686 



sufficiently with the horary variations of the 

 magnetic inclination. Amidst the most violent 

 rains, winds, and storms, the mercury rises or 

 sinks, if it be its time to mount or descend, a$ 

 if the air were perfectly calm. The same varia- 

 tion takes place at Senegal ; for Mr. Adamson, 

 to whom I mentioned it on my arrival in 

 France, had verified the fact by a long series of 

 observations made by a friend in Africa, to 

 whom he had sent a barometer." 



Since the year 1761, Doctor Mutis, who cul- 

 tivated every branch of physical science with 

 success, observed the atmospheric tides at 

 Santa Fe de Bogota, with the greatest assiduity, 

 and during forty years. Above all, he fixed 

 with precision the period of the minimum which 

 precedes the sunrise *. Unfortunately, this 

 great mass of observations, which their author 

 concealed with too much care during his life, 

 was only published after his death. M. Mutis, 

 in New Grenada, and Alzate and Gama, in 

 Mexico, are the first naturalists who examined 

 the phenomenon of the horary variations on the 

 back of the Cordilleras, at 1200 to 1400 toises 

 above the level of the sea. Alzate speaks of the 

 hours of the maximum and the minimum, in the 



* Papel per de Santa Fe de Bogota, para 7 Febr- 1794, p. 

 128 j and Semanario de el Nuevo Hey no de Gran., Tom. i, p. 

 55, 128. 



