THE GULF STREAM. 49 



cended, vertically, six hundred feet ; that is, this stratum has run 

 up hill with an ascent of five or six feet to the mile. 



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

 near the surface ; and as the deep-sea thermometer is sent down, 

 it shows that these waters, though still far warmer than the water 

 on either side at corresponding depths, gradually hecome 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 no- 

 where permitted, in the oceanic economy, to touch the bottom of 

 the sea. There is every where a cushion of cool water between 

 tliem 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 Europe. Now cold wa- 

 ter is one of the best non-conductors of heat, and if the warm wa- 

 ter 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 with a 

 cold, non-conducting cushion of cool water to fend it from the 

 bottom, all 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, and ice-bound. 



D 



