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拍品專文
YARWELL & HIS COMPETITORS
The invention of the telescope and then the microscope at the very beginning of the seventeenth century caused enormous interest well beyond the learned community. New worlds were opened up by these instruments, the worlds of the very distant and the minute. However, there were problems. The performance of early optical instruments was severely limited by the quality of the glass available, and the accuracy of lenses that could be produced. These problems were exemplified by the success of the reflecting telescope, which uses metal mirrors rather than glass lenses. So, by the end of the century, the Royal Society of London was interesting itsaelf in the development of lens-grinding methods, while the optical instrument makers were in fierce competition for trade
John Yarwell (?1648-1712) and his younger rival, John Marshall (?1659-1723) were the leading London optical instrument makers in the later decades of the seventeenth century. Yarwell, who had his premises at the sign of Archimedes & Three pair of Golden Spectacles in St Paul's Churchyard, was twice Master of the Spectacle Makers' Company, and had a royal appointment to King William III. Marshall was free of the Turner's Company, and never became a Spectacle Maker. He was an ambitious and energetic man of business, cultivating acquaintance with the leading scientific figures of his time. His relationship with Yarwell was not improved by his adding the name of Archimedes, already appropriated by Yarwell, to his own shop sign.
Marshall's first major success was to persuade the Royal Society formally to confirm the effectiveness of his method of grinding spherical lenses (Bryden & Simms, 1993). Edmund Halley FRS reported to the Society that "he [Marshall] is enabled to make a great many Optick Glasses at one time, all exactly alike". The examination, by Robert Hooke and Halley, of Marshall's method, and their approval of it, were reported to Marshall in a formal letter from the Royal Society. He lost no time in putting this accolade to good use in advertisements, despite the fact that the Spectacle Maker's Company had formally queried whether Marshall's method was either new or his own invention.
There followed an advertising war that continued well into the new century, and involved not only Yarwell and Marshall, but also younger practitioners, Ralph Sterrop, George Willdey and Timothy Brandreth all, at one time or another, claiming that they had Royal Society approval. The positive effect was that all the leading optical instrument makers were striving to improve their lens-making skills, with considerable success. The optics of the microscope had to wait until the early nineteenth century for the final solution to the problems of chromatic and spherical aberration, but the use of finer glass, more accurate lens-grinding, and the construction of increasingly stable and versatile stands made the compound microscope ever more effective.
The invention of the telescope and then the microscope at the very beginning of the seventeenth century caused enormous interest well beyond the learned community. New worlds were opened up by these instruments, the worlds of the very distant and the minute. However, there were problems. The performance of early optical instruments was severely limited by the quality of the glass available, and the accuracy of lenses that could be produced. These problems were exemplified by the success of the reflecting telescope, which uses metal mirrors rather than glass lenses. So, by the end of the century, the Royal Society of London was interesting itsaelf in the development of lens-grinding methods, while the optical instrument makers were in fierce competition for trade
John Yarwell (?1648-1712) and his younger rival, John Marshall (?1659-1723) were the leading London optical instrument makers in the later decades of the seventeenth century. Yarwell, who had his premises at the sign of Archimedes & Three pair of Golden Spectacles in St Paul's Churchyard, was twice Master of the Spectacle Makers' Company, and had a royal appointment to King William III. Marshall was free of the Turner's Company, and never became a Spectacle Maker. He was an ambitious and energetic man of business, cultivating acquaintance with the leading scientific figures of his time. His relationship with Yarwell was not improved by his adding the name of Archimedes, already appropriated by Yarwell, to his own shop sign.
Marshall's first major success was to persuade the Royal Society formally to confirm the effectiveness of his method of grinding spherical lenses (Bryden & Simms, 1993). Edmund Halley FRS reported to the Society that "he [Marshall] is enabled to make a great many Optick Glasses at one time, all exactly alike". The examination, by Robert Hooke and Halley, of Marshall's method, and their approval of it, were reported to Marshall in a formal letter from the Royal Society. He lost no time in putting this accolade to good use in advertisements, despite the fact that the Spectacle Maker's Company had formally queried whether Marshall's method was either new or his own invention.
There followed an advertising war that continued well into the new century, and involved not only Yarwell and Marshall, but also younger practitioners, Ralph Sterrop, George Willdey and Timothy Brandreth all, at one time or another, claiming that they had Royal Society approval. The positive effect was that all the leading optical instrument makers were striving to improve their lens-making skills, with considerable success. The optics of the microscope had to wait until the early nineteenth century for the final solution to the problems of chromatic and spherical aberration, but the use of finer glass, more accurate lens-grinding, and the construction of increasingly stable and versatile stands made the compound microscope ever more effective.