700 



! A. Within the tropics, or near their limits, 

 A new revision of all the observations I had 

 made, north and south of the equator, in Span- 

 ish America, from 23° north latitude, to 12° 

 south latitude, in the low regions of the steppes, 

 and forests, and on the back of the Cordilleras, 

 where the mean temperature is equal to that of 

 the north of Europe, has not obliged me to mo- 

 dify the results which I published in the Physi- 

 cal Table of the equatorial regions. I every 

 where observed that the barometer attains its 

 maximum at 9 h or 9i h in the morning ; that it 

 descends slowly till noon, but rapidly from 

 noon till 4i h ; that it re-ascends till ll h at 

 night, when it is a little lower than at 9 h in the 

 morning; that it sinks slowly all night till 4 h 

 in the morning, and again rises till 9 h . The 

 duration] of the stationary state was so short 

 at Caraccas, Cumana, and Mexico, that, for 

 the maximum of the morning, for instance, the 

 mean of my observations yields, real epocha, 

 9 h 20' ; apparent epocha, 9 h 5'. I passed a great 

 number of days near the instrument at the tro- 

 pical hours, in order to ascertain if they were 

 rather 9 h than 9i h ; rather 4 h than 4i h ; and I 

 observed, as I have already said, that in some 

 places of the torrid zone, the moment when the 

 pressure of the air begins to dimmish is so 

 marked, that the barometer indicates the real 

 time within a quarter of an hour. When the 



