718 



the equator. M. Leopold de Bach, in his 

 voyage to the Canary Islands, obtained, after 

 twenty days of barometric observations at Las 

 Palmas, in the Gran Canaria, for the extreme 

 limits, 10 h and ll h in the morning, 4 h in the after- 

 noon, and ll h in the evening*. M. Coutelle, 

 during the course of the meteorological obser- 

 vations, which he was charged by the Institute 

 of Egypt to make at Cairo, in 1799, 1800, and 

 1801, did not know the periodicity of the varia- 

 tions of the barometer between the tropics ; but 

 a few weeks sufficed to shew him that at all 

 seasons, in 30° 3' of north lat., the mercury rises 

 from 5 h to 5£ h in the morning, till 10 h and 10i h ; 

 that it descends regularly till 5h or 5h in the af- 

 ternoon ; that it remounts till 10h or 101 h in the 

 evening, and again descends till 5 h or 5£ h in the 

 morning -f". In our more northern regions of 

 Europe, Van Swinden Chiminello Due Ja 

 Chapelle and Hemmer •j-f-, had remarked 

 during forty years, with more or less certainty, 



* Einige Bemerkungen uber das klima der Canarischen In- 

 seln, p. 9. 



t Description de V Egypt, Mem. d'Hist. nat. Tom. ii. p. 

 335. 



J Jourit. de physique, 1778, Tom. xii. p. 301. 

 § Saggi scienti/i ci di P adorn, 1786, Tom. i. p. 46. 

 ** Bulletin des Sciences, an 7, n. 2, p. 1G2. 

 irf Gren, Journ. der Physik., B. ii, p. 223. {Eyhemeride* 

 Manheim 1783 and 1780.) 



