File:Astronomy. Determination of time, longitude, latitude, and azimuth (1913) (14594944029).jpg

Identifier: astronomydetermi00usco (find matches)
Title: Astronomy. Determination of time, longitude, latitude, and azimuth
Year: 1913 (1910s)
Authors: U.S. Coast and Geodetic Survey Bowie, William
Subjects: Spherical astronomy
Publisher: Washington, U.S. Govt. print. off.
Contributing Library: Wellesley College Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

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27. A white or black stripe of paint or signal muslin can be placed on the box, cen-tered over the opening, upon which to make observations during the day in order to refer theastronomic azimuth of the mark to a fine of the triangulation. The location of the mark is generally determined, in part at least, by the configuration of theground surrounding the station, but it should not be placed any nearer than about one statutemile in order that the sidereal focus of the telescope may not require changing between pointingsupon the star and upon the mark, since any such change is likely to change the error of collima-tion. Should the mark be closer to the station than one mile and no change bemade in thesidereal focus when pointing upon the mark, there would probably be errors caused by parallax.If practicable, the mark should be placed nearly in the horizon of the station occupied, in orderthat small errors of inclination of the horizontal axis of the instrument may not affect the point-
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