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.

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.

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.

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.

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.