This essay introduces a special issue of the BJHS on communities of natural knowledge and artificial practice in seventeenth- and eighteenth-century London. In seeking to understand the rise of a learned and technical culture within a growing and changing city, our approach has been inclusive in terms of the activities, people and places we consider worth exploring but shaped by a sense of the importance of collective activity, training, storage of information and identity. London's knowledge culture was formed by the public, pragmatic and commercial spaces of the city rather than by the academy or the court. In this introduction, we outline the types of group and institution within our view and acknowledge the many locations that might be explored further. Above all, we introduce a particular vision of London's potential as a city of knowledge and practice, arising from its commercial and mercantile activity and fostered within its range of corporations, institutions and associations. This was recognized and promoted by contemporary authors, including natural and experimental philosophers, practical mathematicians, artisans and others, who sought to establish a place for and recognition of their individual and collective skills and knowledge within the metropolis.

This article suggests that institutional workshops of assay were significant experimental sites in early modern London. Master assayers at Goldsmiths’ Hall on Foster Lane, in the heart of the city, and at the Royal Mint, in the Tower, made trials to determine the precious-metal content of bullion, plate and coinage. The results of their metallurgical experiments directly impacted upon the reputations and livelihoods of London's goldsmiths and merchants, and the fineness of coin and bullion. Engaged in the separation and transformation of matter, assayers and the affairs of their workshops were also a curiosity for those interested in the secrets of nature. Making use of a wide-ranging body of sources, including institutional court minutes, artisanal petitions, mercantile guidebooks, recipe books and natural-philosophical treatises, this article uncovers a complex culture of metropolitan expertise. We first examine the workshop spaces in which assayers undertook their professional activities, and their secretive corporate cultures. We turn next to the manuscript culture through which assayers codified and communicated knowledge, ‘secrets’ and techniques to broader urban audiences. Finally, we assess exchanges and tensions between assayers and the wider community of Londoners engaged in scientific knowledge production and dissemination.

Mathematical practitioners in seventeenth-century London formed a cohesive knowledge community that intersected closely with instrument-makers, printers and booksellers. Many wrote books for an increasingly numerate metropolitan market on topics covering a wide range of mathematical disciplines, ranging from algebra to arithmetic, from merchants’ accounts to the art of surveying. They were also teachers of mathematics like John Kersey or Euclid Speidell who would use their own rooms or the premises of instrument-makers for instruction. There was a high degree of interdependency even beyond their immediate milieu. Authors would cite not only each other, but also practitioners of other professions, especially those artisans with whom they collaborated closely. Practical mathematical books effectively served as an advertising medium for the increasingly self-conscious members of a new emerging professional class. Contemporaries would talk explicitly of ‘the London mathematicians’ in distinction to their academic counterparts at Oxford or Cambridge. The article takes a closer look at this metropolitan knowledge culture during the second half of the century, considering its locations, its meeting places and the mathematical clubs which helped forge the identity of its practitioners. It discusses their backgrounds, teaching practices and relations to the London book trade, which supplied inexpensive practical mathematical books to a seemingly insatiable public.

This article attempts to think through the logic and distinctiveness of the early Royal Society's position as a metropolitan knowledge community and chartered corporation, and the links between these aspects of its being. Among the knowledge communities of Restoration London it is one of the best known and most studied, but also one of the least typical and in many respects one of the least coherent. It was also quite unlike the chartered corporations of the City of London, exercising almost none of their ordinary functions and being granted very limited power and few responsibilities. I explore the society's imaginative and material engagements with longer-established corporate bodies, institutions and knowledge communities, and show how those encounters repeatedly reshaped the early society's internal organization, outward conduct and self-understanding. Building on fundamental work by Michael Hunter, Adrian Johns, Lisa Jardine and Jim Bennett, and new archival evidence, I examine the importance of the city to the society's foundational rhetoric and the shifting orientation of its search for patronage, the development of its charter, and how it learned to interpret the limits and possibilities of its privileges through its encounters with other chartered bodies, emphasizing the contingent nature of its early development.

This article explores the activities of the Society of Apothecaries and its members following the foundation of a laboratory for manufacturing chemical medicines in 1672. In response to political pressures, the guild created an institutional framework for production which in time served its members both functionally and financially and established a physical site within which the endorsement of practical knowledge could take place. Demand from state and institutional customers for drugs produced under corporate oversight affirmed and supported the society's trading role, with chemical and pharmaceutical knowledge utilized to fulfil collective and individual goals. The society benefited from the mercantile interests, political connections and practical expertise of its members, with contributions to its trading activities part of a much wider participation in London's medical, scientific and commercial milieu. Yet, as apothecaries became increasingly engaged in the practice of medicine rather than the preparation and sale of drugs, the society struggled to reconcile the changing priorities of those it represented, and tensions emerged between its corporate and commercial activities.

