USGS Multimedia Gallery
Title: Gurley Micrometer Alidade
Description: Manufactured by W. & L.E. Gurley, Troy, New York. The micrometer attachment us a modification of the tangent screw attached to the horizontal axis of the telescope and used for measuring vertical angles in terms of their tangents. Relatively few of these types of alidades are listed in early 1900s property records of instruments used by the U.S. Geological Survey. Object ID: USGS-000159
Photographer: USGS Museum Staff , U.S. Geological Survey
Usage: This image is public domain/of free use unless otherwise stated. Please refer to the USGS Copyright section for how to credit the photo.
USGS Museum Collection
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