Meaning of parallel rulers

par'allel rul'ers

Pronunciation: [key]
  1. a pair of straightedges connected by two pivoted crosspieces of equal length so as to be parallel at all times, used for various navigational purposes, esp. for transferring the bearing of a plotted course to a compass rose.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.