38 REPORT. 
the result; the preparation of the general map and its engraving; the compilation of profiles 
of all the routes recently explored and previously examined barometrically; the preparation 
of all the maps, profiles, and other drawings made in the office, comprising the duplication of 
the originals received from the exploring parties; the preparation of reports upon those 
routes and portions of routes and lines formerly explored, but not with a special view to the 
railroad question. In addition to this, he has likewise largely aided me in making this 
report. 
This laborious service has been executed by him with great intelligence, zeal, and energy, 
Lieut. H. L. Abbot, topographical engineers, was assigned to duty in this office in October 
last, and has most zealously aided Lieut. Warren in the compilation of the office profiles, 
and assisted me in investigations connected with this report. 
I would especially call your attention to the admirable arrangement of the profiles which 
have been compiled in the office, by Lieuts. Warren and Abbot, exhibiting so well all the in- 
formation upon, and the data and statistics of the routes, (as far as it is possible to compress 
them into so small a space,) as to serve the purpose of a brief report. 
In making this examination I have had the advantage of frequent personal conferences with 
the chiefs of the exploring parties, and with Dr. John Evans and W. P. Blake, esq., geologists. 
I have also availed myself of the information contained in the memoranda upon various 
practical points connected with the construction and working of railroads; prepared in the 
office by Byt. Capt. George B. McClellan, corps of engineers, as suggested by my letter to the 
department of the 7th October last. 
Very respectfully, your obedient servant, 
A. A. HUMPHREYS, 
Captain Topographical Engineers. 
Hon. Jerrerson Davis, 
Secretary of War. 
