Charles S. Peirce traveled to Europe on five different occasions between 1870 and 1883 in the service of the Coast and Geodetic Survey, at that time the chief scientific agency of the United States. Those trips--which covered a total of thirty-eight months--were a rich mixture of scientific research and tourism, of communication with other scientists and of enjoyment of the artistic treasures of Europe. The 254 letters, telegrams, reports, and inscriptions in books of Peirce's European trips are described in detail. The whole is is transcribed; translations of the French and German correspondence is being published for the first time. The ample documents provide a vivid reflection of his professional and private experiences. The common image of Charles Sanders Peirce as an isolated thinker writing in Arisbe without any contact with the world is not only historically inaccurate, but also makes some key elements of his philosophy difficult to understand. A close study of Peirce's letters and other documents of those years helps to avoid several misunderstandings about his thought and its evolution, highlighting his active participation in the first line of several fields of cooperative scientific research (astronomy, geodesy, etc.

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