33G SEA VOYAGES VEBSU8 LAND JOUIINEYS. 



limit of perpetual snow within the polar circle and on 

 the borders of the torrid zone ; of the variable intensity 

 of the magnetic forces, and of many other phenomena 

 equally important. 



" Maritime expeditions and circumnavigatory voyages 

 have conferred just celebrity on the names of the natur- 

 alists and astronomers who have been appointed by 

 various governments to share the dangers of those under- 

 takings ; but though these eminent men have given us 

 precise notions of the external configuration of countri 

 of the natural history of the ocean, and of the productions 

 of islands and coasts, it must be admitted that maritime 

 expeditions are less fitted to advance the progress of 

 geology and other parts of physical science, than travels 

 into the interior of a continent. The advancement of the 

 natural sciences has been subordinate to that of geography 

 and nautical astronomy. During a voyage of several 

 years, the land but seldom presents itself to the obser- ' 

 vation of the mariner; and when, after lengthened expec- 

 tation, it is descried, he often finds it stripped of its most 

 beautiful productions. Sometimes, beyond a barren coast, 

 he perceives a ridge of mountains covered with verdure, 

 but its distance forbids examination, and the view serves 

 only to excite regret. 



" Journeys by land are attended with considerable diffi- 

 culties in the conveyance of instruments and collections, 

 but these difficulties are compensated by advantages 

 which it is unnecessary to enumerate. It is not by 

 sailing along a coast that we can discover the direction 

 of chains of mountains, and their geological constitution, 

 the climate of each zone, and its influence on the forms 

 and habits of organized beings. In proportion to the 



