INTRODUCTION. 
SIX 
between the rocks of the two hemispheres ; on the physical 
constitution of the air in the equinoctial regions, <fcc. I had left 
Europe with the firm intention of not writing what is usually 
called the historical narrative of a journey, hut to publish the 
fruit of my inquiries in works merely descriptive ; and I had 
arranged the facts, not in the order in which they successively 
presented themselves, but according to the relation they bore to 
each other. Amidst the overwhelming majesty of Nature, and 
the stupendous objects she presents at every stop, the traveller 
is little disposed to record in his journal matters which relate 
only to himself, and the ordinary details of life. 
I composed a very brief itinerary during the course of my 
excursions on the rivers of South America, and in my long 
journies by land. I regularly described (and almost always on 
the spot) the visits I made to the summits of volcanos, or 
mountains remarkable for their height ; but the entries in my 
journal were interrupted whenever I resided in a town, or when 
other occupations prevented me from continuing a work which 
I considered as having only a secondary interest. Whenever I 
wrote in my journal, I had no other motive than the preserva- 
tion of some of those fugitive ideas which present themselves to 
a naturalist, whose life is almost wholly passed in the open air. 
I wished to make a temporary collection of such facts as I had 
not then leisure to class, and note down the first impressions, 
whether agreeable or painful, which I received from nature or 
from man. Far from thinking at the time that those pages thus 
hurriedly written would form the basis of an extensive work to 
be offered to the public, it appeared to me, that my journal, 
though it might furnish certain data useful to science, would 
present very few of those incidents, the recital of which con- 
stitutes the principal charm of an itinerary. 
The difficulties I have experienced since my return, in the 
composition of a considerable number of treatises, for the purpose 
of making known certain classes of phenomena, insensibly over- 
came my repugnance to write the narrative of my journey. In 
undertaking this task, I have been guided by the advice of many 
estimable persons, who honour me with their friendship. I also 
perceived that such a preference is given to this sort of compo- 
sition, that scientific men, after having presented in an isolated 
form the account of their researches on the productions, the 
manners, and the political state of the countries through which 
they have passed, imagine that they have not fulfilled their en- 
gagements with the public, till they have written their itinerary. 
An historical narrative embraces two very distinct objects ; 
the greater or the less important events connected with the 
purpose of the traveller, and the observations he has made during 
his journey. The unity of composition also, which distinguishes 
