File:Report of the Boundary commission upon the survey and re-marking of the boundary between the United States and Mexico west of the Rio Grande, 1891-1896 (1898) (14786292013).jpg

Identifier: reportofboundary00inte (find matches)
Title: Report of the Boundary commission upon the survey and re-marking of the boundary between the United States and Mexico west of the Rio Grande, 1891-1896 ..
Year: 1898 (1890s)
Authors: International boundary commission (United States and Mexico) 1882-1896. (from old catalog)
Subjects:
Publisher: Washington, Govt. print. off.
Contributing Library: The Library of Congress
Digitizing Sponsor: Sloan Foundation

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s, supported only atthe four corners, was laid, on which was erected a tent in the form of a lean-to shed, with roofsloping toward the north, and o))enings the whole length of the roof over each instrument. Thesides and roof of the tent were suijported and stiffened by a framework of wood and held in placeby rope guys at corners and sides. The hollow wooden piers were very satisfactory and proved as firm as masonry. At Nogalesand Yuma the zenith telescope was mounted on the brick piers used by the United States Coastand Geodetic Survey longitude party, and at those places the observatories were of wood. Acomparison of the results obtained at these stations with those where the wooden piers and tentwere used were all in favor of the latter. The instrument changed less in level during the nightwhen mounted on the wooden pier, and the temperature inside the tent was more nearly the sameas the outside air. The usual difference was 1° C. only, which rendered the stars observed verysteady.
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UNITED STATES AND MEXICAN BOUNDAEY. 33 LONGITTDES. The original plan agreed on by the joint commission for running the boundary was to determineboth the latitude and longitude of the extremities and turning points of the boundary, at or nearwhich points the monuments erected by Emory were reported as still standing, and to observe forlatitude and azimuth on the parallels at points about 20 miles apart. Dr. T. (J. Mendenhall, Superintendent United States Coast and Geodetic Survey, at the requestof the State Department, detailed a party to determine the longitude of five points, viz: El Paso,the monument at the intersection of parallel 31° 47 with the meridian, Kogales, Yuma, and oldMonument Xo. 1 on the Pacific, near San Diego. The field work was completed between Januaryand June, 1892. The method used was exchange of signals by telegraph. Usually ten nights exchanges wereobtained, five with one observer at eastern station and the other at western, then five more withthe positions of

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