Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Cornelis] de Waard Informs Professor [Cornelis] de Waard that he was right about the Galileo letter in the Society's collection; there is a misprint in their catalogue and instead of being dated to 1618 it should be dated to 1613. Notes that their letter appears to be a copy of that printed in the National Edition of Galileo's Works. Offers to organise a photographer to photograph the letter for Professor de Waard if that would be useful. 26th June 1919