LETTER TO CAPTAIN HUMPHREYS, TOPOGRAPHICAL ENGINEERS. 



SMITHSONIAN INSTITUTION, Washington, April 7", 185*7. 



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, by the officers in charge, for 

 instructions and suggestions in reference to the development 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 diffusion 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 

 desirable to furnish a general systematic report upon the collections as a whole, and for this 

 purpose the materials were entrusted to competent individuals, the necessary drawings being 

 executed by a skilful artist within the walls of the Institution. 



I now transmit the first part of the general report on the Mammals which has been 

 prepared by Professor Baird, Assistant Secretary of this Institution, and I trust the character 

 of the work is such as to merit the approbation of the Department as well as to advance the 

 interests of science. 



Very respectfully, your obedient servant, 



JOSEPH HENRY, 

 Secretary Smithsonian Institution. 



Captain A. A. HUMPHREYS, Topographical Engineers. 



