OF THE BOUNDARY COMMISSION. 543 
At most of these stations the three elements of inclina- 
tion, declination, and intensity were observed. 
6. A chain and compass survey was made by A. B. 
Gray, Hsq., Principal Surveyor, his first assistants 
being John Bull and J. H. Prioleau, Esqs., from the 
point where the southern boundary of New Mexico 
strikes the river Gila to a point about seventy miles 
above its junction with the Colorado, about four hun- 
dred miles. This survey was independent of that 
made by Lieut. Whipple.* 
7. In returning from San Diego, California, the 
unfinished portion of the survey of the Gila was com- 
pleted by Lieut. Whipple; after which our parties 
again united at the Pimo Villages, on the Gila) We 
then returned together to Hl Paso by a different route 
from that taken on our journey out, thereby enabling 
us to collect much valuable information in the north- 
ern portions of Sonora and Chihuahua not previously 
explored by a scientific party. On this journey or 
reconnoissance (to use a military term), of which a 
detailed account is given in this work, an elaborate 
series of astronomical and meteorological observations 
were made by Lieut. Whipple in the same manner 
as those before mentioned. The true position in lati- 
tude and longitude of Tucson, Tubac, Santa Cruz, Gua- 
dalupe Pass, Janos, and Correlitos, besides intermediate 
points, was then first determined by this officer; and 
the mountains, streams, and other geographical features 
* T regret that [am unable to speak more fully of this survey, as 
Mr. Gray has never furnished me the details or made any official report 
to me. : 
