20 Depth of the Ocea7t. 



of over 2500 fathoms, stretches from the meridian of the Cape 

 of Good Hope towards the angle between Java and north- 

 western Australia, where it attains its greatest depths, forming 

 a depression of over 3000 fathoms. It communicates with the 

 Arabian Sea by two narrow channels, situated north and south 

 of the Chagos Archipelago, being nearly cut off from that sea 

 by a line of islands and shallow soundings, which connect 

 Africa, Madagascar, Bourbon and Mauritius, the Chagos 

 Islands and the Maldivh Islands, with the Asiatic continent. 

 The 2500-fathom line does not enter the Bay of Bengal, but it 

 penetrates, as we have just mentioned, into the Arabian Sea, as 

 far north as the latitude of Cape Guardafui. The 2000-fathom 

 line forms the Bay of Bengal, and also defines the limits of a 

 basin situated between Madagascar, Mauritius, the Seychelle 

 Islands, and the shallow banks which unite the latter with 

 Mauritius. The 1000-fathom line stops outside the Mozambique 

 Channel, the Red Sea, and the Persian Gulf. The 2500-fathom 

 area of the Indian Ocean crosses the parallel of lat. 40° S., 

 between St. Paul and Amsterdam Islands and Cape Leeuwin 

 in Australia, and forms, between the south coast of Australia 

 and the forty-fifth parallel, an area of depression which extends 

 beyond the southern end of Tasmania, includes the deepest 

 portion of the basin between New South Wales and New 

 Zealand, and probably communicates with the depths of the 

 Pacific by a channel situated off the southern extremity of New 

 Zealand. 



The Basin of the Pacific Ocean. — If we divide the Pacific 

 Ocean into an eastern and a western half by a line passing 

 from Honolulu to Tahiti, or by the meridian of long. 150 W. 

 (Plate 2), we observe a remarkable contrast between the two 

 portions thus formed. While the eastern half, extending 

 towards America, presents a vast unbroken sheet of water, 

 almost devoid of islands, the western half, towards Asia and 



