774 



particularly fixed my attention at the peiiod 

 when I quitted Europe. I had carefully com- 

 pared two of my barometers with that from 

 which M. Bouvard published the meteorologi- 

 cal variations made at the observatory of Paris. 

 I thought I should find at Cumana * on the sea 

 shore, the mean height of 337.8 h , or 762.02 rnm , 

 at 25° of the centigrade thermometer, which 

 gives at the temperature of zero, 758.59 mm „ 

 As at this period (1799) the mean height at the 

 level of the sea in Europe -f^, was supposed, ac- 



* M. Caldas, whom sanguinary political re-actions 

 snatched from the sciences at an age when he could still 

 hare rendered them much service, thinks that the difference 

 of the mean height between my observation and that of 

 Shuckburg, arises from the little accordance to be found be- 

 tween a column of mercury boiled, or not boiled in the 

 tubes. (Semanario, Tom. i, p. 52.) This cause could not 

 influence my observations at Cumana and La Guayra. 1 

 had brought from Europe to Caraccas two barometers, of 

 which the mercury had been boiled in the tubes with the 

 greatest care, by very able artists. 



f M. Oriani finds, for Milan, the mean height on the 

 coast of the Adriatic (at 13.5° cent, of temperature) 338.23 1 *, 

 which gives 761.73 mra at the temperature of zero. The mean 

 barometric height at the Havannah, according to M. Ferrer, 

 is 25.7° cent. 338.55 u , or 763.71 mm , or at 0« temp. 760.18. 

 This result is identical with that of M. Boussingault ; but we 

 are ignorant of the elevation of M. Ferrer's barometer above 

 the level of the ocean, and the precautions employed at Mi- 

 lan and the Havannah to know the capillarity of the tubes. 

 See Dei combustibili, Memoria del Conti Bevelacque-Lanzisc, 



