The American practical navigator : being an epitome of navigation and nautical astronomy (1888)
Bowditch, Nathaniel, 1773-1838, United States. Navy Dept. Bureau of Navigation, Cooper, Philip Henry, 1844-1912 · Washington : Govt. Print. Off. · leaf 220
f thesides, and a corresponding notch in the other, which bring the points over each other when the instru-ment is closed, and prevent any shift in the sides when moving the slides to set the instrument. Themilled-head screw is sometimes fitted to move in a rack on the sides, affording a finer… … THREE-ARMED PROTRACTOR.* Alt. 416. The Station Pointer or Three-Armed Protractor is less known than the protractor orscale, though it is an instrument that no Navigator should be without. Its principal use in surveyingis to plot the angles for soundings, but it is also used for fixing the ships…
Navigation · Nautical astronomy
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