PREFATORY NOTE. 



Subjoined are extracts from the Annual Reports of the Secretary of War, transmitted to 

 Congress in December, 1855 and 1856, and also the accompanying yearly reports of Captain A. 

 A. Humphreys, Topographical Engineers, in charge of the office of Pacific Railroad Explora- 

 tions and Surveys. These extracts and reports furnish, up to their respective dates, information 

 in regard to the condition and progress of tlie several War Department explorations, and 

 present the leading facts and results determined by each. They form, therefore, a proper 

 conclusion to the series of special reports upon the different lines of survey. 



An annexed table, similar to that contained in the Report of the Secretary of War, in Vol. I, 

 exhibits the comparative lengths, cost, &c., of the various railroad routes, according to the 

 latest corrections and revisions. Explanations are given of some of the more important modifi- 

 cations of the previously reported results. 



