166 THE PHYSICAL GEOGRAPHY OF THE SEA. 



roving cruiser or an enterprising whaleman passed that way ; but 

 to all else it was an unfrequented part of the ocean, and so re- 

 mained until the gold-fields of Australia and the guano islands of 

 Peru made it a thoroughfare. All vessels bound from Australia 

 to South America now pass through it, and in the journals of 

 some of them it is described as a region almost void of the signs 

 of life in both sea and air. In the South Pacific Ocean especial- 

 ly, where there is such a wide expanse of water, sea-birds often 

 exhibit a companionship with a vessel, and will follow and keep 

 company with it through storm and calm for weeks together. 

 Even those kinds, as the albatross and Cape pigeon, that delight 

 in the stormy regions of Cape Horn and the inhospitable climates 

 of the Antartic regions, not unfrequently accompany vessels into 

 the perpetual summer of the tropics. 



The sea-birds that join the ship as she clears Australia will, it 

 is said, follow her to this region, and then disappear. Even the 

 chirp of the stormy-petrel ceases to be heard here, and the sea 

 itself is said to be singularly barren of " moving creatures that 

 have life." 



457. I have, I believe, discovered the existence of a warm cur- 

 rent from the inter-tropical regions of the Pacific, midway between 

 the American coast and the shore-lines of Australia. This region 

 affords an immense surface for evaporation. No rivers empty into 

 it; the annual fall of rain, except in the "Equatorial Doldrums,'' 

 is small, and the evaporation is all that both the northeast and 

 the southeast trade-winds can take up and carry off. I have 

 marked on Plate IX. the direction of the supposed warm water 

 current which conducts these overheated and briny waters from 

 the tropics in mid ocean to the extra-tropical regions where pre- 

 cipitation is in excess. Here, being cooled, and agitated, and 

 mixed up with waters that are less salt, these overheated and 

 over-salted waters from the tropics may be replenished and re- 

 stored to their rounds in the wonderful system of oceanic circu- 

 lation. 



458. There are also about the equator in this ocean some curi- 

 ous currents which I do not understand, and as to which obser- 

 vations are not sufficient yet to aftbrd the proper explanation or 