Built in Greenwich in 1675–1676, the Royal Observatory was situated outside the capital but was deeply enmeshed within its knowledge networks and communities of practice. Scholars have tended to focus on the links cultivated by the Astronomers Royal within scholarly communities in England and Europe but the observatory was also deeply reliant on and engaged with London's institutions and practical mathematical community. It was a royal foundation, situated within one government board, taking a leading role on another, and overseen by Visitors selected by the Royal Society of London. These links helped develop institutional continuity, while instrument-makers, assistants and other collaborators, who were often active in the city as mathematical authors and teachers, formed an extended community with interest in the observatory's continued existence. After outlining the often highly contingent institutional and personal connections that shaped and supported the observatory, this article considers the role of two early assistants, James Hodgson and Thomas Weston. By championing John Flamsteed's legacy and sharing observatory knowledge and practice beyond its walls, they ensured awareness of and potential users for its outputs. They and their successors helped to develop a particular, and ultimately influential, approach to astronomical and mathematical practice and teaching.

The early East India Company (EIC) had a profound effect on London, filling the British capital with new things, ideas and people; altering its streets; and introducing exotic plants and animals. Company commodities – from saltpetre to tea to opium – were natural products and the EIC sought throughout the period to understand how to produce and control them. In doing so, the company amassed information, designed experiments and drew on the expertise of people in the settlements and of individuals and institutions in London. Frequent collaborators in London included the Royal Society and the Society of Apothecaries. Seeking success in the settlements and patronage in London, company servants amassed large amounts of data concerning natural objects and artificial practices. Throughout the seventeenth and eighteenth centuries, company scholars and their supporters in London sought to counter critiques of the EIC by demonstrating the utility to the nation of the objects and ideas they brought home. The EIC transformed itself several times between 1600 and 1800. Nonetheless, throughout the seventeenth and eighteenth centuries, its knowledge culture was characterized by reliance on informal networks that linked the settlements with one another and with London.

What are cells? How are they related to each other and to the organism as a whole? These questions have exercised biology since Schleiden and Schwann (1838–1839) first proposed cells as the key units of structure and function of all living things. But how do we try to understand them? Through new technologies like the achromatic microscope and the electron microscope. But just as importantly, through the metaphors our culture has made available to biologists in different periods and places. These two new volumes provide interesting history and philosophy of the development of cell biology. Reynolds surveys the field's changing conceptual structure by examining the varied panoply of changing metaphors used to conceptualize and explain cells – from cells as empty boxes, as building blocks, to individual organisms, to chemical factories, and through many succeeding metaphors up to one with great currency today: cells as social creatures in communication with others in their community. There is some of this approach in the Visions edited collection as well. But this collection also includes rich material on the technologies used to visualize cells and their dialectical relationship with the epistemology of the emerging distinct discipline of cell biology. This volume centres on, but is not limited to, ‘reflections inspired by [E.V.] Cowdry's [1924 volume] General Cytology’; it benefits from a conference on the Cowdry volume as well as a 2011 Marine Biological Lab/Arizona State University workshop on the history of cell biology.

Long ago, George Sarton set down criteria for reviewers. In addition to insisting on the need to compose ‘faithful’ reviews, he cautioned against four types of unfit reviewers: the ‘egoist’, the ‘obscure’ reviewer, the one who is noncommittal, and the pedantic critic. Unfortunately, Cohen's review comes short on several counts. Cohen writes that he intends to examine what is ‘new’ in the three books he reviews, and whether the results therein contained are ‘worth learning’ (p. 687). Cohen denies being given to ‘misplaced hero worship’, insisting that his sole aim is to assess whether ‘scholarly novelty’ (p. 693) has been attained. Nevertheless, given his repeated rebuke of the authors under review for ‘failing to refer back to [Richard] Westfall's work’ on Newton – now nearly half a century old – it seems that he grounded his critique principally on Westfall's interpretation.

In a review of recent Newton scholarship, H. Floris Cohen charges that my paper is not a ‘case of worthwhile innovation, or even of any innovation at all’. I beg to differ.