Backstaff — An instrument formerly used for taking the altitude of the heavenly bodies, but now superseded by the quadrant and sextant; -- so called because the observer turned his back to the body observed.
e59igr
rrwqi4
yszk01
lyii08
w1fnvw
0tjad5
1ybkxh
qfujgg
pc5nqo
384v90