SURVEY OF THE GREENLAND SEA. 171 



There are, no doubt, many circumstances which 

 must tend to produce an inequality in the colour, 

 saltness, and component parts of the water of the 

 ocean ; — such as the mingling of the waters of large 

 rivers, conveying saline and earthy substances along 

 with them; and the admixture of the soluble mate- 

 rials of v/hich some parts of the bed of the sea are 

 probably composed. But, at the same time, there 

 are other circumstances which operate in a contrary 

 manner, and have a tendency to equalize and com- 

 bine the various qualities of sea-water, which 

 might at one time have occurred in different re- 

 gions of the globe : these are, tides along most 

 sea-coasts, — currents in the main sea, some running 

 superficially, some bodily, and others counter, — to- 

 gether with the influence of storms, and changes of 

 temperature, causing a circulation among the parti- 

 cles of the water. Hence, perhaps, it is, that the dif- 

 ference in the degree of saltness is not, in the most 

 distant places, very considerable. The highest spe- 

 cific gravity of the water of the main ocean, any 

 where recorded, that has come to my knowledge, 

 is 1.0297, observed by jM. Lamarche, in latitude 

 20° 21' south, and longitude 37' 5' west of Paris * ; 

 and the lowest 1.0259, observed by myself, in lati- 

 tude 78° 0', longitude 7' 0' east f. The saline con- 



* Aiinals of Phil. vol. xii. p. 32. 



t In some inland seas, the degree of saltness is less than 

 in any part of the ocean. In Baffin's Bay, for instance, the 



