The papers received by Darwin, Thomson and Adams are well preserved. Because Thomson's main interlocutor was Darwin, Thomson's tidal correspondence has an aspect of completeness. Roberts worked in the Nautical Almanac Office and that office had its nineteenth century records depredated twice in the century which followed. (They were destroyed by fire.)  Baird worked under the Survey of India and the tidal records of that institution, if any have survived, remain closed. Location of the tidal correspondence that both Roberts and Baird received would be of significant benefit to the study of tidal history.