a1 Wellcome Unit, Department of History and Philosophy of Science, University of Cambridge, Cambridge CB2 3RH.
Early nineteenth-century natural history books reveal that British naturalists depended heavily on correspondence as a means for gathering information and specimens. Edward Newman commented in his History of British Ferns: ‘Were I to make out a list of all the correspondents who have assisted me it would be wearisome from its length.’ Works such as William Withering's Botanical Arrangement show that artisans numbered among his correspondents. However, the literary products of scientific practice reveal little of the workings or such correspondences and how or why they were sustained. An exchange or letters is maintained if the interests of both recipient and writer are satisfied. Withering's book tells us only that his interests were served by his correspondents; it allows us to say nothing with certainty about the interests of those who wrote to him. Published texts effectively hide the means by which the author determined the veracity of distant correspondents and also the way these informants demonstrated their credibility.