THE GULF STREAM. 47 



plan of oceanic circulation and in tlie sj'stem of unequal lieating 

 and cooling, been brouglit together. 



129. Waters of tlie ocean hept in motion hy iliermo-dynamical means, 

 — The waters of the Gulf Stream form by no means the only- 

 body of warm water that the thermo-dynamical forces of the 

 ocean keep in motion. Kearly all that portion of the Atlantic 

 which lies between the Gulf Stream and the island of Bermuda 

 has its surface covered with water which a tropical sun and tropi- 

 cal winds have played upon — with water, the specific gravity of 

 which has been altered by their action, and which is now drift- 

 ing to more northern climes in the endless search after lost equi- 

 librium. This water, moreover, as well as that of the Gulf 

 Stream, cools unequally. It would be surprising if it did not : 

 for by being spread out over such a large area, and then drifting 

 for so great a distance, and through such a diversity of climates, 

 it is not probable that all parts of it should have been exposed to 

 like vicissitudes by the way, or even to the same thermal con- 

 ditions : therefore all of the water over such a surface cannot be 

 heated alike ; radiation here, sunshine there ; clouds and rain 

 one day, and storms the next ; the unequal depths ; the break- 

 iug up of the fountains below, and the bringing their cooler or 

 their warmer waters to the surface by the violence of the waves, 

 may all be expected, and are well calculated, to produce unequal 

 heating in the torrid and unequal cooling in the temperate zone ; 

 the natural result of which would be streaks and patches of water 

 differing in temperature. Hence it would be surprising if, in 

 crossing this drift and stream (Plate YI.) with the water-ther- 

 mometer, the observer should find the water all of one tempera- 

 ture. By the time it has reached the parallel of Bermuda or 

 " the Capes " of the Chesapeake, some of this water may have 

 been ten days, some ten weeks, and some perhaps longer on its 

 way from the " caldron " at the south. It has consequently 

 had ample time to arrange itself into those differently-tempered 

 streaks and layers (§ 127) which are so familiar to navigators, 

 and which have been mistaken for " forlcs of the Gulf Stream." 



130. Fig. A^ Mate YI. — Curves showing some of these varia- 

 tions of temperature have been projected by the Coast Survey 

 on a chart of engraved squares (Fig. A, Plate VI.). These' 

 cui-ves show how these waters have sometimes arranged them- 

 selves off the Capes of Tirginia into a series of thermal eleva- 

 tions and depressions. 



