66 



from south to north, tends at the same time to« 

 ward the east, while the waters, which run from 

 the pole toward the equator, have a tendency to 

 deviate toward the west. We may also be led 

 to think, that these tendencies diminish to a cer- 

 tain point the speed of the tropical current, in 

 the same manner as they change the direction of 

 the polar current, which in July and August, is 

 regularly perceived during the melting of the 

 ice, on the parallel of the bank of Newfoundland, 

 and farther north. Very old nautical observa- 

 tions, which I have had occasion to confirm by 

 comparing the longitude given by the chronome- 

 ter with that which the pilots obtained by their 

 reckoning, are contrary to these theoretical ideas. 

 In both hemispheres, the polar currents, when 

 they are perceived, decline a little to the east ; 

 and we think that the cause of this phenomenon 

 should be sought in the constancy of the westerly 

 winds which prevail in the high latitudes. Be- 

 sides, the particles of water do not move with 

 the same rapidity as the particles of air ; and the 

 currents of the ocean, which we consider as the 

 most rapid, have only a swiftness of eight or nine 

 feet a second : it is consequently very proba- 

 ble^ that the water, in passing through different 

 parallels, gradually acquires a velocity corre- 

 spondent to those parallels, and that the rotation 

 of the Earth does not change the direction of the 

 currents. 



