APPENDIX C. 
LETTER ACCOMPANYING REPORTS OF DR. COOPER AND DR. SUCKLEY 
Washington City, February 3, 1859. 
Sir: We have the honor herewith to present our report on the natural history of the expe¬ 
dition, made in 1853- 54, for the exploration and survey of a route for a railroad near the 47th 
parallel, from the Mississippi river to Puget Sound. 
For the means of preparing these reports in their present form we are chiefly indebted to 
the facilities placed at our disposal by Professor Henry, Secretary of the Smithsonian Institution, 
in the use of office rooms, free access to the library and collections of the Institution, and such 
other aid and counsel as the occasion required. 
For the elaboration of the scientific descriptions, names, and classification of the materials 
collected, we are chiefly indebted to the aid of Professor S. F. Baird, of the Smithsonian 
Institution, and to the gentlemen who assisted him in preparing the general reports on the 
zoology of the various Pacific railroad expeditions, especially to Messrs. G. N. Lawrence, J. 
Cassin, Dr. C. Girard, W. Stimpson, R. Kennicott, and W. Cooper. In the botany, we are 
indebted to Professor Gray, of Harvard University, and to Professor Torrey, late of Princeton 
College, for most of what is scientifically important. In collecting specimens and information, 
we have in the proper places acknowledged the assistance of many gentlemen in Washington 
Territory and elsewhere. 
Our personal labors have been principally in collecting the specimens and information 
concerning them, in comparing and arranging the materials collected, and in making such 
corrections in the technical descriptions as our observations in the field enabled us to do with 
propriety. Otherwise, we have quoted these portions from the elaborate works of the gentle¬ 
men above named. 
It has been our object to present such a report as would be both interesting and instructive 
to the public at large, divested of all such technicalities and discussions as, though eminently 
important and necessary for the establishment of natural science on a true basis, are yet dry to 
the general reader, and unimportant to our present purpose. At the same time we believe, 
that through the completeness in this respect of the general reports referred to, but few 
technical errors will be found to have crept in. Our references to American authors on 
the subjects mentioned are very complete, and the reader will thus find means of further 
information on the more abstruse points referred to. 
We have paid attention particularly to the perfection of those portions relating to Wash¬ 
ington Territory, both because more novelty and interest is connected with the productions of 
that country, and because our residence there of several years each enabled us to collect much 
more than we could on other parts of the route. Still, most of the specimens collected in 
Minnesota and Nebraska are mentioned, especially such as are of new species. 
