Credit: ©The Royal Society
    Image number: RS.18186


    late 18th century
    Jesse Ramsden (1735 - 1800, British) , Instrument maker
    Object type
    Archive reference number
    Content object
    Ten inch brass protractor, divided into 1/2 degrees and indented at 90°, 180°, 270° and 360° of the circular dial. Brass arms extend into the centre, dividing it into quadrants and a movable arm pivots from the centre, carrying a vernier, reading to one minute. A round hole is visible at the centre, where crosshairs would have been placed to mark the origin point for measuring angles.

    Engraved 'Ramsden London' and 'R.S. 61' across the immovable arms.

    Jesse Ramsden (1735–1800) British scientific instrument maker was elected a Fellow of the Royal Society in 1786.
    Object history
    Exact provenance unknown. Possibly connected to the commission in 1784 by General Roy who, under the auspices of the then President of the Royal Society, Sir Joseph Banks (1743–1820), was tasked with surveying & triangulating south-east England to resolve the dispute over the difference in longitude between the Greenwich and Paris observatories. Roy commissioned Ramsden to create several new scientific instruments to aid this endeavour. Among the known commissions was a100 foot steel chain, six glass rods each 1 metre long, and a 3 foot theodolite.

    Loaned to the Science Museum in 1932 and returned to the Royal Society in 2019.
    Associated place
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