LOW BAROMETER OF ANTARCTIC ZONE. 289 



and fall of barometric pressure as we proceed north- 

 wards than as we proceed southwards. In fact, the 

 curve is almost exactly symmetrical on either side of 

 30 north latitude to the equator on one side, and to 

 latitude 60 on the other. From 60 the pressure con- 

 tinues to diminish for awhile, but appears to attain a 

 minimum in about latitude 73, and thence to increase. 

 In the southern hemisphere, if there is any correspond- 

 ing minimum, it must lie in a latitude nearer the south 

 pole than any yet attained. 



The most marked feature in the comparison of the 

 two hemispheres is the difference of pressure over the 

 southern and northern zones, between latitudes 45 and 

 75. This is a peculiarity so remarkable, that for a 

 long time many meteorologists considered that the 

 observations of Captain Eoss were insufficient to warrant 

 our concluding that so important a difference really 

 exists between the two hemispheres. But not only has 

 Captain Maury from a comparison of 7,000 observations 

 confirmed the results obtained by Ross, but, in meteor- 

 ological tables published by the Board of Trade, the 

 same conclusions are drawn from 115,000 observations, 

 taken during a period of no less than 13,000 days. In 

 fact, it is now shown that the difference is yet greater 

 than it had been supposed to be from the observations 

 of Captain Ross. From a comparison of observations 

 made in the Antarctic Seas with those of Captain Sir 

 Leopold McClintock, it appears that the average dif- 

 ference of barometric height in the northern and southern 

 zones, between latitudes 40 and 60, is about one inch. 



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