§ 860, 861. THE ANTARCTIC REGIONS, ETC. 459 



cated by observations at sea; its eddies and whirlpools are ere* 

 ated by the mountains, and the islands, and other inequalities 

 which obstruct its flow in the regular channels. The mean read- 

 ing of the barometer when the rainy season in India is at its height 

 is 0.4 inch less than it is in the midst of the dry. 



860. The figure (§ 858) shows the observations in the southern 

 Agreement of observa- hemisphere to bc SO accordaut, and the curve it- 

 tionsatsea, ggj£ g^ regular, that we feel no hesitation about 

 projecting it into the vacant spaces of the south, and asserting, 

 with all the boldness consistent with the true spirit of philosoph- 

 ical deduction, that, whether the actual barometric pressure at the 

 south pole be as low as 28.14° or not, it is nevertheless very 

 much lower in the antarctic than in the arctic regions. 



861. The question now arises. Whence this unequal distribu. 

 The question why the tiou of atmosphcrc bctwccn the two hemispheres, 



barometer should stand titt ^ • i n i ^ 



lower about the south and whv should thc mcau heipfht of the barometer 



than the north pole . . ^ .. 



considered. m circumpolar regions be so much less for the 



austral than for the boreal ? 'No one, it is submitted, will attempt 

 to account for this difference by reason of any displacement of 

 the geometrical centre of the earth with regard to its centre of at- 

 traction, in consequence of the great continental masses of the 

 northern hemisphere ; neither can it be ascribed to any difference 

 in the forces of gravitation arising from the oblateness of our 

 globe ; neither can it be accounted for by the effects of diurnal 

 rotation after the Halleyan theory : that would create as low a 

 barometer at one pole as the other. The air, in its motions to the 

 east and its motions to the west, is in equipoise between the paral- 

 lels of 85° and 40° K, 25° and 80° S. There is near each pole 

 and about the equator a place of permanently low barometer. 

 The air from all sides is continually seeking to restore the equi- 

 librium by rushing into these places of rarefaction and reduced 

 pressure ; consequently there ought to be between each pole and 

 the equator a place of high barometer from which the air on one 

 side flows toward the equator, on the other toward the pole. Ob- 

 servation (§ 855) shows this high place to be between the paral- 

 lels of 25° and 40° in the north, and of 20° and 80° in the south- 

 em hemisphere : thus the barometer as well as the winds (Plate 

 XY.) indicate a greater degree of rarefaction about the south than 

 about the north pole. Were there no friction, and were the at- 



