§ 460. THE SPECIFIC GRAVITY OF THE SEA, ETC. 233 



cause at tlie south, and in spite of a liiglier thermometer, they find 

 the " middle ice" compact and firm, so much so as to be impass- 

 able. In this fact we recognize another circumstance favoring 

 the theory of an open sea at the north, and giving plausibility to 

 the conjecture that this ^'middle ice" drifts out from the southern 

 edge of the open sea as fast as it is formed during the winter. 

 According to this conjecture, the thickest part of the " middle 

 ice" should be that which has been exposed to the longest and 

 severest cold, and this is probably that which began to be formed 

 on the edge of the open sea in January. As it drifted to the 

 south it continued to form and grow thick, and perhaps would be 

 the last to melt; while that which began to be formed at the 

 edge of the open sea in March or April would drift out, and not 

 attain much thickness before it would cease to freeze and com- 

 mence to thaw. It is this spring-made " middle ice" which, as it 

 drifts to the south, would, being thin, be the first to break up ; 

 and experience has taught the whalemen to look north for the 

 first breaking up and the earliest passage through the " middle 

 ice." 



460. The open sea, therefore, is, it may be inferred, at no great 

 Position of the open distaucc from the several straits which, leading in 

 ^^''' a northwardly direction, connect Baf&n's Bay with 



the Arctic Ocean. It is through these straits that the winter drift 

 takes place. The ice in which the Fox, the Eesolute, the Ad- 

 vance, and the Kescue each drifted a thousand miles or more, 

 came down through these straits. The fact of this annual winter 

 drift from the Arctic Ocean is a most important one for future 

 explorers. Had Captain Franklin known of it, he might have 

 put his vessels in the line of it, and so escaped the rigors of that 

 second winter. It would have brought him safely to the parallel 

 of 65° or 60°, and set him free, as it did four other vessels, in the 

 glad waters of the Atlantic Ocean. 



