Noah Webster
Backstaff
BACK'STAFF, noun [back and staff, so called from its being used with the observer's back toward the sun.]
A quadrant; an instrument for taking the sun's altitude at sea; called also, from its inventor, Davis's quadrant.
BACK'STAFF, noun [back and staff, so called from its being used with the observer's back toward the sun.]
A quadrant; an instrument for taking the sun's altitude at sea; called also, from its inventor, Davis's quadrant.