ON THE EFFECTS OF OCEANIC CURRENTS UPON CLIMATES. 459 



When an ocean-current moving from sontb to north ohtains admis- 

 sion to the Arctic Ocean, it produces necessarily, on hydrodynamical 

 principles, an equal and opposite counter-current moving from north to 

 south. The tepid water-current is forced by the rotation of the earth to 

 shift its direction continually to the right, and thus it happens that the 

 Galf Stream is pressed upon the western shores of Europe and Spitz- 

 bergen, and benefits those localities in winter. On the other hand the 

 cold counter- current returning through Baffin's Bay and along the east 

 coast of Greenland, is also forced by the earth's i-otation to keep to its 

 right, and so is pi'essed upon the coast of Labrador and the east coast of 

 North America as far south as Cape Cod. This return or counter current, 

 known as the Labrador Current, and others, exercises an influence upon 

 climate the opposite of that of the Gulf Stream, and of such a kind as to 

 render it very doubtful whether the Gulf Stream is a I'eal benefit to the 

 climate of the whole globe or not. 



"While the Gulf Stream raises the January temperature of all places 

 visited by it, the Labrador or counter-current loxvers the July tempera- 

 ture of all places affected by it. This is readily shown by the following 



Similar, though lesser, effects are to be found on the east coast of 

 Asia, caused by the counter cold carrent issuing from Behring Strait, and 

 pressing to the right along that coast. 



Remembering that the Gulf Stream is helpless to increase the July 

 temperatures, upon which the reproduction of plants is chiefly dependent, 

 we may confidently assert that the serious lowering of July temperature 

 caused indirectly, by means of its counter-cui-rent, through the agency of 

 the Gulf Stream, has a more important influence upon the geographical 

 distribution of plants than its direct influence in mitigating the severity 

 of the winter months. 



If we imagine the Kuro-Siwo admitted into the Arctic Ocean, by a 

 broad deep channel to the east of Kamtschatka, we must bear in mind the 

 fact already proved, that although its thermal effect is only one and a 

 quarter times that of the Gulf Stream, its actual volume is tvfo and a half 

 times as much ; and by the laws of hydrodynamics, the counter cold 

 current moving south-west produced by it, will be two and a half times 

 greater than the Labrador current. Supposing it to be a little less cold, 

 and discounting the counter-current already issuing from Behring Strait, 

 we cannot estimate the damaging effect of the counter Kuro-Siwo current 

 at less than double that of the Atlantic Labrador current. What effect 

 will this produce upon the climate of eastern Asia ? 



When we remember that the cold counter-currents of the Gulf Stream 

 are able to cover Greenland with perpetual ice, and bring the iceberg- 

 limit down to 60° N., it is not unreasonable to suppose that the North 

 Pacific counter-currents caused by the admission of the Kuro-Siwo through 



' These differences would be still greater if we were to leave out of account the 

 longitudes affected by the higher temperature of the Gulf Stream. 



