696 



is somewhat vague, because the time that the 

 mercury continues to preserve its maximum and 

 minimum of height, is comprehended in the ex- 

 pressed interval. The tendency of the mercury 

 to descend, or rather the interval between the 

 maximum of the morning, and the minimum of 

 the afternoon, can only be determined by 

 knowing with precision the half-duration of 

 the stationary states near the limits of 10 h and 



The observations published at Calcutta being 

 the only ones that have been made during a 

 whole moon, every half-hour, served me to find 

 -the difference between the real and apparent 

 maxima. The following is the tropical instant y 

 and the duration of the stationary state, for 

 twentyrseven days. 



