pl23_theb4091.jpg
![Three-arm protractor in use on a chart, plotting position from two angles theb4091.jpg Three-arm protractor in use on a chart, plotting position from two angles](https://s3.amazonaws.com/s3-east-testmedia-noaa.woc.noaa.gov/dam/Photos/legacy/pl23_theb4091.jpg)
Description
Three-arm protractor in use on a chart, plotting position from two angles.In: Putnam, G.R. 1908. Nautical Charts. J. Wiley and Sons, New York.
Collection
Historic Coast & Geodetic Survey
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