X PREFACE. 



vidaals who united themselves with me in effecting 

 the organization of the Expedition, and who Hber- 

 ally shared with me its expenses. My wishes were 

 always promptly met by them, to the extent of their 

 ability ; and the enterprise was sustained with a zeal 

 and interest rarely accorded to a purely scientific 

 purpose. That I have not before published an ac- 

 count of my voyage, or presented any detailed state- 

 ment of my discoveries to those who had a natural 

 right to expect it, has been entirely owing to the 

 circumstance that my time has been wholly occupied 

 in the public service, from the period of my return 

 until late last year ; and they will, I trust, accept as 

 a sufficient excuse for my silence during that period, 

 the fact that the command of an army hospital, with 

 from three to five thousand inmates, which devolved 

 upon me during the greater part of the recent war, 

 allowed me little leisure for literary or scientific 

 work. It will also be understood that the tempo- 

 rary abandonment of the exploration was due to the 

 same general cause. 



October 23d, 1866. 



