Part I. Correspondence A-Z Correspondence. PP Other personal papers. Part II. Research, lectures and speeches BD Drafts of books. PD Drafts of published scientific papers and lectures. ED Drafts of contributions to dictionaries and encyclopaedia. UD Drafts of unidentified or unpublished works. SN Notes for speeches. NC Notes and calculations. PH Photographs and diagrams. UL University lecture notes. EX Draft Examination questions. Part III. Thomson's work outside physics Government correspondence and papers relating to the Board of Invention and Research. Government correspondence and papers relating to the Scientific Research Department. Government correspondence and papers relating to the Department of Scientific and Industrial Research. Government correspondence and papers relating to the Royal Commission report on the position of natural science in the education system of Great Britain. Cam. Papers relating to the University of Cambridge. Cam. Papers relating to Trinity College, Cambridge. Cam. Papers relating to the Cavendish Laboratory. Soc. Papers related to the Royal Society of London. Soc. Papers related to the Conjoint Board of Scientific Societies. OD Drafts of obituaries written by Sir Joseph John Thomson. TD Drafts of testimonials written by Thomson for his students and staff. Oth. Papers written by other authors. Oth. Examination scripts found among Thomson's papers. Part IV. Additional material Extracts from Engineering, 1897-1928, containing reports of Thomson's speeches and lectures. Supplement (additional notebooks). Part V. Notebooks NB Notebooks.