22 THE PHYSICAL GEOGRAPHY OF THE SEA. 



on the average, the wind from the N.E. quadrant is in excess of 

 the winds from the S.W. only 111 days out of the o65 During 

 the rest of the year the S.W. counteract the effect of the N.E. 

 winds upon the currents. Now can the N.E. trades, by blowing 

 for less than one third of the time, cause the Gulf Stream to run 

 all the time, and without varying its velocity either to their force 

 or their prevalence ? 



79. Sir John Herschel maintains* that they can ; that the trade- 

 Herschd's expiana- wiuds are thc sok causej; of the Gulf Stream ; not, 

 *'°°- indeed, by causing " a head of water" in the West 

 Indian seas, but by rolling particles of water before them some- 

 what as billiard balls are rolled over the table. He denies to 

 evaporation, temperature, salts, and sea-shells, any effective influ- 

 ence whatever upon the circulation of the waters in the ocean. 

 According to him, the winds are the supreme current-producing 

 power in the sea.:j; 



80. This theory would require all the currents of the sea to set 

 Objections to it. with the wiuds, or, when deflected, to be deflected 



from the shore, as billiard balls are from the cushions of the table, 

 making the littoral angles of incidence and reflection equal. Now, 

 so far from this being the case, not one of the constant currents of 

 the sea either makes such a rebound or sets with the winds. The 

 Gulf Stream sets, as it comes out of the Gulf of Mexico, and for 

 hundreds of miles after it enters the Atlantic, against the trade- 

 winds; for a part of the way it runs right in the "wind's eye." 

 The Japan current, "the Gulf Stream of the Pacific," does the 

 same. The Mozambique current runs to the south, against the 

 S.E. trade- winds, and it changes not with the monsoons. The 

 ice-bearing currents of the north oppose the winds in their course. 

 Humboldt's current has its genesis in the ex-tropical regions of the 

 south, where the "brave west winds" blow with almost if not 

 with quite the regularity of the trades, but with double their' 

 force. And this current, instead of setting to the S.E. before 

 these winds, flows north in spite of them. These are the main 



* Article "Physical Geogvaphy," 8th edition Encyclopsedia Britannica. 



t "The dynamics of the Gulf Stream have of late, in the -work of Lieut. Maury, 

 already mentioned, been made the subject of much (we can not but think misplaced) 

 wonder, as if there could be any possible ground for doubting that it owes its origin 

 entirely to the trade-winds." — Art. 57, Phys. Geography, 8th edition Encyc. Brit. 



X Art. 65, Phys. Geography, Encyc. Brit. 



