Object glass

    late 17th century
    Pierre Borel (1620 - 1689, French) , Chemist
    Object type
    Archive reference number
    diameter (object): 248mm
    Content object
    An object glass of 90 feet focal length which belonged to John Flamsteed. The surface is plain with some chips around the glass edge. Thought to be the object glass from Flamsteed's Well Telescope at the Royal Observatory, Greenwich.

    A label at the top of the glass is inscribed: '"Object glass (Venetian) of 90 feet focal legth which belonged to Flamstead: presented to the RS by James Hodgson FRS in 1737" RS. N. 25'

    John Flamsteed (1646–1719), British astronomer and first Astronomer Royal was elected a Fellow of the Royal Society in 1677.

    James Hodgson (1672-1755) British astronomer, mathematical teacher and writer was elected a Fellow of the Royal Society in 1703. He married Flamsteed's neice, Ann Heming, in 1702 and inherited much of his property.

    Pierre Borel (1620-1689) French chemist was not a Fellow of the Royal Society. He was court physician to the King of France, Louis XIV with a keen interest in optics, publishing a history of telescopes in1644-56, De vero telescopii inventore [...].
    Object history
    Presented to the Royal Society by James Hodgson in 1737: 'Mr Hodgson made a present of the object glass of a 90-foot tube, being that which Mr. Flamsteed designed to have used in the well at the Observatory at Greenwich, but was prevented by the damp of the place.’ [JBO/17]

    Loaned to the Science Museum in 1932; loaned briefly to the Royal Observatory in 1955 in order that tests could be carried out to ascertain its optical qualities; returned to the Royal Society in 2019.

    Details of Pierre Borel's involvement unconvered by Philip Stevenson Laurie's research into Flamsteed's well telescope: 'Flamsteed's Well' , The Observatory, no. 890, p.24-25.
    Related fellows
    John Flamsteed (1646 - 1719, British)
    James Hodgson (1672 - 1755, British)
    Associated place
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    ©The Royal Society
    Image number
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