Introduction. 27 



greater when we consider that the polar basin is com- 

 paratively small, and, as has been already remarked, 

 very shallow ; its greatest known depth being from 

 60 to So fathoms. 



" But there is still another factor that must help to 

 increase the quantity of water in the polar basin, and 

 that is its own rainfall. Weyprecht has already pointed 

 out the probability that the large influx of warm, moist 

 atmosphere, from the south, attracted by the constant 

 low atmospheric pressure in the polar regions, must 

 engender so laro-e a rainfall as to augment considerablv 



o o 5 ^ 



the amount of water in the Polar Sea. Moreover, the. 

 fact that the polar basin receives large supplies of fresh 

 water is proved by the small amount of salt in the water 

 of the polar current. 



" From all these considerations it appears unquestion- 

 able that the sea around the Pole is fed with considerable 

 quantities of water, partly fresh, as we have just seen, 

 partly salt, as we indicated further back, proceeding from 

 the different ocean currents. It thus becomes inevitable, 

 according to the law of equilibrium, that these masses 

 of water should seek such an outlet as we find in the 

 Greenland polar current. 



" Let us now enquire whether further reasons can be 

 found to show why this current flows exactly in the given 

 direction. 



"If we examine the ocean soundings, we at once 

 find a conclusive reason why the main outlet must lie 



