29* 



M. Humboldt on the Horary 



In this table, the heights are reduced to 32° Fahr., but, in 

 order to correct them for capillarity, and the error of level, 

 we must add 0.922 of a millimetre. 



2. M. Duperry's Observations at the Port of Payta, in 5° 5' 

 of South Lat. in 1823. 



Mar. 12, C h a. m. 



7 



8 



84 



81 



9 

 10 

 11 

 12 



2 p. M. 



3 



4 



5| 



6 



9 

 10 

 10^ 

 11 



_ Centigrade 

 Ba /°- Thermo- 

 meter - meter. 



762.20 

 762.40 

 762.40 

 762.70 

 762.80 

 762.70 

 762.50 

 762.10 

 761.50 

 759.80 

 759.20 

 759.20 

 759.20 

 759.30 

 761.40 

 762-30 

 762.30 

 762.40 



25.0 

 25.3 

 25.9 

 26.7 

 26.7 

 27.2 

 26.8 

 26.9 

 28.2 

 28.7 

 29.1 

 28.8 

 27.6 

 27.7 

 26.9 

 26.7 

 26.3 

 26.2 



ill 



12 



Mar. 13, 1 a. 

 2 

 2J 

 3 

 4 

 5 



9* 



10 

 12 



M. 



r. si. 



4 



5 



10 



11 



12 



„ Centigrade 



Baro " Thermo- 

 meter. 



762-20 

 762-30 

 761.30 

 761.10 

 760.70 

 760.80 

 761.20 

 761.50 

 762.30 

 762.20 

 761.20 

 759.80 

 759.80 

 760.00 

 761.60 

 762.50 

 762.80 



meter. 



26.1 



26.0 



25.8 



25.5 



25.3 



25.3 



25.3 



25.6 



27.0 



26.8 



29.5 



30.9 



30.5 



30.4 



27-3 



27.4 



26.4 



Although M. Van Swinden announced, in 1776, the exist- 

 ence of horai'y variations in the north of Europe, and fixed 

 the maximum and minimum at -f- lj h ; — 6 h ; -+- 10 h ; — 22 h 

 astronomical time, yet we owe the first precise observations to 

 M. Ramond. " I have obtained," says this excellent observ- 

 er, " results very analogous to those which M. Humboldt has 

 brought from the Equator, but the hours of the variation 

 differ according to the season. For winter, the tropical Iwurs 

 (the hours at which the motion returns upon itself) are 9 h a. m., 

 3 h P. M., and 9 h p. m. In summer, the fall appears to begin 

 from 8 h a. m., and to continue till 4 h p. St., and does not re- 

 commence till 10 h p. m." 



In consequence of the singular regularity of the barometri- 

 cal variations at Bogota, MM. Boussingault and Rivero have 

 detected a monthly variation in the oscillations of the mercu- 

 ry, the mean monthly height being greater in June and July, 



11 



