DISCUSSION AND ANALYSIS OF WINDS. 747 



Especially in the central and western part of the ocean (between 10°-20° S.), are 

 these irregularities noted. It will be seen that in these parallels the S. E. trade is 

 very regular in the Atlantic Ocean. (Plates 5 and 6.) 



The inner boundaries of the S. E. and N. E. trade are given as follows by Kcr- 

 hallet in his " Considerations Generales sur I'Ocean Pacifique."^ 



M"-"'^- N.E, Trade. S. B. Trade Months. N. E. Trade. S. E. Trade. 



January 

 February 

 March . 

 April . 

 May 

 June 



6° 30' N. 5° N. July 



4° II' N. 2° N. August . 



8°15'N. 5°50'N. September 



4° 45' N. 2° N. October . 



1° 52' N. 3° 36' N. November 



9° 56' N. 2° 30' N. December 



12° 5' N. 5° 4' N. 



15° N. 2°30'N. 



13° 56' N. 8° 11' N. 



12° 20' N. 3°32'N. 



5° 12' N. 1° 56'N. 



These observations show that the belt of equatorial calms is always north of the 

 equator. It seems that the figures given by Kerhallet are taken from observations 

 in the eastern part of the ocean, near the American coast, where really the S. 

 E. trade crosses the equator. The wide limits between the two trades in summer 

 are caused by the prevalence of the S. W. monsoon on the coasts of Central and 

 South America. (See Plates 5, 6 and 7.) 



In other parts of the Pacific Ocean the equatorial calms seem to be nearer to 

 the equator, and partly even south of it. According to the statements of numerous 

 navigators the trades are also more easterly there, and often do not leave any calm- 

 belt between them, so that a ship can sail from the one into the other trade with- 

 out interruption, as was also stated for the western part of the Atlantic Ocean. 



The northern limit of the N. E. trade is also in a comparatively low latitude 

 in these parts, as shown, for example, by the observations at the Sandwich Islands. 

 They seem to be already in the zone of variable winds in the winter, N. E. and 

 S. W., the one being noticed about as frequently as the other. Rains are also fre- 

 quent in this season, with S. W. winds, thus corroborating the testimony of the 

 wind observations. 



The system of winds along the western coast of America has been already 

 discussed. 



As to the middle latitudes of the southern hemisphere in the Pacific, the same 

 may be said of them as of the same latitudes of the Atlantic, and Indian Oceans. 



ANTARCTIC ZONE. 



I give next some calculations from the extreme southern part of the Pacific and 

 Antarctic Oceans, comprising the most southerly latitudes to which man has 

 yet penetrated. 



' See Pilot Chiart of Atlantic, Pacific and Indian Ocean, edited by the British Admiralty. Unfor- 

 tunately I could not obtain it iu Washington, and thus have not the possibility of tracing the limits 

 of the trades and monsoons according to the best source, as in the Atlantic. 



