Notebook labelled on first page 'P.M.S. Blackett. King's College. If found please return'. Numerous photographs, of particle disintegration tracks are pasted in the notebook, with a record of measurements. Only a few of the entries (9 July, 23 August, 2 November 1924) are dated. At the end of the book there is an entry for 9 June 1926. Inserted at the back of the book were several sets of loose notes which have been removed and listed separately as B.9. 1924-1926