TO THE COPPER MINES. 
203 
to 22' of arc. This reduced by Francoeur’s tables, is 
equal to 40,659 metres = 25J- English miles ==2192 
Geographical miles. 
“Finally, taking the distance from the point afore- 
said to the extreme Western limit of the Southern 
Boundary of New Mexico, and applying this distance 
to our scale of minutes of arc in longitude, we found it 
to be 3°; which in this latitude, according to tables 
of Francoeur is equal to 2822202 metres = 17528 
English miles = 15414 Geographical miles. 
/ ‘ Therefore, according to this determination, the 
point where the middle of the Eio Grande strikes the 
Southern Boundary of New Mexico, is 22' of arc north 
of the parallel of latitude marked 32° upon the map. 
From the same point thence the Southern Boundary 
of New Mexico extends 3® to its Western termina- 
tion. 
“Signed, A. W. WHIPPLE, 
“ Lieut. U. S. Topographical Engineers, 
JOSE SALAZAR 
Y Larregui. 
“ Paso del Norte, December 23d, 1850.” 
The Astronomers were now directed to determine 
the point referred to by astronomical observation ; and 
as soon as the weather permitted, they entered on the 
performance of their duties. On the 10th of April, 
Lieut. Whipple informed me that Mr. Salazar and him- 
self had agreed upon a point on the Rio Grande, the 
result of nearly five hundred observations on eleven 
stars, which they recommended to the Joint Commis- 
