Natural History of the Ocean^ fyc^ f3f 



A 



ing three miles per hour. * 



Salfncss of the Sea. — Varies in dlirerertt latitudes and lo- 

 calities. In the Tropical and Polar regions, the saltness i.^ 

 the same, diminishing gradually on either side to the Lom- 

 pcrafe. In bajs. arms, and at {he mouths of rivers, the 

 water contains less salt. 



It is doul>tfnl if the sahness does not vary with the depth. 



The salt is deposited when sea water freezes. 



The Mediterranean is salter than the Atlantic ; tfie Bal- 

 tic less salt. 



Generally speaking, the saline matter of the Atlantic is 

 from three to four per cent, say in 1000 grains of sea ivn- 

 ier are the following, viz. : 

 - Muriate of Soda, - - 30.80 



Magnesian Salt^, . ^ ^ 04-00 ^ 



.^Sulphate of Lime^ - - 00.80 



35.60 or 3.56 per cent. 

 Sea Ice. — Sea water freezes at SS''. Buffon doubted if 



it ever froze. Sea ice varies in colour from white and 

 grey, to greenish and sappharine. Its forms are various 

 presenting every shape which fancy can create. Scoresby 

 notices sixteen kinds, known among sailors. Sea ice when 

 melted aifords fresh water. Mountains of ice have been 

 ^ seen on the banks of Newfoundland, above 2,000 mile^ 

 from the place of its formation. They are heavier than 

 the water, and only one eighth appears above the surface. 

 Their approach is known by the effect they produce on 

 the atmosph<3re — ^and by the ice-blink, a lurtiinous appear- 

 an(!e in the air above thenv. It is supposed that the poles 

 are surrounded by ice, which prevents access to them. 

 The nearest approach to the North Pole has beeft the lati- 

 tude of 82°, or within 510 miles. The nearest approach 

 tt> the South Pole, has beert latitude 72, by Cook, or within 

 113^nailes, h i^ a matter of conjecture if either pole will 

 ever be visited. 

 J^htions ^ Iht Sea, are Sf three kinds, viz : 

 1. Motion of Waves. 11. Motion of Currents. III. Mo- 

 tion of Tides. 



The 



rav- 



itation; the sinking of one w^ve raisrteg others. It is nof 

 known how deep the sea is agitated : divers say to a great 



