574 DISCOVERIES OF ROSS, 1818. 



vances, and particularly when the wmd blows 

 from the northward, opens in various places; 

 and when ships have passed through these open- 

 ings to the northward they have generally found 

 the sea clear of ice. 



If therefore the great polar basin should be 

 free of land, the probability is, that it will also be 

 free of ice. It was the opinion of Frobisher, 

 Davis, and most of the old and experienced navi- 

 gators, that the deep blue sea does not freeze. 

 This w^ould be to assume too much, as its surface 

 has frequently been observed to freeze when not 

 agitated by the wind ; but it may be doubted 

 whether a deep and extensive sea can be perma- 

 nently shut up with ice. The almost perpetual 

 agitation of the surface, and the increased tem- 

 perature of the water at great depths, and conse- 

 quently its diminished specific gravity, which 

 wull cause it to ascend, will probably prevent 

 those immense fields and masses of ice from form- 

 ing, which are met with near the land even in 

 very low latitudes. It was, at any rate, desirable 

 to ascertain how the fact stood in this respect, 

 and whether it was practicable to reach the north 

 pole, — in which case, there was no reason to doubt 

 that it would also be practicable to proceed by 

 that nearest route to Behring's Strait. The only 

 expedition which had hitherto been sent out for 

 the express purpose of advancing towards the 

 north pole, was that under the command of Cap- 



