ArgumentThis article examines advertisements for potential solutions to the problem of longitude during the year following the announcement of the maximum £20,000 reward in the summer of 1714. While there have been many studies of the race to determine longitude, advertisements have not received close scrutiny. Little attention has been paid to the commoditization of longitude in the marketplace of public science sold within London's public sphere. Although books and lecture series dominated public science in eighteenth-century England, longitude ads are (...) a unique example of this phenomenon. Unlike lecturers or publishers of natural philosophical tracts who sought audiences for demonstrations or readers for books which contained accounts of nature that were not open to debate, longitude seekers were doing something different. Those who attempted to solve the problem of longitude and advertised their plans to the public sought out witnesses to validate and confirm the effectiveness of their experiments or instruments. In other words, the public sphere became the crucible of judgment for schemes of longitude. (shrink)

The letter sent by the Royal Society to the London optician, John Marshall, in 1694, commending his new method of grinding, has been reprinted, and referred to, in recent years. However, there has been no comprehensive analysis of the method itself, the letter and the circumstances in which it was written, nor the consequences for trade practices. The significance of the approval by the Royal Society of this innovation and the use of that approbation by John Marshall and other practitioners (...) are examined. Gaps in existing accounts of Marshall's method are partly remedied by supplementing surviving written materials with accounts of contemporary, and present-day, trade practices based on his method. The reasons why Marshall and his contemporaries failed to record his method and specify his improvements are discussed. The reactions of the Spectacle Makers' Company and its more prominent members, both to the innovation itself and to the Royal Society's letter, are analysed. The impact of the new technique on contemporary and later opticians is described. (shrink)

Sixteenth-century astrology was considered by its practitioners to be allied to a wide range of disciplines, including medicine, the magical arts and the mathematical arts. The last of these associations was particularly important, since it formed a cornerstone of the legitimation of the celestial art. Astrologers in late Tudor England sought to show, therefore, that astrology shared the characteristics of the increasingly strong and well-defined domain of the mathematical arts, and that it was an important ally of many of the (...) individual arts, such as astronomy, navigation, and instrument-making. This association was demonstrated in practice, where astrology and other mathematical arts were mastered by the same practitioners. (shrink)