744 



The movement of the barometer at Bogota 

 is of surprising regularity ; the mean heights 

 acquire their minimum at the winter solstice, 

 augment till after the summer solstice, and 

 again decrease, without presenting any other 

 anomaly than that of the month of May. This 

 new and curious remark, is owing to the ob- 

 servations of MM. Boussingault and Rivero, 

 and which those able naturalists found confirm- 

 ed by the observations of M. Caldas, made in 

 1807. In our temperate climates, at Stras- 

 bourg for instance, the observations of M. Her- 

 renschneider, during fourteen years, (indicated 

 in lines of the French foot, and reduced to 15° 

 centigrade temperature,) prove that the month- 

 ly mean * is highest in September, and lowest 

 in April ; in general however, the mean heights 

 from June to September exceed those from 

 October to February. The extent of the ex- 

 treme variations in Europe presents great re- 

 gularity ; it decreases from winter to summer. 



In the town of Mexico -f-, although near the 

 tropic, I have hitherto found the extent of the ho- 



* Seven years have proved to M. Ramond (Mem. de 

 VInst., 1812, Tom. ii, p. 44) that the mercury is highest at 

 Clermont, in January and June, and lowest in April and 

 November. ; i ^ 



f This phenomenon, which is very'common at Vera-Cruz 

 in the season of Nortes, was observed at Mexico (at 1168 t. 

 high) once only in a great number of years. (Antonio Gama> 



