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SIXTH OBSERVATION, 



" In calm weather, when the air is inclined to rain, the ^ is 

 " commonly low." 



SEVENTH OBSERVATION. 



" Upon very high winds, though not accompanied with rain, 

 " the ^ finks loweft, having regard to the quarter from whence 

 " the wind blows." 



EIGHTH OBSERVATION. 



" In ferene and fettled weather the ^ is generally high, as 

 " alfo in calm and frofty weather." 



. NINTH OBSERVATION. 



" The greateft heights of the 5 arc found upon eafterly and 

 " north eafterly winds ; to which we may add, that under a 

 " foutherly wind it is commonly low." 



The caufes to which thefe phasnomcna have been afcribcd, 

 are, firft, variations of temperature ; fecondly, the velocity and 

 other qualities of different winds ; thirdly, the agency of 

 vapors. 



Of the Influence of different Temperatures. 



That air is rarified by heat and condenfed by cold is well 

 known ; and it is equally fo, that denfe air is heavier than that 



H which 



