Robert Hooke, Isaac Newton and the Royal Society: three unnoticed letters at the Staatsbibliothek zu Berlin

This article brings attention to three manuscript letters by Robert Hooke and Isaac Newton in the Darmstaedter collection at the Staatsbibliothek zu Berlin, two of which are published here for the first time. Of principal interest is a 1678 letter from Hooke to Newton, which concerns the controversy with Anthony Lucas over Newton's prism experiments and Hooke's disinclination 'to print transactions' on behalf of the Royal Society. A second Hooke letter, written to the French savant Nicolas Toinard in 1680, sends some astronomical observations together with English mathematician Robert Wood's book on a proposed calendrical reform. While the text of the third item, a 1706 letter by Newton welcoming its addressee into the Royal Society, has long been available in draft form, the Darmstaedter manuscript allows the recipient to be identified as a Savoyard diplomat, the Comte de Briancon, who can further be recognized as the intended addressee of another Newton letter.