THE GULF STREAM. 49 



142. The Thermal Charts of the North Atlantic afford for these 

 The resemblance be- yiews other iUiistratioiis which, when compared with 

 in the NorthTtkn- the charts of the North Pacific now in the process of 

 fIc^^ '^' ^'''^' construction, will make still more striking the re- 

 semblance of the two oceans in the general featm^es of their systems 

 of circulation. We see how, in accordance with this princijDle 

 (§ 132), the cmTents necessary for the formation of thickly-set 

 sargassos are generally wanting in southern oceans. How closely 

 these two seas of the north resemble each other; and how, on 

 accoimt of the large openings between the Atlantic and the Frozen 

 Ocean, the flow of warm waters to the north and of cold waters to 

 the south is so much more active in the Atlantic than it is in the 

 Pacific. Ought it not so to be ? 



143. As a rule, the hottest water of the Gulf Stream is at or 

 A cushion of cool j^^car tho smface ; and as the deep-sea thermometer 

 Stom^of medeep is scut do^\Ti, it shows that thcse waters, though still 

 by iS'SJrreSs''*''' far Warmer than the water on either side at corre- 

 sponding depths, gradually become less and less warm until the 

 bottom of the current is reached. There is reason to believe that 

 the warm waters of the Gulf Stream are nowhere permitted, in the 

 oceanic economy, to touch the bottom of the sea. There is every- 

 where a cushion of cool water between them and the solid parts of 

 the earth's crust. This arrangement is suggestive, and strikingly 

 beautiful. One of the benign offices of the Gulf Stream is to convey 

 heat from the Gulf of Mexico, where otherwise it would become 

 excessive, and to dispense it in regions beyond the Atlantic for the 

 amelioration of the climates of the British Islands and of all Western 

 Em'ope. Now cold water is one of the best non-conductors of heat, 

 and if the warm water of the Gulf Stream was sent across the 

 Atlantic in contact with the solid crust of the earth — comparatively 

 a good conductor of heat — instead of being sent across, as it is, in 

 contact mth a cold, non-conducting cushion of cool water to fend it 

 from the bottom, much of its heat would be lost in the first part of 

 the way, and the soft climates of both France and England would 

 be, as that of Labrador, severe in the extreme, ice-bound, and bit- 

 terly cold. 



144. That there should be in the North Atlantic Ocean a con- 

 \vTiy should the Gulf staut and copious flow and reflow of water between 

 SThTGuif'o^MS! that ocean and the Arctic is (§ 107) not so strange, 

 ^^<^- for there are abundant channel- ways between the two 

 oceans. In one water is to be found nearly at blood heat, in the 



