360 



THE PHYSICAL GEOGRAPHY OF THE SEA. 



differ very much. The difference is so wide as to suggest greater 

 regularity and rapidity of circulation on one side of the equator 

 than on the other. 



Average Number of Calms to the 1000 Observations, between the Par- 

 allels OF 30° AND 55°, IN the North and South Atlantic, and between 

 the Parallels of 30° and 60° in the North and South Pacific Oceans, 

 AS SHOWN by the Pilot Charts. 



BETWEEN THE PARALLELS OP 



30° and 35°, No. of observations... 



Calms to the 1000 do 



35° and 40°, No. of observations... 



Calms to the 1000 do 



40° and 45°, No. of observations... 



Calms to the 1000 do 



45° and 50°, No. of observations... 



Calms to the 1000 do 



50° and 55°, No. of observations... 



Calms to the 1000 do 



55° and 60°, No. of observations... 



Calms to the 1000 do 



Total No. of observations 



Average calms to the 1000 do. 



North. 



12,935 



46 

 22,136 



37 

 16,363 



45 

 8,907 



38 

 3,519 



40 



63,050 



41 



South. 



15,842 



26 

 23,439 



24 

 8,203 



27 

 4,183 



25 

 3,660 



16 



55,327 



24 



North. 



22,730 



34 

 13,939 



31 

 12,400 



53 

 15,897 



35 

 32,804 



32 

 15,470 



43 



113,240 



39 



South. 



44,886 



35 



66,275 



23 



31,889 



23 



4,940 



21 



9,728 



17 



9,111 



21 



166,829 



Each one of these observations embraces a period of eight hours ; 

 the grand total, if arranged consecutively, with the observations 

 drawn out each to occupy its period separately, would be equal to 

 873 years. They exhibit several curious and suggestive facts con- 

 cerning the difference of the atmospherical stability in the two 

 hemispheres. 



1011. If we would discover the seat of those forces which pro- 

 duce this difference in the dynamical status of the two great aerial 

 oceans that envelop our planet, we should search for them in the 

 unequal distribution of land and water over the two hemispheres. 

 In one the wind is interrupted in its circuits by the continental 

 masses, with their wooded plains, their snowy mantles in winter, 

 their sandy deserts in summer, and their mountain ranges always. 

 In the other there is but little land and less snow. On the polar 

 side of 40° S. especially, if we except the small remnant of this 

 continent that protrudes beyond that parallel in the direction of 

 Cape Horn, there is scarcely an island. All is sea. There the air 

 is never dry ; it is always in contact with a vapor-giving surface ; 

 consequently, the winds there are loaded with moisture, which, 

 with every change of temperature, is either increased by farther 



