'Early letters': letters from correspondents in natural philosophy sent to the Royal Society and its Fellows Incoming letters to the Royal Society via its secretaries, officers and Fellows, on natural philosophy topics. Generally from the period 1660-1740, but with smaller collections of earlier material; one letter from Galileo dated 1613, two letters dated in the 1630s, one dated 1642, ten items dated to the 1650s (correspondence between Robert Boyle, Henry Oldenburg and John Beale). Some material is not dated. These papers form the raw material from which the Royal Society's Letter Books and Register Books were compiled and many were published in the 'Philosophical Transactions' of the Royal Society. The series also contains English translations of foreign language letters, for example from the Dutch of Antoni van Leeuwenhoek. Other document formats, including printed material, have been preserved within this sequence. 1613-1740