64 PHYSICAL GEOGRAPHY OF THE SEA. 



the analogous trees grow 3° or 4° nearer to the pole, and the 

 aboriginal tribes go naked as far to the north as 52°, a simplicity 

 of toilet that would but ill suit the Esquimaux of Labrador. 



Besides their beneficial influence on different climates the 

 ocean-currents tend to equalise, or to maintain the equilibrium 

 of the saline composition of sea-water, and thus secure the 

 existence of numberless marine animals. Their movements 

 also contribute to the formation of sand-banks, where at certain 

 seasons legions of fishes deposit their spawn and invite the per- 

 secutions of man. 



The rapidity of currents is very different, but always impor- 

 tant enough to be taken into account by navigators. The well- 

 informed seaman makes use of them to traverse wide spaces 

 with greater rapidity, and, after an apparently circuitous course, 

 arrives sooner and more safely at his journey's end than the 

 ignorant steersman, who vainly endeavours to strive against 

 their power. 



Toaia I-actuca, with Pc~; p' 

 in N&i-iirai Poer-ion. 



