IS THE GULF STREAM A MYTH? 145 



preserve a distinctive character for more than three 

 thousand miles." 



The only other theory which has been considered in 

 recent times to account satisfactorily for all the features 

 of the Gulf-Stream mechanism was put forward, we 

 believe, by Captain Maury. In this theory, the motive 

 power of the whole system of oceanic circulation is 

 held to be the action of the sun's heat upon the waters 

 of the sea. We recognize two contrary effects as the 

 immediate results of the sun's action. In the first 

 place, by warming the equatorial waters, it tends to 

 make them lighter ; in the second place, by causing 

 evaporation, it renders them salter, and so tends to 

 make them heavier. We have to inquire which form 

 of action is most effective. The inquiry would be some- 

 what difficult, if we had not the evidence of the sea 

 itself to supply an answer. For it is an inquiry to 

 which ordinary experimental processes would not be 

 applicable. "We must accept the fact that the heated 

 water from the equatorial seas actually does float upon 

 the cooler portions of the Atlantic, as evidence that the 

 action of the sun results in making the water lighter. 



Now, Maury says that the water thus lightened 

 must flow over and form a surface-current toward the 

 Poles ; while the cold and heavy water from the polar 

 seas, as soon as it reaches the temperate zone, must 

 sink and form a submarine current. He recognizes in 

 these facts the mainspring of the whole system of 



