File:Astronomy. Determination of time, longitude, latitude, and azimuth (1913) (14779233964).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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as it crosses the field. As the wire passes the various positions corresponding tocontacts on the micrometer head the transit circuit is automatically made, and through theaction of a relay it automatically breaks the chronograph circuit and produces a record on thechronograph sheet. Where an observing key is used the observer breaks the chronographcircuit directly by pressing the key winch he holds in his hand; this is done as the star transitseach line of the reticle. In each case the position of the additional break or record on the chro-nograph sheet, with reference to the record made by the chronometer, indicates accurately thechronometer time at which it was made, the chronograph being assumed to run uniformlybetween adjacent chronometer breaks. (See illustration No. 7.) To read the fractions ofseconds from the chronograph sheet one may use either a glass scale on which converging linesmake it possible to divide varying lengths of seconds into 10 equal spaces, or a small linear
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