cross-staff
[kraws-staf, -stahf, kros-]
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noun, plural cross-staffs, cross-staves. Astronomy.
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.
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. 2019
Examples from the Web for cross-staff
Historical Examples of cross-staff
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 SpaceHenry Smith Williams
Even the navigators of the fifteenth century were aware of the deficiencies of the cross-staff and sought to improve upon it.
Every-day Science: Volume VII. The Conquest of Time and SpaceHenry Smith Williams
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-BookWilliam Henry Smyth
Iacobs staffean instrument formerly used for measuring the altitude of the sun; a cross-staff.
The Fatal DowryPhilip Massinger
Above, it has the small arc of the Davis quadrant with the sliding rod of the cross-staff below.
Old-Time Nautical InstrumentsJohn Robinson