$20 · Vintage C-Thru 15" Parallel Ruler

This clear plastic ruler has two aluminum arms (hinges) and small positioning knobs that may be tightened or loosened. The lower left and upper right corners of the parallel blades are marked 15". The arms are marked "THE C-THRU RULER CO. / BLOOMFIELD, CONN. U.S.A". Six cork discs on the bottom of the instrument protect the surface on which it is used. Teacher Jennie Zachs established the C-Thru Ruler Company of Hartford, Conn. in 1939. The firm was acquired by Acme United Corporation in 2012.