beam compass

noun

, Drafting.

1. a compass having adjustable legs, set perpendicular to the paper and sliding along a horizontal bar so as to permit the drawing of large circles.

beam compass

noun

1. an instrument for drawing large circles or arcs, consisting of a horizontal beam along which two vertical legs slide Also calledtrammel

Word History and Origins

Origin of beam compass¹

First recorded in 1775–85

Example Sentences

The beam-compass, Fig. 208, consists of two trammel-points running on a beam which may be made of any convenient length.

From Project Gutenberg