Scientific Intelligence — Meteorology. 399 



now find, having vent in both the frigid zones : the volcano of Jan 

 Mayen, actively burning within the Arctic Circle ; and Mount Ere- 

 bus, rising from the lofty mountain-range of the newly discovered 

 continent of Victoria to an altitude of more than 12,000 feet above 

 the Antarctic Ocean, and sending forth its smoke and flame to the 

 height of 2000 feet above its crater, the centre of volcanic action in 

 those regions of eternal snow. — Sir James C. Hoss^s Voyage to the 

 Southern Seas, vol. ii. p. 412. 



METEOROLOGY. 



6. Atmospheric Pressure under Diferent Latitudes, — Our baro- 

 metrical experiments appear to prove that the atmospheric pressure 

 is considerably less at the equator than near the tropics ; and to the 

 south of the tropic of Capricorn, whore it is greatest, a gradual di- 

 minution occurs as the latitude is increased, as will be seen from the 

 following table, derived from hourly observations of the height of the 

 column of mercury, between the 20th November 1839, and the 31st 

 July 1843. 



The mean pressure and the amount of atmospheric tide in each 

 latitude are as follows : — 



The above results are arranged in belts of latitude, the observa- 

 tions at sea being separated from those made in harbour ; this oc- 

 casions more apparent irregularity than would have been the case 

 had they been turned into two distinct tables. 



It has hitherto been considered that the mean pressure of the at- 

 mosphere at the level of the sea was nearly the same in all parts of 

 the world, as no material difference occurs between the equator and 

 the highest northern latitudes. At Melville Island, in latitude 74|°, 

 it was found to be 29-870; at Igloolik, in latitude 69"^, 29-770; 

 and at Winter Island, in latitude 66" 11', 29-798. The cause a£ 



