Chronograph drum without paper.
Used to record time ticks during longitude observations.
Astro party of Charles Whitten
Image ID: theb1520, NOAA's Historic Coast & Geodetic Survey (C&GS) Collection
Location: Western United States
Photo Date: 1935
Credit: C&GS Season's Report Whitten 1935
• High Resolution Photo Available
of the U.S. Department of Commerce, National Oceanic & Atmospheric
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April 30, 2013