608 



Dr. W. B. Carpenter on the 



[June 13, 



" deep, voluminous, warm stream " is derived), and imparts additional 

 warmth (either in the form of sensible Caloric, or as the Latent Heat of 

 watery vapour) to the South-westerly winds which move over its surface. 



115. Now, as I have already remarked elsewhere*, although "to the 

 " mere Physical Geographer it may perhaps seem of little importance which 

 " of these views is the correct one," — the transfer of avast amount of heat 

 from the Equator towards the Poles by a continual movement of a great 

 body of water being admitted on both sides, — " the question is one of the 

 " highest scientific interest, from its relation to the general theory of Ocean 

 " Currents, past as well as present. For if the doctrine of a General Oceanic 

 " Circulation depending only on differences of Temperature be correct, it 

 " comes in as an important element in the study of all other great Currents 

 " at the present time, and especially of those of the Southern Oceans, which 

 r< seem much less attributable than those of the Northern to the primum 

 " mobile of the Trade-winds. . Further, the question is of yet greater im- 

 " portance in its Geological relations ; since any Circulation that has its 

 " origin simply in difference of Temperature must have been maintained 

 " throughout all geological epochs ; and the formation of Glacial beds, 

 " marked by the presence of the marine types of Polar waters, may have 

 " been taking place at any time and in any part of the Equatorial Ocean, 

 " without any reduction of the land temperature. Whereas if these glacial 

 " currents are dependent for their origin on the motion communicated to 

 " the true Gulf-stream (as Prof. Wyville Thomson maintains), they would 

 " cease to flow over the deep bed of the Atlantic, if that stream were di- 

 " verted by the free passage of the Equatorial current into the Pacific.' 5 



116. I propose, then, to consider: — 



I. The general Distribution of Heat in the Atlantic Ocean ; especially 

 with reference to the differences between the North and the South Atlantic. 



II. The Thermal condition of the Gulf-stream, and its influence on that 

 of the North Atlantic. 



III. The evidence of amelioration in the Climate of the British Isles and 

 of the regions still further north, by a North-easterly flow of Oceanic water. 



IV. The question whether this flow is attributable to the initial force of 

 the Gulf-stream proper, supplemented by the general North-easterly sur- 

 face-drift of the Atlantic ; or whether it is a larger and deeper movement, 

 forming part of a General Oceanic Circulation sustained by difference 

 of Temperature. 



117. General Distribution of Heat in the Atlantic Ocean. — A compa- 

 rison of the positions of the Summer and Winter Isotherms f in the North 



* Proceedings of the Royal Geographical Society, Jan. 9, 1871, p. 70. 



t I adopt as my authority for the Isothermal lines of the South Atlantic, and of the 

 North Atlantic as far :,s 50° N. Lai, the 1 Current and Temperature Chart,' issued by 

 the Hydrographic Department in 1868, and the Monthly Temperature Charts of the 

 North and South Atlantic, recently issued by the Meteorological Department; while 



