226 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOKOLOGY. 



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 commence to thaw. It is this spring-made " middle ice " then, 

 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, 

 not south, 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 Bafiin's Bay with 



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

 takes place. The ice in which the Fox, the Kesolute, the Advance, 

 and the Eescue 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 Erankhn known of it, he might have put his vessels 

 in the line of it, and so escaped the rigours 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. 



CHAPTEE X. 



§ 461-499. THE SALTS OF THE SEA. 



461. The brine of the ocean is the ley of the earth (§ 43). 

 The brine of tiie From it the sca derives dynamical power, and its 

 ocean. currcuts thcu' main strength. Hence, to understand 



the "dynamics of the ocean, it is necessary to study the efiects of 

 their saltness upon the equilibrium of its waters ; wherefore this 

 chapter is added to assist in the elucidation of what has already 

 been said concerning the currents and other phenomena of the sea. 

 Why was the sea made salt ? It is the salts of the sea that im- 

 part to its waters those curious anomalies in the laws of freezing 



