Definition of "forestaff" []

• An instrument formerly used at sea for taking the altitudes of heavenly bodies, later replaced by the sextant. (noun)

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• "Schouten and other heroic marine worthies of distant times had navigated the globe, discovered new worlds, penetrated into the most secret solitudes of the deep without any notion of longitude and with no better instruments to take the sun's height than the forestaff and astrolabe."
• "Here also our gunner took an observation with his forestaff, to determine our latitude, and he found now, that having marched about thirty-three days northward, we were in 6 degrees 22 minutes south latitude."