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30 



JOURNAL OF THE JOINT COMMISSION. 



eed 



That the plan of triangulation is impracticaLle; that the American and Mexican surveying 

 -rty shall proceed forthwith to run the unfinished portion of the line ; take the topography 

 Rr thft line : erect monuments at points where the line crosses a mine, a settlement, a road. 



or water. 



It is agreed if either party hreak down^ the other is not to suspend or delay operations in 

 consequence of it. 



determine 



he furnished 



American commissioner^ who agrees to accept that determination. 



It is further agreed that the convention entered into between Senor Jimenez 

 Michler^ April 26, and the additional article agreed upon May 1, 1855; are ap] 

 articles not in conflict with this convention. 



W, H. EMORY, 



United States Commissioner 

 FEANO, JIMENEZ, 



First Engineer de la Como. de Limitcs 3Iexicano 



Los NoGALES, June 21, 1855. 



The Mexican commissioner having approved this step on the part of the first engineer of his 

 commission, the United >States commissioner gave a hrief legend of operations up to the 111th 

 meridian of longitude^ and invited Mr. Salazar to inspect the notes, astronomical and geodetic, 

 upon which the line was hased, and the rough draughts of the maps made in the field. 

 The following is the substance of the legend ; 



After concluding all operations in the vicinity of the Rio Bravo, and pushing the line as far 

 as was convenient, from that place, an astronomical station was estahlislicd at Carrizalillo, 

 which proved, from *I2 ohservations with 46-inch zenith telescope, to he in latitude 31^ 50' 

 55^'. 23 north ; and longitude 107^ 56' 03'^90, the result of ohservations during one lunation. 



Carrizalillo was t"he nearest water to tlie terminal point of the 100-mile line near to parallel 

 31° 47'. A monument was established on the road due south of the observatory, and the 

 parallel extended in both directions — east, until it met, in the sand-hills, the line produced from 

 the Eio Bravo; west, it was extended to the end of the 100 miles, and the parallel was obtained 

 by measuring ordinates from the tangent. The 100 miles was obtained by combining the 

 observed longitude at Carrizalillo, and the distance actually measured. 



From the end of the 100 miles a line was produced due south to meet the parallel of 31° 20'. 

 The reconnoissance to find water at the junction of the meridian and 31° 20' failed, and the 

 observatory was established at the Espia, on the Rio Janos, ten or twelve miles cast of the 

 meridian. An elaborate set of observations (81) with zenith telescope, gave us the latitude of 

 this observatory 31° 20' 56".45 ; the tangent of 31° 20' was determined from this by direct 

 measurements and produced to Intersect meridian, and ordinates laid off to ascertain parallel. 

 After producing parallel about seven miles, it was ascertained, as will be seen by the map, that 

 the Ojo del Perro was near the line. The zenith telescope was reset, and a new tangent ob- 

 tained ; which result corresponding well with the last, this tangent was produced to the San 

 Luis range of mountains. At the San Luis springs, about thirty miles west of the initial point of 

 the parallel Sl° 20', a new observatory was erected, the latitude of which (31° 20' 31".51) was 



