198 PHYSICAL GEOGEAPHY OF THE SEA, AND ITS METEOROLOGY. 



where they are and tell how they run, in order that he may he cer- 

 tain of their help when favourable, or sui'e of avoiding them if adverse. 

 409. There are other currents, such as the Greenland Current, 

 The Greenland the cold curreut ft'om Davis' Strait, the ice-bearing 

 current. cmTcut fi'om the antarctic regions, all setting into 



the Atlantic and the Gulf Stream, one branch of Avhich finds its 

 way into the Arctic Sea ; the other (§ 89) finds its way back to the 

 south partly as Eennell's current, all of which have been fully 

 treated of in Chap. II., or are delineated on Plates YI. and IX. 

 Judging by these, there would seem to be a larger flow of po^ax 

 waters into the Atlantic than of other waters from it, and I cannot 

 accoimt for the preservation of the equilibrium of this ocean by any 

 other h^Tpothesis than that which calls in the aid of under cm-rents. 

 They, I have no doubt, like the water-ways, the mineral veins, the 

 passages in the bowels of the earth, bear in then- secret ways, an 

 important part in the grand system of the terrestrial economy. 



CHAPTER IX. 



§ 420 — 460. THE SPECIFIC GRAVITY OF THE SEA, AlW THE 



OPEN WATER IN THE ARCTIC OCEAN. 



420. The crust of the planet upon which we live, mth the forces 

 Interesting physical that havc bceu and are at work upon it, is the most 

 inquiries. interesting subject of physical inquiry and study that 



can claim the attention of diligent students. Precisely as the pro- 

 gress of man has been upward and onward, precisely has he looked 

 more earnestly and with deeper longings towards the mysteries that 

 encircle this crust. It is but a shell, and at most we can reach 

 only a little way either above .or below its very surface, and yet 

 upon the tablets of this thin shell are the records of all that he may 

 ever know concerning this his cosmical hearthstone. 



421. Researches have been carried on from the bottom of the 

 Voyages of discovery decpcst pit to the top of the highest mountain, but 

 to the North Pole, ^j^ggg j^g^^g ^^j. gatisficd. Voyagcs of discovcry, with 

 their fascinations and their charms, have led many a noble champion 

 of human progress both into the torrid and frigid zones ; and not- 

 withstanding the hardships, sufferings, and disasters to which many 

 northern parties have found themselves exposed, seafaring men, as 

 science has advanced, have looked mth deeper and deeper longings 



