1870.] 



Deep-sea Researches. 



217 



which, at depths exceeding 1000 fathoms, are occupied by Polar water, more 

 or, less diluted by admixture according to the length of the course it has 

 had to travel ; whilst between this stratum and that other stratum of warmer 

 water which (on the hypothesis) is slowly moving Pole-wards, there is a 

 "stratum of intermixture," in which there is such a rapid change of Tem- 

 perature as might be expected from the relation of the upper and lower 

 masses of water. This "stratum of intermixture" showed itself in a 

 most marked manner in the Atlantic Temperature-observations of the 

 present Expedition (§ 80) ; the descent of the Thermometer, which had 

 been very slow with increase of depth between 100 and 800 fathoms, 

 becoming suddenly augmented in rate ; so that between 800 and 1000 

 fathoms it fell nine degrees, namely from 49°\3 to 40 o, 3. 



131. On the other hand, it was shown in the previous Report (§§ 119- 

 121) that there is evidence of the slow Pole-ward movement of a great upper 

 stratum of Oceanic Water, carrying with it a warm temperature ; which 

 movement cannot be attributed to any such local influences as those which 

 produce the Gulf-stream or any other currents put in motion by surface- 

 action. Of such a movement, it was contended, we have a marked example 

 in that north-easterly flow which conveys the warmth of Southern latitudes 

 to the West of Ireland and Scotland, the Orkney, Shetland, and Faroe 

 islands, Iceland, Spitzbergen, and the Polar basin generally. This flow, 

 of whose existence conclusive evidence is derived from observations of the 

 Temperature of these regions, is commonly regarded as a prolongation of 

 the Gulf-stream ; and this view is maintained not only by Dr. Petermann*, 

 who has recently collected and digested these observations with the 

 greatest care, but also by Prof. Wyville Thomson f, as well as by Mr. 

 Croll X- Having elsewhere fully stated our objections to this doctrine, and 

 discussed the validity of the arguments adduced in support of it§, we 

 shall here only record the conclusions which a careful examination of the 

 present state of our knowledge of the subject has led us to form : — 



I. That there is no evidence, either from the Surface- temperature 

 of the Sea or from the temperature of sea-bord Stations along the 

 western coast of Southern Europe, that the Climate of that region is 

 ameliorated by a flow of Ocean-water having a temperature higher than 

 that of the Latitude, — the surface-temperature of the Mediterranean Sea, 

 which is virtually excluded from all Oceanic Circulation, being higher than 

 that of the eastern margin of the Atlantic in corresponding latitudes, and 

 the Climate of sea-bord Stations on the Mediterranean being warmer than 

 that of Stations corresponding to them in Latitude on the Atlantic Coast ; 

 and this not merely in summer, but also in winter. This Oceanic 

 region may therefore be designated the neutral area, 



* Geographische Mittheilungen, 1870, p. 201. 



t Lecture " On Deep-sea Climates," in Nature, July 28, 1870. 



X Memoir " On the Physical Cause of Ocean-Currents," in Phil. Mag. Oct. 1870. 



§ Proceedings of the Royal Geographical Society, for Jan. 9, 1871. 



