The Library of the Royal Society of London contains a large collection of manuscript material relating to Henry Oldenburg and his correspondents. Oldenburg was one of the two Secretaries of the Royal Society when it was founded in 1662. For many years he acted as intermediary between British and Continental philosophers: and scientists. He also edited the early volumes of the Royal Society's Philosophical Transactions. His contacts were accordingly very extensive. Nearly all the seventeenth-century pioneers of science were among his correspondents. In his role of intermediary he was in the habit of sending extracts from some of his foreign letters to