THE SALTS OF THE SEA. 



243 



waters of tlie Arctic Ocean at the surface, below, and at the bottom, 

 and as often as he tried he found this arrange- 

 ment : warm and hght water on the top, cool in the 

 middle, " hot and hea\^ " at the bottom. His experi- 

 ments were made near Behring's Straits in August, 1855, between 

 the parallels of 71^-2^, and are as per example following : 



Layers of water of 

 different tempera- 

 ture in the Arctic 

 Ocean. 



Place. 



Lat. 72^ 2' Long. 174° 37' W. 



)> 9> >> >> 



,',' 71""2r " 1750 22' 



1 Near bottom. 



Assuming the surface water which Eodgers used for these experi- 

 ments to be a fair average of arctic surface waters generally, this 

 table affords data that show the proportion of rain and river water 

 that the Arctic Ocean receives annually. The quantity may be in- 

 ferred from the fact that average sea water has ten per cent, more 

 salt than attained by Eodgers in the Arctic. 



481. Eeturning now to the drift of the ice, and the drift of the 

 The ice-bearing drift Advauco and hcT foUowcTS, WO SCO that, so far as 

 from ihe Arctic like curreuts are conccmed, we have in the Arctic Ocean 



the ordmarv dnit /> i o •^• i 



from the Baltic. a repetition merely of the more lamiliar phenomenon 

 that is seen in the Baltic, where (§ 383, note) an under current of 

 salt water runs in, and an upper current of brackish water runs out. 

 Then, smce there is salt alvrays flowing out of the north polar basin, 

 we infer that there must be salt always flowing into it, else it would 

 either become fresh, or the whole Atlantic Ocean would become 

 more and more briny, and be finally silted up with salt. It might 

 be supposed, were there no evidence to the contrary, that this salt 

 was supplied to the polar seas from the Atlantic around North 

 Cape, and from the Pacific through Behring's Straits, and through 

 no other channels. But, fortunately, arctic voyagers who have 

 cruised in the direction of Davis' Straits, have confirmed by theu' 

 observations a law of natm-e (§ 474), and afforded us proof positive 

 as to the fact of this other som'ce for supplying the polar seas with salt. 

 They tell us of an under current setting from the Atlantic towards 

 the polar basin. They describe huge icebergs, mth tops high up 

 in the air, and of course the bases of which extend far do^vn into 



