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This fuperior current is inceff^ntly propelled forward by the 

 inceflant fucceflion and propulfion from behind ; and its rapidity 

 increafed proportionally to the decreafed denfity of the more 

 northern columns to which it proceeds. 



The heat it polTeffes at the height of 21800 feet was given at 

 the average both of the fupra-marine and fupra- terrene columns ; 

 but it is evident that the heat of the fupra-marine columns at that 

 height is fome degrees lower, and that of the fupra-terrene fome 

 degrees higher. At the height of 1 000 feet the heat of the fupra- 

 marine intra-tropical air is 57'', 6, and of the fupra-terrene 70^,6. 



Sir Charles Blagden, in a very interefting paper inferted in the 

 Philofophical Tranf. 1781, p. 341, has fhewn that the Gulf ftream, 

 paffing northwards from the Gulf of Mexico through water feveral 

 degrees colder, lofes only two degrees of heat for every three 

 degrees of latitude it pafTes through ; and Dr. Franklin, in a paper 

 of four years later date, in the fecond volume of the American 

 Tranf. p. 316, informs us that this ftream preferves its fuperiority 

 of temperature at leaft from latitude 25^ to latitude 44^, which 

 it reaches in twenty or thirty days, that is through ig degrees 

 of latitude about 1300 miles; but Sir Benjamin Thompfon (now 

 Count Rumford) in the Phil. Tranf. of 1786, p. 304, has fhewn 

 that atmofpheric air is four times a worfe condudor of heat than 



water 



