‘Beneath the rhetoric of discovery, encounter and invention lurks the go-between's world’, writes Lissa Roberts (p. 234) in this fascinating collection of essays on the largely ignored roles of go-betweens in the domains of knowledge and science across the world in the eighteenth and nineteenth centuries. While themes familiar to historians emerge, such as travel, the administration of empires, commerce, or scientific inquiry, these authors argue that by paying attention to translators, knowledge collectors, diplomats, writers, inventors, castaways – those mobile, often unreliable, and self-shaping go-betweens – we can better understand that the modern world emerged not in Europe but in global exchanges.

Kapil Raj identifies five types of go-between who brokered the relationships between maritime Asia and western Europe, which include most of those investigated in this book: the interpreter-translator, the merchant-banker, the procurer, the attorney, and the knowledge broker. To these roles played by individuals, some of the authors add an expanded definition of go-betweens that includes material objects (Emma Spary), disease (David Turnbull), fossils (Juan Pimentel), and even colour (James Delbourgo), which, they argue, also mediated encounters between peoples. While I prefer the former focus – on individuals as go-betweens – the broad definition of who or what is a go-between used here opens up new ways of seeing contact, exchange, travel, scientific collecting, power, and modernity.

Some of the go-betweens described are persons familiar to historians, such as Bungaree in Turnbull's essay on the duality of the go-between as trickster in Australia, or Hipólito José da Costa in Neil Safier's essay on this Luso-Brazilian diplomat, Freemason, prisoner of the Inquisition, and newspaper editor. Yet even these familiar individuals are set in different contexts, associations, and roles. Hipólito is shown by Safier to be impecunious in Philadelphia, struggling to complete a quixotic diplomatic mission to acquire cochineal secretly as a means of reviving Portugal's declining economy, while Bungaree is shown by Turnbull to have served as intermediary on five separate voyages of exploration around Australia. Most of the go-betweens who appear in this book, however, have remained invisible to historians, even though in their own times and places they were formidable knowledge brokers. A case in point is Edward Bancroft during the time of the American Revolution. Delbourgo's reconstruction of Bancroft's residence in Guiana, his subsequent authoring of Essay on the natural history of Guiana, and his three-volume novel The history of Charles Wentworth reveal that the scientific, cultural, linguistic, and spiritual knowledge of go-betweens in the Atlantic world could create a powerful yet unknowable broker.

New kinds of go-between who emerge in this collection are the intermediaries who connected scientists to each other and allowed correspondence between them to flourish, which is explored by Margaret Meredith in her study of the essential importance of sociable networks among eighteenth-century natural scientists. Similarly, Roberts argues that the connections between entrepreneurial engineers, many of whom are unknown, is an unacknowledged factor in the rise of innovation and technical design in the late eighteenth century. Congregations of such men in urban centres mediated between supply and demand, diffused technology, and substantively advanced industrial design. The role of industrial foods, scientific experimentation with them at sea, and their part in maintaining and reproducing social status and creating the identity of the European body while travelling or living in the colonies is the subject of Spary's detailed investigation of French food on board ship.

As scientific knowledge is the major theme of this book, the roles of go-betweens in fostering scientific knowledge, exchange, collection, and invention appear in all of the essays. Simon Schaffer's contribution on intellectual and political networks between Britain and northern India focuses on Tafazzul Husain Khān, and illustrates that this go-between's role included not only translating Newton's Principia into Arabic but also serving as diplomat, acquiring ancient manuscripts, shipping goods, double-dealing, and connecting groups of scholars working in the English, Persian, Arabic, and Sanskrit languages. The allure of scientific collections to eighteenth-century elites, and the roles of go-betweens in creating such collections is revealed in Pimentel's characterization of Pedro Franco Dávila, originally a criollo from eighteenth-century Guayaquil, who left the uncertain Spanish-colonial mercantile world and settled in Paris. There he refashioned himself as an intellectual and travelled through Europe acquiring the collections of others in order to create the ultimate cabinet of curiosities, which became the nucleus of the National Museum of Natural Sciences in Madrid. Unknown to Dávila, but later a central attraction in the collection, was the fossilized remains of the giant American ground sloth, which Pimentel argues attained the status of an individual that bore news from the ancient past and, because it acquired a biography, became a virtual go-between.

The volume benefits from the fact that all of the contributors have been in conversation with each other for some time. Common patterns and similar roles played by go-betweens in widely divergent contexts are recognized, and the authors are able to build on each other's work, lending a cohesiveness to the book. Sanjay Subrahmanyam concludes by asking why go-betweens exist. And he reminds us that, while a go-between possesses the missing piece that allows a transaction to be completed, the role of the go-between is eventually ephemeral. As transactions multiply, new institutions are created and new kinds of situation emerge, making the old go-between increasingly irrelevant, a point well made by Robert Liss in his explanation of the roles of translators in Nagasaki. Set in a historical time when unreliable and untrustworthy go-betweens often had to be used by expanding empires, these essays convincingly illustrate that go-betweens could be powerful agents, if only briefly. The book leaves open the question of how successful the institutionalization (or bureaucratization) of the role of the go-between was. Perhaps studies on Africa, the Ottoman world, and Latin America, which are largely missing from this extraordinary collection, will help answer that question. Go-betweens are ephemeral certainly, but equally certainly their roles are never fully supplanted.