General correspondence file of H. Eustace Mitton on the British Empire Exhibition for 1925 Including photograph (mutilated) of colliery engine patented by Walker Brothers (Wigan) Limited, May 1925, envelope of photographs (3) of Mining Association Research Exhibit and cuttings (2) of the Bituminous Coal Tree, showing the diversified products based on coal tar, from "Scientific America" and "The Coal Trade Bulletin", 17 Nov 1924 Dec 1924-Jan 1926