Astronomical Ring of an unusual type, signed "Butterfield Paris". Showing the opposite side of the instrument to that on which Butterfield's signature occurs. Undated, circa 1690. This instrument is closer to an equinoctial ring dial than most astronomical rings.

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Astronomical Ring of an unusual type, signed "Butterfield Paris". Showing the opposite side of the instrument to that on which Butterfield's signature occurs. Undated, circa 1690. This instrument is closer to an equinoctial ring dial than most astronomical rings. Wellcome Collection. Attribution 4.0 International (CC BY 4.0). Source: Wellcome Collection.