VI 



peared to me, that the importance of the 

 results hitherto obtained did not keep 

 pace with the immense progress, which se- 

 veral parts of science, and particularly geo- 

 logy, the history of the modifications of 

 the atmosphere, and the physiology of 

 animals and plants, had made at the end 

 of the eighteenth century. I saw with re- 

 gret, and all scientific men have shared 

 this sentiment, that whilst the number of 

 accurate instruments was daily increas- 

 ing, we were still ignorant of the height of 

 so many mountains and "elevated plains ; 

 of the periodical oscillations of the aerial 

 ocean ; the limit of perpetual snows under 

 the polar circle, and on the borders of the 

 torrid zone; the variable intensity of the 

 magnetic forces, and so many other phe- 

 nomena, equally important. 



Maritime expeditions, voyages round 

 %e world, have conferred just celebrity on 

 the names of those naturalists and astro- 

 nomers, who have been appointed by go- 

 vernments to encounter the dangers they 

 present ; but while those distinguished per- 

 sons have given precise notions of the ex- 

 ternal configuration of countries, of the 



