According to the received view, the first spyglass was assembled without any theory of how the instrument magnifies. Galileo, who was the first to use the device as a scientific instrument, improved the power of magnification up to 30 times. How did he accomplish this feat? Galileo does not tell us what he did. We hold that such improvement of magnification is too intricate a problem to be solved by trial and error, accidentally stumbling upon a complex procedure. We construct (...) a plausibility argument and submit that Galileo had a theory of the telescope. He could develop it by analogical reasoning based on the phenomenon of reflection in mirrors—as it was put to use in surveying instruments—and applied to refraction in sets of lenses. Galileo could appeal to this analogy and assume Della Porta’s theory of refraction. He could thus turn the spyglass into a revolutionary scientific instrument—the telescope. (shrink)

The emergence of instrument-making trades in early-modern England tested the power of established guilds. From the seventeenth century, instrument makers were able to exploit growing markets for scientific apparatus and attempted to exploit connections with the Royal Society. Given the growth in both local and international demand, and in new methods of manufacture, instrument makers were frequently able to evade the diminishing power of guilds to police the efforts of the makers.

In this paper I analyse some resources for the history of manipulative skill and the acquisition of knowledge. I focus on a decade in the life of the ‘ingenious’ Robert Hooke, whose social identity epitomized the mechanically minded individual existing on the interface between gentleman natural philosophers, instrument makers and skilled craftsmen in late seventeenth-century London. The argument here is not concerned with the notion that Hooke had a unique talent for working with material objects, and indeed my purpose is (...) to rethink the ways in which we account for such virtuosity. In this vein, I do not adopt solely a realist or constructivist attitude to skill but seek to show how, in a purposeful way, Hooke drew from the resources of techniques and information made available to him by his social interaction with labourers, servants, craftsmen, gentlemen and noblemen. In Hooke's local culture, intelligence flowed between the sites where these individuals worked and socialized. I examine the practical, social and situational links between the worlds of the coffee house, the workshop and the rooms of the Royal Society at Arundel House and Gresham College. From this perspective, there were no rigid boundaries between the domains of natural philosophy, banausic culture and construction work on which Hooke was engaged, and I argue that we should examine his world in term of a series of networks of capital exchange comprised of finance, social power and mechanical expertise. (shrink)

While Newton tried to make his telescope into a proof of the supremacy of his theory of colours over older theories, his instrument was welcomed as a way to shorten telescopes, not as a way to solve the problem of chromatic aberration. This paper argues that the image published together with the report on Newton’s telescope in Philosophical Transactions (1672) encouraged this reception. The differences between this visualization and other images of Newton’s telescope, especially that published in Opticks (1704), are (...) discussed. This paper shows that the image in Opticks adopted characteristics of a Cartesian program of visualization of machines and instruments which complemented a rhetoric which attributed primacy to theory over practice. The differences between the images in Philosophical Transactions and Opticks are also considered within the broader institutional context of Newton’s attitude towards the Royal Society. (shrink)

Few accounts have survived detailing the techniques employed for the production of optical glass for astronomical and microscopical instruments during the seventeenth century in Italy; the period during which the art was being developed in the shops of Eustachio Divini and Giuseppe Campani, and other optical instrument-makers. Indeed, few of the tools of the lens-makers have been described in any detail, and few if any have survived. Consequently, the discovery of a hitherto apparently unknown Italian treatise, or what appears to (...) have been notes for a shop manual of the period, is a contribution to present knowledge of lens-making technology even though the identity and region of the author remain unknown. (shrink)