Letter from Archibald Geikie, Geological Survey of Scotland, Edinburgh, to [William Fletcher] Barrett Barrett's note found them at the fireside reading Mrs Somerville's Memoirs. He has looked at both Tyndall's lecture and Barrett's paper and notes Tyndall's acknowledgements, but none are to Barrett. Comments also that Tyndall does not actually claim the discovery of making use of sensitive flame. Urges Barrett to be cautious. 20 January 1874