LETTEB TO CAPTAIN HUMPHREYS, TOPOGRAPHICAL ENGINEERS. 



Smithsonian Instiiution, Washington, March 1, 1856. 

 Sir : During the first organization of the parties for the survey of a railroad route to the 

 Pacific, application was made to the Smithsonian Institution, hy the officers in charge, for in- 

 structions and suggestions in reference to the investigation of the Natural History of their 

 respective lines. These were cheerfully furnished, as in accordance with the objects of an 

 establishment intended for the increase and difi'usion of knowledge. The specimens in Zoology, 

 as collected, were transmitted from time to time to the Institution, and properly preserved 

 until the return of the parties. A series of special reports was prepared by the naturalists of 

 the expeditions ; but as these were necessarily disconnected and incomplete, it was deemed 

 advisable to furnish a general systematic report upon the collections as a whole ; and this being 

 sanctioned by the War Department, the materials were entrusted to competent individuals for 

 this purpose, the necessary drawings being made by a skilful artist within the walls of the 

 Institution. 



The first part of the general report having been already furnished, I now transmit the 

 remainder, with the hope that its execution will be satistactory to the Department. 

 Very respectfully, your obedient servant, 



JOSEPH HENRY, 

 Secretary Smithsonian Institution. 

 Captain A. A. Humphreys, Topographical Engineers, 



In charge q/" Office of Explorations and Surveys, War Department. 



