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Amgueddfa Cymru – Museum Wales
Letter of advice from J.M Horsely (H.M. Inspector of Mines) to E. Ivor David (consultant engineer), concerning slip ring induction motors and flameproof enclosures. On cream coloured Mines Department headed paper, typed in black ink. Dated 2nd March, 1931. Attached to 83.184I/25 (5) with a staple.
