166 



humboldt's cuba. 



thermometer has been observed at 27°.7, 28°.6, and 

 27°.2 C. (81°9, 83°.5, and 81° F.), consequently at a 

 temperature equal to that of the air at these places. 



The great changes of temperature to which coun- 

 tries on the borders of the torrid zone are subject, 

 have a connection with certain oscillations of the 

 barometer, which are not observed in the regions 

 near the equator. At Havana, as well as at Vera 

 Cruz, the regular variations of atmospheric pressure 

 experienced at determinate hours of the day, are 

 interrupted when strong northerly winds prevail. 

 I have observed that the barometer in Cuba gene- 

 rally stands, when the sea-breeze is blowing, at 0.765, 

 and that it fell to 0.756, and even lower, when the 

 south wind blew. 



It has been stated in another place, that the mean 

 barometrical altitudes of the months when the baro- 

 meter is highest (December and January), vary in 

 respect to the months when the barometer is lowest 

 (August and September), from 7 to 8 millimetres, 

 that is to say, almost as much as at Paris, and five 

 or six times more than at the equator, and 10° north 

 and south latitude. 



Mean altitude. — December 

 " January . 



July 



" August... 



0.76656 or 22.1 Cent, of T. 



0.76809 " 21.2 



0.76453 " 28.5 " 



0.76123 i( 28.8 



