24 PHYSICAL GEOaiiAPHY OF THE SEA, AXD ITS METEOROLOGY. 



cexeeds in discliarge tlie miglity Mississippi a thousand times ? 

 Keason teaches and examination shoYvs that they are not. With the 

 "sdew of ascertaining the average number of days during the year 

 that the N.E. trade-winds of the Atlantic operate upon the currents 

 between 25° N. and the equator, log-boolis containing no less than 

 380,284:* observations on the force and direction of the wind in 

 that ocean were examined. The data thus afforded were carefully 

 compared and discussed. The results shovv- that within those lati- 

 tudes, and 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 365. 

 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, byblov^-- 

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

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

 their prevalence ? 



79. Sii* John Herschel mamtainst that they can ; that the trade- 

 Hersciiei's expiana- wiuds are the sole causeX of the Gulf Stream ; not, 

 ^^"^^^ indeed, by causing "a head of water" in the Y/est 

 Indian seas, but by roUmg particles of water before them somewhat 

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

 temperatm^e, salts, and sea-shells, any efiective influence vrhatever 

 upon the cu^culation of the waters in the ocean. According to him 

 the winds are the supreme current-producing power in the sea,§ 



80. This theory would require all the cm-rents of the sea to set 

 Objections to it. Yni]i the wiuds, or when deflected, to be deflected 



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

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

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

 liundi^eds of miles after it enters the Atlantic, against the trade- 

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

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

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



* Nautical Monographs, Washington Observatory, No. 1. 



t Article " Physical Geography," 8th edition Encyelopeedia Britannica. 



X " The dynamics of the Gulf Stream have of late, in the work of Lieutenant 

 Maury, already mentioned, been made the subject of much (we cannot but think 

 misplaced) wonder, as if there could be any possible ground for doubting that it 

 owes its origin entirely to tlie trade-winds.'' — Art. 57, Phys, Geography, Stli 

 edition Encyc, Brit. 



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



