MARINE CUEEENTS. 23 



of tlie conflicting winds at times gives rise to tremendous hurricanes, especially at 

 the change of the monsoons and during the summer heats. These disturbances 

 are most disastrous in the neighbourhood of the Mascarenhas, although they 

 also occasionally spread havoc over the waters of the Gulf of Aden and the Bay of 

 Bengal. 



On their outer borders in the direction of the poles the region of the trade 

 winds is skirted by zones of variable currents, the mean result of which generally 

 takes the direction from west to east. Being enclosed towards the north, the 

 Indian Ocean has naturally one only of these zones comprised mainly between 28° 

 and 60° south latitude. But the Pacific, as well as the Atlantic, has its two 

 systems of variable winds, one in the northern the other in the southern hemi- 

 sphere, the latter merging westwards in that of the Indian Ocean, eastwards in 

 that of the Atlantic, and thus completing the circuit of the globe. The discovery 

 of these oceanic regions dominated by the western currents, that is by the counter 

 trade winds, has been of paramount importance in the history of maritime research. 

 Guided by his knowledge of the Atlantic Avinds, Urdaneta was thus enabled to 

 direct vessels across the Pacific towards the shores of the New World, while by fol- 

 lowing the corresponding zone of variable winds in the southern hemisphere Cook 

 successfully accomplished the circumnavigation of the planet in the contrary 

 direction to that followed by Magellan. 



Marine Currents. 



The movement of the marine corresponds to that of the aerial currents in the 

 great oceanic basin, but the former, belonging to a more stable element, are 

 naturally of a more constant character than the latter. Thej- represent, so to say, 

 the fly-wheel of the great terrestrial mechanism. Hence the rythmical displace- 

 ments of the waters across the boundless oceanic spaces have been of even greater 

 moment than those of the atmosphere in the history of human progress. If the 

 trades and counter-trades have enabled European navigators the more easily to 

 traverse the ocean between the Old and the New World, and thus hastened the 

 work of exploration amongst the oceanic islands and austral lands, to the marine 

 currents w^as largely due the dispersion of mankind and gradual peopling of half 

 the globe. 



The prominent feature in the vast system of oceanic movements is the great 

 stream which in the equatorial seas sets in the same direction as the apparent 

 course of the sun between the shores of the New World and those of New Guinea 

 and the Philippines. The liquid volume which thus trends from east to west has 

 a mean breadth of probably over 3,000 miles, for it is occasionally observed 

 ranging from 26° south to 24° north latitude, but with a reflux or a zone of calm 

 waters in its central parts. The whole body of equatorial seas moves with a 

 velocity varying from 20 to 40 miles a day according to the seasons and the 

 surroundings, and to a depth which certainly exceeds 750 fathoms in the axis of 

 the stream. And this prodigious moving mass traverses nearly one-half of the 



