PREFACE. Xi 
barometrical profiles, and elaborate maps, I could not 
do justice to the subject. In the extensive journeys 
of the Commission through Texas to the shores of the 
Pacific, by the route south of the river Gila, I was 
enabled, with the assistance of the engineers intrusted 
with the survey of this ‘portion of the line, to collect 
much valuable information on the topography of the 
country, for the purpose of enabling the public to 
judge whether or not it is practicable to construct a 
railway there. It is tobe hoped that Congress will see 
fit to lay this information, obtained with so much toil 
and expense, in a suitable manner before the people. 
The maps of the survey, as well as the astronomi- 
cal, magnetic, and meteorological observations, with 
all that strictly appertains to the running and mark- 
ing of the boundary line, were, by the instructions of 
the Secretary of the Interior, placed in charge of the 
surveyor, Brevet Major W. H. Emory, who alone is 
held responsible for the faithful performance of these 
duties. From the high character of that officer as an 
engineer, the public may expect, in proper season, a 
satisfactory account of his labors in these departments. 
Some time must elapse before the maps to illustrate the 
whole Boundary, from one ocean to the other, can be, 
completed ; I have therefore been compelled to con- 
struct meanwhile the map prefixed to this work from 
my own itinerary and from the most authentic informa- 
tion that could be obtained. 
