737 



the extent of every tide, produces on the back 

 of the mountains, a surprising uniformity in 

 the mean barometric heights of the months. I 

 shall here present successively the results of the 

 observations made on the same spot (at Santa 

 Fe de Bogota), in 1 807 and 1818, by M. Caldas, 

 and in 1823 and 1824, by MM. Boussingault 

 and Rivero. The latter, made with much more 

 exact instruments, merit the highest confidence. 

 M. Caldas finds for the twelve months of the 

 year 1807: 



MAXIMA. 





MINIMA. 



DIFFERENCE. 



January 



247.23 



247.60 



1.65 



February 



249.33 



248.33 



1.00 





249.33 



247.93 



1.40 





249.42 



247.92 



1.50 



May 



249.67 



248.00 



1.67 





249.67 



248.00 



1.67 



July 



249.50 



247.83 



1.67 



August 



249.42 



247.92 



1.50 



September 



249.42 



248.00 



1.42 



October 



249.33 



247.91 



1.42 





248.92 



248.00 



1.92 





248.85 



247.60 



1.15 



The mean of 642 barometric heights, observed 

 by the same naturalists, from January to July 

 in the year 1808, presents the following re- 

 sults : 



VOL, VI. 



