PREFACE. ix 
be found in the narrative ; but I wish here publicly to 
acknowledge my obligation to Mr. McLane for his gener- 
osity to the expedition. Besides the sympathy accorded 
me by private individuals, I have to thank the Hon. Gideon 
Welles, Secretary of the Navy, for a general order, received 
on the eve of my departure, desiring the officers of the 
United States Navy, wherever I should fall in with them, 
to afford me such assistance in my scientific researches 
as would not interfere with the regular service ; and 1 
learned at Rio that Mr. Seward had warmly recommended 
the expedition to General Webb, at that time United 
States Minister to Brazil. Finally, I would express my 
thanks also to Messrs. Garrison and Allen for the free 
passage offered to myself and my companions for our 
return, on board the line of steamers established be- 
tween New York and Rio de Janeiro during our stay in 
Brazil. 
It will be seen hereafter what facilities were granted 
me throughout this journey by the Brazilians themselves, 
and that the undertaking, so warmly speeded on its way, 
was welcomed no less cordially in the country to which 
it was bound. 
One word as to the manner in which this volume has 
grown into its present shape, for it has been rather the 
natural growth of circumstances than the result of any 
preconceived design. Partly for the entertainment of her 
friends, partly with the idea that I might make some use 
of it in knitting together the scientific reports of my 
journey by a thread of narrative, Mrs. Agassiz began this 
