571 



The mean temperatures of twenty-one fine days differed 

 lat Cumana 3*4° ; at Caraccas, 3° cent, therm. The least 

 differences between the mean temperatures of the two places 

 did not always take place, when the weather was hottest 

 at Caraccas j they oscillated between 4*8°, and 8*2°. The 

 mean of all the differences was 6*8o (5*5 0 Reaumur), nearly 

 one hundred and thirty-two metres to a centesimal degree. 

 The valley of Caraccas is colder than it should be for an 

 elevation of nine hundred metres, and this circumstance 

 renders the decrement of heat extremely rapid. The mean 

 of all my observations made between the tropics gave me, 

 for the first strata of air comprised between the level of the 

 sea and one thousand metres of elevation, one hundred and 

 seventy metres corresponding to 1° of the cent, therm v or 

 one hundred and nine toises to 1° of Reaumur. 



