238 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



matter which the sunbeam, the zephyr, and the infusorial insect 

 keep in perpetual motion and activity. 



474. If these inferences as to the influence of the salts upon • 

 Deductions. the cmTeuts of the sea be correct, the same cause 

 which produces an under current from the Mediterranean (§ 471), 

 and an under current from the Eed Sea into the ocean, should 

 produce an under current from the ocean into the north polar ba- 

 sin ; for it may be laid down as a law, that whenever two oceans, 

 or two arms of the sea, or two sheets of water, differing as to salt- 

 ness, are connected with each other, there are cm-rents between 

 them, viz., a smface current from, and an under current into the 

 sea of lightest water. In every case, the hypothesis with regard 

 to the part performed by the salt, in giving vigour to the system 

 of oceanic circulation, requires that, counter to the surface current 

 of water with less salt, there should be an under current of water 

 with more salt in it. That such is the case with regard both to 

 the Mediterranean and the Eed Sea has been amply shown in 

 other parts of this work (§ 471), and abundantly proved by other 

 observers. That, in obedience to this law, there is a constant cur- 

 rent setting out of the Arctic Ocean through Davis' and other 

 straits thereabout, which connect it with the Atlantic Ocean, is 

 generally admitted. Lieutenant De Haven, United States Na'\^, 

 when in command of the American expedition in search of Sir 

 John Franklin, was frozen up with his vessels — the Advance and 

 the Eescue — in mid-channel near Wellington Straits ; and dming 

 the nine months that he was so frozen, his vessels, hke H.B.M. 

 ship Eesolute and the Fox (§ 431), each holding its place in the 

 ice, were drifted with it bodily for more than a thousand miles to- 

 wards the south. 



475. The drift of these vessels is sufficient, were there no other 

 Drift of ttie Reso- ovideuce, to estabhsh the existence of an open sea 

 ^^^^- in the Arctic Ocean; for this drift cannot be ac- 

 counted for upon any other hypothesis, as a sHght examination 

 of the arctic regions on a terrestrial globe, and a careful study of 

 the facts (§ 459), and other phenomena will show. 



476. About the middle of September, 1850, being in latitude 

 De Haven's drift. 74° 40', and in the fair way of Wellington Channel, 



De Haven found himself, with the Advance, frozen in her tracks, 

 as M'Chntock did the Fox,* m August, 1857, who tried to reach 

 the shore, but he was fast bound, and driftmg to the west. De 

 * A screw yaclit of 177 tons. , 



