663 



zone, had been conjectured from the beginning 

 of the 18th century ; and the questions which 

 the Academy of Science addressed to M. de la 

 Perouse * tended to explain the part which the 

 attraction of the moon might have in these pe- 

 riodical changes. MM. de Lamanon and 

 Monges made, in 1785, a series of very valuable 

 observations in the Atlantic Ocean, lat. 1° 5' 

 N. and 1° 34' S., during three days and three 

 nights, from hour to hour, at a season when the 

 temperature did not change from night to day 

 li° Reaum. : but it remained to verify the 

 uniformity of the progress of the barometer in 

 the interior of the continents, in changeable 

 weather, at various heights above the level of 

 the sea. The solution of those problems was 

 the object of a study which I pursued with the 

 greatest care during four years, north and south 

 of the equator, in the plains and on the table- 

 lands of the Cordilleras, at the height of from 

 1800 to 2100 toises. As no other naturalist has 

 hitherto had the facility of devoting himself to 

 those researches on a scale of height so con- 

 siderable, I shall insert by degrees, in this 

 work, an extract of my horary observations. 

 In order to give more interest to those I made 

 at Venezuela, I have added the barometrical 



* Voyage de la Perouse autour du moade, Vol. \, p. 161 ; 

 Vol. iv, p. 257. 



