208 THE PHYSICAL GEOGRAPHY OF THE SEA. 



vations upon the specific gravity of the water there at the surface 

 and at various depths would indicate to us not only the extent 

 to which the water there is diluted by the rivers and the rains, 

 but it would yield other highly interesting results. Now this 

 salt and heavy water, whose specific gravity at 27°. 2 would have 

 been 1.0303, is the very water which Kodgers observed in the 

 Gulf Stream on its way to the arctic regions. This is the water 

 which, after passing the Grand Banks, and meeting the diluted 

 water as an ice-bearing current from the north, dips down, but 

 continues its course as an under current. It is protected from 

 farther loss of heat, after the manner of our own littoral waters, 

 by the colder but lighter current from the north, until it enters 

 the Arctic Ocean, there to rise up like a boiling spring in the 

 centre of an open sea. 



428. Eelying upon a process of reasoning like this, and the de- 

 De Havcn'3 water ductious flowlug thercfrom, Licutenaut De Haven, 

 ^^^' when he went in command of the American expe- 



dition in search of Sir John Franklin and his companions, was 

 told, in his letter of instructions, to look, when he should get well 

 up into Wellington Channel, for an open sea to the northward 

 and westward. He looked, and saw in that direction a " water 

 sky." Captain Penny afterward went there, found open water, 

 and sailed upon it. The open sea in the Arctic Ocean is proba- 

 bly not always in the same place, as the Gulf Stream (§ 126) is 

 not always in one place. It probably is always where the waters 

 of the under currents are brought to the surface ; and this, we may 

 imagine, would depend upon the freedom of ingress for the under 

 current. Its course may perhaps be modified more or less by 

 the ice on the surface, by changes, from whatever cause, in the 

 course or velocity of the surface current, for obviously the under 

 current could not bring more water into the frozen ocean than the 

 surface current would carry out again, either as ice or water. Ev- 

 ery winter, an example of how very close warm water in the sea 

 and a very severe climate on the land or the ice may be to each 

 other is afforded to us in the case of the Gulf Stream and the Lab- 

 rador-like climate of New England, Nova Scotia, and Newfound- 

 land. In these countries, in winter, the thermometer frequently 

 sinks far below zero, notwithstanding that the tepid waters of the 

 Gulf Stream may be found with their summer temperature within 

 one day's sail of these vorv. very cold places. 



