65 



Considering the velocity of the molecules, 

 which, on account of the rotatory motion of the 

 globe, vary with the parallels, we may be tempt- 

 ed to admit that every current, in the direction 



under the equator than in the temperate zone, as several na- 

 turalists pretend, a current at the bottom, from the equator 

 towards the pole, would be the result : for 0 005 produce a 

 difference of density^ of 0'0017, while, according to the tables 

 of Hallstrom, a refrigeration of 16 centesimal degrees, be- 

 tween the 20th and 4th of temperature, causes only a change 

 of 0- 00015 in the specific gravity. After attentive examina- 

 tion of the results of the experiments of Black, reduced by 

 Mr. Kirwan to the temperature of 16°, I find on the average 

 the density of the water of the sea, 



from 0° to 14° latitude at 1-0272 

 from 15° to 25° 1 0282 



from 30° to 44° 0 0278 



from 54° to 60° 1-0271 

 The proportion of salt corresponding to these four zones 

 are, according to Bishop Watson, 0 0374 j 0 0394 • 0'0386 ; 

 and 0 05572. Those numbers sufficiently prove, that the expe- 

 riments hitherto published do not in any way justify the renew- 

 ed opinion, that the sea is salter under the equator than under 

 the 30th and 44th degrees of latitude. It is not therefore a 

 greater quantity of saline substance held in solution, which 

 opposes itself to this inferior current, by which the equinoc- 

 tial ocean receives particles of water, which during the win- 

 ter of the temperate zones have sunk towards the bottom of 

 the sea, from the 30th to the 44th degree of southern and 

 northern latitude. Baume has analysed the sea-water collect- 

 ed by Mr. Pages in different latitudes, and found in this wa- 

 ter 0-005 less salt at 1° 16 7 of latitude than between the 25th 

 and 40th degrees. {KirwarCs Geol, Essays, p. 350. Pagbs 

 Voyage round the Word, vol. ii, p. 6 and 275.) 

 VOL. I, F 



