224 PHYSICAL GEOGRAPHY OF THE SEA. 



superiority, whether by sail or steam, is still almost exclu- 

 sively between England and the posterity of England in 

 America; the two great commercial communities of the 

 world. Though the Indian and Pacific Oceans form part of 

 the scene of contest, the Atlantic is the arena where science 

 and skill, aided by abundant capital and incited by strenuous 

 emulation, have achieved results which only a quarter of a 

 century ago would have been deemed impossible. These 

 results are too well known to need relation here; but we 

 may notice briefly one or two facts, illustrating the wonderful 

 changes now in progress in commercial navigation. We 

 should scarcely err in stating the average duration of long 

 ocean voyages as those to or from China, Australia and 

 India, performed by the best sailing ships at barely half 

 what it was at the period just named. Among the causes 

 concerned in this great result must first be noted, the im- 

 proved construction and fitting of ships ; and especially with 

 reference to what Mr. Eussell has called the wave principle 

 of construction ; or, in other words, the form of least resist- 

 ance of a solid moving through water. Connected with 

 this, and in practice now applied to the same end, is the 

 direct relation ascertained to exist between the length of the 

 vessel, and the speed it is capable of attaining. But beyond 

 these altered conditions of the vessel itself, comes in the en- 

 larged and more exact knowledge of the seas it traverses ; of 

 the winds and currents, the shoals and depths, and the 

 various other physical phenomena of the ocean, which have 

 been brought to the aid of practical navigation, and to which 

 we have already so copiously referred. To the combination 

 of these causes, and the record of the tracks and times of 

 many hundred voyages, upon methods which Captain Maury 

 has done much to enforce, we owe those feats of seamanship, 

 which have brought India and our Australian colonies within 

 ten or twelve weeks of England, and made the circumnavi- 



