139° [ 26] 
THE MAP. 
The map which accompanies this work is based, as far as my own route 
is concerned, upon astronomical observations made at the principal places, 
upon daily observations of the compass, and in regard to localities which 
I have not visited, upon the best authorities in existence. The latitude 
and longitude of many places in Mexico will be found to differ often 
widely from their positions on Mexican maps, which lay the latitudes gen- 
erally too far north ; the longitudes too far east. 
Being rather poorly provided with astronomical instruments; occupied, 
besides that, in the most various pursuits, and having no scientific assist- 
ance whatever, I had to confine my astronomical observations only to th 
principal stations. But as on the northern part of my route many points 
ad bee already determined by former explorers, and in the southern 
part I enjoyed the valuable aid of Dr. J. Gregg, (as mentioned in the 
preface,) sufficient points have been ascertained for the practical purposes 
of a map, whose principal object is to enable the reader to follow my route 
and to correct the many gross errors, not only in minutes but even in 
degrees, that are commonly found in Mexican maps. In connecting my 
daily sketches, I have laid down the country only as far as it fell under 
my own observation, leaving to future explorers to ascertain the regions 
beyond that. : 
Taken as a whole, therefore, I believe that this map, though by no 
means as tas I wish it fo be, will at least be found more correct 
7 
rest to the public. Besides that, I have laid down the march of General 
Fort to Santa Fe, according to the unofficial memoranda of several offi- 
cers of those corps, (I claim, therefore, no authenticity for them,) and have 
added all the rest of the most interesting routes that have ever been trav- 
elled from the United States and Texas, to New Mexico and Chihuahua. 
oa” agli’ Si i eens 
