A mid-19th century ivory rectangular protractor, an ivory folding rule and a 6' ivory two-bar parallel rule, the protractor marked 'Elliot Bros., London', engraved with various scales, .6 x 1¾'; the 12-inch four-fold ivory rule, marked 'J Rabone & Sons', with white metal round joint middle plates, edge and face pins; the parallel rule; with brass hinges. Provenance: The Jack Thornton estate collection.