600 APPENDICES. 
nada must be traversed to Tucson in Mexico; thence crossing the Rio 
San Pedro, a road may pass from spring to spring—leaving the Guada- 
lupe Pass to the south—and may proceed in the vicinity of the south- 
ern boundary of New Mexico to Dofia Ana. Four permanent military 
posts should at the same time be established near this route; one at 
Col. Craig’s “ Cantonment Dawson” among the Copper Mines of New 
Mexico, where a well-watered and fertile valley, rich in precious metals, 
would soon support a flourishing settlement; one at the mouth of the 
Rio San Pedro, where the Pinal Llefio Indians would be intercepted in 
their marauding expeditions to Sonora; and the third upon the excel- 
Jent cotton-lands at the mouth of the Salinas. The fourth, upon the Co- 
lorado, has already been established by order of the War Department. 
By treaty stipulations with Mexico, it is solemnly agreed, that all in- 
cursions into her territory of our savage tribes shall be forcibly re- 
strained by the government of the United States. At present, Indian 
depredations in Sonora are notorious. Scores of our own citizens also 
have been slaughtered by these roving robbers, and we have seen their 
bones bleaching by the road-side. The government is, therefore, bound 
to station a strong military force upon the frontier. Protection to the 
settlers will enable the resources of the country to be developed ; emi- 
grants, assured of safety and supplies at these depots, will avoid the perils 
and expense of a sea yoyage; and it will soon be seen whether the 
wants of the people require, so as to render advantageous, the construc- 
tion of a canal or railway which may in part run upon the river Gila. 
The construction of a wagon road by the route proposed through 
Sonora for the use of both countries, would be of no Jess advantage to 
Mexico than to the United States. An agreement to this effect is, in 
fact, necessary to the fulfilment of the treaty stipulations with reference 
to the protection of the frontier. This done, and some slight encour- 
agement given to trade, and the now half-depopulated province of Sonora 
will soon become one of the most flourishing States of Mexico. 
From the day of first striking the Gila to the time of reaching its 
mouth, seventy days, astronomical observations were made every night 
except two, which were cloudy. The whole number of astronomical 
and meteorological stations upon the Gila were forty-six. Nearly all of 
these were also magnetic stations. Between the mouth of the Gila and 
‘this place are three intermediate astronomical and magnetic stations, 
besides those made on my trip from San Diego to the Colorado in Sep- 
