- 

 derstood as extending only to the question of sensible currents. As to the 

 existence of any more general, though less perceptible, surface-movement 

 of Oceanic water from the Temperate towards the Polar seas, Sir J. 

 Herschel offered no opinion ; nor did he at that time (so far as I am aware) 

 anywhere express himself as either favouring or opposing the hypothesis 

 of a movement of deep water from the Polar to the Equatorial areas, 

 which would seem necessary for the maintenance of a bottom-temperature 

 even of 39° in the latter, much more of a bottom-temperature but little 

 above 32°*. 



* As the doctrine advocated in my previous Reports, of a General Oceanic Cir- 

 culation sustained by difference of Specific Gravity arising out of difference of Tem- 

 perature, differs essentially from that of Capt. Maury, — in that it leaves unquestioned 

 the Trade-wind origin of the Gulf- stream, and touches only that deep N.E. movement 

 of Warm water which the Gulf-stream (on Sir J. Herschel' s own showing) could not 

 produce, and that still deeper return-movement of Cold water of which Sir J. Herschel 

 was then ignorant, — I cannot but feel surprised at finding his authority cited against 

 me, not only by Mr. Croll, but also (inferentially at least) by Sir Charles Lyell ; who, 

 in the recently published Eleventh Edition of his ' Principles of Geology,' speaks as 

 follows (vol. i. p. 505) : — " Besides those sensible currents arising from the various 

 " causes already mentioned, a theory of general oceanic circulation first propounded by 

 " Maury has lately been brought into great prominence by Dr. Caipenter." Now, as I 

 have shown, the " theory of general oceanic circulation propounded by Maury," had 

 special reference to sensible currents ; and it was the inadequacy of the causes assigned by 

 him (not by me) for their production, which was the subject of Sir John Herschel's de- 

 monstration, cited by Sir C. Lyell in a subsequent page (p. 507). Yet by representing 

 my views as identical with Capt. Maury's, Sir C. Lyell has (perhaps unintentionally) 

 given the impression that Sir J. Herschel's demonstration was equally applicable to 

 both. And he has been so understood by an anonymous writer in the ' Athenaeum ' 

 (March 2, 1872) ; who, in a notice of Sir Charles Lyell's new edition, asserts, with 

 reference to " the question of Ocean-Currents, which has been lately brought very pro- 

 " minently forward by Dr. Carpenter," that "Sir Charles shows that the theory which 

 " refers oceanic circulation to difference of specific gravity is founded upon erroneous 

 " observation and incorrect application of the facts observed."- — How differently Sir 

 John Herschel thought of the doctrine as advocated by me (not in substitution for the 

 Trade-wind origin of the Gulf-stream, but as supplemental to the whole Oceanic 



