-CHAPTER VIIT. 



ASTRONOMICAL AND GEODETIC WORK. 



PREFACE. 



1. Classes of observations, 



2. Longitude. 



3. Latitude. 



4. Geodetic measurement of azimuth lines 



5. Tracing of parallels. 



6. Computations. 



A. — Determination oe Boundahy Line from the Initlil Point on the Pacific Ocean to 



JUNCTION OF THE GiLA AND COLORADO, 



f 



1. Longitude of Camp Riley, near Initial Point, on tlie Pa- 



cific. 



2. Longitude of junction of Gila and Colorado. 



3. Latitude of Camp Riley, 



4. Latitude of junction of Gila and Colorado. 



6. Triangulation, transferring the determination at Camp 



Riley to Initial Point, on the Pacific. 

 6. Azimuth of straight line from Initial Point, on Pacific, 



to junction of Gila and Colorado. 



B. — Determnation of Boundary Line from Eio Colorado to intersection of 111th meridian 



OF longitude west of Greenwich and parallel 31^ 20' N. 



1* Azimuth line — astronomical positions. 



2. Triangulation for determining longitude of Initial Point 



on the Colorado. 



S. Tabulated results of latitude. 

 4. Distances between monuments 



C. — Determinations 



1. Latitude and longitude of Los Nogales, near intersec- 



tion of 111th meridian and 31^ 20'. 



2. Latitude near the head of Santa Cruz river. 



3. Latitude of San Bernardino. 



4. Latitude of San Luis springs. 

 6. Latitude of Agua del Perro. 

 6. Latitude of Espia. 



7. Latitude and longitude of Carrizalillo. 

 8- Latitude of Initial Point on Rio Grande, 

 9. Azimuths for laying oil the Prime Vertical at above 

 stations. 

 10. Elements for marking parallels of latitude Sl'^' 20' and 



31^ 47'. 



1. Of Longitudes : 



a. Frontera. 

 a'. San Elceario. 



p, — Boundary Line foRMed by the Kio Grande. 



2. Of Latitudes : 



a. Frontera 



6. El Paso del Norte. 



c. Mouth of caSon -where road from San Antonio 



to El Paso strikes the Rio Grande. 



d. Presidio del Norte. 



e. Fort Duncan. 



/. Ringgold barracks. 



g. Mouth of the Eio Bravo del Norte. 



b, San Elceario. 



cailon 



to EI Paso strikes the Rio Grande. 

 d. Presidio del Norte. 

 tf. Fort Duncan. 

 /. Ringgold barracks. 



g. Mouth of Rio Grande. 



E. — Table of Latitudes 



Longitudes of points on and near the Boundary Line between 

 THE United Stated and Mexico. 



Vol . I 



18 



