132 [May 22, 



greatest percentage of saline matter, arid that this peculiarity is 

 owing to the evaporation under and in the neighbourhood of the line 

 being greater than the quantity of water supplied by the rain falling on 

 the sea and by the rivers flowing from the land ; that the equilibrium 

 is maintained by polar currents, which bring water with less saline 

 matter to the equatorial regions. The mean quantity of saline in- 

 gredients in the equatorial regions of the ocean is about 36*2 per 

 1000, while in the polar regions it is about 33*5. 



The North Atlantic Ocean contains much more salt than the South 

 Atlantic, which the author explains by the prevailing influence of the 

 Gulf- stream ; and from his analyses of many samples of water taken 

 in the current which flows from N.E. to S.W., between Iceland and 

 the east coast of Greenland, he thinks it highly probable that this 

 East Greenland current is in reality not a polar current, but a return- 

 ing branch of the Gulf-stream, its mean quantity of salt being nearly 

 the same as in the northern part of the Atlantic Ocean, viz. 35 '5 

 per 1000. 



The author then compared the Mediterranean with the Baltic, and 

 stated that there is a double current at the entrance of the Baltic as 

 well as in the Straits of Gibraltar ; but with this difference, that the 

 under-current of the Mediterranean runs out of, and the surface- 

 current generally runs into, that sea ; whereas the under-current of 

 the Baltic is an entering one, and the surface-current of the Sound 

 generally runs out into the Kattegat and North Sea. He showed, 

 moreover, that the deep water in both seas is richer in salt than that 

 from the surface, and consequently has a greater specific gravity. 



In the Atlantic he found the reverse, viz. that the quantity of 

 saline ingredients in the water decreases with the depth, if the sam- 

 ples are taken at some distance from the shore ; and as his analyses 

 are sufficiently numerous, and include specimens from great depths 

 (12,000 feet), he considers this unexpected result to be tolerably well 

 established. He thinks that this fact would prove the existence of 

 a polar current in the depths of the Atlantic, as well as in some parts 

 of its surface. 



In the sea to the east of Africa he found the quantity of saline 

 matter slightly increasing with the depth. 



