Antique Drawing Instrument Collection - Protracted Rolling Parallel Rule

Bookmark this page Protracted Rolling Parallel Rule

  • Maker: W. H. Harling Ltd.
  • Date: c1930
  • Description and Notes:

    This finely made brass and boxwood rolling parallel rule is dated to c1930 as the maker, W. H. Harling Ltd., was located on the address shown (117 Moorgate, London) in the 1930s.

    It should be noted that this rule is different from the ordinary rolling parallel rules in that the upper three edges of which are protracted to a degree. This additional feature was first invented by W. F. Stanley based on the suggestion of the steam ship captains in the Oriental Company, and he called this as a "naval protractor" for laying down a ship's course, see A Descriptive Treatise On Mathematical Drawing Instruments, p. 239.

  • More Pictures:

    Overview of the Rule  | View of the Solid Mahogany Case

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