344 On Currents in Water. 



If the cause assigned is the true one, we may deduce the follow- 

 ing consequences. 



1. That whirlpools and whirlwinds, in the southern hemisphere, 

 revolve in the contrary direction to those in the northern. 



2. That at the equator this tendency to rotary motion does not 

 exist, and if such motion is produced by other causes, the direction 

 will be determined by the cause producing it. 



3. That this cause, producing whirlpools, acts with more force 

 near to the poles, than near to the equator. 



4. And that, in a long narrow vessel, a whirlpool will be more 

 readily formed, when the vessel is placed north and south, in the di- 

 rection of its length, than when placed east and west in that direc- 

 tion ; inasmuch as the currents from the east and west are not in- 

 fluenced or acted upon, so as to produce a difference in direction, by 

 the motion of the earth on its axis. 



The motion, caused by the diurnal revolution of the earth, of any 

 point P' on its surface, is as the cosine of the latitude of that point ; 

 and the tendency to produce whirlpools increases or decreases, as 

 the ratio of the cosines of the consecutive degrees of latitude in- 

 creases or decreases. 



It is therefore probable, if the foregoing theory is true, that the 

 tendency to produce whirlpools exists, in different degrees of force, 

 in every different parallel of latitude, and that the rotary motion 

 produced in fluids, contained in vessels of equal size and under 

 equal circumstances, will differ in velocity and force in different lati- 

 tudes, and that the velocity and force will be constant in the same 

 latitude. It is therefore possible that an instrument may be formed, 

 by which the latitude may be determined, especially towards the 

 poles, where it would be most sensible, and where it is most needed. 

 It is not expected that such an instrument would supersede those 

 now used for the purpose, but that it would be a valuable addition 

 to them, when 



"Nor sun, nor moon, nor stars appear." 



As the truth or falsity of this theory may be established, by de- 

 termining whether whirlpools move in different directions in the 

 northern and southern hemispheres, it is desirable that this should 

 be enquired into by scientific travellers, for if it shall be confirmed, 

 it will afford additional data for accounting for currents, trade winds, 

 and other motions in fluids, and will be additional evidence of the 

 diurnal revolution of the earth. 



