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cross-staff

[kraws-staf, -stahf, kros-]
noun, plural cross-staffs, cross-staves. Astronomy.
  1. an instrument for measuring the angle of elevation of heavenly bodies, consisting of a calibrated staff with another shorter staff perpendicular to and sliding on it.
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Origin of cross-staff

1400–50, for an earlier sense; late Middle English
Also called forestaff, Jacob's staff.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for cross-staff

Historical Examples

  • The simplest and crudest form of measurer of which the record has been preserved is known as the cross-staff.

    Every-day Science: Volume VII. The Conquest of Time and Space

    Henry Smith Williams

  • Even the navigators of the fifteenth century were aware of the deficiencies of the cross-staff and sought to improve upon it.

  • The vane of a cross-staff, made to slide along it by means of a square socket; it may be set to any of the graduations.

    The Sailor's Word-Book

    William Henry Smyth

  • Iacobs staffean instrument formerly used for measuring the altitude of the sun; a cross-staff.

    The Fatal Dowry

    Philip Massinger

  • Above, it has the small arc of the Davis quadrant with the sliding rod of the cross-staff below.