204f ACCOUNT OF THE ARCTIC REGIONS. 



problem attended with much difficulty and uncer- 

 tainty. These motions, denominated Currents, be- 

 ing under the influence of some of the same princi- 

 ples as regulate the winds, are found to be some- 

 what similar to the movements of the atmosphere, 

 though more regular and steady. The general 

 agents employed in the production of currents, are 

 considered to be the rotatory motion of the Earth, 

 the varying attractions of the Sun and Moon, diffe- 

 rences in temperature, and particularly strong or 

 prevailing winds. These, when combined with the 

 peculiarities of form in sea-coasts, and in the bed of 

 the ocean, with other topical circumstances, may 

 serve to account for many of the currents hitherto 

 . observed. 



Currents, as regards their permanency, are either 

 general, particular, or variable ; and, as relates to 

 their situation, or to the depth at which they pre- 

 vail in the sea, are called cither bodily, upper, or 

 under currents. 



General currents are such as are always directed 

 towards the same point of the compass. Particular 

 currents change their direction periodically : and 

 variable currents are such as have no stated period, 

 being chiefly produced by the action of the wind. 



A bodily current prevails where the whole mass 

 of waters, from the surface to the bottom, moves in 

 the same direction, and with similar velocity. An 

 upper or superficial current, is where a stratum at 

 the surface of the sea is in motion, while the lower 



