Cite
 

Meaning of back staff

back' staff"

Pronunciation: [key]
  1. an obsolete instrument for determining the altitude of the sun by facing away from the sun, sighting upon the horizon, adjusting a cursor until its shadow falls upon the sight through which the horizon appears, and measuring the resulting arc.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.