PREFATORY NOTE. 
Subjoined are extracts from tbe 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 the 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 Yol. 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. 
