LARGE ELEGANT PARALLEL RULE, English, c. 1800, hand-engraved on the reverse “J. Watkins, Charing Crofs, London.” This all brass rule is 12″ (30 cm) wide, constructed with a massive scissor hinge elegantly shaped and pierced, designed with opposing slots which provide an offsetting parallel motion as the rule is opened. There are two small knobs for grasping, and both outer edges are beveled for precision in course marking and chart reading. Condition is good noting some stains and darkening,
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