1872.] 



' Shearwater 1 Scientific Researches. 



607 



tion of the Climate of the region still further north, extending from Iceland 

 to the east of Spitzbergen : — 



i. That of Mr. Findlay, Mr. Blunt, and Dr. Hayes, who regard this 

 elevation of Temperature as having no immediate relation to the Florida 

 Gulf-stream, and attribute it mainly, if not entirely, to the prevalent influ- 

 ence of South-westerly winds and of the surface-drift they maintain ; the 

 surface-temperature of the Sea being in their view entirely dependent on 

 that of the Atmosphere above it. 



ii. That of Dr. Petermann, who attributes it in great part to the north- 

 easterly flow of a " deep, voluminous, warm stream," which he designates 

 as the " Gulf-stream," while admitting that a large part, both of its move- 

 ment and its temperature, may be due to the "tributaries" which the 

 Florida current receives in its course. He does not, however, specially in- 

 dicate any of these tributaries ; nor does he attribute the movement of his 

 " deep, voluminous, warm stream " to any other agency than the residual 

 force of the Florida current, aided by surface-drift. 



in. That of Prof. Wyville Thomson, who explicitly refers the North- 

 easterly flow of Dr. Petermann's "deep, voluminous, warm stream" to the 

 propulsive force of the Trade- winds acting as a vis d tergo through the 

 Florida current, and attributes the Thermal influence of that stream almost 

 exclusively to the heat which the Florida Current transports into high 

 latitudes from the Gulf of Mexico ; while he regards the underflow of 

 Cold water into the Equatorial Ocean as an indraught to replace the Warm 

 water carried off from its surface by the Equatorial current and Gulf- 

 stream. 



iv. My own view, which is partly coincident with the first, and partly 

 with the second of those just enunciated. In common with Mr. Findlay, 

 Mr. Blunt, and Dr. Hayes, I regard the progressively diminishing influence 

 of the Florida Gulf-stream as scarcely traceable, either by movement or 

 temperature, to the European border of the Atlantic ; whilst, in common 

 with Dr. Petermann, I maintain (as I have maintained from the first) that 

 a "deep, voluminous, warm stream" of Oceanic water, not to be accounted 

 for by surface-drift, is continually flowing in a North-easterly direction 

 between the parallels of 50° and 60°, the extension of which into still higher 

 parallels is the main source of the amelioration of their climate. But I 

 differ from him and from Prof. Wyville Thomson in maintaining that the 

 northward movement of this deep voluminous stream is produced, not by a 

 vis a tergo, but by an indraught of the Warm upper stratum of the Mid- 

 Atlantic towards the Polar area, to replace the outflow of the Cold under- 

 stratum which is constantly taking place over the Deep-sea bed, in virtue 

 of the increase of Density which the Polar column acquires by the reduction 

 of its Temperature. And I also maintain that the amelioration of the Tem- 

 perature of the Northern area is only due to the Florida Current, in so far 

 as it raises the temperature of the portion of the North Atlantic that lies 

 between the parallels of 40° and 50° (it being from this portion that the 



