I48 TRAVELS IN UPPER 



breaks ; that all her productions were mutually 

 connected ; that the transition from class to class, 

 from genus to genus, from species to species, was 

 conducted by gradual shades of difference ; and 

 that those classes, those genera, those species were, 

 in the eyes of the philosopher, only so many signs 

 calculated to relieve the mind, so many divisions 

 to assist the memory. 



Though the transition from quadrupeds to birds 

 has not been hitherto distinctly traced, though all 

 the points of it be not yet ascertained, we are not 

 the less warranted to consider this union as existing : 

 we have the commencement of it in the jcrbo, and 

 the last gradation in the bat. There is all the rea- 

 son in the world to believe, that the series of suc- 

 cessive shades will unfold itself in proportion as good 

 observers shall devote themselves to travelling, in 

 countries not yet disclosed to natural history. I am 

 convinced that the interior of Afriea, a region to 

 this day virgin in respect of discovery, contains a 

 multitude of new and valuable objects, the know- 

 ledge of which would diffuse light inconceivable 

 on all the parts of general physics. May I be per- 

 mitted, in this place, to communicate the design 

 which I had formed, some years ago, of penetrat- 

 ing into those regions which, till now, have been 

 deemed, inaccessible ? jMy intention was to range 

 the whole length of the continent of Africa, through 



its 



