Until recently it was believed that Sir George Cayley's note-books had been lost. In 1927 Mr. J. E. Hodgson, the Honorary Librarian of the Society, learnt that a quantity of miscellaneous manuscript papers were in existence in the home of the Cayley family, and permission was obtained to sort out from such papers matter bearing on Cayley's aeronautical and other engineering or technical labours. Among them was the Note-book, which will shortly be published in full by the Newcomen Society, by kind permission of Sir Kenelm Cayley.