An instrument formerly used for taking the altitude of the sun; a cross-staff.
| 单词 | θ205999 | 
| 释义 | society > travel > travel by water > vessel, ship, or boat > equipment of vessel > navigational aids > 			[noun]		 > cross-staff (11)		 Jacob's staff1559 An instrument formerly used for taking the altitude of the sun; a cross-staff. cross-staff1594 An instrument formerly used for taking the altitude of the sun or a star. Obsolete. David's staff1623 Originally an error of Pietro della Valle's, who gave Dauidstoff as the English name of an instrument for taking the altitude of the sun. This was… back-staff1627 A peculiar kind of quadrant formerly used in taking altitudes at sea, so called because the observer turned his back to the sun. fore-staff1669 = cross-staff, n. 2 (see quot. 1867). radiometer1728 An instrument for measuring angles: = cross-staff, n. 2a, Jacob's staff, n. 2a. Obsolete. rare. jackstaff1886 U.S. An instrument used in navigation to measure the angles between distant and celestial objects, consisting of a graduated staff equipped with one… Subcategories:— 			limb of			(4)		 | 
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