4 
ORGANIZATION OF PARTY. 
“From the point marked ‘ Brackish pools/ just east of Salt lake, as far east as the first 
stream marked £ Sienega,’ along the dotted red line, a survey and line of barometric levellings 
has been carried by the Mexican boundary survey. But it would he well to make the survey 
continuously along the red and blue line eastwardly until it strikes Cook’s wagon trail, and 
thence by the shortest distance and most practicable route to the valley of the Bio Bravo, to 
some point between ‘ Dona Ana’ and ‘Frontera,’ eight miles north of El Paso. 
“ A more eligible and direct route from the region of the said Salt lake to the point indicated 
on the Bio Bravo may he found. If information or observation on the ground shall so suggest, 
you will not confine yourself to the wagon trail described, hut depart from the line indicated 
at any convenient point. 
“Bear in mind these wagon trails are faint, and not as broad or well marked as the great 
emigrant trail known as Cook’s route, which, having been sufficiently explored, will not re¬ 
ceive your attention. The levels have been carried continuously by Major Emory along the 
valley of the Gila, and it might facilitate the operations not to unpack the barometer until the 
party shall have reached the point of departure from the Gila. 
“As the whole, country between the Gila and the Bio Bravo embraced in the parallels of lati¬ 
tude 32° and 34° has been well covered with astronomical observations, it will probably not he 
necessary for you to impede your progress in checking the run of your work by elaborate astro¬ 
nomical observations. A sextant and chronometer, by which you can obtain your latitudes, will, 
it is believed, prove sufficient to check your work. 
“The profile of the region traversed, showing the gradients which a road passing over it 
must encounter, is the information most wanted. It is therefore recommended that you take 
the barometric height at every point on the line to he surveyed which may he important in the 
elucidation of this subject. 
“On reaching the Bio Bravo, it may add little to the expense of your party to bring it all the 
way in to the settlements on the Bed river. If so, you will take some new route from Dona 
Ana, passing through the northern part of Texas, and make a barometric levelling of the same. . 
“Very respectfully, your obedient servant, 
“ JEFFEBSON DAVIS, 
“ Secretary of War. 
“ Lieut. J. G. Parke, 
“ Corps of Topographical Engineers, San Diego, California.” 
These instructions, with passport accompanying them, were received in San Diego, California, 
December 20,1853,* on my return from an examination of the Jacum Pass, made under orders 
from Lieut. Williamson, corps topographical engineers. After receipting to Lieut. Williamson 
for so much of his property, including instruments, as was serviceable and necessary, I com¬ 
menced the organization and equipment of a party, hut found it imperative on me to repair to 
San Francisco for the purpose of securing the services of an assistant, and procuring funds and 
additional instruments ; in all of which I succeeded, with the exception of obtaining a mountain 
barometer, there not being a single one available in that section of the country. Having re¬ 
turned to San Diego and completed the outfit of the party, which numbered in all fifty-six souls, 
we took our departure from the quartermaster’s depot on the afternoon of January 24, 1854. 
The party was organized as follows : Mr. Henry Custer, assistant and topographer; Dr. A. L. 
Heermann, physician and naturalist; Lieut. George Stoneman, first dragoons, commanding 
escort of twenty-eight men, and also undertook the duties of quartermaster and commissary of 
the expedition, in the discharge of which were employed eighteen men ; five additional men 
assisted in carrying barometers and tripods. 
From San Diego we followed the emigrant route known as the Southern, via Warner’s rancho, 
in the coast range, across the Colorado desert, to Fort Yuma, at the junction of the Gila and 
* See “ A, ” in the Appendix. 
